ad io - · pdf file6 basic electronics 26- lesson course covering automation -elec- ......

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admo-E ectronics4GERNiACK

PUBLICATION

New Tricks With aDifferent Photocircuit

Sweep -Aligning Resistor Decade BoxThe TV L F. Handles High Wattage

HICO GE1NSBACK, Editor -in -chief

Ten Tubes in One -New Klystron Puts Out40 Kw at 8.4 Gigacycles

ELECTRO

TUBES

Amperefor over35 yea

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Now you can carry the identical tubes that you finddesigned into most of the quality TV sets you serv-ice. Chances are, you were not aware that these TVsets were designed around special Frame Grid tubesoriginated by Amperex and that even more tubetypes originated by Amperex are being designed intothe Sets you'll be handling in the future. Amperexframe grid tubes provide 55`, higher gain -bandwidth,increase TV set reliability by simplifying circuitsand spend up your servicing because their extraor-dinary uniformity virtually eliminates need for re-alignment when you replace tubes.

Tubes introduced by Amperex, currently used bymajor TV set makers include:

Frame Grid Others2GK5 4G K5 6G KS 6EH7 HAL3 DAB2555 4E1-17 HESS 6EJ7 6BL8 15CW53G,K5 4517 6555 611G8 6BQ5 16AQ335147 4ES8 6FY5 7HG8 12AX7 27GB5

For optimum satisfaction for your customers and abetter profit operation for yourself, make room inyour caddy now for these matchless quality tubes.Next time you visit your distributor, look for thegreen -and -yellow boxes and enjoy confidence inyour work such as you never have before, AmperexElectronic Corporation, Hicksville. I I., New York.

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NOW 10 WAYS Pick Your Electronics

Field and Train at Home with the Leader

Which field of Electronics is foryou? NRI's 10 specialized in-struction plans give you a choiceof ways to go within the amazingElectronics field. Mail coupon forfull information.

TELEVISION -RADIO SERVICING-1. Learn to fix black -and -white and color sets,

AM -FM radios, stereo hi-fi, etc. A profitablepart or full-time business of your own.

9 INDUSTRIAL -MILITARY1- ELECTRONICS

Learn Principles, Practices, Maintenance ofElectronic equipment. Covers computers,servos, telemetry, multiplexing, other subjects.

Q COMPLETE COMMUNICATIONS4-1 Comprehensive training for broadcasting or

mobile, marine, aviation communications.Learn to operate, maintain transmittingequipment. Prepares for FCC License.

A FCC LICENSEPrepares you quickly for First Class Licenseexams. Every communications station musthave licensed operators. Also valuable forService Technicians.

MATH FOR ELECTRONICSA short course of carefully prepared textsfrom basic arithmetic to graphs and electron-ics formulas. Quick, complete, low in cost.

BASIC ELECTRONICS26 -lesson course covering Automation -Elec-tronics, TV -Radio language, components,principles. Ideal for salesmen, hobbyists,others.

7 ELECTRONICS FOR AUTOMATIONFor the man with a knowledge of basic elec-tronics who wants to learn process control,ultrasonics, telemetering and remote control,electromechanical measurement, others.

8 AVIATION COMMUNICATIONSFor a career in and around planes. Coversdirection finders, ranges, markers, loran,shoran, radar, landing system transmitters.Prepares for FCC License.

9MARINE COMMUNICATIONSLearn to operate, repair transmitters, direc-tion finders, depth indicators, radar, otherElectronic equipment used on commercialand pleasure boats. A growing, profitablefield. Prepares for your FCC License.

10 MOBILE COMMUNICATIONSLearn to install, operate, maintain mobileequipment and associated base stations asused by police, fire departments, taxi com-panies, etc. Prepares for FCC License.

NOTE: Vou must pass your FCCLicense exam (Communications courses) orNRI refunds in full the tuition you have paid.

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NRI CUSTOM -DESIGNED TRAINING KITS

MAKE LEARNING EXCITING, FASTTens of thousands of hours have been in-vested by NRI engineers and technicians intesting, changing, retesting and improvingNRI training kits. Their aim: to simplifyand speed your training, make it absorbing,exciting, fun to learn. Unlike other schools,"stock" or "standard" equipment has neverbeen good enough. NM custom -designsequipment exclusively for training. It dem-onstrates the theory you read about inclearly written, well illustrated lesson texts.It brings to life circuit action, defects,end -results. You learn operation, mainte-nance, trouble -shooting, by the exciting"discovery" method.

50 YEARS OF LEADERSHIPIN ELECTRONICS TRAININGFifty years of leadership in home -studyRadio -TV, Electronics training is behindthe NRI instruction plan you select. A halfcentury has been devoted to simplifyingand perfecting training to make home -studyeasier, more interesting, more meaningfulWhatever your reason for wanting knowl-edge in Electronics (hobby, part-time earn-ings, retirement income or full career) . . .whatever your education, you'll find anNRI plan to fit your needs. Before you con-sider enrolling with any school, you owe itto yourself to see what NM offers you.Mail coupon for catalog. No salesman willcall. National Radio Institute, Washington,D.C. 20016.

BUILD ACTUAL TRANSMITTERComplete your Communications courseby building an actual phone-CW trans-mitter with components NRI sends.Complies with FCC regulations. Canbe put on the air.

BUILD COMPUTER CIRCUITSIn NRI's Electronics course you solvemathematical problems with analogcomputer circuits you build yourself.One of 10 training kits you get.

BUILD YOUR OWN TV SETAs part of NRI's Servicing course youget everything to build this completeattractive set from "the ground up."What better way to learn, than to do it?

MAIL NOWNATIONAL RADIO INSTITUTEWASHINGTON, D.C. 20016I have checked the field(s) of most interest(No salesman will call.) Please PRINT. TV -Radio ServicingO Industrial Electronics Complete CommunicationsO FCC Licenseo Math For Electronics

3-74

to me. Please send me your catalog.

Basic ElectronicsElectronics For AutomationAviation CommunicationsMarine CommunicationsMobile Communications

Name Age

AddressZip

City State CodeACCREDITED MEMBER NATIONAL HOME STUDY COUNCIL

JULY, 1964 3

Radio -ElectronicsJULY 1964 VOL. XXXV NO. 7

Over 55 Years of Electronic Publishing

EDITORIAL26 Electronics' Future Hugo Gernsback

AUDIO-HIGH FIDELITY-STEREO30 Notes From A Tape Recorder Service Book Steve P. Dow

Valuable hints for the audio technician

48 Center Bass Channel for Stereo Robert F. ScottCost and space -saving manufacturers' methods can be adapted to your own

small system

57 Equipment Report: KLH Model Sixteen and Heath AJ-33Transistor audio amplifier and all -transistor AM -FM -stereo tuner

ELECTRONICS38 Try a Selective Photocircuit Tom Jaski

A what?

50 Tachometers for Speed Control Matthew MandlHow the two basic types operate

53 Transistors Keep a Roof On J K. Bach

62 Re: Transistors Save Your Breaker Points

GENERAL43 What's New?

Pictorial reports of new developments

44 Decibels Debugged H. R. HoltzMake db calculations in seconds with only simple arithmetic

45 What's Your EQ?47 Junk Parts Go to the Devil

RADIO32 Private -Brand Sets-Who Makes 'em? L. A. James

How and where to get information on house brands

37 Equipment Report: Knight C-555 CB Transceiver Elmer C. CarlsonLong range with low power in this little set

COVER STORY 40 Multiple -Beam Klystron Pushes Back Microwave Frontiers Eric Leslie

TELEVISION34 Sweep -Aligning TV I.F.'s Jack Darr

The elegant way of lining up the video i.f.

52 Versatile Converters for the UHF

54 Service Clinic Jack DarrRadio -controlled garage doors

TEST INSTRUMENTS28 Decade Box Uses Power Resistors Joseph H. Sutton,

Easily built, this box will pinch-hit for burned bleeders, etc.

42 Align -and -Find Meter Bill Hutchison

46 Simple Inductance Bridge Checks Unknown Coils John A. DewarInexpensive instrument will find many uses in your shop

59 Equipment Report: Lafayette TE-60 and Mercury 50130,000 -ohm -per -volt multitester and a component substitutor

THE DEPARTMENTS61 Correction16 Correspondence78 New Books62 New Literature

76 New Patents66 New Products61 New Semiconductors & Tubes6 News Briefs

72 Noteworthy Circuits70 Technicians' News63 Technotes74 Try This One71 50 Years Ago

... Member,

Institute of High FidelityRadio -Electronics

Is indexed InApplied Science

& Technology Index(Formerly

Industrial Arts Index).

HUGO GERNSBACK, editor -in -chief and publisher. M. HARVEY GERNSBACK, editor. Fred Shunaman, managing editor. Robert F. Scott, W2PWG,technical editor. Peter E. Sutheim, associate editor. Jack Darr, service editor. I. Queen, editorial associate. John J. Lamson,

eastern sales manager. Wm. Lyon McLaughlin, technical illustration director.GERNSBACK PUBLICATIONS, INC., 154 W. 14 St., N.Y. 10011. AL 5-7755. Board Chairman HugoGernsback, President M. Harvey Gernsback, Secy. G. Aliquo, Treas. Charles A. Raibi

A NEW WORLD OF OPPORTUNITY AWAITS YOU WITH

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You can install and maintain elec-tronic circuitry in missiles and rockets...specialize in micro -waves, radarand sonar.

You can succeed in TV -Radio Commu-nications ... prepare for F.C.C.License, service advanced satellitesfor industry and defense.

The N.T.S. Master Course enablesyou to do more, earn more in

ELECTRONICSTEL.EVISIONRADIOYet N.T.S. Training costs no more

than other courses far less completeThere's a good reason why N.T.S. Master -Training opens a wide newworld of opportunity for you in Electronics, Television, Radio.

Everything you learn, from start to finish, can be applied directly toall phases of the Electronics Industry.

As a result, the N.T.S.-Trained Technician can move ahead faster,in any direction -from TV -Servicing to Radio Communications toSpace -Missile Electronics and Automation for industry and defense.You can go wherever pay is highest andooportunity unlimited.

Electronic circuitry, for example, is one of science's miracles thatis basic to the entire field of Electronics. It is used in satellites, com-puters and space capsules as well as in today's television sets and highfidelity equipment. N.T.S. shows you how to service and repair elec-tronic circuitry for all electronic applications.

You work on many practical job projects. You build a short-wave,long -wave superhet receiver, plus a large -screen television: set fromthe ground up. N.T.S. training kits contain E 11 the parts you need ...atno extra cost. (See box at right.) You also receive a professionalMultitester to use during training and on the job.

ONE LOW TUITION. You need training related to all phases of Elec-tronics. Industry demands it. Only N.T.S. provides it... in ONE MasterCourse at ONE low tuition.

RESIDENT TRAINING AT LOS ANGELESIf you wish to take your Electronics -TV -Radio training in our famous ResidentSchool in Los Angeles - the oldest and largest school of its kind in the world -write for special Resident School catalog and information, or check coupon.

NATIONAL SCHOOLSWORLD-WIDE TRAINING SINCE 1905

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You can service and repair the elec-tronic "brains" of industry-com-puters, data processmg, and otherautomation equipment.

You can become a highly -paid TV -Radio Technician, an electronics fieldengineer, or succeed in your ownsales & service business.

YOU ENROLL BY MAIL AND SAVE MONEY. No salesmen means lowercosts for us, lower tuition for you.

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I Please Rush FREE Electronics-TV -Radio "Opportunity"I Book and Actual Lesson. No Salesman Will Call.

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school home study courses also offered. Check for free catalog.Eusom IMO 111IN

IIII

RADIO -ELECTRONICS published monthly at Concord, N. IL, by Gernsback Publications Inc. Second-class postage paid at Concord, N. H. Copyright1964, by Gernsback Publications Inc. All rights Deserved under Universal, International and Pan-American Copyright Conventions. SUBSCRIPTION RATES:US and possessions, Canada: $5 for 1. $9 for 2, $12 for 3 years. Pan-American countries: $6 for 1, $11 for 2, $15 for 3 years. Other countries: $6.50 for 1,$12 for 2, $16.50 for 3 sears. Postmaster send form 3579 to 154 W. 14th St., New York 10011.

A person using AT&T's new Picturephone can push buttons to control whether he wantsto be seen, see himself, see the other person, or nothing at all. Vidicon lens is smallcircle at upper left of screen. Speaker is behind grill to right. Control set uses no dial,but new "Touch -Tone" pushbutton calling system.

New York to California "Picturephone"Scores Hit at World's Fair

"See -as -you -talk" telephone wasdemonstrated publicly across thecountry for the first time at the open-ing of the New York World's Fair.West Coast reporters at Disneylandin southern California participated ina coast -to -coast press conference, ask-ing questions of Bell System execu-tives in New York via "Picturephone"hookup.

The installation in the AmericanTelephone & Telegraph pavilion atthe fair has been drawing greatcrowds. Soundproofed booths equip-ped with Picturephones have been setup, allowing visitors to talk with eachother and with a telephone oper-ator nearby. At occasional intervalsthroughout the day, a long-distancePicturephone call is placed to a wait-ing participant at Disneyland.

Callers sit about 3 feet from theinstrument's screen, housed in a com-pact desktop set. Normal room illu-mination is sufficient for the tiny vid-icon tube, next to the receiving screen,to generate a good picture. The callerhas his choice of a view of himself,or of the party he's talking with orno picture at all.

Picture size is 43/8 x 53/4 inches,with a scanning rate of 275 lines perframe, 30 frames (60 fields) per sec-

ond. The bandwidth required is about500 kc (equivalent to about 125 tele-phone circuits). Each Picturephoneset has three pairs of wires-one forthe audio signal and two for the four -wire video transmission.

Vlf Signal PuzzleNear Solution

The strange behavior of very -low -frequency (vlf) radio signals,which may be received better in onedirection than in the other whentransmitted between two points, maybe near explanation, according toDouglass D. Crombie of the NationalBureau of Standards.

Radio signals do not travelequally well in opposite directions,and a number of theories have beenproposed to explain this anomaly.Crombie believes that the cause maybe magnetically caused changes inthe radio waves' coefficients of re-flection or transmission at the ion-osphere. In other words, the differ-ence is due to the earth's magneticfield. Greater signal loss on reflec-tion in one direction is probably dueto increased transmission out throughthe ionosphere.

RCA Stockholders Meet2,500 Miles Apart

The first stockholders' meetingever held by RCA outside New YorkCity was also the first transcontinentalmeeting ever held by any companyby two-way closed circuit color tele-vision. Increasing profits and a jumpin color TV were reported to the"most broadly based annual meetingyet devised" in a meeting room "about2,500 miles wall-to-wall."

President Engstrom said elec-tronics has now passed the $15 billionannual sales level, and is on the wayto an anticipated $22 billion annu-ally by the end of the decade.

Other highlights of the meeting:color TV set sales for the first quar-ter of 1964 are 65% ahead of thesame period in '63; black -and -whitesales are up 21% . The RCA ServiceCo. is now making more on installa-tion and maintenance of color TVthan from black -and -white. A pro-duction line has been set up for thenew 25 -inch 90° rectangular colorTV tube, and some will be sold during1964. Color tubes made in Canadawill also come on the market duringthe summer.

General Sarnoff reported that thefirst quarter of 1964 is the 13th con-secutive quarter of increasing profitsfor RCA and, despite some cutbacksin government business, increasingconsumer demands indicate that theupward trend will continue throughthe year.

Advertising Representatives:EAST MIDWESTJohn J. Lamson P. H. Dempers Co.Eastern Sales Manager 740 North Rush StreetRadio -Electronics Chicago, Illinois 60611154 West 14th Street (312) Michigan 2-4245New York, N.Y. 10011(212) ALgonquin 5-7755

SOUTHEASTNeff Associates15 Castle Harbor IsleFort Lauderdale. Fla.(305) LOgan 6-5656

J. Sidney Crane, Assoc.22 Eighth St., N.E.Atlanta 9, Ga.(404) TRinity 2-6720

WEST COAST/SOUTHWESTHusted-Coughlin, Inc. Husted-Coughlin, Inc.1830 W. 8th Street 444 Market StreetLos Angeles 57, Calif. San Francisco 11, Calif.(213) 389-3132 (415) GArfield 1-0151

UNITED KINGDOMPublishing & Distributing Co., Ltd., Mitre House,177 Regent' St., London W.1, England.

Subscription Service: Address form 3579 andcorrespondence to Radio -Electronics, Sub-scriber Service, 154 West 14th Street, NewYork, N. Y. 10011. When requesting a changeof address, please furnish an address labelfrom a recent issue. Allow one month forchange of address.

6 RADIO -ELECTRONICS

Men 17.55 ow"""1"...1...J08 OPPORTUNITIES!EXCITEMENT!MONEY!

All thiscan beYours as a trained

ElectronicsTECHNICIANOVER 6,000 FIRMS HAVE EMPLOYED

e.rt r-,1

Thousands of companies in the United States and Canada whohave employed DeVry Tech men prove two most important facts:(1) Electronics is one of the biggest, fastest growing opportunityfields of our time; and (2) DeVry Tech graduates are "WANTED"MEN.

Whether DeVry Tech prepares you in spare time at home or in itsmodern Chicago or Toronto Laboratories, your training is designedto get you ready to meet the exacting standards of industry. You getpractical training that not only helps to fit you for a job or a serviceshop of your own - but also gives you a foundation for a career thatcan be profitable the rest of your life.You work over 300 learn -by -doing experiments at home, using DeVryTech's exclusive Electro-Lab method. You build and KEEP valuable equip-ment. With another DeVry Tech exclusive, you have the benefit of trainingmovies that you can show over and over again until basic points are crystalclear. Special texts guide you every step of the way as well.

HOW DeVRY TECH CAN "BLUEPRINT" YOUR CAREER !DeVry's faculty not only know how to teach Electronics, but they also under-stand men. They most likely know the type of problems you face. From this staffyou get help, advice and understanding. It is this "human" side of DeVry'sprogram that has caused many of our graduates to say: "DeVry Tech not onlytrains you for a job, they actually help you blueprint a profitable future!"

NO ADVANCED EDUCATION NEEDED!Why don't you write for FREE FACTS today? Learn how you TOO can be a

member of the great fraternity of DeVry Tech graduates across the conti-nent . . . men who were properly trained, encouraged, appreciated andunderstood! SEND IN COUPON NOW!

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2 FREE BOOKLETS!Send Coupon Today!

"One of North America's Foremost Electronics Training Centers"

DeVryTECHNICALINSTITUTE

Accredited Member of National Home Study Council

CHICAGO TORONTO

Let DeVry help you toprepare andblueprint aSolid Careerin this fast-

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TELEVISION

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DeVRY TECHNICAL INSTITUTE4141 Belmont Ave., Chicago, III. 60641, Dept. RE -7-U

Please give me your two free booklets, "Pocket Guide to Real Earn-ings" and "Electronics in Space Travel"; also include details on howto prepare for a career in Electronics. I am interested in the followingopportunity fields (check one or more):D Space & Missile Electronics D Communications Television and Radio El ComputersD Microwaves BroadcastingEl Radar EI Industrial ElectronicsAutomation Electronics CI Electronic ControlName Age

Address AptCity Zone StateD Check here if you are under 16 years of age.

Canadian residents: Write DeVry Tech of Canada, Ltd.2075-A 970 Lawrence Avenue West, Toronto 19, Ontario

JULY, 1964 7

TUNER REPAIRSIncludes ALL parts (except tubes)...ALL labor on ALL makes for com-plete overhaul.

FAST, 24 -HOUR SERVICE

with FULL YEAR WARRANTY

Sarkes Tarzian, Inc., largest manufacturer ofTV and FM tuners, maintains two completely -equipped Service Centers, offering fast, de-pendable tuner repair service. Tarzian-madetuners received one day will be repaired andshipped out the next. More time may be re-quired on other makes. Every channel checkedand realigned per manufacturer's specs. Tar-zian offers full, 12 -month guarantee against de-fective workmanship and parts failure due tonormal usage. Cost, including all labor andparts (except tubes), is only $9.50 and $15 forUV combinations. No additional costs. Nohidden charges. You pay shipping. Replace-ments at low cost are available on tuners beyondpractical repair.

Always send TV make, chassis and Modelnumber with faulty tuner. Check with your localdistributor for Sarkes Tarzian replacementtuners, parts, or repair service. Or, use theaddress nearest you for fast factory repairservice.

SARKES TARZIAN, INC.TUNER SERVICE DIVISION

Dept. 200537 South Walnut St.,Bloomington, IndianelTel: 332-6055

Dept. 20010654 Magnolia Blvd.,North Hollywood, Calif.Tel: 769-2720

New Color TV SetsDegauss Automatically

A color TV receiver that can berotated on its stand for better viewingor moved from room to room wasdemonstrated by RCA in its recentshowing of new products in NewYork City. Previously a color set hadto be degaussed by the service tech-nician when installed, to neutralizethe effects of the earth's magneticfield. If moved, it had to be degaussedagain.

The new set has a built-in de-gaussing coil, which operates everytime the set is turned on. There is aninitial surge of current in a cold set.This current energizes the degaussingcoil. As the set warms up, the currentthrough the coil decreases, reducingthe magnetic effect much as the serv-ice technician does as he backs awayfrom the screen. Once the set is warmthe circuit through the degaussing coilis cut off with a thermistor.

The new 25 -inch 90° rectangu-lar picture tube, with 300 squareinches of viewing space, and 41/2inches shorter than previous colortubes, was also demonstrated.

National Bureau of StandardsBroadcast Changes

Transmitting clocks for stationsWWV, WWVH, WWVB (and alsoNavy stations) were retarded 100 mil-liseconds April 1 because of changein the speed of the earth's rotation.

As of April 1, WWVB and WWVLbegan broadcasting continuously from1630 UT (Universal Time) Wednes-days to 2230 Fridays. Saturday, Sun-day and Monday they broadcast from1630 to 2230 UT; they alternate onsuccessive Tuesdays.

Geophysical alerts are broadcaston WWV and WWVH in Interna-tional Morse code (7 words per min-ute) during the first half of the 19thminute on WWV, and on WWVHduring the first half of the 49th min-ute past each hour:

GEO-MMMMM (Magneticstorm)

GEO-NNNNN (Magnetic quiet)GEO-CCCCC (Cosmic ray event)GEO-SSSSS (Solar activity)GEO-QQQQQ (Solar quiet)GEO-WWWWW (Stratospheric

warning)GEO-EEEEE (No geoalert issued)

By agreement with the NavalObservatory, WWV and WWVHstarted broadcasting on May 1 dailycorrections to the regular time signalsto enable users to obtain a very accu-rate value of UT2. During the lasthalf of the 19th minute of each houron WWV and the last half of the49th minute of each hour on WWVH,code signals will be broadcast as fol-lows: UT2 (space) AD or SU (space)three digits. UT2 is obtained by add-ing or subtracting (as indicated) thenumber of milliseconds indicated bythe last 3 digits to the time as broad-cast. The symbols will be revised ona daily basis, the new value appear-

ing for the first time during the hourafter midnight UT, and continuingfor the following 24 -hour period.

Radio Pioneer Passes

Melvile Eastham, as he appeared inthe early days of General Radio.

Melville Eastham, known tomany old-timers through the Clapp-Eastham equipment of the early yearsof the century, died May 7 at 79.

After a number of years withClapp-Eastham, he founded the Gen-eral Radio Co. in 1915. He was itspresident till 1944, continued as chiefengineer till 1950, when he retired.

During World War II Mr. East -ham served in the Office of ScientificResearch and Development, playinga leading role in the developmentof Loran navigational guidance.

Mr. Eastham was a pioneer inindustrial relations as well as in elec-tronics. General Radio started witha 40 -hour work week and paid vaca-tions in 1915.

Trans -Moon CommunicationsLunar communications over 600

miles or more with frequenciesaround 350 kc may be possible, ac-cording to Prof. Newbern Smith ofthe University of Michigan.

Speaking at the US NationalCommittee of the International Sci-entific Radio Union, Professor Smithsuggested that a "solar wind" con-sisting of electrons and protons con-stantly streaming from the sun wouldcreate the equivalent of a lunarionosphere. This would refract orbend radio waves in the same waythat our ionosphere bends waves onthe earth. Thus radio waves could bereceived at greater ranges over themoon's surface than previouslythought possible.

Range and quality would, ofcourse, be sensitive to variations inthe ionosphere, which depends onsolar activity, as well as the time ofthe lunar day. Communications overdistances even greater than 600 milesmay be possible with elevated an-tennas, Smith stated.

8RADIO -ELECTRONICS

Get Your First Class Commercial F.C.C. LicenseIn a Hurry - Or at Your Own Pace!

Is the Course Proven?A high percentage of Grantham resident stu-

dents get their 1st class FCC licenses in the shortperiod of 12 or even 8 weeks from the time theystart the course. Many others choose home study,completing the course and getting their licensesat their own convenience.

Is the Course Complete?Not only does the Grantham course cover all

required subject matter completely; it growsand changes and expands in phase with changeand expansion in the electronics field generally.With the Grantham course, you are assured ofmodern, up-to-the-minute instruction.

Is the Course "Padded"?The streamlined Grantham course is designed

specifically to prepare you to pass FCC exami-nations and examinations given by electronicsfirms. What you need to know to achieve thesegoals, you are taught completely and in detail.The course is not "padded" with information youwill not need.

Is It a "Coaching Service"?The weakness of the "coaching service" or

"Q & A" method employed by some schoolsand individuals is that it presumes the studentalready has a knowledge of basic electronics.

The Grantham course is presented from theviewpoint that you have no prior knowledge ofthe subject; nothing is taken for granted whereyour training is concerned. We "begin at thebeginning" and progress in a logical, step-by-step manner from one point to another, with thenecessary math taught as an integral part of thecourse. Every subject is covered simply and indetail; the emphasis is on making the subjecteasy to understand.

With each lesson you receive an FCC -type testso that you can discover after each lesson justwhich points you do not understand and clearthem up as you go along. In addition to the les-son tests, ten comprehensive Review Exams aregiven throughout the course.

JimimmiKomwsimiammiNgismodp-Ai__Wrioa4f9Aspomia

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Sto .010 OPERAYOR, AurX0.4,0. SIMKO ANy ENDOW...I FLAao RADIO STATIONS fOft rd.. AN, CtASS Of 15 vAt.rD ONDIR ifIr

ANIS Oct.. IS GRANTED t A01,40.1., Or 'X< C0.11.1.1/NEIIEW AND of ALL LE015LAilvt Aft,. RECOIVE OPOE. A. TREATIEShtlES LAO RIGuLArtONS Yr, r[OFPAL CallmuNICAAION [0.111310.,...EOF As 11.10U4N S/ECMCALLY ser our tiLl.

NE.11... TN. LICENSE. .111E0 it.,E4 ALL 0 0 OR 01-N.E.WPSE ArtAN

PiCE AND DATE Of 13SuANct

TO OPE0.00. of il'irrf'DIAT:.

0 i'EAYS"Al'O'CONOITIONS

,E.PEOTo ANY

.tlATE A. INIE OP lArIRATiox AV 1.1.4( 0 CLOCK A Y. EAST

aFEciA, EN00.[VENT i

cn- in on,.NOT ',LID LINT, SIGNED

OAR° 110AG

Is the School Accredited?Grantham School of Electronics is accredited by

the Accrediting Commission of the National HomeStudy Council.

Is It a "Memory Course"?Grantham School has never endorsed the "memory"

or "learn by rote" approach to preparing for FCClicense exams. This approach may have worked in theearly days of broadcasting, to the extent that a mancould get his license that way; but, Heaven help theemployer who expected this man to be able to demon-strate abilities implied by possession of the license !

Fortunately for all concerned, it is no longer pos-sible for a man to pass FCC exams by spilling outmemorized information which is essentially meaning-less to him. Advances in the field of electronics-andthe desire of the FCC to have the license really meansomething - have caused upgrading of the exams tothe point where only the man who is able to under-stand and reason electronics can acquire the 1st classFCC license.

Learn to thoroughly understand basic electronicsfrom the school whose graduates are successfully em-ployed by virtually every major electronics firm in theUnited States. Why not join them through Granthamtraining?

For further details concerning F C.C. licenses and our training, send for our FREE booklet

GRANTHAM SCHOOL OF ELECTRONICSLos Angeles Division Phone:1505 N. Western Ave., Los Angeles, Calif. 90027 HO 7-7727South Gate Division Phone:9320 Long Beach Blvd., South Gate, Calif. 90280 564-3421Seattle Division408 Marion Street, Seattle, Wash. 98104Kansas City Division3123 Gillham Road, Kansas City, Mo. 64109Washington Division821 - 19th Street, N.W., Washington, D.C. 20006

Phone:MA 2-7227

Phone:JE 1-6320

Phone:ST 3-3614

(Mail in envelope or paste on postal card)

To: GRANTHAM SCHOOL OF ELECTRONICSNATIONAL HEADQUARTERS OFFICE1505 N. Western Ave., Hollywood 27, Calif.

Gentlemen:

Please send me your free booklet telling how I can get my com-mercial F.C.C. license quickly. I understand there is no obligation

Name Age

Address

City State

I am interested in:111 Home Study, [7] Resident Classes

t.44-K

1

JULY, 1964

FULL FIDELITYHI-FI SPEAKERSSlim -line styling! Ceramic magnets!Superb reproduction over the full audiospectrum! Complete choice: coaxials,extended range, tweeters, woofers! Thenew Quam hi-fi line is as modern astomorrow-and it's designed to offer theserviceman a top-quality product at a listprice that's lower l han others' "audiophilenet." (Quam never advertises net prices-to protect your mark-upi)

Use Quam Hi-Fi Speakers in newsystems, as extension speakers In existinghi-fi systems, and as replacement improve-ments in stereo consoles. They'll openyour way to exciting new sales!

Write for your free copy of the newQuam Hi-Fi Catalog HF-64.

QUAM-N1CHOLS COMPANY234 East Marquette Road Chicago,. III. 60637

Cockroaches Key toComputer Problems?

The nervous system of the lowlycockroach may hold the answer toelectrical circuit problems that frus-trate computer designers. Two pro-fessors at Purdue University, Law-rence L. Ogborn and Daniel Shank -land, are using microscopes andelectrical test instruments in a re-search project on cockroach sensors,nervous systems and reflexes. Theyfeel that nature has installed specialcircuitry to insure reliability, amongother things, and that they may learnsomething about why nature's trans-ducers are more efficient than manyof the man-made devices used tomeasure such things as position, ve-locity and temperature.

Radio Signals from JupiterShow Strange Variation

Observation of radio signals fromfour places on Jupiter gives rise to thesuggestion that this largest of all theplanets has abruptly changed its speedof rotation. This suggestion was of-fered by University of Florida radioastronomer Prof. Alex G. Smith.

The radio signals from the fourJovian radio sources sweep throughspace like the beams of a lighthouse,and have been measured accuratelyfor some years. A short time ago, anabrupt change was noted in the rota-tional rate of the radio sources. Meas-

urements indicated that the rotationhad slowed by 1.3 seconds.

If the signals are coming fromsome solid part of the planet, saysDr. Smith, "the implication is strongthat the planet itself, or at least a por-tion of the interior, has suddenly al-tered its rate of spin."

The change in rotational ratewould be 1.3 seconds in every 10 -hourrotation of Jupiter, something me-chanically almost inconceivable forsuch a large planet. Dr. Smith pointsout, however, that a nearly identicalshift occurred in the rotational speedof the Great Red Spot, the one per-manent marking of Jupiter's that isvisible to astronomers.

Satellite DiscoversHuge Ray Zone

An 188 -pound paddle -wheel sat-ellite called Imp (for InterplanetaryMonitoring Platform), launched Nov.26 from Cape Kennedy, has discov-ered an energetic radiation zone thatengulfs the Van Allen belt. It alsoconfirmed that the earth is envelopedin a turbulent shock wave of streamsof energetic particles from the suntraveling at speeds up to 300 miles asecond, giving a new clue to thesource of the particles making up theVan Allen belt.

When the sunlit side of the earthcollides with this shock wave (as closeas 40,000 miles from the earth), itcreates an ever -broadening wake thatstretches as far as the moon.

SUNSPOT CYCLE NEARLY OVER

210

200

FEEMEMIlir,111111111111111111WAIL

MAX 201.3INIMMIIMIIIIIIIIIIIIMIIIIINMI= IN

M1111111111111111MMONNIMMEN180 1111111=11, 011111=1111111MEMMAX 151.8

CYCLE 17-1933-4418-1944-'5419 -1954-

'6° IMIIIIIIIIIIVAIMINIIMININIIIIIIIIIIIIIIMMIll140 ill11lli"41"5111%1111111111111111111=

l° 1201111111.Midir 120.4 1111.1aaEEIMIIIMIMIIIMIIIIMINIMMIIIMMANIIMIKVIII 11111111MNIMIIIIIII

a) 111111111MMEMINEMIIIIM MEW_MIE

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1933 1934 1935 1936 1937 1938

1944 1945 1946 1947 1948 1949

1954 1955 1956 1957 1958 1959

1939 1940 1941 1942 1943 1944

1950 1951 1952 1953 1954

1960 1961 1962 1963 1964 1965

The present sunspot cycle No. 19 (the heavy solid curve on the chart) is approachingits end. Current estimates are that cycle 19 will bottom out somewhere betweenNovember, 1964 and April, 1965. (The curve is dashed from November 1963 on sinceexact information is not available beyond that date). The two previous sunspot cycles(17 and 18) are shown for comparison. The peaks of cycles 18 and 19 were the highestmeasured in the nearly 200 years of recorded sunspot history.Chart courtesy of the BBC.


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JULY, 1964 11

Must -Reading since 1930-Sylvania News

Sylvania and its distributors have long known that it pays to keep their customers informed.That's why 35,000 dealers today receive, read and depend on Sylvania News for useful infor-mation. Now in its 35th year of continuous publication, the News is still one of the mostimportant dealer publications in the industry. Dealers aren't the only ones who read SylvaniaNews-it also serves some 70,000 distributors, engineers and technical service men. Are yougetting your copy? It's free. You can request it by asking your Sylvania distributor or droppinga line to: Editor, Sylvania News, 1100 Main Street, Buffalo, N. Y. 14209.

SYLVANIASUBSIDIARY OF r-1-1

GENERALTELEPHONE & ELECTRONICS G

12 'ADIO-ELECTRONICS

MICROELECTRONICS - Medium -size ant dwarfs integrated semi-conductor circuit (black square)containing 8 transistors, 12 re-sistors.Photo courtesy of Business Week.

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JULY, 1964 13

This one istwice as safe.When Sonotone designs a retractable cartridge, you can be sure it offers some-thing extra. Like other retractable cartridges, the new Sonotone "21TR" with-draws into the safety of the arm to avoid bumps and bruises. Further, it has"bottoming" buttons which act as shock absorbers between the needle assemblyand the record. Unlike other retractables, the "21TR" features the exclusiveSono -Flex© stylus, which can be dropped or mauled and still continue to pro-vide superior performance. The high -output "21TR" is a direct replacementfor the thousands of record players requiring a quality retractable cartridge.

This one istwice as safe andtwice as compliant.The new Sonotone "23T" offers performance specifications never before avail-able in a budget -priced ceramic cartridge-plus record protection. High com-pliance of 10; channel separation of 24 db; output voltage of 0.38; low trackingforce of 2 to 4 grams make it the ideal replacement in quality stereo phono-graphs. Performance is only half the story of the "23T". This new cartridgefeatures "bottoming" buttons And the flexible Sono -Flex@ needle. AnotherSonotone cartridge, the "22T offers the high performance of the "23T"with a slightly higher output. Both feature the Sono -Flex plus a uniquesnap -in mounting bracket, for rapid replacement without tools.

Both are directreplacementsfor popular makes

...and themselves.

SONOTONEaudio products Sonotone Corp., Electronic Applications Div., Elmsford, New YorkCartridges Speakers Microphones Headphones Hearing Aids Batteries

CALENDAR OF EVENTS

San Fernando Valley Radio Club Hamf est and Picnic,June 21; Sunset Farms, Sylmar, Calif.Statewide CB Jamboree, Naugatuck Valley CB RadioClub, June 21; Lake Quassapaug Pavilion, Route 6-A,Middlebury, Conn.Conference on Precision Electromagnetic Measure-ments, June 23-25; National Bureau of Standards Lab-oratories, Boulder, Colo,International Conference on Magnetic Recording,July 6-10; London, England.

First Radar Contacts by A10With Mercury in April

The Arecibo Ionospheric Ob-servatory, discussed in RADIO -ELEC-TRONICS' June editorial and in theFebruary cover story, made its firstradar contacts with the planet Mer-cury on April 7 and 8.

Gordon Pettengill, associate di-rector of the observatory, said Mer-cury was about 90,000,000 milesfrom the earth at the time of thecontacts. Signals would have beenabout 10 times stronger April 30,when Mercury was at its nearest pointto the earth this year. Round trip timefor each radar signal was about 14.5minutes. Radar pulses travel at thespeed of light, or about 186,000 milesper second.

Such contacts may provide ac-curate information on Mercury'sorbit, and the nature and density ofthe planet's surface.

Electronic Vein EraserTested at U. of Minnesota

Medtronic, Inc. has devised avein eraser which can disintegratevaricose veins, eliminating the needfor multiple surgical incisions, dissec-tions and chemical injections.

The unit is a 12 -pound gene-rator with plug-in electrode handleand probe, and has been tested forthe last 2 years in the surgery depart-ment of the University of Minnesota.

Brief BriefsAn all -channel, all -transistor

uhf-vhf TV receiver with a 9 -inchscreen has been introduced by SonyCorp. of America. The set operatesfrom a 12 -volt battery, weighs 9 lb.

RCA reports that color sets ac-counted for 3 out of every 10 set salesduring the first part of 1964.

An experimental portable elec-tronic organ has been developed forthe Army's Chaplain Corps, for usein services in the field.

High-speed experimental datacommunications system developed byBell transmits black -and -white fac-simile 16 pages per minute, with 100 -line -per -inch definition. Present trans-mission systems send 1 page in 6minutes. END


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Corre ponden e

Matching and Splicing"G -Line"

Dear Editor:The many inquiries on my "G -

Line" article (February issue) are grati-fying, but the questions asked make itapparent that I goofed in two phases ofthe description:

1. The matching transformer andits connection to the surface -wave line.

2. Ways of splicing the G -line it-self.

The launcher, one terminal of theG -line system, and the surface -wave con-ductor itself, the other electrical termi-nal, are physically different and there-fore present different capacitances toearth ground. This means that differentamounts of rf will be present in thelauncher and in the line. It is also com-mon practice to ground the launcherand, when this is done, clearly all rfpotential appears on the surface -waveconductor.

Whether or not the launcher isgrounded, the G -line is electrically un-balanced. This unbalance makes theG -line compatible with coaxial linessince they are normally operated withgrounded outer conductors. Direct con-nection to coax could be made exceptfor one thing: the impedance range ofcommonly available coaxial lines is 50to 95 ohms and does not match the 300 -ohm nominal impedance of the G -line.A transformer is required. If connec-tion to a balanced line such as a 300 -ohm ribbon lead is desired, the G -linemust be isolated to prevent unequal cur-rents in the balanced conductors.

G -LINE

LAUNCHER

WEATHER -TIGHT TRANSJERROLD N° TO -374TACO N°1597NMILLER N° 6162

3000TERMINALS

CONN FOR 720 OPERATION (CATCHER OR LAUNCHER)

F ig .1

If the currents in parallel -conduc-tor transmission lines are not equal,magnetic -field cancellation will not bemaximum and radiation losses from theline will increase markedly. Althoughthe nominal impedance of the G -lineclosely matches that of the ribbon, bal-anced -to -unbalanced conversion must bemade. The schematics (Figs. 1 and 2)illustrate both transitions.

720 LINECOAX CONNECTOR

Splicing is not as ticklish as youmight suppose, so long as the discon-tinuities caused by splicing are a smallfraction of a wavelength and do not oc-cur too often. I have made temporarytwisted splices as an electrician might,without measurable electrical changes.However, many excellent splices forconductors are manufactured, and Irecommend them instead.

Graybar Electric Co. has a full lineof splices for all sizes of conductors.Their catalog No. AL61 is a splice forNo. 6 solid aluminum. It is a slim, dou-ble -tapered cylinder with axial holes ineach end to receive the conductors. Tomake the splice, simply push the con-ductors in from each end as far as theywill go. They won't come out.

G -LINE

LAUNCHER

1(4-5;;WINDING

MILLER TV ANTENNA COUPLINGTRANSN° 6201

30011 WINDING

3000 LINE

CONN FOR 300A BALANCED LINE (CATCHER ORLAUNCHER

Fig .2

Similar tension splices, as they arecalled, are made for copper. If you havea friend in the electrical business, youmay be able to borrow a crimping toolthat will enable you to use compressionsplicing sleeves. They are available forboth aluminum and copper conductors,solid or stranded, and are preferable tothe tension splices because they aresmaller in diameter and much cheaper.After the splice is made, wrap poly-ethylene or polyvinyl tape over the splic-ing device to restore the all-importantdielectric.

Carmel, Calif.OWEN G. PATRICK

RADIO -ELECTRONICS

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JULY, 196417

The Colortron Antenna's "BALANCED DESIGN"is the Winegard secret of superior color reception:

It takes a combination of high gain, accurate impedancematch, complete band width and pinpoint directivity tomake the perfect color antenna. Only the WinegardColortron gives you all 4 with BALANCED DESIGN.

What is Balanced Design ?It's not enough to design an antennafor high gain alone and expect good color reception. A high gainantenna without accurate impedance match is ineffective. Or anantenna with good band width but poor directivity characteristics isunsuitable for color. The Winegard Colortron is the one antennawith balanced design, excellence in all the important characteristicsthat a good color antenna requires.

For example:Gain and Bandwidth-A superior color antenna must have highgain and complete bandwidth as well. But the response must beflat if it is to be effective. Peaks and valleys in the curve of a highgain antenna can result in acceptable color on one channel andpoor color on another.

No all -channel VHF -TV antenna has more gain with completebandwidth across each and every channel than the Colortron. Lookat the Colortron frequency response in this oscilloscope photo.

Note the consistent high gain in all channels.Note the absence of suck -outs and roll -off onend channels. The flat portion of the curveextends on the low band from the channel 2picture carrier past the channel 6 sound carrier.On the high band, it is flat from the channel 7picture carrier to the channel 13 sound carrier.There is less than.'/2 DB variance over any channel.

Impedance Match-the two 300 ohm "T" matched Colortrondriven elements have far better impedance match than any antennausing multiple 75 ohm driven elements. The Colortron transfersmaximum signal to the line without loss or phase distortion throughmismatch. Winegard's "T" matched driven elements cost more tomake, but we know the precision results are well worth the addedmanufacturing expense ... because a mismatched antenna causesloss of picture quality which might get by inblack & white, but becomes highly disturbingin color.

The oscilloscope photo here shows theColortron VSWR curve (impedance match).No current VHF -TV antenna compares withit across all 12 channels,

Directivity-Equal,' important for superior color pictures isfreedom from interference and ghosts. Therefore, an antenna withsharp directivity and good signal-to-noise characteristics isnecessary. Extraneous signals picked up at the back and sides pro-duce objectionable noise and ghosts in Slack and white reception. . . frequently ruin cdor reception.

Winegard's Colortron has the most ideal directivitypattern of any all channel VHF antenna made. Ithas no spurious side- or large back lobes . . . is ab-solutely dead on both sides. Colortron does not pickup extraneous signals, and even has a higher front -to -back ratio than a single channel yagi.

Look at this Colortron polar pattern. No otherVHF -TV antenna has sharper directivity on a channel -for -channelcomparison.

BALANCED DESIGN CoLORTRONS HAVE SUPERIOR MECHANICALFEATURES, Too!

Every square inch of the Colortron has been engineered formaximum strength, minimum weight and minimum wind loading.Even the insulators are designed for low wind resistance. The result

TYP CALCHANNEL

is a streamlined, Hell:weight 'antenna that stays stronger longer.Colortrons have been wind tested to 100 mph.

Colortrons are simpler to put up, toc. Easier to carry -.:p a lad-der and mount on a !ugh mast. No exzra weight and bulk tofrustrate the antenna installer.

And, you can see the diffetence in quality when you examile aWinegard COLORTRION. The GOLD Arr%roorzao finish is 'arightweather-proof gold that won't fade, rust or corrode. It's the samefinish specified by the Navy for military antennas. Full attentionis paid to every detail.

Winegard Helps You Sell-does more national advertisingthan all other brands combined. When you sell Winegard,, you sella brand your customer knows . . . backed by a written factoryguarantee of satisfaction.

It's not surprising that Winegard leads the field in the number ofantennas installed with color sets. And Colortrons have been in-stalled by the hundreds of thousands for black and white sets too-for the antenna that's best for color is best for black and whiteas well. Why don't you try a balanced design Colartron and seefor yourself?

Winegard CaCOLORTRON ANTENNA COLORTRON ANTENNA COLORTRON ANTENNA COLORTRON ANTENNA

Nadel 1.4d Gold Anodized $64.95 Model 1.43 Sold Anodized $51.90 Model 1-42 Gold Anodized $14.95 Nadel 5-41 Gold Anodized $24.35 3013-G K I FIKWOOD BURLINGTON, IOWA

Coming Next Month

in Radio -Electronics

NEED A LITTLE DICTATOR?

It is easy to modify one of thecheap tape recorders now beingsold in large quantities, andmake it a very efficient little dic-tating machine, complete withfoot -pedal, start -stop, etc. Thesame techniques can be usedon a standard recorder, too, ofcourse.

WATCH THOSE SHIFTY RESISTORS

This article explains how ther-mistors and varistors work, withsome hints about practical ap-plications.

ANTENNA ROTATOR REPAIR

Mechanical troubles always givethe service technicians moreproblems than electronic ones.But the antenna rotator is nota difficult device to repair if youunderstand it, and understand afew good techniques. Homer Da-vidson explains both the "how"and the "how to."

DESIGN YOUR SPEAKER ENCLOSURE

Have you ever had a speaker ofa given size and supposed fre-quency response, and wonderedwhat to do with it? This articletells you exactly what : coversthe important questions of en-closure size, shape ducting andother features.

You'll find these and many otherarticles, features and regulardepartments in next month'sRADIO -ELECTRONICS.

AUGUST ISSUE

(on sale July 16)

Another (Ultra-) SonicBurglar Alarm

Dear Editor:"Ultrasonics Stops Burglars"

(RADIO -ELECTRONICS, May 1964) seemsto go a long way around to solve a rela-tively simple problem. Since sound trav-els at about 1100 ft/sec, and a burglarwould move at only 1 to 2 ft/sec, theDoppler shift in frequency wouldamount to only 0.1 to 0.2%, a prettydifficult job for discrimination devices.Since only a minute portion of the totalsound energy is so modulated in fre-quency, there is another difficult jobfor amplitude discrimination betweenthe direct, fixed frequency and the in-truder -modulated frequency.

A much simpler and more directmethod, which also uses ultrasound, re-lies on a standing -wave system whichshifts about with the motion of anysizable objects in the room, the openingof a door or window, etc. It involvesonly an ultrasonic (or sonic) variable -frequency oscillator and reproducer anda receiver, which may be untuned, whoseoutput is rectified to operate an alarmdevice.

After vacating the room and lock-ing all entrances, the owner, having al-ready switched on the apparatus, ad-justs the transmitter frequency from anoutside control until the receiver's soundfield reaches a maximum of intensity inthe standing -wave system of the room.This holds the alarm relay open untilthat system is shifted by intrusion, pow-er failure or tampering, thus providingfail-safe operation.

Anyone who has run an audiooscillator into a speaker will recall howthe sound level varies greatly as the fre-quency is changed (especially at fre-quencies of several kc) or, when steady,as the operator moves his head about,and most if he holds a finger over oneear.

If the frequency used is several kc,any intruder would have ample warningthat he would surely be caught, so thatforced -entry damages might be avoided.Yet the sensitivity would still be ample.

For those who may care to set upsuch an alarm system, its details can befound in my patent No. 2,071,933,issued Feb. 23, 1937, and sold to theRadio Corporation of America. It is ofcourse now 10 years expired.

B. F. MIESSNERMiami Shores, Fla.

Author Fasal RepliesDear Editor:

The principle Mr. Miessner citeswould be very promising were it not forone neglected detail that suggests thatthe system has never been tried inpractice:

The standing -wave pattern in anenclosure can never be considered as aninvariable sound field whose intensityat a given point is constant. The velocityof sound in a medium determines thewavelength of the sound wave, and thisvelocity depends on temperature, hu-

midity, barometric pressure and other,uncontrollable, factors. Therefore, thewavelength of the sound wave, and withit the standing -wave pattern, is contin-ually changing. These changes are greatenough to vary considerably the ampli-tude of the sound field at a given point.

A relatively stable pattern could beexpected only in an enclosure whose di-mensions do not exceed a few wave-lengths-at most a few feet, at the fre-quencies being considered here. Also,the field intensity depends on not justone reflection but on an infinite numberof superposed reflections, which result inan average value over time and over thesurface of the receiving transducer.

Thus the proposed adjustment ofthe receiver to maximum output bychanging the radiated frequency wouldnot last long. False alarms would beinevitable. This automatic variation ofthe standing wave pattern in a room isundesirable, and circuits to compensatefor it had to be designed into the unitdescribed in my article.

Using audible sound for room pro-tection is not too good an idea. At thosefrequencies, doors, windows, etc., act asdiaphragms and permit the sound energyto penetrate to the outside. There, theyprotect not only the intended room butalso the busy hallway outside, and theneighboring premises. The result wouldbe an infinity of false alarms!

In addition, warning an intruderencourages him to prepare his job betterfor the next attempt. And the audibleprotection would drive the neighborscrazy!

May I ask, if Mr. Miessner's sys-tem is so much simpler, better, less ex-pensive, more reliable, why his 1937patent has never been used? It is appar-ently completely unknown to interestedalarm manufacturers. And why is theKidde Ultrasonic Alarm, based on theDoppler effect as described in my article,accepted as the most efficient and de-pendable room protection?

JOHN H. FASALWalter Kidde & Co., Inc.Alarms Div.Clifton, N. J.

Electronic Organ Debate:Round 2

Dear Editor:I have just read Mr. Brounstein's

letter in the May issue of RADIO -ELEC-TRONICS. My experience has mainlybeen with Baldwin organs, but I do notagree with Mr. Brounstein on severalpoints.

Baldwin has a set of 12 tuningforks for tuning their organs. Theseshould work well on any frequency -di-vider type organ. Procedure is to con-nect the organ output to a pair of head-phones, hold the base of the vibratingtuning forks against the shell of theheadphones, and adjust the organ tun-ing for zero beat.

Several manufacturers do provideservice manuals for owners.

Only the harmonics in a Hammond


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For a complete catalog on theFastatch II Control System, write toCentralab or contact your distributor.

JULY, 1964 21

Outperforms Finest Vacuum Tube Units

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are not tempered -scale. A Hammondcan be played with other tempered -scale instruments, so tape-recorded notesshould be accurate enough for tuning, ifthe tape recorder has sufficient accuracy.

In addition to the Conn Strobo-tuner, the Schober Organ Co. has aportable, relatively inexpensive strobo-scopic tuner.

Mr. Brounstein is right about thelimited need for full-time organ techni-cians. When I was doing installation andrepair work for two dealers, I spent onlyabout 3 or 4 days a month in organwork. I believe that electronics organwork is a good means of diversifying anelectronic technician's work in loca-tions where part-time work is available.Smaller organ dealers have told me it isvery hard to find a technician well-grounded in electronics and interested inlearning organ work on a part-timebasis.

W. J. STILESHumphreys, Mo.

?esioN weNDear Editor:

I read with interest the article aboutimplosion and explosion on page 48 ofthe April RADIO -ELECTRONICS.

Just recently there was an articlein one of the trade magazines about agroup of scientists who made a study ofthe sound made by an implosion. Aftermuch research and experiment they ar-rived at the conclusion that an implo-sion goes "GNAB."

H. L. SINGLETARYEngineering Dept., WEAR -TVPensacola, Fla.

More on PatentsDear Editor:

Couldn't help noticing in the Cor-respondence column the comment en-titled "Our Patent System Not So Bad?"by Ronald Klett.

I am not going to try to arguewhose patent system is best, since I amnot fully versed in the various systems.

But, I would like to take exceptionto Mr. Klett's comment in paragraph 5about the difficulty in invalidating anAmerican patent. In some circumstancesit is difficult and expensive but, in themajority, cheap and dirty.

This sounds like a strong accusa-tion, but let us turn to Alexander Gra-ham Bell who in numerous articlesmentioned his complete financial lossdefending his patents. The same is trueof Lee de Forest (R -E, September 1961,page 33, paragraphs five and six).

With that issue of R -E in hand, Iasked for and was granted an interviewwith the Senate Committee on Patentsand Trade Marks in October 1961, withthe hopes of creating interest in thisdirection.

In the interview I pointed out theBell and de Forest situations. The com-mittee agreed that it was most unfortu-nate. The conversation then drifted to

other individual inventors and it wasagreed that many an inventor had losthis patent by not being financially ableto answer an infringement suit, the plain-tiff winning by default. It was alsopointed out that it is nearly impossiblelegally to prove dishonorable intentionsof a plaintiff even though they may bequite evident. It was estimated that about$50,000 would be required to follow aninfringement suit through the courts.The committee acknowledged the situa-tion but expressed little interest.

A patent law that will permit theoutstanding inventors of our time to bedriven into poverty in defending theirrights definitely needs revision. It is cer-tainly no incentive for other inventors.

THOMAS L. BARTHOLOMEWSilver Spring, Md.

Capacitive -Dischargeignition

Dear Editor:Mr. Palmer's letter, published in

your January 1964 issue on page 47, wasinformative but did not go quite farenough for a good system comparison.

First, let me state that the classicalpolarity problem stems from the beliefthat a negative -going plug voltage firesthe gap more easily than a positive -going one. In a slow -rise -time systemthis is true to some extent, because theplug center electrode is hotter, therebycapable of emitting electrons more eas-ily, which in turn causes an earlier gapionization or breakdown. The differencein voltage, positive or negative, is smallso that in a fast -rise -time system it mat-ters little.

My own developments in the ca-pacitor discharge system have comefar from my original description inJuly 1955 and my more recent descrip-tion in the July 1962 issue of RADIO -ELECTRONICS. In fact, a complete SCRcapacitor discharge system with a trueignition pulse transformer can be builtat a cost less than that of a good tran-sistor switched system, and draws lessthan 0.3 amp starting current.

As Mr. Palmer pointed out, theignition coil today is the limiting factorin all systems that use it. With one ex-ception, all ignition coils are wound ona low-cost iron -wire core but in a uniquemanner-for two very good reasons. Thewinding nearest the core is the high -voltage secondary. In fact, the core isitself tied to the high -voltage end of thewinding, making an inside -out configu-ration. The reason for this is that it'seasier to insulate from inside out to themetal can. The primary is the last (out-ermost) winding nearest the metal con-tainer, and can dissipate primary heatimmediately to the can. This is extremelyimportant, particularly in transistor sys-tems, which draw from 3 to 16 ampsand result in coil primary heat genera -


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JULY, 1964 23

tion in the order of 20 watts. Perhapsyou have noticed the color change onthe outsides of some epoxy molded coilsin transistor systems. By comparison, thecapacitor discharge system coil dissipa-tion increases linearily with engine rpmbut at most never exceeds 0.5 watt.

A detailed look at this construc-tion immediately shows the reason fora low secondary resonance frequency ofeven the coil above. If you now con-sider a considerably more up-to-datecoil such as the Mallory Flash Fire se-ries (U-6 or U-12), you have a moreconventional construction of excellentquality with the high -voltage winding

and terminal where it should be, on theoutside. This coil's only disadvantage isthat it can't dissipate high primary heat.Its secondary characteristics are excel-lent, with a resonant frequency muchhigher than the conventional coil, orabout 5,000 cycles.

There are two additional ways anignition coil can be made to have theextremely fast rise time of the capacitordischarge system. They both involve re-ducing secondary self-inductance. Thefirst is to employ fewer total secondaryturns and much lower turns ratio. Theresult is that obtained with the EI-4system manufactured by Motion, Inc.,

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an expensive unit using thyratron tubesbecause of the high primary dischargevoltages (1 to 2 kv), but giving an ex-tremely fast rise time.

The second method was impliedpreviously when I mentioned a com-plete SCR capacitor discharge systemusing an ignition pulse transformer.Present-day ignition coils are very poortransformers because of their low mag-netic -path efficiency. The effective per-meability of the straight unclosed coreis only about 4. This is to say that thecoil inductance is only four timesgreater than that of an air core. Theobvious answer is to provide a trueclosed -path magnetic core with an ef-fective permeability of 1,000 or more.For the same value of primary induc-tance this then means fewer turns or aprimary turns reduction of ,/4/1000.

While the secondary inductancealso remains the same, the secondaryself- or leakage -inductance is drasticallyreduced. That is what determines risetime, so an ignition pulse transformerusing this technique can still use anominal 100:1 ratio with fewer turnsand much smaller physical size. Aworking model has been constructed inthe volume of a 3 -inch cube.

Now comes the question, whycan't this construction be used with thetransistor switching system? The reasonis simple and mainly why even transis-tor systems must use the same old-fashioned coil of the early 1900's: dcsaturates the core and dictates the useof the straight -rod core type coil. Thecapacitor discharge system, since thetransformer is coupled through a capaci-tor, cannot send any dc through the pri-mary, thus, no saturation.

For original manufacturers, then,the SCR capacitor discharge system witha very -low-cost multiple -wound igni-tion transformer and fired by eitherbreaker points or an extremely low-cost,speed -insensitive transducer system islikely to be able to meet any futureengine requirements.

H. W. LAWSONRochester, N. Y. END

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25

ELECTRONICS' FUTUREThe Great Things in Electronics are still to come...

Late last March, Prof.Seymour Melman of Co-lumbia University madepublic certain importantfacts about the economicconsequences of the con-templated long-term re-duction in US arma-ment.

His findings were soimportant that he pre-sented them to Congresson March 24. They werepart of a survey by theSeminar on IndustrialConversion of Colum-bia's Department of In-dustrial Engineering.

The gist of the reportis that at the time ofthe announcement 67,-000 professional engineers, technical and production work-ers as well as clerical personnel of 19 major defense andelectronic concerns in 6 states had been laid off due to cut-backs and cost-cutting programs.

This is not surprising if we consider how much of today'smilitary equipment is electronic and that more than 50%of the electronics industry's output is for defense.

Normally-if history had repeated itself-with the comingof peace at the end of World War II, the arms race shouldhave terminated. But then came the Cold War, followed bythe Korean war in 1950 to 1953. The Cold War-while ithas abated-is still with us.

Washington, to be sure, long ago foresaw what was goingto happen in the age of electronic decompression, in whichwe find ourselves now. When part of the second largest in-dustry in the country, with annual sales of $16 billion a year,is slowed down, the consequences at best must be disastrousto many of its workers as well as employers.

As long ago as Dec. 21, 1963, Gardner Ackley of the

Electronics Industry Growth1914-$1,000.000

1963-517,000,000,000

Council of EconomicAdvisers was named byPresident Johnson tohead a 10 -man Commit-tee on the EconomicImpact of Defense andDisarmament.

The path of electron-ics for the past 60 yearshas by no means beensmooth. It has beenmarked by periodic upsand downs, soaringbooms and depressions.This is true for most in-dustries, whether theybe motor cars, oil orelectronics.

The young radio in-dustry received its firstsetback in 1917. This

was before the US entered World War I. Then, by Presi-dential decree, it became unlawful to operate any radio sta-tion. Nor could radio supplies be sold during the duration ofthe war, from April 6, 1917 to Nov. 11, 1918.

This was followed by the electronic construction boom of1919 to about 1925, the so-called "set builder's" parts boom,the heyday of the radio components expansion, when thewhole country was building every imaginable type of radioset-the first broadcasting boom.

Then the builder's boom collapsed, bringing in its wakethe factory -made receiver. Where heretofore componentsbrought fancy prices and vacuum tubes sold for as high as$12 apiece, many electronics manufacturers began to makeparts themselves and the ensuing harsh competition loweredall component prices drastically.

Nevertheless, by 1929 the electronics industry had be-come much bigger than ever, in output as well as dollarvalue. Electronics had started to expand in all directions-communication, hundreds of different tubes, every imagin-


able type of radio receiver-industrial electronics.In the meanwhile, in the late 1920's experimental tele-

vision became a fact. It was first demonstrated by the presentwriter in August 1928 over his station WRNY in New Yorkon a regulation broadcast wavelength of 362 meters (andshortwave of 30.91 meters). This was not television as weknow it today-the resulting picture was postage -stamp size,and at first there was no sound. But the picture was clearand sharp.

Not until the late 1930's did the modern cathode-ray tubeTV make its appearance. Before it could expand normally,World War II started for the US on Dec. 7, 1941. Few homeTV (or radio) sets were made from then until the end ofthe war in 1945. After that, electronics grew at an unprece-dented rate without letup until the early 1960's.

We felt it necessary to present this thumbnail sketch ofelectronic history to give the reader a better idea of theelectronics economy and of its future.

In our opinion, the latter part of 1964 should see the endof the current devolution. This probably will be followed bythe greatest electronic boom of all times.

What of the future?

End of Japanese InvasionFor a number of years, the Japanese have been inundating

the US with low-priced, yet excellent electronic parts andsets with which we have been unable to compete. The valueof Japanese imports amounts to $176 million per year.

Within the next year or two much of this traffic shouldstop, for one simple reason: microminiaturization. The artand our know-how, plus certain patents, now make the mostelectronic components obsolete. In the long run we prob-ably can do better than the Japanese, particularly if ourmanufacturers go all out in automated microminiaturization.

SupermagnificationWe will not conquer virus diseases until we really have

electronic magnification at an atomic level. The cancer virus,if cancer is a virus disease, is invisible unless enlarged towhere atoms become visible. We believe electronic super -magnification is now on the horizon. Vastly more powerfulelectromagnets such as used in electron microscopes, if

Radio -ElectronicsHugo Gernsback, Editor -in -Chief

energized by superconductors, could effect much highermagnification.

Miniature TelevisionThanks to the Japanese, we now have small-scale portable

TV sets. The smallest current Japanese model has a screen31/2 x 23/4 inches. This, however, is comparatively large.

For the Christmas 1945 issue of the writer's booklet en-titled Tame, the inside cover showed the picture of a pro-posed television wristwatch, the Teleview. In the center wasa watch, to the left the TV screen, to the right the loud-speaker. The miniature screen showed a "magnilens" forenlarged viewing of the picture.

This is about as small as TV's are likely to get, except foreven smaller medical ones that surgeons or doctors will sooninsert into patients' bodies for diagnostic purposes.

Such miniature TV's will probably be manufactured notlater than 1970. There will be a good demand for them bythat time. The key, of course, is microminiaturization. Thesesets will not have bulky cathode-ray tubes. They will bereplaced by a special vacuum -fluorescent screen.

Space ExplorationIt is in future space exploration that electronics will earn

its laurels. Up to now we really have not explored thevacuum of space seriously. We merely have been theorizingand preparing ourselves for the coming electronic onslaughton space.

The great wonders of space will come after 1970. Entirelynew means of space propulsion, not even seriously consid-ered today, are yet to come. And they will be electronic inpart. They will be better and faster than the slow ionicmeans.

The Administration is now committed irrevocably to theserious exploration of space-the neighboring moon and themore distant planets. Our future destiny depends on it, justas the Old World's destiny depended on Columbus andothers for the exploration of the New World in the 16thcentury.

More important, immense treasures-dozens of billions-will be poured into the coming space research, far morethan electronics has ever before received from the Govern-ment. It will probably make electronics the greatest indus-try in the US. -H. G.

JULY, 1964 27

By JOSEPH H. SUTTON

A POWER DECADE BOX HAS INNUMERABLEuses around the shop or lab: checkingpower transformer output, amplifieroutput, temporary substitution in bleedercircuits or anywhere you want to find theright -value resistor without (ordinarily)worrying about possible resistor burnoutin your box. (For applications where thecurrent is near the box limit, it is alwayswise to connect a low -resistance ammeterin series with the box, or a high -resist-ance voltmeter across it.)

This decade box ranges from 1 to100,000 ohms in 1 -ohm steps. It willhandle moderate current, 30 ma to 3amps at up to 1,000 volts ac or dc (theswitch breakdown rating). Each decadeuses five resistors: one 10 -watt and four20 -watt, so each step will dissipate 10watts, and each decade 90 watts (Fig. 1) .Wirewound power resistors are neithereasily burned out nor permanently dam-aged by temporary overloads and, ifinadvertently burned out, are inexpen-sive to replace.

DECK B

R5

R4

R3

R2

DECK A(NEAREST PANEL) POSITION

9

Fig. 1-Schematic of one resistance decade,with values shown for first (lowest) decade.For higher decades, multiply resistance val-ues by 10, 100, etc.

By contrast, most commerciallyavailable decade boxes, even expensiveones, will handle only one-fourth to one -eighth as much current as this box, andcorrespondingly only from one -sixteenthto one -sixty-fourth as much power. Thecommon kit -variety decade box uses four1 -watt resistors per decade, in 1, 2, 3,6 combination, so from 1 ohm to100,000 ohms, it will handle only 400 to4 ma. For light loads, such a box is handyto have. But, in it, any carbon resistormay be ruined by temporary overload,and for expensive boxes, the wirewoundreplacements are costly. Hence the needfor a moderate power box, even (or

30 MA

COM 99,999

DANGER!MOMENTARY ZERO

BETWEEN POS. 1,2

MAX10 WATTSPER STEP

POWER

RESISTANCE

DECADES

99

3 AMPS

9

Panel of decade box shows maximum current rating for each decade and carries oilierreminders.

DECADE BOXUSES POWER RESISTORS

EASY -TO -BUILD, EASY -TO -USE SWITCHBOX HANDLES HIGHER

CURRENTS THAN COMMERCIAL JOBS - AND COSTS LESS

especially) if you already have a low -power box.

Construction layout is not critical.Wire each decade completely before youmount it in the chassis. Either end ofeach decade is then soldered in thechassis to the outside terminal as shownin the schematic. Make all leads as shortas convenient, and use No. 18 hookupwire.

Since the voltage rating of this boxis 1,000 maximum, the two highest20,000 -ohm resistors can be rated lessthan 20 watts, say 10 watts for R4 and5 watts for R5. I did not use these valuesbecause the construction symmetrywould have been altered.

If this power box were intendedfor more than short -duty heavy -current

applications, ventilating holes could bepunched in the chassis sides and bottom.Because such holes let dirt and dust intothe switches, I decided just to removethe chassis bottom in the rare event ofa long -duty heavy -current application.

In checking power transformer out-put, you may find it necessary to extendthe 100 -ma range with an externallyconnected 5,000 -ohm 50 -watt or 10,000 -ohm 100 -watt resistor.

Accuracy of this wirewound boxcan be high. Originally I aimed for 5%,the usual commercial rating for powerresistors. With a bridge you can makefiner adjustment: select the 1 -ohm to2,000 -ohm units a trifle "long", thenparallel with carbon resistors. The10,000- and 20,000 -ohm units can be


TOP OF BOXTO COMMON OUTPUT TERMINAL OR LOWER DECADE

B ELITE BOARD

TO NEXTDECADE OR

HIGHEROUTPUTTERMINAL

ADJUSTINGRESISTORFOR R2(OPTIONAL)

DECK B

DECK ANEARESTPANEL

ADJUSTING RES FOR RI(OPTIONAL)

Fig. 2-Switch and Bakelite board wiring,rear view. Photographs show further details.

5 wirewound power resistors, 5% or better, 10 watts,one of each: 1, 10, 100, 1,000 and 10,000 ohms

5 wirewound power resistors, 5% or better, 20 watts,four of each: 2, 20, 200, 2,000 and 20,000 ohms

5 rotary switches, 2 gangs, 2 poles, 11 positions, short-ing type (Mallory 1221 L) with dial plates and knobsas desired

1 dual binding post10 brass spacers, 3/s -inch OD., hole for No. 6 screw,

unthreaded10 machine screws, 5-40 x 1 V2 inches, and nuts50 spade mounting boltsBakelite (see text)Hookup wire, chassis, miscellaneous hardware

ADDEDSPACER

Interior view of the completed box.

chosen "short", and resistance added inseries. The trimming resistors must bewattage -rated to stand more than themaximum voltage rating across the wire -wound resistor. By this adjustment, thebox error at room temperature (could bebrought down to 1% or less. Wirewoundswill ordinarily gain 1/2 % between roomtemperature and current -rated hotcondition.

Switch wiring is in Fig. 2. Malloryswitch 1221L seems to be the only cata-log item adequate to carry the current.The switch must be a shorting (make -before -break) type to prevent openingand closing the circuit on high current.The four -resistor decade switch (MalloryI54L) will not do for this box becauseof the low current capacity of the 1, 2,3, 6 combination.

There is a momentary short be-tween positions 1 and 2 (Fig. 1). This is

Decade switch detail.

BAKELITE BOARD

TRIMMING RESISTORS

noted on my box by a decal zero affixedbetween positions 1 and 2. Commercialboxes using this circuit (e.g. Leeds &Northrup 4775) normally fail to tell youthat, with sometimes unpleasant conse-quences. But when you know the limita-tion, it is always easy to switch inadditional resistance temporarily whilecrossing this zero.

The 21/2 x 23/B -inch mounting plat-form for the resistors was cut from1/4 -inch scrap electrical Bakelite. (Donot use cloth -filled Bakelite, which iselectrically too leaky.) Spade lugs weremounted on the long side, and this plat-form affixed to the switch with 11/2 -inch5-40 bolts through 3/8 -inch unthreadedbrass spacers. These dimensions are pre-cisely right for this switch; no cutting orfiling has to be done. The wirewoundswere then soldered to the lugs, the switchwired, and the adjusting resistors at-tached to the switch lugs as necessary.Actually, the box would have been quitegood without these adjusting resistors:the maximum error was 2%.

I provided separate outlets for 9and 99 ohms to circumvent the contactresistance of the three higher switches.Actually, this contact resistance provedto be very small, and I would now omitthese outlets. The dual binding postsanchor easily and firmly to the chassis.

If the Mallory switch index mecha-nism appears too stiff, remove one of theindexing wheels and, only if necessary,bend the resulting free spring end so thatit does not touch the index track. Youcan wait to make this adjustment untilafter the decades are installed in thechassis.

To apply decals, I use an eye loupe,small brush and toothpick. Let decalsdry overnight, then lightly spray (don'tbrush) with lacquer thinner to makethem adhere. END

JULY, 1964 29

CAPSTAN SLEEVES AND SPEED CHANGES. Many imported machines are equippedfor both 50- and 60 -cycle operation. Most inexpensive models use capstan sleeves toadjust speed accordingly. Photograph shows three capstan sleeves used on Daiwa(Japanese). It is a two -speed machine, so it needs four capstan sizes: two speeds at 60cycles, and two at 50. Fourth size is capstan diameter itself, not shown.

On a ma chine with mechanical shift, usually only one sleeve is needed to change

frequency.Should you want to figure speed of two- or four -pole motors, use 120 F/N. If F is

power frequency in cycles and N is the number of poles, the result is the speed in rpm.A 50 -cycle motor on 60 -cycle current runs about 20% too fast. Easiest way to reduce

speed is to reduce capstan diameter by 20%.When you run a "switchable capstan" machine on 60 cycles, select smallest sleeve

for 31/4 ips and second largest for 71/2 ips. Smallest sleeve is usually capstan itself; whenthere are four sleeves, disregard capstan diameter.

On more expensive recorders frequency is changed by replacing motor pulley andchanging motor capacitors, taps, etc.

These seven service tips grew out of

actual experiences, and can save you lots of time

ACTIVATOR ARM

ECCENTRIC NUT (CAM)

PIN ENGAGESSWITCH BARBELOW

WOLLENSAK 1500 AND 1600. A Wollen-sak 1500 came in recently with a complaint oferratic playback. We confirmed it and foundthat record/play switch lever arm was notlined up with mechanical actuating mecha-nism.

We corrected this by adjusting the cam -pin (see photo). Put machine in "play" andadjust plastic nut until operation is normal.Check "record" position and seal nut withservice cement. Wollensak 1600 uses sametype of switch-trouble has come up in those,too.

NOTES FROM A TAPERECORDER SERVICE BOOK

WATCH THAT REEL! Some recorders still use old -type reel with smallcenter (see photo). Though this was popular and practical some years ago,many modern machines do not have automatic tape tensioning and are designedto provide constant tape speed with standard 2'/4 -inch -center EIA reel. Whenold-style reels are used on newer machines, speed may decrease near end ofreel because of increased pulling force required. During rewind machine issubjected to far greater stress than it is designed to take, and so are tape andtape guide parts.

Prerecorded tapes are usually supplied with large -center reels, becausesmaller angular variation of tape on supply reel means less variation intape drag and less flutter.


NORELCO/PHILIPS BRAKE. Photo showsbrake arrangement on Norelco/Philips series200. (Also, 300, 400.) When tape spindle runscounterclockwise, rubber strip acts only as slightdrag and cork pad brakes. When direction isreversed, rubber strip brakes by catching drumat angle that throws strip back against brakeassembly platform. Platform shown is takeupspindle; supply spindle has same arrangement.

Idea behind this is to insure that supplyreel is stopped quickly with rubber strip andtakeup .reel slowed gently by cork pad, regard-less of direction of tape travel. Smooth, tangle -free operation with minimum of brake parts.

Machine is shown here in playback positionwith brake off.

By STEVE P. DOW

KORTING 158S LIMIT SWITCH. Limit switchcanceling bar on this machine prevents auto-matic stop from operating during loading orrewinding. Bar seldom causes trouble on itsown, but any change in backswing of capstanroller arm directly affects it. May cause tape tospill.

To adjust bar, bend end nearest capstanroller arm slightly forward, advancing tripswitch further into correct position.

Be sure machine operates normally forregular cutout operation. Do not adjust capstanroller arm-you'll have to tamper with severalother critical adjustments.

TAP] Usual remedy here is to clean heads and pads. This usuallyworks only for a while. This trouble is generally caused by mechanical oscillationcif some part-like the spring -loaded pressure arm shown in the photo. A goodcure is to cement small damping pad of foam rubber onto the arm so as not tointerfere with normal operation.

Photo shows tiny square of foam rubber cemented to arm between heads.Use alligator clip to hold pad while cement dries.

HI -LEVELAUDIO FROMRECORDINGAMPLIFIER

NORMALADJUST

NE -45

(ii -

8+

DISTORTD JUST

TA PE FEF.:!_ER LEF7 GUIDE POST

CAPSTAN ROLLER ARM /PIVOT SCREW

NEON LEVEL- INDICA-TOR POSITION. Manymachines use NE -45 neonlamp as record -level indi-cator in circuit like thatin schematic. During nor-mal levels only one side oflamp lights. Above presetmaximum level, bias isovercome and ac signalflashes both sides.

Recorder control panelis usually lettered withNORMAL and DISTORT, orsuch. When you replacethis kind of lamp, be sureto line it up so the ele-ments inside it correspondto the panel markings. Se-cure with drop of cementto prevent loosening androtation.

Photo shows Wollensak1500. Lamp is securedwith piece of tape. END

TRIP SWITCH BARRESTORATION SPRING

LIMIT SWITCHCANCEL BAR

JULY, 1964 31

HAVE YOU EVER MADE A SERVICE CALLwhere a familiar -looking radio or TVset had a strange name or the name ofa well-known mail -order -house or chainstore? Your familiarity-or lack of it-with these "private -brand" sets dependson how long you have been in the radio-TV game.

What is a private brand? We areall familiar with the big brand names-Zenith, RCA, Westinghouse, etc. Thesecompanies put their own brand nameson the sets they make. Private -brandsets are made by a manufacturer whosells his sets to a retail store company.Private -brand retailers include chainssuch as Sears, Roebuck; MontgomeryWard, Western Auto Supply and Gam-ble Stores. Outlets of one or all of theseare found in cities of 5,000 or morethroughout the United States and Can-ada. Although I could find no figuresto prove it, I believe that these fourcompanies account for the largest shareof radios, TV's and stereo sets soldtoday.

Probably your next question is,"Who makes private -brand equipment?"

Private -brand radios, TV sets, uhfconverters and other home entertain-ment equipment are made by severalvery large as well as many small com-panies. At present, the field is dominatedby three large manufacturers. One, War-wick Manufacturing Co. in Chicago, isa captive plant of Sears, Roebuck & Co.The other two supply numerous retailorganizations and are Wells -GardnerElectronics Corp., Chicago, Ill., andTrav-Ler Industries Inc., whose officesand laboratory are in Chicago and whoseassembly plant is at Orleans, Ind.

Several companies make private -brand automobile radios for Ford,Chrysler and Rambler. The Delco RadioDiv. of General Motors is a GM sup-plier and makes Studebaker radios too.

Another private -brand operationthat was really big was the uhf converterbusiness. One company (P. R. MalloryCo., Inc.) made several thousand con-verters a day for 20 or more of the best-known names in the industry. Some ofthe smaller private -brand manufacturersare listed in the chart with several ofthe name -brand companies that havebuilt private -brand sets.

Many small auto parts chains, fur-niture stores, five-and-dime stores anddrug stores have had their own brandnames. You will also remember thatonly last year RCA was making colorTV chassis for every company in theUnited States except two. The other setmanufacturers bought the chassis fromRCA, mounted them in their ownnets and put their own brands on. Thismay have been the largest private -brandoperation of all time.

The charts are intended to give youquick, concise information that will help

By L. A. JAMES

Private Brands Who Makes 'em?Think you've seen that same chassis before

with a different name? You have!

Both of these uhf converters were made bythe P. R. Mallory Co. The one on the topcarries the Mallory medallion, while theone on the bottom carries the name Arvin,trademark of Arvin Industries, Inc.

you identify strange sets by their brandnames. Most of the sets in use sinceWorld War II are listed here. Some soldonly in limited markets haven't been in-cluded because of lack of space. Thecolumns, reading from left to right, list:

1. The trade name on the radio orTV set, with a notation of the re-tail company selling it.

2. The name of the company actu-ally making the set.

3. The code letters in the model num-ber that designate who made the

set. Not all manufacturers includethis code.

4. The EIA identification number as-signed by the Electronic IndustriesAssociation to member companies.

5. The address of the set manufac-turer, not of the retail company.

Most electronic components are in-terchangeable from one model to an-other, but there comes a time in everyserviceman's life when he needs a specialpart-a cabinet, a coil, a dial glass, atransformer, a speaker or some otherpart obtainable only from the factory.This is when the chart will come inhandy. A letter to the company will usu-ally bring information on how to get theneeded part. Most set manufacturers arevery cooperative when it comes to sup-plying parts to insure customer satis-faction. The repairman is often the onlylink between the manufacturer and thecustomer. Many people who retail pri-vate -brand sets have no repair facilities,and farm out their repair work to pri-vate service contractors.

Using the information in the ac-companying tables and on the name-plates of the sets will make your repairwork easier and more profitable.

[Merit Coil & Transformer Corp.,Merit Plaza, Hollywood, Fla., publishesa catalog (Form 810) which carries onpage 57 a list of manufacturers andtrade names. No addresses are given,but the list includes some names not inthe table published here. The Guide Sec-tion of the Triad Replacement Hand-book for Professional Servicemen (TriadDistributor Div., 305 No. Bryant St.,Huntington, Ind. contains similar infor-mation, with part numbers.-Editor]

The small Airline radio on the right was made by the Kingston Products Corp. for Mont-gomery Ward. With different -colored knobs and a Kingston decal, we have another model.


WHO MAKES AND SELLS PRIVATE -BRAND SETS

TRADE NAMERETAIL OUTLET

OR AUTO MAKEMFR. NAME

CODE

LETTER

EIA

CODEADDRESS OF MANUFACTURER

Arvin Ind., Inc. 248 1513 13th St., Columbus, Ind.Many department stores Trav-Ler Ind., Inc. 571 W. Jackson Blvd., Chicago, Ill.

AMC 320Also Orleans, Ind.

Wells -Gardner Electronics 334 2701 N. Kildare Ave., Chicago 39, Ill.

Audio Industries GAA W. 4th St., Michigan City, Ind.

Pentron GPL 1214 N. Wells St., Chicago, Ill.Trav-Ler Ind., Inc. GTC 320 Chicago, Ill. Also Orleans, Ind.

Wells -Gardner Electronics WG 334 2701 N. Kildare Ave., Chicago 39, Ill.Philco Corp. GPS 260 C and Tioga Sts., Philadelphia, Pa.

Airline Montgomery Ward Westinghouse GTM 337 Box 71, Metuchen, N. J.Esquire Radio Corp. GEN 742 6201 15th Ave., Brooklyn 19, N.Y.

Waters Conley Co., Inc. JWR 382 645 N. Michigan Ave., Chicago 11, III.Belmont Radio Corp. BR (Out of business)Kingston Radio Corp. KR (Out of radio business)

Airline, Riverside Montgomery Ward Automatic Radio Sales, Inc. FJB 120 122 Brookline Ave., Boston 15, Mass.

Allstate, Silvertone Sears, Roebuck Various

571 W. Jackson Blvd., Chicago, Ill.Ambassador Various Trav-Ler Ind., Inc. 320Also Orleans, Ind.

Bendix Radio Div. 125 Baltimore 4, Md.American Motors American MotorsMotorola, Inc. 185 9401 W. Grand Ave., Franklin Park, Ill.

Bradford W. T. Grant & Co. Wells -Gardner Electronics WGEC 334 2701 N. Kildare Ave., Chicago 39, Ill.

Buicl,

Cadillac GMC Delco Radio Div. 466 Kokomo, Ind.Chevrolet

571 W. Jackson Blvd., Chicago, III.Columbia CBS Corp. Trav-Ler Ind.. Inc. 320

Also Orleans, Ind.

571 W. Jackson Blvd., Chicago, III.Trav-Ler Ind., Inc. 320

Also Orleans, Ind.Coronado Gamble Stores Elco Michigan City, Ind.

Hinners-Galanck Not knownWells -Gardner Electronics TV2 334 2701 N. Kildare Ave., Chicago 39, III.

571 W. Jackson Blvd., Chicago, III.Firestone Firestone Tire & Rubber Co. Trav-Ler Ind., Inc. 320Also Orleans, Ind.

Bendix 125 Baltimore 4, Md.FordFord Motor Co. Motorola, Inc. 185 9401 W. Grand Ave., Franklin Park, Ill.Mercury

Bendix 125 Baltimore 4, Md.

Bendix 125 Baltimore 4, Md.Mopar Chrysler Corp.Motorola, Inc. 185 9401 W. Grand Ave., Franklin Park, Ill.

Oldsmobile GMC Delco Radio Div. 466 Kokomo, Ind.

Symphonic Electronic Corp.Penncrest J. C. Penney Co.

Arvin Industries 248 1513 13th St., Columbus, Ind.

Pontiac GMC Delco Radio Div. 466 Kokomo, Ind.

Renault Ford Motor Co. Motorola, Inc. 185 9401 W. Grand Ave., Franklin Park, Ill.

Warwick Mfg. Co. 332 7300 N. Lehigh Ave., Chicago 48, Ill.Silvertone Sears, Roebuck Waters Conley Co. 382 645 N. Michigan Ave., Chicago 11, Ill.

Arvin Ind., Inc. 248 1513 13th St., Columbus, Ind.

Studebaker GMC Delco Radio Div. 466 Kokomo, Ind.

Triumph Ford Motor Co. Bendix 125 Baltimore 4, Md.

571 W. Jackson Blvd., Chicago, Ill.Trav-Ler Ind., Inc. 320

Also Orleans, Ind.Hinners-Galanck Not known

Truetone Western Auto Supply Co. Wells -Gardner Electronics 2DC 334 2701 N. Kildare Ave., Chicago 39, III.Elco

Esquire Radio Corp.

4DC

DC 742

Michigan City, Ind,

6201 15th Ave., Brooklyn 19, N. Y.Arvin Ind., Inc. 248 1513 13th St., Columbus, Ind.

Volkswagen Ford Motor Co. Bendix 125 Baltimore 4, Md.

JULY, 1964 33

By JACK DARRSERVICE EDITOR

Fig. 2-Embryonic sweep curve: not enough width (sweepdoesn't cover wide enough frequency range), phasing slightlyoff, and retrace blanking turned off.

Fig. 3-Sweep width OK, curve well centered, but phasing stilloff. Curves should coincide exactly.

SWEEP -ALIGNING TV IF'SWHAT A SWEEP CURVE MEANS, HOW TO MAKE IT, HOW TO LOCATE IMPORTANT FREQUENCIES

LAST MONTH, WE COVERED SINGLE-FRE-quency alignment of i.f. stages. Now let'ssee how to sweep -align the same cir-cuits.

What is sweep alignment, anyhow?Why do we use it? Same reason weuse any "dynamic" test in any circuit-it gives us a better picture of whatthe circuit does under actual operatingconditions, which is what "dynamic"means. Instead of using a single -fre-quency rf signal, we use a signal froma special generator whose output sweepsfrom one end of the band to the other.

By displaying the result on a scope,we can see what the circuit response is

to all frequencies simultaneously. (Or,at least, at intervals of 1/60 second,which is close enough for me.)

We must keep the swept signalfrom the generator exactly in step withthe horizontal sweep of our scope to beable to lock the pattern. So we sweepboth of them from the handiest source,the 60 -cycle sine waves from the acpower line. About this time, someoneasks the question, "But doesn't a sine -wave sweep give you distortion? Whydon't we use a sawtooth sweep?" Yes,Elmer, it would cause distortion, unlesswe swept both from the same source!Since we do, it means that the scopesweep and the frequency sweep are insync at all times. We could use a zig-zag sweep and they'd still be in step, aslong as both are swept from the samesource,

Another question-does a sweepgenerator have to be absolutely accu-rate? The answer is no. All this genera-tor has to do is generate a reasonablyfiat rf output over the entire band offrequencies being swept; in this case,from about 40 to 47 me (minimum).In other words, its output must havethe same amplitude at all frequencies asit sweeps the band. If it has a peak atone end or the other, this could cause

ZERO -BEAT POINT(MARKER & SWEEP AT SAME FREQ

BEAT-FREQ TOO BEAT-FREQ TOOHIGH TO BE SEEN HIGH TO BE SEEN

Fig. 1-a-Expanded view of unbypassed markerpip. It's too wide to be useful. In Fig. Lb, thescope's vertical input terminals have beenshunted with a small capacitor, which bypassesthe higher beat frequencies (the ones fartherfrom the center of the marker), leaving only thelow ones near zero -beat point. Nice, sharp pip.

distortion of the scope trace. (Not ofthe i.f. strip: just of the scope trace!)However, most commercial sweep gen-erators are pretty flat, so you won't haveto worry too much about it.

After we get a sweep curve fromthe generator set up on the scope, wefind the location of each frequency byfeeding in markers. Now, a markergenerator has to be accurate. Should bewithin about 1%. If it isn't, our pointson the curve will be way off.

Markers can be fed into a circuitin two ways: through a marker adder,which is by far the best way, since themarkers are actually added to the signalafter it has gone through the i.f. stages(see "Marker Adder for Your SweepGenerator," RADIO -ELECTRONICS, July1963, page 62) or by feeding them intothe i.f. input along with the sweepsignal.

Markers are single rf frequencies.As the swept signal passes a marker, itquite naturally beats with it, producingthe familiar zero -beat. In this case, wecan't hear it, but we can see it. Amarker beat on a curve looks like Fig.1-a. This is pretty fuzzy. To get rid ofthe fuzz, we add a small bypass capaci-tor across the scope input terminals.(Something like a .001 /if- not toocritical.) This bypasses the higher fre-quencies and leaves us with a nice sharp"pip" (Fig. 1-b). The sharply definedpips give a better idea of where eachsignificant frequency is on the curve.


Fig. 4-Zero bias on i.f. stages makes them saturate with evensmall rf input voltages. Curve is flat even when alignmentis way off.

Instrument setup for a sweep jobWhere most of us get into trouble

is in the first setup of the test equip-ment, particularly in adjusting the sweepgenerator. In a normal sweep, you canget quite a few different curves, veryfew of which look anything like "whatit shows in the book"! Now we'll show

to get all of these wrongcurves, and also how to identify theright ones.

First, set up the instruments as nearto each other as possible. Ground allcases together. Turn 'em all on and letthem warm up for a few minutes. Setup the TV chassis so that you can getat the alignment adjustments easily. Inmost cases, it makes things easier if youkill the horizontal sweep. It causes"hash" in the patterns, and we'll haveenough trouble as it is.

If the tube heaters are in parallel,pull the horizontal output tube (neverthe oscillator!). If yours is a "series"chassis, best way is to open the cathodeof the horizontal output tube. You canunsolder a wire or make up an adapterwith the cathode open. It's not a goodidea simply to lift the top cap off. Youmight damage the tube by drawing toomuch screen current.

If we kill horizontal sweep, wealso kill keyed agc stages! So we mustuse a bias box on such sets to take theplace of the missing agc voltage. Set thisto whatever the alignment instructionscall for.

Now we're about ready to go. First,connect the sweep generator output tothe i.f. input. The alignment instructionsusually tell where and how to do that:loose tube shield over the mixer tube,looker point on the tuner, etc. Connectthe scope, with a direct probe, across

Fig. 5-Same conditions as in Fig. 4, but bias is more nearlycorrect. Curve is beginning to look right.

the video detector load resistor (instruc-tions usually give you this, too). Setthe scope sweep to EXT, and connect alead between that binding post and thehorizontal sweep output on the sweepgenerator. A lot of scopes have a built-in 60 -cycle sweep, marked LINE on thesweep selector switch. If there is aphasing control with it, you can useeither that or the one on the sweepgenerator.

Next, set up the sweep generator.The main dial is set to the center ofthe i.f. band, in this case about 44.0 mc.We've got to sweep a band of frequen-cies at least 4.5 mc wide, and we wouldlike to see what's going on for a littleway past, so set the sweep width con-trol at about 10 mc. Now our signalwill sweep from 39 to 49 mc-plentyof room to get outside of the bandpassand give us the full picture. Turn theoutput attenuator (rf output from thesweep gen) to maximum.

Now, with the TV set turned on,you ought to get something on thescope. Set the vertical gain high. Youought to see several vertical lines on thescreen. These will be the sides of the re-sponse curves you want. Turn the verti-cal gain down until you can see thewhole pattern. Keep the scope gainpretty high. In fact, it's best to turndown the rf output of the sweep genera-tor, although either one will do it. Ifyou see any signs of flattening on thetop of the curve as the rf gain is in-creased, turn the generator rf outputdown, and bring the pattern height backup with the scope's vertical gain con-trols.

Funny pictures on the scopeNow the fun starts. Look at your

pattern. Look like anything you've ever

seen? Probably not. You'll probablyhave some wild -looking thing like Fig. 2.You may have several curves, in fact.Let's find the right one.

First step, get the sweep in phasewith the scope. Move the phasing con-trol until you can see the patterns startto overlap. Move slowly: sometimesthey're hard to recognize! You shouldbe able to find some place where youcan see definitely that you have a traceand retrace that are alike. Now, if you'llturn on the horizontal blanking control,one of them will disappear. Both ofthem can be seen in Fig. 2. Anothercommon fault shows in Fig. 2: notenough sweep width. This was delib-erately set up to illustrate this point. Seehow the curve has one leg in the air?This means that the generator isn'tsweeping far enough to cover the i.f.band. Fig. 2 was made with 4-mc sweep,in fact.

Now let's correct the faults. In-crease the sweep width to 10 mc. Thisbrings both feet back to the ground.Moving the dial of the sweep generatorslightly brought the curve to the centerof the scope screen.

Now look at Fig. 3. The phasingisn't right yet, but I left it there to showyou that each trace consists of twotraces; by the position of the singlemarker, you can see that only a littlebit of movement (phase adjustment)will make both overlap. Turning theblanking on will eliminate the retracecurve and make things less confusing.

If you can't get a curve at all,check every connection, especially thebias -box setting. Too much negative biaswill cut off the i.f. amplifier tubes, andyou'll get nothing but a straight line. Setthe bias to make a good curve; don't

JULY, 196435

be afraid to experiment with it a little.See what too much bias and too littlebias will do.

The curve of Fig. 4 was made withno bias at all (zero). Note the weirdshape and the "flat -topping". Watchout for this! If your curves ever showa very distinct, sharp -cornered flat -top,you're more than likely overloading theinput! You can't get any results at allthat way. When you see a flat -top, re-duce the rf input or increase the bias(more negative). Either will bring thecurve back down to where it should be.Best way is to reduce the rf from thesweep generator.

Fig. 5 shows the curve of Fig. 4,with the proper bias. Now, this begins

far toward the edge of the band. In thisinstance, instead of the correct 44-mcsetting, it was around 39 mc. So we'reactually sweeping only about half of theband, and we get the peculiar markeraction.

Cure: first, overlap your curveswith the phasing control. Second, checksweep width and center -frequency set-ting. Finally, check the position of thecurve by adding markers. When you getset right, the markers will behave better.By running a marker up, across anddown the other side of the curve, you'llbe able to tell when you've hit theright curve.

Keep your marker amplitude aslow as possible, to avoid distorting the

Fig. 6-How your curve will look when you do everythingwrong!

to look more like it. You can see afairly symmetrical top on the curve, plusthe characteristic "sound notch" on theleft side. There are no markers on thiscurve.

How to misalignI promised to show you how to

do it wrong, and I will. Look at Fig. 6.This curve has everything wrong with it!One of the distinguishing characteristicsis the peculiar action of the markers. In-stead of sliding along the curve as theyshould, you'll get two markers. Whenthe marker generator dial is moved,they'll promptly run together and disap-pear! Or run off the ends and disappear!Also, we've got a squarish -looking loopinstead of a curve. This is caused by thehorizontal phasing being as far off aspossible: 180°! You can also get thispattern as a sort of "squared -up U"shape from the same cause.

The markers act the way they dobecause the sweep generator is set too

curve. Fig. 7 shows the same curve, butwith the marker generator turned wideopen. See what happened? Even thephasing went off!

Best way to use markers: set upeach frequency you need, as specifiedin the alignment instructions, and locatethe marker on the scope trace. Markits location on the plastic screen with agrease pencil. Unless you move thesweep generator dial, this position willremain on that frequency. Mark each ofthe frequencies you need: sound carrier,pix carrier, color, etc., and you canshape up the curve accordingly. Afteryou find the marker locations, turn themarker generator completely off or dis-connect it. This way, you'll know that

Fig. 7-Too-high marker signals mess up entire curve.

400% MODULATION ON MARKER GEN

traps is tomodultaed marker signal at trap's

frequency. When ripples along base linedisappear, trap has removed marker.

Fig.use

8-Simple way to align

it couldn't be the cause of any curve dis-tortions.

Ordinarily, we use unmodulatedmarkers to get cleaner pips. However,we can set traps a lot easier if we simplyflip on the 400 -cycle modulation and setthe marker generator at the trap fre-quency. Now, our patterns will looksomething like Fig. 8. If the trap isoff -frequency, you'll see the audio mod-ulation in the form of "squiggles" alongthe base line, with the sweep still on.Just tune the trap for the least squiggleson the base line, and there you are;that frequency has been neatly removedfrom the circuit.

So there it is. We've not onlyshown you how to do it right, but howto do it wrong! By taking advantage ofthe errors shown here, you won't haveto bother making them yourself. Fromno other technical magazine do you getthis service! Aside from this, if you fol-low the alignment instructions in theservice data, you've got it made! END


EQUIPMENT REPORT

Knight -Kit C-555 CB Transceiver

A 100 -Mw CITIZENS -BAND TRANSCEIVERmust have a receiver with good selec-tivity and sensitivity. The superhetro-dyne receiver in the Knight -kit C-555does not pick up adjacent -channel sig-nals with the desired ones, as do manysets with superregenerative circuits.

The single transistor in the trans-mitter can be heard more than fourtimes as far as with a superregen receiverunder the same suburban QRM condi-tions. In open country away from otherCB traffic, the improvement is not asapparent.

By carefully tuning and retuningboth C -555's for maximum signals (asthe distance between the two units isincreased), it is possible to communicatebetween units nearly a mile apart.

The instructions tell you to tune thetransmitter of the C-555 before theprinted -circuit chassis is mounted in itscase-before the whip antenna is con-nected.

A small lamp is supplied as a tuningindicator. With pigtail leads soldered on,it is soldered to the output coupling loopon the printed -circuit board of the tankcoil (L4 in the schematic).

The slug inside the coil is adjustedfor consistent oscillator operation-itshould glow each time the TRANSMITbutton is pressed.

When the adjustment has beenmade and the lamp unsoldered, the whipantenna connected and the printed-cir-

Allied RadioThe C-555 in use.

ANT 56PF RCVR OSC-MIXER

XTALT200=--

.0015 PF

L61.5µH

PHONES

IK

= XTAL

XMIT OSC

5.I I< .005n;

Inn CHASSIS GND

a; 9V BATTC

1000SPKR

cult board mounted in the plastic case,the tuning will change slightly. Thechange is not enough to be noticed un-less you are striving for maximumdistance.

The transmitter should be tuned formaximum output with a field -strengthmeter when you want to communicateover the longest possible distance. Aslight slug adjustment will often show anincrease over the original setting. If afield -strength meter is not available, ornot sensitive enough, a receiver with anS -meter can be used when tuned to thefrequency of the C-555.

The tank coil (L4) is not the onlyinfluence on the output-the whip an-tenna can also change the ERP (effec-tive radiated power) since it (along withL6) is a tuned circuit too.

Antenna tuning affects directionalcharacteristics. A A/2 (half -wave) an-tenna has, for all practical purposes, adoughnut -shape radiation pattern-butonly when it is tuned exactly to a halfwavelength-an electrical A/2, which dif-fers from the measured length becausecurrents travel at a different speed alonga conductor than through what is com-monly called "free space" (air).

Transceiver antennas should also beoriented with regard to one another-as near parallel as possible. When thewhip antennas are at a skew angle toone another, the signal strength is re-duced-just like turning a TV antennaaway from the station antenna.- ElmerC. Carlson.

MOD/AF OUTPUT

1000

10

.021

oT

18 K o l -.0033

4.7K ÷ 10 rn1 0

60 +.ON -OFF

12K

AF AMPL

100 K

12K

470U

VOLUME

1.0033

CAPACITORS IN p.f, UNLESS SPECIFIED

The C-555 uses crystal control in the receiver as well as the transmitter.JULY, 1964

-.37

Two -transistor circuit countsmoney, sizes objects.

Front of perforated board the entire chassis. At left, two photocellsconnected for testing. Power supply separate.

Try a Selective Photocircuit

MOST PHOTOELECTRIC CONTROL CIR-

cuits are designed for simple on-off op-eration, as in counting or safety devices.This circuit, however, is far more versa-tile. Besides the usual on-off countingoperations, it can also selectively countobjects of different sizes. It can countonly objects which move in one direc-tion; it can prevent an operation whena condition is not satisfied, and so on.

Fig. 1 shows the entire schematicdiagram. Two photoconductive cells areshown in each circuit branch to thebase of the first transistor. As many pho-tocells as desired can be used in eachbranch, provided they all normally re-ceive plenty of light. Let us call cells P1and P2 the "action" cells, and P3 andP4 the "inhibit" cells. When light isblocked from the "action" cells, the ef-fect is to decrease the negative bias onthe base of Ql, which would tend tomake the transistor conduct (this is ann -p -n transistor). Normally the cellshave a low resistance when lighted andthe high negative voltage applied to thebase through the cells keeps QI cut off.Thus blocking the light on P1 or P2 hasthe effect of inserting a high resistance

By TOM JASKI

in series with the bias source, and Q1will conduct. Depending on the settingof R2, this will increase or decrease thecurrent through Q2, and will either at-tract the relay armature or release it.

PHOTO CONDUCTIVECELLS (4)

2N438OR

2N448

Normal operation should call for the re-lay to be energized when light is blockedoff from the "action" cells.

Now if we also block the light tocell P3 or P4, Qrs base will again be

2N241 -A TO

Q IQ2 ))--. CONTROLLED

CKT

RI-pot, miniature, 1 megohmR2-pot, miniature, 50,000 ohmsR3-4,700 ohmsCl, C2-500 pi, 15 volts, electrolyticDI, D2 -1N91 or equivalent01-n -p -n transistor (2N438, 2N448, 2N1306 or

equivalent)Q2-p-n-p transistor (2N241A, 2NI307 or equivalent)S-spst switch

-12V T-24-26 vct, i-amp filament transformer (StancorP-6469 or equivalent)

Relay-Lafayette F-260Photocells-Lafayette cadmium sulfide cells, catalog

No. MS -855.Miscellaneous hardware, perforated board, etc.

Fig. I-The circuit. Any number of photocells can be used in each leg.


OBJECTCOUNTED

Other side. Tiny, but uncrowded.

INHIBIT SLOT

PHOTOCELL BEHIND SLOT

ACTION SLOTOBJECT NOTCOUNTE5

Fig. 2-Direction-sensing arrangement.Slots should be about 14 by 1/16 inch.

OBJECTS COUNTED

ACTION INHIBITSLOT SLOT

)fr'1-.:1 ACTION

SLOT-+fs OBJECT

NOTCOUNTED

Fig. 3-Here, large and small objectsare counted, medium-sized ones pass bywithout registering. Fineness of discrim-ination depends on slot placement.

INHIBIT HOLES ACTION HOLES FOR QUARTER 3/32" DIA EA1/16" DIA EA --S- _O

-QUARTER 7.5'_ - DIME SIZE.

------kVNICKEL ............-:

DIME INCLINED MONEY-CHUTEACTION HOLES FORNICKEL a DIME 1/16" X 3/16" EA

Fig. 4-Money counter. Slots are set upto count in terms of smallest value(nickel), not smallest size (dime). Nickelactivates only second "action" hole;dime, first and second (two counts);quarter, second through sixth (fivecounts). Five more holes are needed tocount half dollars. Rate depends on holespacing and coin speed.

negatively biased, because of the highresistance inserted "in shunt" with thebase circuit. The balance of the circuithas been changed, and Q1 will oncemore be cut off. If one cell in the P3-P4circuit is blocked before the light isblocked from the "action" cells, these"inhibit" cells will prevent operation ofthe circuit.

H !.--3/32"

4[¢¢C)PHOTOCELL

SECTION OF CHUTE

/I I, 0

0 0

0

CADLAMP

So?This opens up all kinds of possi-

bilities for selective operation. For ex-ample, the simple arrangement in Fig. 2provides unidirectional counting. Ob-jects coming from the left will be count-ed, but objects coming from the rightwill not. An object coming from theright will obscure the inhibit cell open-ing before the "action" cell is blocked.But an object coming from the left willblock the "action" cell before enough ofthe "inhibit" opening can be blocked.

Fig. 3 shows how the circuit canbe used to discriminate between objects

of different sizes. The circuit will countlarge objects and small, but will ignoremedium -size ones. This kind of arrange-ment could be used to reject over -and undersized objects, passing only theproper size. Some "reject" mechanism,rather than merely a counter, can thenbe operated by the relay. (Consider allthe items in our economy that are sortedby size, from jelly beans to Florida or-anges!) Different sets of "selective" cir-cuits can grade such objects with greatspeed. The same idea is applied in Fig. 4for counting coins. When a nickel passesby the slots, only one pulse will be re-corded. When a dime passes by, eventhough it is smaller than the nickel, twopulses will register. When a quarterpasses by the slots, five pulses will becounted. Voila-a money counter,which can operate as fast as the relayor readout device will operate-con-servatively, something like 10 coins persecond.

The circuit has many other appli-cations. It can be used as a secret lockon electrically operated doors. An ob-ject or animal taller than a human beingcould be blocked from entering. Youcan use it to solve the age-old questionof whether the refrigerator light goesout when you close the door. Shut offthe light from the action cell with thedoor, and, if the light inside the box goesout, it will prevent the relay from oper-ating. The inhibit cell has operated.

With a low resistance (approxi-mately 10,000 ohms) replacing the "in-hibit" cells, the circuit is converted to asimple counter. The cells can be mount-ed any distance from the control cir-cuit. The greater the amount of lightthat hits the cells, the more positive theoperation when the light is blocked.

AdjustmentWith lights on both sets of cells, ad-

just R2 until the relay just energizes.Then back off R2 until the relay justreleases. Block light from the "action"cells and adjust R1 until the relay justenergizes. Now the relay should de -energize when light is again admittedto these cells. The amount of light re-duction required for inhibition dependson the setting of R1. With the particularhole configurations of Fig. 2 or 3, somereadjustment of RI may be necessaryfor satisfactory operation. Anotherway of adjusting operation of the circuitis to control the amount of light whichreaches each type of cell (action or in-hibition), leaving R1 set in its initial po-sition. At some settings of R1, both setsof cells will become "action" cells. Inthat position the circuit acts as an "or"circuit: it will count objects passing byeither cell set.

Q2 can be replaced with a powertransistor. No other circuit changesneed be made. END

JULY, 196439

MULTIPLE GUN ASSEMBLY

CATHODE SEAL

HEATERCONNECTION

RF OUTPUTWINDOW

MULTIPLE -BEAMINTERACTION AREA

Multiple -Beam Klystron PushesBack Microwave Frontiers

New breed of tube puts out more continuous power at higher frequencies than anyone thought possible

COVERSTORY

By ERIC LESLIE

THE KLYSTRON - THE TUBE OF THE Fu-ture- handles far higher frequency sig-nals than the tubes we are used to. Avery different kind of tube, it has a spe-cial approach to the job of generating oramplifying signals.

To find out how klystrons work,let's see what happens in the output cir-cuit of an ordinary tube. For instance,take an audio signal generator, workingat, say, 1,000 cycles-the type that would

supply a bridge or similar device. Theoutput is produced across the secondaryof the transformer in Fig. 1. But thecurrent in the plate circuit of the tube,and therefore in the primary of thetransformer, is not alternating current.It is a direct current of varying strength.We have little surges of electrons flow-ing 1,000 times a second through theprimary winding. As each of thesebunches of electrons flows through theprimary, it creates a stronger -than -aver-age field around the core. This field actson the secondary and produces a truealternating current.

Thus there is not essentially sucha tremendous difference between alter-nating and pulsating direct current. (Amathematician would call the pulsating

current in the primary a direct currentwith an alternating current superim-posed on it.)

The klystron gets the same resultin a different way-a way that works atextremely high frequencies, where ordi-nary tubes become too inefficient. Kly-strons work from the uhf band to wellup in the gigacycles. (A gigacycle is1,000 mc.) One reason for its far betterhigh -frequency performance is that in-stead of external coils and capacitors(which would be mere bits of wire above1,000 mc), its tuning elements are insidethe tube. They are resonant cavities.

You have probably read articlesthat derived the resonant cavity from acoil and capacitor. The description startsout by showing the capacitor as two


plates with a single half -turn of wirebetween them. Then more half -turnsare placed in parallel with the first-re-ducing the inductance each time-un-til a solid wall has been built betweenthe two plates. If you haven't run intothis, Fig. 2 is the classical illustration,and you can get more detail in any text-book on klystrons. (Also, see "Klystron,Tube for Outer Space," RADIO -ELEC-TRONICS, February 1961.)

Here, let's just say that a resonantcavity tunes to a much higher frequencythan any coil-capacitor combinationcould, unless it were fantastically smallerthan the cavity.

This resonant cavity-or a numberof them, in most klystrons-is used to

in the bottom cavity, they repel elec-trons in the metal around them as theyapproach it. These electrons circulatearound the walls of the first cavity to thetop, producing a negative charge at thatend. (Because electrons are repelledfrom it, the bottom has a slightly posi-tive charge.) The first electrons travelingon through the resonant cavity nowapproach the second tunnel, repellingthe electrons from it back toward thebottom section of the first cavity. Thismakes it negative, while the top sectiontends to become positive.

As the bottom section becomes neg-ative, it starts to retard electrons ap-proaching it from the cathode, whilegiving those that have just passed it a

Fig. 1-Pulsating dc in transformer primary becomes ac in secondary.

bunch the electrons in the stream flow-ing through the tube to produce an alter-nating current like the one in Fig. 1.This is done by varying the velocity ofthe electron stream. For that reason,klystrons are called velocity -modulatedtubes.

Electrons in bunchesFig. 3 is a simplified sketch of a

single -beam klystron. Electrons areemitted from a cathode at the bottom,and picked up by the collector at thetop, which is maintained at a high volt-age. We want to convert this high -volt-age power, now being used to draw theelectrons through the tube, into an acpower source that can supply ultra -high -frequency power to an external circuit.

Let's suppose that the cathode ishot and that the high voltage has justbeen turned on. Electrons start fromthe cathode toward the collector. Asthey approach the first section or tunnel

boost.If the voltage (or rather the speed

of the electron stream) and the dimen-sions of the cavity are correctly matched,the cavity will resonate at its naturalfrequency and build up high alternatingcharges at the top and bottom ends ofthe resonant cavities. An rf drive signal,injected into the first cavity, will helpthe process.

This process tends to bunch theelectrons into groups by pushing thoseahead of each negatively charged areawhile retarding those coming toward itor, on opposite alternations, holdingback those above while attracting thosebelow. As the electrons travel throughthe tunnels between cavities, the bunchesare tightened as they catch up withslowed -down electrons ahead and arejoined by speeded -up ones from the rear.

The electron stream goes throughseveral other cavities, where the effect

Fig. 2-Classic derivation of microwaveresonant cavity from lumped -constant L -Ccircuit. In (a), schematic of ordinary coil -capacitor tank; b-highest possible fre-quency for discrete L -C components; c-"transition" step: paralleled "turns" to re-duce inductance; d, cylindrical resonantcavity, logical outcome of step c; e-klys-tron cavity.

is made greater as it passes through eachone. By the time the last cavity isreached, we have a true pulsating elec-tric current, the same as in our trans-former primary. The resonant cavitieshave slowed down the first electrons ineach bunch, and speeded up the lastones to where we have distinct "clumps"of electrons, traveling toward the col-lector.

As the electrons approach the lastcavity, they are organized into very tightclusters or bunches-one such bunch foreach rf cycle. These bunches of chargerepel the like charges in the metal gaptips of the last cavity. This action estab-lishes a very large voltage or electricfield across these tips.

To move across the gap againstthis large electric field, the electronsmust overcome the opposing electricforce. In so doing they give up a largeportion of their kinetic energy. This istransformed into microwave energy,which is piped through a section ofwaveguide located in the vacuum en-velope, then through a vacuum -sealing

JULY, 1964 41

COLLECTOR

Fig. 3-Principle of single -beam,multiple -cavity klystron.

window of special alumina ceramic ma-terial to the external waveguide.

Very large klystrons have beenbuilt. But voltage has to be increasedto increase output, and more power wasneeded than can be obtained from apractical single klystron.

The natural step would be to coupletwo klystrons together. This has beendone. In fact, as many as 8 have beencoupled. But external coupling circuitryis complex. Slight misadjustments cutefficiency tremendously and, if a single

Fig. 4-New G -E multiple -beamklystron, in part.

WATER INLET

F INPUT

HEATERCONNECTION

CATHODE SEAL

klystron fails, the whole group goes outof operation.

To avoid this, General Electric en-gineers developed the idea of buildinga new type of tube-one that would ineffect be 10 klystrons with a commongroup of resonant cavities. Fig. 4 showsa portion of that tube. The broken sec-tion in the center is occupied by a simi-lar set of cavities and 6 more electronbeams. This makes it possible to get 10time the power of a single klystron,while keeping many of the advantagesof single klystron operation. Since thecavities are common to the 10 beams,they must remain in phase. If a singlecathode breaks down, it simply meansthat one -tenth less power is produced.(By raising the voltage slightly, it mayeven be possible to compensate for that.)The General Electric 6601, shown onour cover, produces about 45 kilowattsoutput at about 8.4 gc, with a beamvoltage of 12.4 kv and a cathode cur-rent of 11 amperes - a little over 1ampere per gun.

In use, the tube is surrounded by amagnet coil, to focus the electron beams.Also important: The tube can be tunedover a range of 80 me by varying thecapacitance of the resonator. Coolingis needed to carry away the tremendousheat generated, so a water jacket circu-lates 30 gallons per minute around thetube.

Since the photograph on our coverwas taken, a larger tube, the ZM6602,with a 17 -kilowatt operating voltage anda cathode current of 17.5 amperes, hasbeen introduced. It produces 100 kilo-watts CW. Even larger tubes may bemade in the future. END

WATER OUTLET

COLLECTOR

MULTIPLE GUN ASSEMBLY

R F OUTPUT

WINDOW

TUNINGCONTROL

Align -and -Find MeterHere's a handy piece of equipment

that you can build in less than 2 hoursand for about $6. It takes the place of avtvm when aligning the rf and i.f. stagesof a receiver, and it will find the fre-quency of an unknown L/C circuit.Hence the name, Align -and -Find Meter.The unit (Fig. 1) is ultra -simple, accu-rate and reliable, and makes a worth-while addition to your bench. There'sno waiting for warmup, and the vtvm isleft open for other jobs.

IN34-A 0-IMA

Fig.t

Lead dress isn't overly critical. See Fig.2. I wired the circuit three ways, andvery short leads failed to show muchimprovement.

Make your test leads from a pieceof microphone cable instead of ordinaryhookup wire. Use miniature clips onone end and pin or banana plugs on theother. The center conductor connectsto J3, and the shield goes to J4, whichis ground.

Fig.Z

To find the frequency of an un-known L/C circuit, clip the leads fromJ3 and J4 across the capacitor, then con-nect the hot lead from your rf gene-rator to J1 and the ground lead to J2.Advance the rf output control until themeter climbs to about half scale. By ro-tating the signal generator's tuning dialyou will find the point of resonance foryour problem circuit and the needle willmove upscale. At that point where themeter peaks, your previously unknownfrequency can be read on the genera-tor's dial.-Bill Hutchison


WHAT'S NEWINSTRUMENTS THAT "REMEMBER" VOLTAGES hold any de-sired reading with an accuracy of of full scale, Movingcoil of meter movement is held by cushioned spring that pre-vents all movement as Ion as actuating solenoid is de -ener-gized. When new reading is desired, solenoid is actuated bypushbutton, releasing spring and allowing pointer to deflect.Pointer is "frozen" the instant that solenoid is energized, sooperator can easily read simultaneous indications of manymeters by actuating all solenoids with one pushbutton. West-inghouse has developed the new instrument.

LIGHTING BY THE YARD might be how you will specify Illumina-tion some time in the future. Sylvania's Tape-Lite comes inribbons up to 150 feet Hong that can be coiled, bent, twistedor tied in knots. Sealed in plastic, it works by electrolumi-nescence-phosphor excitation by alternating current. Tapeis only 1/32 inch thick, can be made in green, yellow,, whiteand blue,

THERMOELECTRIC EPDXY CEMENT COOLER works withoutmoving parts. Solid-state thermoelectric modules cool epoxyresin compounds to as much as 28°C below room temperatureto keep them usable twice as long. Disposable aluminum con-tainer tits in aluminum -lined cavity set flush in foam insulation.Three -position (center -off) switch selects high" or "low" cool-ing. Unit is made by Carter -Princeton, Princeton, N. J.

LATEST "GOLDEN EARS" let user locate sound remotely asthough he were present at source. Replicas of human ears arefastened to two condenser microphones, which drive two -chan-nel amplifier and semi -insertion condenser headphones. Sys-tem bandwidth is 40 to 40,000 cycles. Researchers have foundthat outer ear is vital to sound localization. Device (which costs$3,125) is being used for psychoacoustic research, trainingof newly blind persons, experiments in recording. Manufac-turer is United Research, Inc., Cambridge, Mass.

H--. -ci [I t 1

-1- - ,---r-r -1-1

-Ti1

_i_ H ![

I -Iii: -,-,- FT1

5 5 7 8 9100

2 4 5 7 84.114 2

FRECtENCO N. ER S?t3N1 D

0 2040

DECIBELSDEBUGGEDCringe at the thought of figuring ratiosto db and the other way 'round? It's easy!

By H. R. HOLTZ

CONVERTING A DECIBEL FIGURE TO Apower or voltage gain (or loss) is a simplemathematical proposition. But it as-sumes that you have a slide rule or tableof logarithms handy. That may not betrue, particularly in the field. If youneed only normal accuracy, as is usuallythe case, there is a simple method thatgives pretty good accuracy, in most cases,and may be performed mentally or, atworst, with a hasty scrawl on any con-venient surface.

To master the system you need toknow only that any 2:1 power ratio isequal to 3 db or a 2:1 voltage ratio to6 db, and that 10° = 1, 10° = 10, 102 =100, etc.

Table ILogio

(Number Db Power Db Voltage

Ratio of 0's) (10 login) (20 logio)

1 0 0 010 1 10 20

100 2 20 401,000 3 30 60

10,000 4 40 80100,000 5 50 100

Suppose you have an amplifier thatputs out a 100 -watt output signal for a1 -watt input signal. You say that theoutput is "up 20 db." This means, simply,that the gain of the amplifier is 100:1.Let us first convert the power ratio,100:1, to decibels:

db = 10 log10 fi.1r 2

If P1 represents the output and P2

the input,

1

"Log, 100" simply means the loga-rithm, to the base 10, of the number 100or, to put it another way, the power of10 that equals 100. This is 2, since 102is equal to 100. Therefore

db = 10 X 2 = 20 db

db = 10 lo100gi

110

6'o

Observe that 100 contains two 0's,1,000 three 0's, etc. The number of 0'sis the logarithm of 10. Multiply the num-ber of O's by 10 and you have the dbfigure! 1,000:1 is equivalent to 30 db,10,000:1 to 40 db, 1,000,000:1 to 60 db.(See Table I.)

For voltage or current ratios, theformula is slightly different:

db = 20 toE, (or Ii)

g , E, (or I,)Therefore, for voltage or current,

multiply the number of O's by 20. Then,1,000:1 equals 60 db, 1,000,000:1 120db, etc. This holds only if the impedancesacross which E, and E2 (or 1, and 12) arebeing measured are the same.

To go from decibels to ratio, simplyreverse the process: Given a power gainor loss of 30 db. divide by 10 and get 3.This means a 1 followed by three Ws,or 1,000. A voltage gain of 60 db isconverted by dividing 60 by 20 and get-ting 3, again resulting in 1,000.

Until now, our db figures have beennice round numbers, easily divisible by10 or 20. In practice, the numbers wehave to work with are not always so co-operative. Suppose we must transpose apower gain of 27 db to a ratio. Dividingby 10 yields 2.7, which is 102:7, or 10followed by 2.7 zeros!

The number 102 represents 100;102 represents 1,000. Therefore, 102.7represents a number between 100 and1,000. We are dealing with an exponen-tial quality, like the charging curve of acapacitor. Therefore, we cannot takeseven -tenths of the difference. Instead,we shall resort to a trick used in grade -school arithmetic: we shall borrow.

Let us raise our 27-db figure to 30db by borrowing 3 db. Now we have aneasy figure to work with, since 30 canbe divided evenly by 10. As shown inan earlier example, 30 db represents apower ratio of 1,000:1. Remember, weborrowed 3 db to make the conversion

3 4 5 e 7 8 9 1

10000

00

.00

easy. Now we must pay itback. It was pointed outthat 3 db is equal to apower ratio of 2:1. Rais-ing 27 db to 30 db is,therefore, doubling theratio. If 30 db is 1,000:1,then it follows that27 db must be 500:1.

Suppose the db fig-ure given is 23 db. Toconvert this to a figure that is amenableto the method, let us lend 3 db. The re-sultant 20 db is half the ratio repre-sented by 23 db. Since 20 db is 102, or100, and is one-half 23 db, 23 db mustrepresent 200.

The object, then, is to use decibelfigures evenly divisible by 10 for powerratios, or by 20 for voltage and current

Table IIDb Power Ratio Db Voltage

6121824

369

12

248

16

ratios. In lending or borrowing db toconvert to such figures, use incrementsof 3 or 6 db (for power or voltage andcurrent, respectively) because these rep-resent simple multiplications or divisionsby 2 in ratio.

To illustrate the method for voltage,let us convert a 52-db gain to voltage: 46db is one-half 52 db, 40 db is one-half46 db. Thus 40 db is one-fourth 52 db.

Forty db (voltage) is 102 (20 db is10°, or just 10; 40 db-double the num-ber of db-is 102, or 100). Doublingtwice or multiplying by 4 yields 400 (40db = 100, 46 db = 200, 52 db = 400).

Suppose, now, that we run across areally recalcitrant number: 25 db powergain. Since this number does not lenditself readily to conversion, we have tointerpolate. First, we determine that 23


db represents the ratio 200. You mayhave observed by now that adding deci-bels is equivalent to multiplying thequantities they represent (20 db =- 100,3 db = 2; 20 db plus 3 db = 100 X 2 =200). Although we are dealing with anexponential, not a linear function, forpractical purposes we can treat a smal

Table IIIRatio Db Power Db Voltage

5 7 1410 10 2020 13 2650 17 34

100 20 40200 23 46500 27 54

1,000 30 602,000 33 665,000 37 74

10,000 40 8020,000 43 8650,000 47 94

100,000 50 100200,000 53 106

remainder (2 db in this case) as thoughit were linear. That is, we shall say thatthe final ratio is 2/3 the difference be-tween 23 db (200) and 26 db (400).This gives us a final answer of about 332.The exact answer is slightly less than 317.Our accuracy is about 5%, more thanadequate.

Reversing the process, consider theratio 1,700. We split this into 1,000 and700. The first, 1,000, we know to be 30db, 2,000 would be 33 db. We know,then, that our figure is between 30 and

33 db. Interpolating the difference, againassuming linearity, we calculate seven -tenths of 3 db (3 db represents here thedifference between 30 and 33 db, or1,000 and 2,000) : 0.7 X 3 = 2.1 db.Rounding off and adding to our earlierfigure of 30 db, we have a final answerof 32 db. Since the exact answer is 32.3db, we have come very close, especiallysince the commonly accepted ratio of2:1 for 3 db is approximate (it is exactly1.995 :1 ) .

Expanding and combining TablesI, II and III and rounding off the num-bers, we can easily evolve Table IV.Again, this table does not reflect theexact values of all the quantities shown,but it can be easily made up in a fewminutes, if there are a number of con-versions to be made under improvisedconditions, and is accurate enough to beuseful. Generating such a table is alsogood practice in understanding decibels.It was created entirely by combining theearlier figures and continuing the processof halving and dividing the ratios, sub-tracting and adding decibels in 3-dbunits. Every ratio shown is either half ortwice the value of another entry.

To verify the accuracy of Table IV:15 db = 9 db + 6 db = 8 X 4 (from thetable) = 32

Verify this by finding the exact ratiofor 15 db.

If further proof is desired, find theratios for 3 db and 12 db and verify that12 db + 3 db = 15 db = 16 X 2 = 32

Multiplying the ratios of any com-bination of decibels that adds up to 15db will result in a ratio of 32, within the

accuracy of the table. This is of coursetrue for any other figures. If you wishedto find the ratio of 45 db, not given in thetable,

Table IV

Db

Power Ratio

Db

Voltage

Db

Power Ratio

Db

Volt -

age

1 1.25 2 21 125 422 1.56 4 22 156 443 2.0 6 24 250 484 2.5 8 25 312 505 3.125 10 27 500 546 4.0 12 28 625 567 5.0 14 30 1,000 608 6.25 16 31 1,250 629 8.0 18 33 2,000 66

10 10.0 20 34 2,500 6811 12.5 22 35 3,125 7012 16 24 36 4,000 7213 20 26 37 5,000 7414 25 28 38 6,250 7615 32 30 39 8,000 7816 40 32 40 10,000 8017 50 34 41 12,500 8218 63 36 44 25,000 8819 80 38 47 50,000 9420 100 40 50 100,000 100

45 db = 35 db + 10 db = 3,125 X 10= 31,250.

The procedure may be reversed.Assume you wish to find a db figure forthe ratio 40,000, not given in the table.Factoring 40,000 into convenient num-bers,40,000 = 10,000 X 4 = (from the table)40 db + 6 db = 46 db. END

What'sYourEq?

Conducted byE. D. CLARK

Unsquare WavesMy audio generator was producing

very bad square waves. It was new andI expected better from it, but the scopetrace was rounded even at 1,000 cycles,worse at 5,000, and a misshapen sinewave at 10,000. My first impulse was todistrust the simple clipper -type shapingcircuit. I recalled a similar circuit used ina Lafayette audio generator which gavevery good square waves to 10 kc; thechief difference being small chokes usedas peaking coils at two points.JULY, 1964

I bought suitable chokes, wired themin-nothing. No improvement whatever.Still blaming the clipper, and knowingthat my scope couldn't be as bad as allthat, I even tried two Schmitt -triggersquaring circuits. When they failed to

I2AU7VERTAMPL

375 VVERTICALDIRECT

TO CRTVERTPLATES

do any better, I began to wonder aboutmy scope, and I decided to feed the sig-nal direct to the CRT vertical -deflectionplates, bypassing the amplifier. If thescope amplifier's response was reallyso bad, that test would show it.

Before I actually tried the directfeed, I found the trouble. It was thescope, but there wasn't really anythingwrong with it! Can you figure out what

happened, with the help of the partialschematic.-Peter E. Sutheim44:11'

Three capacitors, each charged ini-tially as shown, are connected in serieswith a resistor and a switch. Determinethe steady-state voltage on each capacitorafter the switch is thrown.-Oscar D.Anderson

CI C22p.f 3,41

- -I- -)I+150V 50V

IK

Two puzzlers for the students, theoreticianand practical man. Simple? Double-check youranswers before you say you've solved them. If youhave an interesting or unusual puzzle (with ananswer) send it to us. We will pay $10 for eachone accepted. We're especialy interested in serv-ice stinkers or engineering stumpers on actualelectronic equipment. We get so many letters wecan't answer individual ones, but we'll print themore interesting solutions-ones the original au-thors never thought of.

Write EQ Editor, Radio -Electronics, 154 West14th Street, New York, N.Y. 10011

Answers to this month's puzzles are onpage 58.

45

Put those unmarked coils to work withthis low-cost bridge. Covers 50 ph to 100 h

Simple InductanceBridge ChecksUnknown Coils

By JOHN A. DEWAR

TEST EQUIPMENT FOR RESISTANCE ANDcapacitance measurements is common,but instruments to measure inductanceare rare outside the laboratory. Thischecker contains few parts and is easy tobuild and operate.

It is used with a 1,000 -cycle audiosource capable of delivering 10 volts ormore. This can be an audio generator ora one -tube oscillator built for the pur-pose. The actual frequency is not critical.In a spot check of six inductances rang-ing from 200 itth to 15 h there was novariation in bridge reading from 400 to2,500 cycles, though 1,000 cycles is thebest for all ranges.

Due to losses in the bridge, a signalsource variable up to 10 volts or betteris necessary, particularly on the lowerranges.

The best null detector is also thecheapest: a little crystal earphone suchas that used with portable transistor ra-dios. A standard vtvm is not sensitiveenough; an oscilloscope works, but notas well as the earphone. A tuning -eyetube requires a lot of amplification andwas discarded in preliminary develop-ment.

With an oscilloscope, adjust forminimum trace height. The earphonedoes not give a silent null but a pitchchange either side of the correct reading.Careful adjustment of balance controlR6 gives a very sharp null. The residualtone is due to stray capacitance.

Ganged rotary switch S 1 coversthese ranges:A - 50 p,h to 1,000 ,uJitB - 1 mh to 20 mhC - 20 mh to 400 mhD- 0.4 h to 8 hE -5 h to 100 h

S2, the HI-Q-LO-Q switch, convertsthe unit to either a Hay or Maxwellbridge. Both basic types are shown in Fig.1. The Hay is best for high -Q coils whilethe Maxwell bridge gives best resultswith low -Q ones. The Q can be estimated

Original version used banana jacks and patch -cords to change ranges. Rotary switch, as shownin Fig. 2, is more convenient.

roughly by examining wire size, numberof turns, dc resistance and core type.Most low -frequency iron -core chokesand transformers are low -Q. Small coilssuch as rf and i.f. transformers are high -Q and will give a null only in the Hayposition. Note (from Fig. 1) that thebridge is little altered. In the Hay bridge

bFig. 1-Maxwell bridge (a) and Hay bridge(b) differ in connection of resistive balancepot. Hay bridge works best with high -Qcoils, Maxwell with low.

the resistive balance potentiometer (con-nected as a rheostat) is in series with therange capacitors. In the Maxwell it is inparallel.

The complete circuit is shown inFig. 2. Resistors R1 to R4 need not behigh -precision but should be selected foraccuracy with a good ohmmeter. Sim-ilarly, capacitors Cl to C4 should bechecked on a capacitance bridge for cor-

C1-2 piC2-0.1 ).i.f

C3-.01 [IfC4-.001All capacitors 100 v, paper (see text)R1-25,000 ohmsR2, R3-1,000 ohmsR4-500 ohmsR5-pot, 2,000 ohms, linearR6-pot, 2,000 ohmsAll fixed resistors 1/2 watt (see text)SI-rotary switch, 2 poles, 5 positions (Mallory 3129.1 or

32291, or equivalent)S2-dpdt switch (rotary, toggle or slide)6 binding posts, banana jacks, Fahnestock dips, etc.Crystal earphoneBase, panel, miscellaneous hardware

rect value. Most stock capacitors tendto be lower in capacitance than marked.

The calibrated potentiometer (R5)must have a linear taper if used with thedial shown in Fig. 3. Other tapers, evenif individually calibrated, will crowd por-tions of the scale. The dc resistance read-ing of R5 bears a direct linear relation-ship to the calibration. Taking range Eas a reference, it will measure 100 ohmsat 5 h, 200 ohms at 10 h and so on up to2,000 ohms at 100 h. Taper of R6doesn't matter.

Using the bridgeWith the 1,000 -cycle signal, the ear-

phone and the unknown inductance con-nected, set the range switch to an esti-mated value and rotate the calibrateddial, looking for a null. If the inductanceis larger than the maximum covered bythe range, the tone will become loudestat the high -inductance end of the scale;if smaller, it will be loudest at the mini-mum end. Switch to the next range ac-cordingly and repeat the procedure. Ifyou cannot find a null, switch to the otherbridge circuit.

The balance control compensatesfor the dc resistance of the coil. Onceyou have found a null, start at zero andadvance the balance control a little, stepby step. Swing the calibrated dial backand forth through the null until thesharpest null is obtained. Incorrect ad-justment of R6 will give a false reading.

This is not a precision instrument.For instance, iron -core inductors, suchas filter chokes, will have a lower in-cir-


0IKCINPUT

SI-a

RI 25K

R2IK

R3

R4 5000 C3

C2 I

CI

UNKNOWN INDUCTANCE

Fig 2-Circuit of the twin bridge. You mayquency is not critical. Try what you have.

cuit inductance, when carrying large di-rect currents, than the value indicatedon the bridge. But the bridge does elim-inate a lot of guesswork when dealingwith unknown values. And it is easy tobuild and cheap.

A wooden base and hardboardpanel should suffice for chassis and panel.

2p.f

C4 .001

01 A

E S2Sl-b HI Q -LO

HI Q

LO Q

R6 2K

RESISTANCE BALANCE

PHONES

R5 INDUCTANCE

already have most of the parts. Source fre-

Fahnestock clips, screwed to the base,make good connections.

Another use for the bridge is detect-ing shorted turns in flyback transformers.Compare the suspected transformer tothe manufacturer's specifications or to aknown -good flyback of the same type.

END

Fig. 3 - This dialworks for a linear2,000 -ohm pot as R5.For other resistances,tapers or connec-tions, you will haveto make your owndial.

Junk Parts Go to the DevilCERTAINLY ONE OF THE MOST EVIL -EYEDpieces of modern art around, this wink-ing Satan was built by men of the FlagAdministrative Unit of Fleet Air Hawaii.

The circuit is just a "push-pull" re-laxation oscillator, and the two neonlamps, the eyes, wink alternately aboutonce every second.

The 0.5-p.,f capacitor forms thetorso, while the resistive part of the timeconstant makes up the legs. The ax bladewas made from an old meter face, itshandle and that of the mace from No. 8wire. (The ax handle serves as "groundreturn" to the battery.) Bits of hookupwire and a small wooden ball comprisethe mace and chain. A red plastic alliga-tor -clip insulator is the hood. The feetare small mica capacitors.

RIGHT ARM

NO

CONTINUITY )

RIGHTLEG( I MEGTOTAL)

NE -5I(2)

I'll90-100V BATT ( IN BASE)

LEFT ARM

(PARTSUSED FORAPPEARANCEONLY)

LEFT LEO(I MEGTOTAL)

Three feedthrough insulators orcapacitors on the base support the figureand pass current from the battery, lo-cated in the base.

While R1, R2 and C determine thewink rate, the other parts are there justfor looks and to complete the circuit.Use components with low dc resistance.

END

JULY, 1964 47

By ROBERT F. SCOTTTECHNICAL EDITOR

UNTIL A RELATIVELY FEW MONTHS AGO,a center or bass channel in stereo instal-lations was restricted to a few componenttype systems. Now, center -channel bassspeakers are featured in many stereoconsoles and even in some inexpensiveportables. Several unusual circuits havebeen developed to derive the center orbass channel. They are simple and easyto add to your stereo system or to theamplifier you are planning to build.

Fig. 1-a shows the output circuits ofa typical ac-dc stereo amplifier withsingle -ended channels. Similar circuitsare used by Motorola, Truetone, Philcoand others. Note that there are three out-put transformers, one for each side chan-nel and one for the bass content of theleft and right channels. (Low notes donot have a pronounced directional char-acteristic so they don't have to be sepa-rated for stereo.)

The primary of the center -tappedbass output transformer has a muchhigher impedance than the primaries ofthe left and right output transformers.The middle and high -frequency notesfrom the left and right channels are de-veloped across the respective right andleft output transformers. They do notappear in the center channel becausethey are bypassed around the transformerby the 0.1-p,f capacitor. Only the lowsfrom either channel are developed in thebass transformer. The output grids arefed 180° out of phase and the bass signalsappear in push-pull across the center out-put transformer. Since the grids are 180°out of phase, the phase of one of the sidespeakers is reversed so the outputs arein phase.

Fig. 1-b is the output circuit usedin some of the 1964 Philco radio-phonocombinations. Note that the bass outputtransformer has a grounded center -tapped secondary and that the threesecondaries are connected in series. Ad -

Motorola SP53 is typical of many stereo portableswith center or bass channel output.

Center Bass Channel For Stereo35C5 OR 5005 (2)

LEFT OUTPUT

FROM AI- )1LEFTVOLTAGEAMPL

BALANCE

FROM DI)1

RIGHTVOLTAGEAMPL

*4.4K FOR ECL82/68M8'S.12K CT " "

7.002

LEFT OUTPUT TRANS

*Z=1.7K

Z.8S1.

BASS OUTPUTRANS

ITS a

Z.441

4 8K,CT

Z=8S1

Z=1.7K qa

125V

118V

RIGHT OUTPUT TRANS

aFig. 1-a-Typical low-cost single -ended stereo output usedcial phonos. A medium-sized universal output transformeroutput transformer in a home -built version of the circuit.ondaries in Philco phonos.

LEFT EXT SPKR

LEFT OUTPUT I=

RIGHT OUTPUT

RIGHT EXT SPKR

b

in many small commer-can be used for the bassb-Series-connected sec-

ditional jacks are provided for externalspeakers, which are fed the high andmiddle frequencies from the side speak-ers and the lows developed across halfthe bass secondary.

Fig. 2 shows the push-pull stereooutput circuits in the Motorola HS -1130,a recent -vintage all -transistor stereo pho-nograph chassis. Two output transform-ers are used in the collector circuits ofeach push-pull channel. The bass out-put transformers (T3 and T6) are woundon large cores with a large number ofturns so they present higher impedancesat all frequencies than T2 and T5. The10-4 capacitors bypass the highs and

Westinghouse M-1350transistor stereo console


TO LEFT CHANDRIVER EMITTER

TO LEFTCHANDRIVER

COLLECTOR

TO RIGHTCHANDRIVER

EMITTER

TO RIGHTCHANDRIVER

COLLECTOR

3.9 K

II.8V

(4) 2N176 OR MOTOROLA SPI108LEFT CHANPWR AMPL

1.5K

RIGHT CHANPWR AMPL

1(15 V

only the lower notes are developed acrossthe bass transformers. The highs are de-veloped across the lower impedances ofT2 and T5. The primaries of T3 and T6are paralleled so the lows in either chan-nel are fed to the bass speakers.

Westinghouse uses a simple L -Ccrossover network and carefully selectedspeakers to separate the ultra -highs, highsand middle frequencies in the side chan-nels and to mix the lows in the bass chan-nel. Fig. 3-a shows the output circuit ofthe V-2528-1 chassis used in theH -M1350 and H -M1450 series all -tran-sistor AM-FM stereo phonograph com-binations. Each channel has a push-pullOTL (Output-TransformerLess) poweramplifier circuit. The 4 -inch 45 -ohmspeakers have soft cones and the 4 -inch6.4 -ohm units have hard ones. The threespeakers in each side channel are care-fully selected for smooth wide -rangeresponse through the middle and highfrequencies. The woofer is fed from eachchannel through a 2.5-mh, low -resistancechoke. Fig. 3-b is a similar arrangementused in a single -ended vacuum -tube amp-lifier. The 6 -inch speakers carry the mid-range frequencies and the 31/2 -inchershandle the highs.

Service notesWhenever the complaint is poor

bass response, check the capacitor acrossthe bass output transformer for a short.The capacitor is likely to be open if thecomplaint is poor separation or severeloss of highs.

.02

390.a

T3,f1

o

lOpfNP

5µf -NP)1

Z=812

LEFT CHAN MID& HIGH SPKRS

NP NONPOLARI ZED

5µf- NP

- Z=812

RIGHT CHAN MIDa HIGH SPKRS

Fig. 2-Motorola transistor circuits useapproach similar to that in Fig. 1-a.

Many stereo units use plugs or clip -on connectors between the amplifier andthe speaker leads. If you have troublewith a dead or intermittent channel, al-ways check the speaker connections be-fore the electronic circuitry. Severalrecent complaints have been traced to

Fig. 3-a -L -C crossover inWestinghouse transistor pho-nographs. b - Tube version,with output transformers.

TERMINALBOARD PLUG

LEFT EXTSPKR JACK

intermittent or open speaker circuits.Some units have circuit -transfer jacksfor external speakers (Fig. 3-a). Checkthe jacks for continuity, particularly ifthe external jacks are used for remotespeakers.

Always check speaker phasing andcartridge connections when servicing astereo system. Reversed cartridge con-nections cause poor bass response. Incor-rect speaker phasing causes poorseparation and some loss in the middlerange.

To check speaker phasing, momen-tarily connect a 1.5 -volt battery acrossthe secondary of the left output trans-former with the positive terminal on oneof the marked or coded leads. Notewhich way the speaker cone moves whenthe circuit is made. Now, move the bat-tery to the secondary of the right outputtransformer-making sure that batterypolarity is the same as for the left chan-nel. Speakers are in phase when theircones move in the same direction.

If possible, consult the manufac-turer's service data. (Remember that insome systems, like the one in Fig. 1-a,speakers should be out of phase.) Trans-former leads are generally color -coded,and speaker terminals are numbered orcoded with a colored dot. The RCA WG-360A Phase Checker is handy when serv-icing stereo in the field, especially incases where cone movement is not easyto see.

Always use exact replacements fordefective speakers in high -quality sys-tems. Speakers are generally matched tothe enclosure and to each other forsmooth response. Universal replacementspeakers may result in a loss in overallresponse or in objectionable peaks. END

U-

12"CENTEROR BASSCHANNEL

6"

RIGHTPWRAMPL

LEFTPWRAMPL

JULY, 1964 49

tachometers forspeed control

By MATTHEW MANDL

Accurate speed control cuts costs and re-

duces delays along the production line

AN IMPORTANT DUTY OF INDUSTRIAL Au-tomation is keeping conveyor belts, ma-chinery, processing equipment, motorsand other related gear at the rightspeed. This is necessary to keep thevarious processing operations synchro-nized. Steady operating speed also as-sures troublefree performance of theautomatic processes and minimizesequipment damage.

As in many other phases of indus-trial automation, speed control requiresa sensing device (transducer). It deter-mines the speed of the object under testand indicates the exact number of revo-lutions per minute-or feet per secondfor moving belts and pulleys. When thespeed or motion deviates from normal,it can be reset manually or automati-cally. For automatic operation, thetransducer provides an output signalwhich is used to keep the speed withinpreset limits.

The tachometer is the sensingtransducer that measures rotation.There are two basic types and both areused extensively in industry. One usesflashes of light and is based on thestroboscope principle used to measurethe speed of phonograph turntables ortime your car engine. The other is basedon the de generator principle-the out-put voltage is proportional to the ro-tation of the tachometer's shaft.

Generator type tachometerServo-Tek Products

Stroboscopic tachometerThe type 1531-A Strobotac made

by General Radio is a portable unit con-taining a strobotron lamp in a parabolicreflector, an electronic pulse generatorto control the flashing rate, and an acpower supply. The flashing light fromthe lamp is directed at the rotating ob-ject to be checked and the dial turned tochange the repetition rate of the lightflashes. When the speed of the lightflashes match the speed of the object,

motion freezes-the object appears tostop. The exact speed is then read onthe dial.

The Strobotac has a range of flashspeeds from 110 to 25,000 flashes perminute and can read speeds up to: 250,-000 rpm with flash rates that are sub-multiples of the speed to be measured.Light duration is between 1 and 6 mi-croseconds with a peak light intensityup to 4,000,000 candlepower. Accuracyis within 1% of the dial reading afterthe unit's middle range is calibrated.An output trigger signal of 600 to 800volts (negative pulse) is available forautomatic control purposes.

The Strobotac can be used for ob-serving latch operation of a hosiery-knitting machine, accurately measuringlathe speed, slow-motion observation ofcutting action of tools, checking ma-chines in underload and overload tests,and speed control and measurement ofall sorts of rotating and reciprocatingmachine elements.

Generator type tachometerBy rotating the coil of a generator

type tachometer in fields produced by50 RADIO -ELECTRONICS

Strobotac Tachometer.General Radio

permanent magnets, we get a de outputvoltage whose amplitude is in direct pro-portion to the speed of rotation. Toproduce fairly ripplefree dc, however,a number of commutator segments mustbe used. This can be more easily under-stood by referring to the basic two -polede generator shown in Fig. 1.

The rotating armature has a num-ber of slots containing coils. The indi-vidual wires of the coils are shown assmall circles to represent the cross-sectional view. All the coils are wired inseries, and a number of commutator seg-ments contact the two carbon brushes.As the armature rotates, the individualcoils cut the lines of force of the mag-netic fields and generate electric power.

When a single coil is turned in amagnetic field, the energy builds upfrom zero, reaches a maximum peak anddeclines again, producing a single half -cycle. As the coil is continuously turned,pulsating de appears at the outputleads. When a number of coils are em-ployed, the pulsating de of each coilcombines with the others to produce low -ripple dc, as in Fig. 2. Before the peakdc from one coil can decline, the nextcoil takes over, and the result is asshown.

A typical tachOmeter, with a speed -indicator dial, is the type SA -757 indus-trial tachometer of Servo-Tek ProductsCo. For long life, its commutator is al-most pure silver, and the brushes aredesigned for continuous operation andcarry a guarantee of a minimum 10 -year life. Various indicators can be sup-plied for speeds ranging from 0 to 100up to 12,000 rpm. A center -zero scale isalso available. It indicates direction ofrotation and speed. For increasing thescope of applications of this tachometer,a scale is also furnished which reads"0 to 100% of full speed" instead ofactual revolutions per minute.

Speed -control systemsIn a complete industrial speed -

control system, the tachometer sensesthe actual speed, and control circuitskeep it within a predetermined range.To do this, the speed indicated by thetachometer is compared to the desiredspeed of the moving belt, assembly lineor other unit. Electronic circuits handlethe comparison and correct for any de-viation.

A block diagram of a basic systemis shown in Fig. 3. The tachometer is somounted that the moving belt or assem-bly line rotates its shaft and producesan output voltage proportional to thespeed of belt movement. An indicatordisplays the speed visually at all times.

The voltage generated by the ta-chometer is applied to a de amplifier.Output signals from the amplifier aresent to a phase -control unit that con-trols the firings of a gas -tube thyrationor a silicon -controlled rectifier. The rec-tifiers, under control of the phase unit,regulate the speed of the driving motor.

With the arrangement shown inFig. 3, the tachometer can also be at-tached to the motor assembly instead ofdirectly to the moving belt. With thetachometer shaft applied to the driveroller of the motor shaft, a direct read-ing and control of motor speed are alsopossible. With the tachometer applied tothe motor shaft, the sensing is in motorrpm. Most tachometers, however, can becalibrated to read rpm in terms of feetper minute. A number of manufacturersof industrial control devices now fur-nish complete speed -control packagescontaining essentially the various itemsand circuits shown in Fig. 3.

A schematic of the Series 100 pre-cision drive with tachometer feedbackmade by Servo-Tek Products is shownin Fig. 4. The ac line input is applied tothe primary of the power transformerand converted to de by the silicon rec-tifier and filter capacitor C. Filter re-sistors R1 and R2 are used instead offilter chokes, and together with the filtercapacitor smooth out the ripple. A gas -tube voltage regulator is also includedin the circuit.

The tachometer shaft is attachedto the motor armature shaft and itspositive -polarity output voltage is ap-plied to the adjustable arm of R3. Thenegative output from the tachometer issent to the dc control amplifier. The am-plifier output is applied to the phasecontrol circuit, where it causes the thy -

COMMUTATOR SEGMENTCARBON BRUSH

Fig. 1-Basic two -pole generator.

SINGLE COILOUTPUT LOW -RIPPLE DC RESULTANT

\ A /11 I "

A l X

/\I

\t) II

k

"I/ I

%1 ki II II I/V

PULSATING DC FROM INDIVIDUALCOMMUTATOR COILS

Fig. 2-Multi-pole tachometer produceslow -ripple dc by combining the outputfrom individual commutator coils.

MOVING BELT OR ASSEMBLY LINE

TACHOMETER

e--abi

DCCONTROLAMPL

PHASECONTROL

SPEEDINDICATOR

THYRATRON ORSILICONCONTROLLEDRECTIFIER

Fig. 3-Tachometer speed -control sys-tem.

Fig. 4-Circuit of the Series 100 pre-cision -drive motor -control system madeby Servo-Tek Products.

SERIES --ns-FIELDMOTOR QSL9

ACLINEINPUT

SILICONRECT

REGULATEDREF VOLTAGE

DC CONTROL

1111131uomb411VOLTAGE REG

R3

TACHOMETERGENERATOR PHASE

CONTROL

THYRATRON

Strobotac used in hosiery knittingprocess to observe needle action.

General Radio

ratron to fire by increasing grid voltage.The motor is in series with the cathode -plate of the thyratron, and ac line volt-age is applied to it only when the thyra-tron is conducting.

The system shown, actually aservo device, is sometimes called a ve-locity servomechanism, because it is anautomatic control assembly. With allsuch systems, the actual speed is firstmeasured with an accurate tachometermounted so it is part of the motorassembly. The voltage signal from thetachometer is compared with the refer-ence voltage across potentiometer R3.It is adjusted to the proper level for themotor speed required. (The referencevoltage is connected to oppose the po-larity of the tachometer output voltage.Thus, any difference in the values ofthe reference voltage vs the tachometervoltage becomes an error voltage.) Be-cause there is a complete closed circleof operation, the system is also knownas a closed -loop velocity servo.

The error voltage produced whenthe motor speed varies above or belowthe preset value controls the firing timeof the thyratron. Depending on the typeof correction necessary, the error volt-age either advances or retards the timeof thyratron conduction. The resultantchange in thyratron output causes acorresponding motor speed change, be-cause the thyratron supplies current tothe motor armature.

Many of the packaged speed -con-trol systems available from variousmanufacturers contain patented cir-cuits and assemblies. These, combinedwith matched units and circuits, makefor highly efficient and accurate speed -control devices. With well designed sys-tems, changes in line voltage have noappreciable effect on motor speed. Also,motor speed is held substantially con-stant even when the load changes. Thespeed is also virtually independent ofthe temperature of the motor and ofcomponent aging. Because a manual ad-just is provided, the assembly -line mo-tion or other speed can be set to meetvarying conditions of automation andthe servo system will maintain this pre-cise speed until the manual control isreset. END

Versatile Converters For The UHF

One antenna is for vhf, the other for uhf.The cabinet appearance is identical withthe UC-100A, and, without the antennas,with the UC-410, -310 and -200.

TV RECEIVER MANUFACTURERS ARE MAK-ing a serious effort to meet the newchallenge of uhf. TV auxiliary equip-ment and accessory manufacturers areno less active. New antennas, convertersand boosters are being designed to coverthe uhf spectrum. At least one piece ofequipment-one of six converters put outby Winegard-combines all three in oneunit. The UC-200A, a two -tube con-verter for medium ranges, has built-inuhf and vhf antennas, plus a nuvistori.f. stage (operating at the frequency ofa vhf channel). The added stage makesup for frequency conversion losses.

ANT

A companion converter, the UC-200, is identical except that it has noantennas. It is designed for use with anoutdoor antenna instead.

For the fringe areas, a transistor rfstage is added to the circuitry of the200, giving us the UC-310. In the far -fringe UC-410, the rf stage is a separateunit with its own power pack. It is placedat the top of the mast and supplied with7 milliamps at 14 volts through thelead-in. The little power supply, whichis inserted in the lead-in near the set, hasits own power transformer, and is effec-tively isolated from the line.

(The rf unit and power supply isalso available separately as the UHF -110broad -band uhf antenna amplifier.)

The transistor type booster-whichuses one 2N2966 in the circuit shown inthe figure-is noticeably effective, evenwhen the lead-in is not particularly long.Used with a Blonder -Tongue GoldenDart uhf antenna mounted indoors ina third -floor room, it made the differencebetween a recognizable -but -snowy pic-ture and one with real entertainmentvalue.

A pair of converters for listeners instrong -signal areas completes the half -dozen. Identical in appearance to thoseillustrated, they have one tube. The UC-100A has built-in uhf and vhf antennas;the UC-100 is intended for outside an-tenna use. END

The UHF -110 transistor broad -band amplifier in position on a TV mast.

Schematic of the Winegard broad -band uhf amplifier.

UHF ANTENNA AMPL

rI5PF

10%

I5PF

10%

2.2 PF .3V 2N2966

10%

10%

IMEG

1 _

I.8K

100 PF

4.7K

I.6V 100 f

25WVDC

3.3PF10% 5 OPF I

70V RMS 100PFT100 MA

330K

POWER SUPPLY

1 I\I I4V

LEAD- Ni6ort,

I

I7MA

i-7.6V

100PF

100 PF

TO SET

117 V

60%7/10W


Transistors Keep A Roof OnAN ADVENTURE IN INDUSTRIAL ELECTRONICS

By J. K. BACH

RECENTLY THE LOCAL GAS AND ELECTRIC

company had to reroute a gas main. Thegas was cut off while the new pipe wasbeing connected. Immediately after thegas was on again, one of the company'sbiggest customers complained, and aserviceman was dispatched. His reportwas confused and unlikely: he hadlighted the first two heater pilots OK but,when he approached the third, he foundthe burner valve wide open and gas his-sing out of the unlighted burner. He shutthe whole system down immediately andcalled in.

Gas burners were the very first de-vices with a fail-safe feature built in.(The feature, in fact, antedated the term"fail-safe" by many years.) Originally,this comprised a heat -actuated mechan-ical element which operated the mainburner valve directly. This has now givenway to the thermocouple, because wirescan easily be extended to a remotethermostat for automatic operation.

THERMOSTAT(CLOSED)

PILOT I-.- I=1/8AFLAME_

<- THERMOCOUPLE (HOT)

-1- .6V GAS VALVE (OPEN)

2a _fkr.c.250 MVP=.03 WATT

Fig.)

Fig. 1 shows the usual arrangement.The pilot flame to light the main burneralso heats a thermocouple (in practice,a number of such junctions, called athermopile). This generates a potential-in this particular case, about 0.6 volt-sufficient to operate the gas valve to themain burner, when the contacts of thethermostat are closed.

When the room is warmer than thethermostat setting, its contacts are open.When the room cools, the contacts close,and voltage from the hot thermocoupleopens the main valve to the burner,which is then lighted by the pilot flame.When the room warms up enough, thethermostat opens, the burner valve closesand the burner goes out. Only the pilotlight remains lit.

If the pilot should go out-as hap-pened in this case, because of the gasbeing shut off in the mains-the thermo-couple cools and there is no voltage toopen the burner valve. Until the pilot islighted again, the valve should remainclosed. How, then, could gas be coming

out of a cold burner? Though the burn-ers are vented through the roof, gas isso dangerous one cannot afford to takeany chances with it. Gas explosions areviolent and destructive.

The company sent its ace trouble-shooter to the scene. He found that thetrouble was even worse and more dan-gerous than the serviceman had indi-cated. The location was a large garage:large enough to require 18 big space -heaters, suspended from a trussed ceilingin six rows of three. Each row had itsown thermostat mounted on the far wall,and the wiring to them was encased inthin -wall conduit.

The trouble was not just in oneburner-it was in all of them. There wasno clearcut pattern. When two burnersof any group were lighted, the thirdwould gush out gas, but the lightingcould be in any order: 1-2-3, 3-2-1,2-3-1 and so forth. Sometimes even oneburner of a group would operate thevalve of another. There were "maybe"factors at work, too: whether the ther-mostat was "calling for heat" and howlong the burner had been operating. Ittook a whole day of climbing laddersand tying up the garage space to workout most of the permutations, but thebasic cause of trouble was obviousenough from the start. The burners weredesigned to be used singly, and each wasintended to have its own thermostat. Theman was all but certain that installing 12more thermostats would solve the prob-lem satisfactorily.

Except for the expense. The cus-tomer might stand still for the cost ofthe additional thermostats, but installingmore conduit was another matter. Norcould the space be tied up for any ex-tended time.

The consultant had a small labora-tory in the main office building. Here,he assembled a mockup of the custom-er's layout, using three pilot units withtheir associated solenoid valves for themain burners. The burners themselveswere not needed, and little wire "flags"

<TC (HOT)

_.19P (OPEN)

TC (HOT)

...fPP(OPEN)

showed when the valves were operated.These valves work much like the watervalves on an automatic washer-the sole-noid opens a tiny needle valve which un-balances gas pressure on an operatingdiaphragm, which does the actual open-ing and closing. It is actually a servotype, since the power from the thermo-couple is too small to work the valvedirectly.

A few minutes' testing confirmedwhat he already suspected: current froma hot thermocouple would flow back-ward through a paralleled cold one andoperate the wrong valve. Fig. 2 showsthis, and shows the thermostat open forsimplicity. But if the wiring is extendedfar enough, the wire resistance plus thethermostat contact resistance may behigh enough to permit the second valveto open even when the thermostat isclosed. This is more likely when thereare two hot thermocouples in the group,as in Fig. 3.

Fig.2

He worked out the current -flow dia-grams using Kirchhoff's law in case theEngineering Department had any ques-tions, and with the lab mockup he wasable to demonstrate the problem to thecompany Brass.

They were impressed, but clearlyexpected him to come up with sometechnical trick that would cost little ornothing. Also, time was important. Theweather was mild, but in a mountaintown it could change without notice.

There were several possible solu-tions, but not many practical ones. Re-sistances could be added to the circuitto reduce the operating margins so thatno hot thermocouple would be able tooperate any but its own solenoid valve.But this would make for cranky and un-satisfactory operation.

The solenoids could be polarized,but modifying the valves was out of thequestion, and the technician found itimpossible to get enough residual mag-netism in the cores.

This led to an idea that seemed tobe a winner: simply put a rectifier in

<Tc (COLD) (CLOSED)

1'D(OPEN)

Fig.3

JULY, 1964 53

series with each solenoid, and the prob-lem should be solved. And at little ex-pense, making the Brass happy, andmaintaining ample operating margin.But the idea failed, and because of mar-gin. There wasn't any, and there wasn'tany operation either, with any rectifierthe technician could lay his hands on.

The Brass helped. They secured adouble handful of diodes from a largecomputer manufacturer, includingmostly high -current and low -forward -resistance types, yet with the best ofthem the lab setup worked poorly whenit worked at all.

They next consulted my company,and I suggested power transistors as rec-tifiers. They are cheap, widely distrib-

Fig.4

uted, and the germanium types have alow forward resistance. Happily, this no-tion worked like a charm (Fig. 4).

Not content with one transistor persolenoid, the power company man usedtwo in parallel, with lowered forward -voltage drop, theory to the contrary not -

(CLOSED)

withstanding. This provided additionaloperating margin; though not equal tothe original, there was ample for reliableoperation.

Everyone concerned was happy,and at last report the customer's roof isstill on. END

ervice clinicRADIO -CONTROLLED GARAGE -DOOR OPENERS CAN BE SERVICED

by the TV technician. They're pretty simple: they can haveone -tube transmitters and one -tube receivers, although mosthave more than that. Transistor sets are also plentiful.

Mechanically, they're just as simple, as you can see inFig. 1. The "traveler" is moved along the support rail by themotor (taking the door with it). The relay in the receiverstarts the motor. As soon as the traveler moves, the limitswitches take over. So, the relay doesn't have to be closedall the time the motor's running. When the traveler reachesthe other end, the limit switch there stops the motor andcocks itself to start the motor in the other direction, the nexttime the relay is closed.

Most of the systems work on 27.255 mc, which is theradio -control channel (23) in the Citizen's band. Delcomakes a system that radiates (as an "rf" signal!) between 5and 10 kilocycles, to avoid interference in the radio band.This gets rid of some of the troubles, like the garage dooropening every time Junior calls someone on his slightly off -frequency CB walkie-talkie!

Transmitter antennas range from small rods mounted onthe case, in the 27-mc band, to cylindrical coil types, in the5-10-kc sets. These can be moved and mounted elsewhereon the car, if the signal isn't strong enough.

Receiving antennas can be critical, too, especially if theyhave been installed pointing in the wrong direction or (asI've found a few) taped tightly to pipes, conduits or steelbeams! This does nothing at all to aid rf pickup, believe me!For the best results, position the receiving antenna so that itis broadside to the position in which the car (transmitter)will be when the signal is sent out. In a very few cases, youmay have to set this antenna outside the garage itself-ifmetal walls or large machinery interfere with the rf pickup.

This column is for your serviceproblems-TV, radio, audio or generaland industrial electronics. We answerall questions individually by mail, freeof charge, and the more interestingones will be printed here.

If you're really stuck, write us.We'll do our best to help you. Don'tforget to enclose a stamped, self-ad-dressed envelope. Write: Service Edi-tor, Radio -Electronics, 154 West 14thStreet, New York 10011.

Metering points are usually provided for tuning up, onthe receiver. If not, you can always measure grid current witha milliameter, or grid voltage with a vtvm. While a signalgenerator can be used, the set's own transmitter is the bestsource of signals. Always tune for maximum reading, withthe car in the "normal" position-in the driveway as it wouldbe when approaching the door.

LIMIT SW

rrSWITCH TRIP BLOCK

II TRAVELER

DOOROPEN

LIMIT SW

DRIVEN BY MOTOR,CARRIES DOOR

bo1,

DOORCLOSED

Basic mechanics of ra-dio -controlled garagedoors are quite simple.The traveler glides alongthe rail, driven by themotor via cable and pul-leys or a rotating lead -screw. Limit switches ateither end stop it andset it up to start againin the opposite directionthe next time the trans-mitter is keyed.

Watch out for one peculiarity found in some systems:"pulsing" of the transmitter's rf signal. Many units have"timer" circuits: when the operating button on the dash ispressed, the transmitter is keyed, and holds "on" for about2 seconds. Then it shuts itself off. This can be confusing ifyou're trying to realign the receiver! For tuning purposes,defeat the timer circuit. Block the relay closed, hook jumpersacross the keying circuit, etc.

You'll find schematics on most of the popular units inSams Photofacts, listed under their maker's names.

By the way, watch out for "tricky" tubes: not unusualtypes, but critical tubes in a few sets that use regenerative oreven superregenerative receivers. It is entirely possible for anew tube to refuse to work in such circuits! If that happens,try another tube before pulling the receiver chassis forservicing.


THIS HATIKITRif STEREO GENERATOR

CAN PUT EXTRA PROFITS IN YOUR SHOP Produces all signals required for trouble -shooting and alignment of multiplex adapters, FM tuners and receivers Generatesmono FM or composite stereo FM signals Crystal -controlled 19 kc ( 2 cps) pilot signal, level adjustable from 0 to 10% forcheck of tuner lock -in range Switch selection of 400 cps, 1000 cps, 5000 cps, 19 kc, 38 kc, 65 kc or 67 kc SCA test signals forcomplete alignment capability 100 mc sweep signal (adjustable t2 mc) for overall RF & IF alignment Built-in markers for10.7, 90.95, 96.3, 101.65 & 107 mc No balance adjustment required for equal right and left channel modulation levels Phasetest for accurate adjustment of subcarrier transformers

Here is an outstanding new instrument thatwill add extra profits to your service opera-tions . . . the new Heathkit FM StereoGenerator! This completely self-containedinstrument provides all the signals neces-sary for fast, easy alignment and trouble-shootir g of FM stereo tuners, receivers andmultiplex adapters in addition to standardmono FM.Versatile Performance! Signals generated bythe Heathkit IG-112 include an audio orcomposite stereo signal for multiplex adapteradjustments or an RF carrier modulated bythese same signals to produce an "on -the -air" signal just like that transmitted by anFM station. A sweep function is also pro-vided for over-all RF-IF alignment withmarker frequencies at 90.95 mc, 96.30 mc,101.65 mc and 107 mc for checks of dialtracking. Instant selection is made betweeneither Right or Left channels, as well as aspecial "Phase Test" for accurate adjust-ment of stereo subcarrier transformers. Nobalancing is required for equal right andleft channel modulation.Advanced Design! Switch -selected audio fre-

r

quencies include 400 cps, 1000 cps, 5000cps, 19 kc, 38 kc and special SCA frequenciesfor either direct or RF carrier modulationuse. The SCA frequency is selected by a rearpanel switch to be either 65 kc or 67 kc, pro-viding a versatile system capable of aligningeven the most deluxe tuners of advanceddesign. A crystal -controlled 19 kc ( cps)pilot signal adjustable in level from 0 to 10%is provided to check the lock -in range ofstereo receivers.Easy To Use! RF signals supplied by thegenerator terminate at a 300 ohm balancedoutput, designed for direct connection to theantenna terminals of the tuner or receiverbeing tested . . . no complicated matchingnetworks for impedance or balance required.A three -step (20 db per step) RF attenuatorin addition to the variable output control,prevents overloading tuner input, and thecarrier is adjustable t2 mc up or down topermit alignment on a clear portion of theFM band.Easy To Build! Clean, open circuit layoutprovides easy access to all components forgreatly simplified assembly. Complete with

FREE CATALOGFully illustrates over 250 excitingHeathkit products at savings of50% or more! Chcose from theworld's largest selection of qual-ity instruments in easy -to -buildkit form. Send for 'our free copytoday!

test leads and detailed stereo alignment in-structions. Order your Heathkit FM StereoGenerator now for faster, easier servicing. . . extra profits in this greatly expandingfield of Stereo FM.Kit IG-112, 10 lbs . $99.00Export model available for 115/230 V. AC,50-60 cps: write for details.IG-112 SPECIFICATIONS-RF Signal Output: Centerfrequency: 100 mc adjustable by approx. ±2 mc. Pilotmodulating frequency: 19 kc ±2 cps. FM modulation:Left channel (stereo), right channel (stereo), Phasetest (left plus right channel in phase). Monophonic FM.Deviation: Adjustable to 75 kc. Sweep rate: 60 cps.Sweep width: Adjustable to 750 kc. RF attenuatorrange: 60 db in 20 db steps. Crystal -controlled mark-ers: 10.7, 90.95, 96.30, 101.65, & 107 mc. Compositesignal output: Left channel (stereo). Right channel(stereo). Phase test ()err plus right channels in phase).Audio output: 400, 1000, & 5000 cps; 19 kc (+2 cps);38 kc; & SCA (65 or 67 4c). Maximum distortion: (at400, 1000 & 5000 cps) Front panel controls: 19 kcpilot level control, deviation -sweep width -composite,level -audio level control, function switch, frequencyswitch, & RF attenuator switches. Rear panel adjust-ments: Balance adjust, 38 kc sync, pilot level adjust, &SCA frequency switch. Chassis adjustments: Oscillatoradjust, irequency adjust & modulation adjust. Tubecomplement: 12AT7-19 kc oscillator & 19 kc doubler;6AU8-19 kc buffer & 38 kc amplifier; 6AN8-React-once tube modulator & 100 .mc oscillator; (3) 12AU7-Audio osc.; audio cathode follower & 19 kc pilotamplifier; composite/audio amplifier & 5.35 mc crystalosc. Power requirements: 105-125 volts AC, 50/60 cps,35 warns. Dimensions: 10'/," H x 8" D x 13" W.

X-X MATH NEI Te.64. ...Drzyda,Lernot.

HEATH COMPANY, Dept. 20-7-1Benton Harbor, Michigan 490230 Please send Free 1964 Heathkit Catalog.

Enclosed is $ plus postage. Send IG-112 FM Stereo Generator.

NAME

ADDRESS(Please Print)

CITY STATE ZIPPrices & specifications subject to change without notice, TE-129

-1

JULY, 1964 55

Disc recorder cut too shallowI'm restoring an old Philco 42-1008

disc-recorder-radio combination. I can'tget a satisfactory cut: the stylus eithercuts too deep or not deep enough. Wherecan I find the service data on this?-M. T.,San Antonio, Tex.

Service data are in Rider's Vol.13-9, Perpetual Trouble Shooter's Man-uals. Nothing on the recorder unit here,though: you'll find that in Sams 1947Record -Changer and Recorder Manualunder G -I (General Industries) RC -130L.

From experience, I'd say that yourtrouble is due to the "straddle -plate" ofthe recording arm being loose. There isa "staked" bushing at the pivot point,which used to work loose; this makes itimpossible to get a good adjustment onthe cutting depth.

Take this apart and see if you canrestake it with a sharp punch and a lighthammer. Be careful! In a few cases, youcan carefully flow solder into this bush-ing and get it to hold.

Be sure that the knife edge of thefollower arm, which rides on the leadscrew under the turntable, is bearing justenough on the arm. It should hit thescrew about 1/2 inch before the armreaches the surface of the disc. With thecutter arm down, you shouldn't have any"slack" at all when you try to move thearm sidewise.

Watch the "chip" (the thread ofplastic which curls up from the disc whileyou're cutting) . If it is kinky and breaksup in short pieces, you're cutting tooshallow. If it's long and curly, stayingin one piece and wrapping around thespindle, you've got it just right.

Hi-fi won't turn offI've a Motorola hi-fi console with

an unusual condition. The owner hookedup a Collaro changer to it. He cut upthe line cords and soldered them all to-gether! When he turned it on, there wasa "burst of light," he said. Now, theamplifier won't work with its own linecord, but it will when the cord to thechanger is plugged in! You can't turnthe amplifier off! Could this be a shortedcapacitor, or what the heck?-T. B., EastPaterson, N. J.

These things happen, don't they? Idon't think this is a shorted capacitor.Line bypass capacitors are ordinarilyconnected in shunt between the ac lineand chassis. They wouldn't be in a posi-tion to shunt the switches.

The most likely thing here is thathe managed to get a short so that theswitch contacts have welded themselvesclosed. (This is commonly caused bylightning, too.) The switch will stillclick, but that's all.

Remedy: take a pair of diagonals,

cut the whole mess out, and start all overagain. If he wants to use the automaticshutoff switch in the changer to controlthe amplifier, this can be done-just hookthe amplifier ac input on the motor sideof this switch. While I don't recommendusing too much load on these switches,they seem to be able to carry the ampli-fier current OK. (The one on mine hasfor some years now!)

Suggestion: get one of the smallsurface -mounted "table -tap" triple ac re-ceptacles, and screw it to the back of thecabinet under the changer shelf. Thenhook that up to a single line cord. Makesthings a lot simpler.

Flashover and convergenceI've got troubles with two sets! In

one, I can't get the blue lines the way Iwant them. All of the adjustments seemto work right, but I can't get the endsof the lines to converge properly.

In the other, with the same chassis,(RCA CTC 5) I've got a severe arcingat the end of one of the PC boards, Itflashes with a noise like a rifle shot!There is a burned area on the board.Other technicians have told me to drillholes in the board, but I don't like todo this. What would you recommend?-J. B., Bradenton, Fla.

Let's take your convergence troublefirst. Since all your adjustments seemto be working right, try a slightly differ-ent method of convergence. You see,you have all kinds of adjustments onyour blue, while the other colors haveonly two major adjustments, both diago-nal. So I'd run the purity, degaussing,etc. adjustments first, then turn the bluecompletely out (with the blue screencontrol, or shunt the blue gun, etc.)then run the red-green convergence untilyou get a good yellow line or lines. Nowturn your blue back up and see if it isn'teasier to get the blue to move over toconverge with the yellow; I think you'llfind it will be. You can move the bluelaterally, horizontally and vertically, oralter the shape, by setting the blue ad-justments: horizontal tilt, vertical tilt,blue lateral and blue static, etc. Mosttechnicians use this method, and I thinkyou'll find it easier.

As to the flashover trouble. Thereare several ways to cope with this, anddrilling holes in unused sections of theboard is one of them. This increases thegap the voltage has to jump.

A good general remedy is this:clean the bad section of the board verywell, with a good solvent type servicecleaner. Take a small burr and a hand -grinder, and carefully cut out the partsof the board that have been burned, likea dentist cleaning out a bad tooth. Theseparts are carbonized, and hence willcarry current, so take 'em out entirely.

If any of the PC wiring goes with it,replace the conductors with very smallinsulated wire, "tacked" from point topoint to complete the circuits (Fig. 1).In fact, it's a good idea in some cases toreplace the PC wiring entirely, in thecircuits causing the flashover. Run wellinsulated wire from the nearest terminalpoint on the PC board to the other ter-minal.

CUT AND PULL OFF OF BOARD ENTIRELY

REPLACE WITHINSULATED WIRE

Fig. 1-Sometimes the wisest thing, incase of persistent flashovers, is to removethe offending strip of printed -circuit foilentirely and replace it with a piece of in-sulated hookup wire between the samepoints.

After you've made these repairs,spray the whole area with a good acryliccoating. Best way to do this is spray ona thin coat, allow to dry for 4-5 hours,then spray on another. Three coats won'thurt anything.

In some cases, you can kill an arc -over by painting the area with coronadope or a similar insulating compound.In other, you can lift the edge of the PCboard and insert a piece of plastic tapeto cover the damaged place.

RCA KCS-12.1 vertical troublesThe owner wants this RCA KCS-

121 serviced in his home! It's got allkinds of vertical troubles: roll, notenough height, poor vertical linearity.You name it, we got it! New tubes didn'thelp too much, and it won't hold adjust-ments once made. I'll appreciate anyhelp!-G. E. G., Baltimore, Md.

While I do not ordinarily rec-ommend "shotgun replacement," I thinkthat you'll save time here by doing it.Lift the vertical sweep board away fromthe chassis enough to let you get at it,and replace all the capacitors on it(about 8 or 9) ! Check the schematic be-fore you leave the shop, and pretest allof the replacement capacitors on some-thing like a Sprague TO -5 or a capacitortester which will detect even very smallleakages. This circuit is critical, andprone to developing small de leakages inthe original capacitors. Replace all ofthem and you'll probably solve theproblem. END


AUDIO EQUIPMENT REPORT

All -Transistor Stereo AmplifierKLH Model Sixteen

IF THERE ARE ANY AMPLIFIERS THAT CANbe counted on to clear away any re-maining notions of the inferiority oftransistors to tubes, the KLH Sixteenis certainly one of them.

I received what was apparently anearly production model; the only litera-ture with the amplifier was a 10 -page"Instruction Sheet" that told how toconnect the amplifier, phase the speak-ers, and use the controls.

SPECIFICATIONS(All specifications are the manufacturer's)

Power output: 70 watts rms, +0, -1 db from 25 to20,000 cycles, both channels driven simultaneouslyinto 8 -ohm loads. Decreased by 2 db with 16 -ohmloads

Music Power IHF rating: over 100 wattsHarmonic distortion: Less than 2% from 25 to 20,000

cycles at 35 watts, both channels operating simul-taneously into 8 -ohm loads. Mid -band distortion atfull power less than 0.5%

Response intentionally rolled off below 25 cycles toprevent high -power, low -frequency transients fromdamaging speakers

Semiconductor complement: 22 transistors, 8 diodesDimensions: 41/2 in. high by 113/4 in. wide by 101/2

in. deep including knobsPrice: $219.95, fair traded. Oiled walnut case, $19.95

extra

Hooking it up, I was rewarded withsome uncommonly good sound. I don'tlike to lapse into audiophilic jargon, butthe well worn expression "effortless"sound applies so well to what I heard!

Impressed and curious, I discon-nected the amplifier after a while andmade a few measurements. At that timeI had no idea even of the power outputto expect from it, so I began completelyunprejudiced. I got 33 watts of purestsine wave from one channel at 1,000cycles. When clipping did set in (35watts) it was clean and symmetrical.

What was much more impressivewas the fact that the amplifier was stillputting out 30 watts per channel at10,000 and at 30 cycles! Very few tubeamplifiers can equal that performance,and no transistor amplifier I have yetseen can either. I decided to be brutaland leave the amplifier carrying 30 wattsat 10,000 cycles, watching carefully forany creeping distortion (on the scopescreen) or wisps of smoke, and feelingthe output transistors every few secondsfor signs of overheating.

":11,:ft:,..7.cnt..-{XXX:tteSX-.1P1Xx-xx '111W.XXXstx.:1XXX:mvxrs..w...wrsssm

From the time I began to the timeI got bored with it, none of the outputtransistors got warmer than a casualhandshake. Power stayed right where itwas, and the scope trace did, too.

I was surprised not to see anywherein the instructions the usual cautionarynote about shorting speaker terminals.Whether this was an oversight, a pieceof brash confidence or just candid hon-esty on the manufacturer's part, I de-cided it ought to be reported on.

So ... with the amplifier going fulltilt into an 8 -ohm resistive load-I short-ed the output terminals! (Very tenta-tively at first.) Naturally the scope traceflattened out into a straight horizontalline. But the instant I disengaged thescrewdriver, the old sine wave bouncedright back, and the meter again read 33watts! I tried again, this time bridgingthe screws firmly with a big, fat screw-driver for 5 or 10 seconds. The modelSixteen couldn't have cared less.

I tried various capacitive loads, noload at all, square waves at all frequen-cies, but the amplifier would not mis-behave. There was nothing to do but goback and listen to it.

Which I did, with renewed enthusi-asm. I have been using it almost dailyfor several weeks, and I can't think ofanything unfavorable to say about it.Oh-except that hiss! This one is not asbad as some, but the hiss is quite clearlyaudible in a quiet room during spots ina program. At least it is so soft and ofsuch a "temperature" that it can beignored.

One of the things I liked best aboutthe model Sixteen is its solid construc-tion and cool, low-key elegance. Thepanel is thick aluminum, with a brushedfinish, the "grain" of which is horizon-tal above the knob axes and verticalbelow, giving the panel a two-tone effectbut without paint. The knobs are solidaluminum with narrow grooves milledout as position indicators. Panel mark-ings are black, simple and legible. Theonly color is the "vertical lines" back-ground for the KLH emblem in theupper left corner: pale blue. A veryhandsome piece of design, carried eveninto the feel of the controls and switches,which handle as though they were allindividually machined.

The tone controls have an unusu-ally large amount of boost and cut. TheSixteen offers two loudness compensa-tion positions (besides OFF-none at all).One is for very low levels or for highlydamped or bass -deficient speakers, theother for moderate levels.

A STEREO-MONO mode switchmakes it possible to feed the same signalto both channels from only one input

jack if desired, and to parallel the twochannels for vertical -noise cancellationWhen you play mono records with astereo cartridge. There is also a front -panel headphone jack and a speakeron-off switch. The amplifier has a high -cut filter and the very useful tape moni-tor switching facility.

There are only four inputs: phono,tuner and two auxiliary. The phono in-put can be switched to accommodatelow-level or high-level cartridges, andthe Aux 1 input to LO, MED or HI, de-pending on the source signal level.

Particularly appealing, too, are theSixteen's weight and size: about 12pounds and 113/4 inches across the panel.Pretty good for a 70 -watt stereo ampli-fier with controls!-Peter E. Sutheirn

All -Transistor AM -FM -StereoTuner Heathkit AJ-33

AM-FM STEREO TUNERS OF A FEW YEARSback fed AM to one channel and FM tothe other, for the experimental stereotransmissions of the day. Those tunershad dual tuning: one knob for AM, onefor FM. This tuner does not. It has onlyone tuning knob, with separate dialscales for AM and FM. It operates inthree clearly indicated modes, selectedby a switch.

In the AM and FM positions, both

SPECIFICATIONS(All specifications are the manufacturer's)

FM sectionSensitivity (for 30 db quieting): 31/2 tivCapture ratio: 7.5 dbImage re)ection (30-p_v input, mod 30%). 40 dbAM suppression: 22 dbOutput impedance (emitter follower): variable to 3,000

ohmsOutput voltage: 0.5Audio -frequency response: 20 to 20,000 cycles ±1

dbHarmonic distortion (25t,tv input at 98 mc, 100%

mod): less than 1%Hum and noise (25 p.v, 100% mod): -48 dbMax channel separation: 30 db min at 1 kc; 25 db

min at 10 kc

AM- sectionUsable sensitivity (20-db quieting at 1000 kc): 15 1ivImage rejection (1,000 kc): 40 dbHarmonic distortion (750 [iv input, 95% mod): less

than 1%Output voltage (750 p.v input, 30% mod): 0.45Dimensions: 155/s x 33/4 x 111/2 in. in walnut cabinet

suppliedPrice: $99.95 in kit form

JULY, 1 9 6 4 57

monophonic, the output emitter follow-ers feeding left and right channels de-liver identical program. The FM STEREOposition is for FM multiplex reception.

The circuit includes a stereo indi-cator light, which lights up when an FMmultiplex signal is tuned in, regardlessof which FM position of the mode switchis selected. In the FM (monophonic)position, the 38-kc locked oscillator isdisabled, preventing noise from produc-ing spurious stereo effects when receiv-ing a monophonic signal.

The squelch circuit is very valuablefor FM, because it kills the signal chan-nel between stations, where little or noagc voltage is developed. The point atwhich this killing occurs is adjustableby a preset knob behind the trim flap.

Accurate tuning is facilitated bythe clearly readable pointer type indi-cator. The only manual controls on themain panel are tuning, mode switch andon-off (pushbutton type) ; everythingelse is located behind the trim flap in thelower half of the front panel. There wefind, reading from left to right: SCA fil-ter switch, controlling a filter for rejec-tion of the 67-kc SCA subchannel, whenit is present; squelch control, to set thelevel at which the FM signal is squelched;separation and balance controls for theFM stereo mode; left and right outputlevel controls (which serve as amplifierinput level controls, if the tuner is usedwith an amplifier without them) ; phasecontrol for stereo multiplex (this adjuststhe phase at which the 38-kc oscillatoris locked, on which accurate separationdepends); FM antenna switch, markeddistant-local (puts attenuation in localreception, where the signal might bestrong enough to overload the rf sec-tion); noise filter on-off (this is simplyincreased high -frequency rolloff), andAFC on-off, which serves the usualfunction in FM reception.

As a tuner, this one handles verynicely in all three modes. Where twotransmissions share the same frequency,it cannot separate them, of course.Means must be found to do this at theantenna, by using directivity. But fortransmissions on adjacent channels theseparation is unbelievably good. On AM,it seems to "cut" from one station toan adjacent one, rather than blendingover with that horrible distortion sometuners have, often difficult to eradicateon either individual channel.

Compared with other tuners, theHeath AJ-33 gives the impression thatit will get any station that can possiblybe pulled in. Dead fringe areas proveto be not so dead as other tuners wouldhave us believe! And noise, which pre-viously seemed inevitable with distantreception, is astoundingly low. The qual-ity is indistinguishable from high -qualityrecord reproduction.-Norman H. Crow-hurst END

Answers to

This month's puzzles are on page 33

Unsquare WavesAs I prepared to feed the square -

wave signal to the vertical plates directly,I reached for the INT-EXT switch at theback of the scope. It had been in the EXTposition for months!

Why hadn't I noticed? Because ofR13 and R14, the deflection circuit waselectrically continuous even though theswitch was set to EXT. Because scopeplates draw virtually no current, therewas tittle voltage drop across R13 andR14. But the resistors, together withstray shunt wiring capacitance and thecapacitance of the deflection plates them-selves, formed a very effective low-passfilter that rounded off the square wavesby progressively attenuating higher har-monics. On sine waves and most otherwaveforms, the discrimination wasn'tnoticeable.

I slid the switch back to INT, andfound I had beautiful square waves-even from the original clipper circuit!

The resistor has no effect on thesteady-state values, so it can disregarded.By using the reciprocal of the sum of thereciprocals (the capacitors -in -series for-mula) , and the sum of the voltages, theeffective capacitance of the three isfound to be 1µf at 300 volts, and acharge Q of 300. (Q = CE)

C2 C3

- -OV +50V 50V

IK

This is the total charge obtainablefrom the circuit after switch is thrown.The charge remaining on each capacitorin the steady state equals its originalcharge minus 300.

Volts

Original Q -300 Final Q E = (I))

Cl 300 -300 0 0

C2 150 -300 -150 -50C3 600 -300 300 50

The polarity of C2 is reversed in the finalor steady state.

Alternate Designs

We have received two similar alter-nate circuits for the April "Design Prob-lem" puzzler in which the diagram sub-

mitted by Frank Hanzsek is typical. Inthis circuit, only an spst relay is re-quired, but there is no danger of the re-lay dropping out while switches arethrown.

Two Ways to DistortThere is another possible cause of

distortion in Jack Darr's "A DistortedPuzzler," page 37 of the March issue.My solution was that the 6 volts on thecontrol grid was caused by grid emission.

I check for grid emission by pull-ing the tube. If the voltage disappearsI suspect the tube. If it remains, I suspectthe coupling capacitor.

Miniature and subminiature powertubes are more susceptible to grid emis-sion caused by excessive heat than arevoltage amplifiers-a point Mr. Darr mayhave had in mind.-James B. Edgerton

That Two -Meter PuzzlerThe solution to this April puzzler

evoked some comment about the cor-rectness of the dc ammeter reading.Reader Richard Mirdas came up with asolution using "ideal" components (zerometer resistance-diode with zero for-ward, infinite back resistance). When di-ode conducts, the current divides equallybetween diode and meter, allowing ameter peak -reverse current of 2.With Irms = 1.15 amp, and using theformula:la ve = Irme/4 X 0.637/0.707 = dc amps,the dc ammeter reads 0.2587 amp.

Reader Jesse T. Hancock Jr. sug-gests (again using ideal components),that the original given solution could begotten by inserting an additional diode inseries with the meter, connected so thatmeter current is cut off while "black -box diode" conducts.

We ran bench tests with practicalcomponents (two different dc ammeters,two different -type diodes). Due to the di-ode's requiring a few -tenths -volt forwardbias before it conducts, reverse currentflows in the meter during part or all ofthe negative half -cycle. There would beno definite dc value indicated; it dependson the meter sensitivity and the diodecharacteristics. A sensitive meter wouldread zero, and an insensitive one (highvoltage -drop for full-scale deflection)would approach the given reading of0.515 amp.-Editor END


MIRM10.5.i:ZE.MMECMGRIii.!::igiSMIREMASNAUSWESIEINECESIGNONNWP.A.M$NNEliiMg:iMISM:]ii.:Egl

test equipment reportsMUMINCOMENSM,INaziammuml

Lafayette TE-6030,000 ohms/volt multitester

HIGH SENSITIVITY (30,000 OHMS PERvolt) is not common in an economy -priced meter. This compact (35Ar, x 6%3x 23/4 inches) meter was designed forfield servicing.

Lower -than -usual dc voltage ranges(0.25, 1, 2.5 and 10 volts) are made toorder for transistor circuit testing. At30,000 ohms per volt, the resistance ofthe meter circuit is 7,500 ohms on. the0.25 -volt range-this will not seriouslyload a circuit resistance that is less than750 ohms. (Voltage readings takenacross a resistance of 750 ohms will beonly 10% lower than normal.)

Many times an ohmmeter is usedjust to test circuit continuity. A smallbuzzer has been mounted in the caseof the TE-60 to make continuity andshort tests easier. You don't have tolook at the meter-you can hear whenthe circuit has been completed. Wire -men and industrial technicians haveused this method for years to speedup cable testing. This buzzer uses thesame jacks that are used for most othermeasurements. You don't have to shifttest leads around. Just switch to BUZZ.

The OFF position on the rangeswitch is called "transit" by some manu-facturers. It shorts the meter movementto damp pointer swing while the instru-ment is being moved.

The shorted coil becomes an elec-tromagnet. Any movement of the coilgenerates (induces) a current in it. Thiscurrent forms a magnetic field whichopposes its movement in the magnetic

field of the permanent magnet of themeter assembly.

Just because this meter is sensitivedoesn't mean it is limited to low -voltagetesting or to transistor circuits. The dcand ac voltage ranges include 100-, 250-,500- and 1,000 -volt positions that aresuitable for most vacuum -tube circuits.Special jacks are used for the 1,000 -voltranges-the selector switch is set to the500 -volt position.

Specifications(All specifications are the manufacturer's)

Basic movement: 33 µa, 4 -inch, 2.color scaleOverall sensitivity: 30,000 ohms/volt dc; 15,000

ohms/volt acDc ranges: 0-0.25, -1,

-500, -1,000 volts;0-12 amps.

-2.5,0-0.05,

-10,-5,

-25,-50,

-100,-500

-250,ma,

Ac ranges: volts only, same as dc, from 2.5 volts upOhms: 0-60,000, -6 meg, -60 megDb: -20 to 561% resistors in all multipliers35/16 x 65/16 a 21/4 inches, 1 lb. 6 oz.

Another special jack is used for 12amperes dc. The shunt for this range(.01 ohm) looks like a wire handle. Itgoes from the COMMON jack to the DC12 A jack.. The heavy current does notflow through the selector -switch con-tacts-they would be burned by a 12 -ampere current. Also, the contactresistance of the range -selector switchcould be as much as (or more than) theresistance of the shunt.

Center -scale readings of 400, 40,-000 and 400,000 ohms make most com-mon resistor values easy to read. A15 -volt battery is used for the high -resistance (RXIOK) range. This is highenough to burn out some transistors andcomponents-like electrolytic capacitorsrated at less than 15 volts.

There are 24 basic ranges plus sixoutput ranges (-20 to +56 db) and thebuzzer. The scales are well spread out.Testing most hi-fi and TV circuitsshould give little trouble-as far as read-ing the meter scales is concerned.

The TE-60 is well built and ruggedenough to be carried in the tube caddy-and so inexpensive ($17.95) you canhardly afford to be without one forservicing trips.-Elmer C. Carlson

25 -Inch Color Tube ComingA total of 1,700,000 color tubes

will be produced in 1964, of which1,300.000 will be RCA tubes, saysDouglas Smith, vice president, RCAElectronic Components & Devices.Nearly all will be 21 -inch round,though some will be rectangular 25 -inch 90° tubes. In spite of the largeproduction, Mr. Smith believes de-mand for color tubes will exceed thesupply throughout 1964.

New,

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NAME.

ADDRESS.

I CITY STATE. .ZIP._L _ _ _ _

JULY, 1964 59

the oldest, mostwidely proved and

sold radio and TV

lubricant

oz. bottlewith dropper

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A oz. bottle(brush -n -cap)

8 oz. bottle

6 oz.sprayextender

oz. spray can - with extender

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Quietrole is your guarantee of themost effective, quick silencer ofnoisy radio and TV controls - thequality product that is a top value.Get Quietrole at quality jobbers.

Some territories still available forexperienced representation.

manufactured by

QUIETROLE CompanySpartanburg, South Carolina

A SIMPLE SOLUTIONThat Solves All YourTV Tuner Problems

One Price 8.95 All Makes

P & H replaces all defective parts, (tubesand major parts extra) and aligns tunerto exact original specifications.

Send us your defective tuner complete;include tubes, shield cover and anydamaged parts with model number andcomplaint.

Try our service and prove to yourselfyou simply can't afford to handle yourtuner problems any other way.

Your tuner will be overhauled and re-turned promptly, performance restored,aligned to original standards and war-ranted for 90 days.

TVTUNER

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Mercury 501 Component Substitutor

THIS FOUR -IN -ONE INSTRUMENT CAN SUB-stitute for five components-at once-orbe interconnected with itself to make acomplete circuit!

Servicing by substitution has al-ways been popular. Often it has been adangerous method because of the usualhaywire connections used to stick aknown -good component temporarily intoa circuit.

The resulting rat's nests of wiresand components often shorted, burnedout parts, and even technicians!

Neatly packaged substitution com-ponents will simplify and speed testingand make it much safer. Substitution nolonger has to be a solder -in and unsolder,pick a different value, solder -in and un-solder time-consuming chore.

The Mercury 501 gives a choice ofup to four different -type components(I/z- or 1 -watt resistors, 20 -watt powerresistors or diodes, coupling or bypasscapacitors, dual electrolytics).

It is actually four substitution boxesin one. It contains twelve 1 -watt resistors(ranging from 10 ohms to 5,600) andtwelve 1/2 -watt resistors (from 10,000ohms to 5.6 megohms) on one selectorswitch. Either 1/2- or 1 -watt resistorsmay be selected-but not at the sametime.

A second selector has 20 -watt resis-tors and 3 diode positions. Resistancevalues range from 2.5 to 15,000 ohms.

One diode position will substitutefor the 1N34, 1N48, 1N60, 1N64, etc.and similar detector diodes.

The silicon and selenium powerrectifier substitute is a 750 -ma, top -hatsilicon rectifier, used alone in one posi-tion and with a series resistor in anotherto simulate the characteristics of the se-lenium rectifier.

It is possible to interconnect thefour selectors to make a substitute trans-

formerless half -wave power supply. Thecircuit is shown in the diagram. Thetubular capacitors can be connectedacross the ac input to bypass line -volt-age transients.

The tubular and ceramic capacitorsinclude all the popular values from 100pf to 0.5 pi at 600 volts. A single ce-ramic plate contains the six lowest -capacitance units.

CARBON RES RECTIFIERSECTION SECTION

100ff/IW SIL RECT 4711 30 50

II7V AC INPUT

ELECTROLYTICSECTION

B

DCOUTPUT

With the Mercury 501, you can even whipup a little ac-dc power supply in about10 seconds. Puts out up to 150 volts atup to 100 ma.

Two four -section 450 -volt electro-lytic capacitors provide all the capaci-tance values from 4 to 150 pf. Therotary switch selects most popular dualcapacitors. For example, 30-50 pf isused as the filter in many half -wavepower supplies. Other combinations from4-8 to 80-150 are available. Of course,the 80-150 sections can be connectedin parallel to make 230 juf.

Surge protection is also a part ofthe electrolytic substitution section. Aresistor is connected in series with eachcapacitor initially to allow it to chargeslowly to the working voltage-the resis-tor is then switched out. Permanentlyconnected 330,000 -ohm bleeders dis-charge the capacitors. Net price of theunit is $37.50.-Elmer C. Carlson


New

emiconductors

andirbes6HB7

Here is another vhf TV oscillator -mixer triode -pentode. The pentode sec-tion of this RCA tube has a relativelyhigh transconductance (6,400 µmhos)and a low plate -to -grid capacitance: .01pf maximum, for low feedback between

H

K,G3pIS

Glp

K,G3p ,IS

Pp

G2p

PT

GT

6HB7plate and grid. Two base pin connectionsto the pentode cathode minimize cath-ode lead inductance. Triode and pentodeare separated by an interunit shieldbrought to pin 1 on the base.

The 6HB7 is a 9 -pin miniature typewith RCA "Dark Heater" and controlledwarmup time for series heater strings.High -power epitaxials

Four new high -power silicon epi-taxial transistors with an fT of 20 mc

and a continuous collector -current rat-ing of 25 amperes maximum, have beenannounced by RCA. They are expectedto be used in high -reliability aerospaceand industrial applications where fastswitching of high currents is necessary.

Typical proposed applications in-clude switching control amplifiers,switching regulators, dc -ac inverters,and rf power oscillators and amplifiers.

Two of the devices, the 2N3263and 2N3265, are electrically identicalbut are packaged differently. The2N3263 is in a 3/4 -inch diameter flatcase with radial leads for physically"tight" locations (right in photo). The2N3265 is in a Ys. -inch hexagonal dou-ble -ended stud package for maximumdissipation (left in photo). Collector -to-base voltage, 150; collector -emitter, 90.

The other two transistors, 2N3264and 2N3266, are identical electrically.with lower maximum voltage ratingsthan the first pair. The 2N3264 is inthe radial -lead package; the 2N3266 inthe stud -mount housing. Collector -to -base voltage is 120; collector -to -emit-ter, 60.

DX247 klystronThis reflex klystron is claimed by

Amperex, the manufacturer, to be thehighest -frequency unit of its kind so farcommercially available. It operates inthe 2 -mm wavelength region-mechanic-ally tunable from 140 to 150 gc, and

"features an exceptionally high poweroutput of 20 mw over the band."

The DX247 is expected to aid re-search in areas like dielectric measure-ments, microwave spectrography, para-magnetic resonance and space com-munication.

Resonator voltage is 2,500. END

CorrectionIn the article "Don't Miss the

Boats" in the May issue, the marinesafety and calling frequency is errone-ously listed as 158.6 mc (page 40, thirdcolumn, 8th line). The correct frequencyis 156.8 mc. Our thanks to Awrey'sRadio Service of Hamilton and St.Catherine, Ont., for calling this errorto our attention.

ALL NEWSENCoREcomponentsubstitutor MODEL RC121

All your favorite Sencore Substitution Time -Savers in One Compact UnitA complete range of carbon resistors, wire wounduniversal selenium and silicon rectifiers.Imagine, all of these hard to locate parts at your fingertips for on the spot substitution. Say goodbye to messy,crumpled parts, unnecessary unsoldering and solderingof components for testing purposes only. Save valuableservicing time and be sure, by substituting.NEW . . . each section operates independently with avalue close enough for every substitution need. Com-ponents in each section are isolated from chassis andfrom the other sections. For example, a complete powersupply can be constructed using the RC121 Compo-nents only.

Now in stock at your Sencore Distributor. See him today:

power resistors, capacitors, electrolytics, and

NEW . . . dual electrolytics provided. A new circuitenables you to substitute up to 25 single electrolyticvalues or 9 duals. Exclusive surge protector providesprotection on both singles and duals for both you andthe circuit.You save space and money. Equivalent Sencore sub-stitution -pieces purchased individually (H36, PR111,ES106, ES102) cost you $54.00RC121 (all hand wired, all American made) only 3995RC121K (Kit) 27.95

SENCORADDISON 2, ILLINOIS

JULY, 1964 61

TOlets

ivew LiterattliW

Iatalagsl

CATALOG, Spring -Summer No. 643, 136 pp.Latest in electronic components, hi-fi stereo, taperecorders, CB equipment, transistor radios, hamgear, tools, test equipment, optical goods. autoaccessories, intercoms, cameras, mikes, PA sys-tems, musical instruments, tools. -Lafayette RadioElectronics, 111 Jericho Turnpike, Syosset, N. Y.

CATALOG, Spring -Summer Supplement No.235, 144 pp., featuring among other items manytransistorized products: walkie-talkies, AM porta-bles, AM and short-wave portables, AM car radios,AM -FM portables, FM -AM -short-wave portables,41/2 -in. TV set to operate from rechargeable bat-teries or 12 -volt car battery or 110 -volt 60 -cycleac outlet, hi-fi tuners and amplifiers (kits and fac-tory -assembled), portable tape recorders, electronictachometer, transistor ignition system, code -prac-tice oscillator, intercoms, electronic lab kits, multi-function Ten -2 CB -band tester, all -in -one hi-fireceiver.-Allied Radio, 100 N. Western Ave.,Chicago 80, 111.

WIRE -CABLE GLOSSARY of common ab-breviations for wire, cable and portable cord indus-try in pocket -sized 12 -page booklet.-Royal Elec-tric Corp., Pawtucket, R.I.

BEAT -FREQUENCY OSCILLATORS de-scribed in 16 -page technical brochure on mod-els 1013, 1017 and 1022, with applications, curvesand dimensional drawings. Photos and specs.-B&K153, B&K Instruments Inc., 3044 W. 106 St., Cleve-land it, Ohio

PRESSURE -FIT RECTIFIERS MANUAL, 90pages, covers applications of 2 families of silicon

diodes: 18 -amp family in 5 voltage ratings from 50to 400; 25 -amp family in 7 voltages from 50 to600. Basic rectifying theory and standard circuitsshown and explained, 27 special circuit applica-tions, mounting methods.-Tung-Sol Electric Inc.,Technical Publications Dept., 1 Summer Ave.,Newark 4, N.J. 75f1.

CB ANTENNAS CATALOG describes in 16pages complete line of base -station and mobileantennas and accessories for Citizens -band market.Photos, specs, charts, drawings.-Hy-Gain AntennaProducts Corp., N.E. Highway 6, Lincoln, Neb.

DEALER'S CATALOG, Radio & TV CatalogNo. RT-64. 84 -page catalog lists radio, audio, TV,electrical supplies with illustrations of available dis-play cards.-Fedtro Inc., Federal Electronics SalesDiv., Federal Electronics Bldg., Rockville Centre,N.Y.

TIN -LEAD RATIO CHART shows meltingtemperatures of different solder alloys. One loose-leaf page.-Alpha Metals Inc., 56 Water St., JerseyCity 4, N.J.

INVERTERS & CONVERTERS catalog 300.details more than 60 static dc -to -ac inverters andstatic frequency -converters rated at 6 to 15,000 va,variable -frequency and ultra -stable power sources.4 pages, photos and specs.-CommunicationsMeasurements Lab, Inc.; Tenney Engineering Inc.,350 Leland Ave., Plainfield, N.J.

TOOLS CATALOG. Universal arms, vises, cir-cuit -board holders, board holders, chassis holders,chassis and harness board fixtures, clamps andtable and arm assembly are described with dimen-sions and photos in 8 -page catalog.-Matrix Engi-neering Corp., 6160 Lemona Ave., Van Nuys, Calif.

SEMICONDUCTORS CHART, Section 1/In-dex and Replacement Guide. 6 -page folder in 2colors charts and outlines in drawings company'sline of transistors, diodes, rectifiers.-Bendix Semi-conductor Div., Holmdel, N.J.

TUBE WALL CHART of "Five Star" tubeline gives base diagrams, classifications by func-tion, average characteristics.-General Electric,Distributor Sales, Electronic Components Div.,Owensboro, Ky.

STATIONARY BATTERIES Instruction book,revised edition of Installation and Operation In-structions for Stationary Batteries. 24 -page booklet

COMPUTERTECHNICIANS

Stateside & Overseas Openings

Must have a minimum of 2 years' experience inthe maintenance of military or commercial com-puters or data processing systems.

Excellent benefits including stock savings plan.

Qualified candidates please send complete re-sume to Mr. Don Kirkland, Dept. 806.

PHILCO TECHREP DIV.A Subsidiary of Ford Motor Company

P.O. Box 4730 Philadelphia, Pa. 19134

An Equal Opportunity Employer

with tear -out summary sheet for posting in batteryroom. Sections on receiving, unpacking and han-dling, installation and initial charging, hydrometerreadings, and a table of battery types.-C & DBatteries, Conshohocken, Pa.

TRANSCEIVERS CATALOG. 16 page, 2 -

color brochure with photos of CB equipment andaccessories.-International Crystal Mfg. Co., Inc.,18 No. Lee, Oklahoma City, Okla.

STEREO TAPE TRANSPORT, model T-347,described in 4 -page brochure. Photos, diagramsand specs.-Bell Sound Div., Thompson RamoWooldridge Inc., 6325 Huntley Rd., Columbus 24,Ohio

HI-FI/STEREO EQUIPMENT. 6 -page folderlists stereo amplifiers, tuners and tape transports.Photos, illustrations and spec.-Bell Sound Div.,Thompson Ramo Wooldridge Inc., 6325 HuntleyRd., Columbus 24, Ohio

Any or all of these catalogs, bulletins, orperiodicals are available to you on request directto the manufacturers, whose addresses are listedat the end of each item. Use your letterhead -donot use postcards.To facilitate identification, men-tion the issue and page of RADIO -ELECTRONICSon which the item appears.UNLESS OTHERWISE STATED, ALL ITEMS AREGRATIS. ALL LITERATURE OFFERS ARE VOIDAFTER SIX MONTHS.

Re: Transistors SaveYour Breaker Points

A number of readers have re-quested information on adapting thetransistor ignition system ("TransistorsSave Your Breaker Points", Gyorki,April 1964) for positive -ground opera-tion and for installation in cars with6 -volt batteries.

Mr. Gyorki says that the system asshown in the April issue will not workon 6 -volt electrical systems. He is test-ing a modification for 6 -volt negative -ground operation and will give us fulldetails if it is successful.

TRANSISTOR PACKAGE

BALLAST 3

.75S1/100W

ORIGINALBALLAST

PART OFIGN SWLI RUN

2

BREAKERPOINTS

IGNCOIL H V

AUXRY

BATT

STARTERSOLENOID

alkI

START

12V CAR BATT

--+

STARTER

0The diagram shows how the origi-

nal system can be installed in a car witha 12 -volt positive -ground electrical sys-tem. Note well that the points must beinsulated from ground. We understandit is relatively easy to insulate the breakerpoints in most distributors. We have un-confirmed reports that insulating kits areavailable at some speed shops and autoaccessory stores.

The heat sink is a Delco part No.7281352, available from Delco distrib-utors for $1.00.-Editor


TECHNOTESI \

Motorola 17T1This one gave us three callbacks-speaker field burned

out each time. Comparing its schematic with one of a sim-ilar but later model showed that an extra 150 -ohm 15 -watt

to

5U4 -GRECT

SPKRHELD 50.11

15 W

.1-76/400--4-V

resistor had been added in series with the B -plus of thenewer set. We added it to the 17T1, and had no moreburned -out field coils.-Carl Hennig

Admiral 15C1 Chassis - Horizontal TroubleIf this set drifts off horizontal sync and requires read-

justing the horizontal hold control again after playing awhile,try using two 500-pf N750 -coefficient ceramics in parallel

FROM HORIZ

PHASE DET 2

TRY 2 - 500PFN750 CERAMICS

6CG7HORIZ OSC

.0039

6 TO HORIZ OUTPUT

820 PF

OK 47K 8

HORIZ HOLD

250 V

.21<

to replace the 820-pf coupling capacitor shown in the dia-gram.

Simple replacement of all critical parts had no effect onthis chassis.-Charles Andrews

Line Voltage Loosens Tight YokesWhen you come across a frozen -on CRT yoke, discon-

nect the horizontal coil leads. Now connect them, in serieswith a 150 -watt light bulb, to the set's ac line cord. Plug theline cord into an ac outlet and leave things for a few minutes.When the yoke gets warm, it will slide off the neck easily.Don't overdo it, though.-A von Zook

Steelman Transitapeand Airline 7111-M Recorders

Trouble: tape speed steady but wrong.The tape speed is controlled by the position of the small

rubber drive wheel on the face of the large brass flywheel.The closer this wheel is to the rim of the flywheel, the slowerthe tape speed. The position of the wheel is controlled bythe speed -selector switch which affects a V-shaped bracket.The two tabs on this bracket are bent to stop it in its twopossible positions. When bending the bracket make certainthat the idler does not hang up in the V, but can move freely

Everything you ever wanted in a CB transceiver!

.1111155115

SOUELCH

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Newest! Most Versatile! Most Power Out!The 11 channel "Messenger -III" will change every idea you everhad about what a Citizens Band unit should offer! Tiny, alltransistor, it's really quiet, really hot! Interchangeable for baseor mobile-use it as a full 5 -watt battery powered portable packset or a 3 -watt PA system. The "Messenger III", with an aero-space transistor developed for the "Relay" communications

satellite, delivers more power output with maximum legalinput! Double conversion receiver with high 1st I.F.

provides excellent spurious and image rejection. Set -and -forget "Volume" and "Squelch" controls make

it possible for the first time to work "close -in" orat extended range with initial settings. Furnishedwith dynamic microphone-full line of acces-sories available for selective calling, portablefield pack, or public address use!

Cat. No. 242-150 $189.95 Net

WRITE TODAYfor details on the"Messenger" CBline-or see yourdistributor!

E. F. JOHNSON COMPANY® 2510 Tenth Ave. S.W. Waseca, Minnesota

Please send full details on the "Messenger" CB line.

NAME

ADDRESS

CITY STATE

service faster with Fast -Fax

Raytheon Fast -Fax puts tube data for 600 types rightat your fingertips. Stays up-to-date with "pop -in" supple.ments (including new types in '65 sets). Operates as aninterchangeability guide and inventory control. See it atyour Raytheon Distributor. You'll wonder how you evergot along without it. Fast -Fax. Only $3.95.

JULY, 196463

BECOME A RADIO TECHNICIANfor only 526.95

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FREE EXTRAS SET OF TOOLS RADIO & ELECTRONICS TESTER ELECTRICSOLDERING IRON TESTER INSTRUCTION MANUAL. MEMBER-SHIP IN RADIO -TV CLUB: CONSULTATION SERVICE 0' HI-FI GUIDE QUIZZES TV BOOK FCC AMATEUR LICENSE TRAINING RADIO BOOK PRINTED CIRCUITRY * PLIERS -CUTTERS ALIGNMENT TOOL WRENCH SET CERTIFICATE OF MERIT

VALUABLE DISCOUNT CARDWHAT THE "EDU-KIT" OFFERS YOU

The "Edu-Kit" offers you an outstanding PRACTICAL HOME RADIO COURSE ata rock -bottom price. Our kit is designed to train Radio & Electronics Technicians,making use of the most modern methods of home training. You will learn radiotheory, construction, servicing, basic: Hi-Fi and TV repairs, code, FCC amateurlicense requirements.

You will learn how to identify radio symbols, how to read and interpret sche-matics, how tomount and lay out radio parts, how to wire and solder, how to operateelectronic equipment, how to build radios. Today it is no longer necessary to spendhundreds of dollars for a radio course. You will receive a basic education in radio,worth many times the small price you pay, only $26.95 complete.

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The Progressive Radio "Edu-Kit" requires no instructor. All instructions areincluded. Every step is carefully explained. Yes cannot make a mistake.

PROGRESSIVE TEACHING METHODThe Progressive Radio "Edu-Kit" is the foremost educational radio kit in the

world, and is universally accepted as the standard in the field of electronics training.The "Edu-Kit" uses the modern educational principle of "Learn by Doing."Therefore, you will construct radio circuits, perform jobs and conduct experimentsto illustrate the principles which you learn.

You begin by examining the various radio parts included in the "Edu-Kit." Youthen learn the function, theory and wiring of these parts. Then you build a simpleradio. With this first set, you will enjoy listening to regular broadcast stations,learn theory, practice testing and troubleshooting. Then you build a more ad-vanced radio, learn more advanced theory and techniques. Gradually, in a pro-gressive manner, and at your own rate, you will find yourself constructing moreadvanced multi -tube radio circuits, and doing work like a professional RadioTechnician.

Included in the "Edo -Kit" course are 20 Receiver, Transmitter, Code Oscillator,Signal Tracer, Signal Injector, Square Wave Generator and Amplifier circuits. Theseare not unprofessional "bread board" experiments, but genuine radio circuits, con-structed by means of professional wiring and soldering on metal chassis, plus thenew method of radio construction known as "Printed Circuitry." These circuitsoperate on your regular AC or DC house current.

In order to provide a thorough, well -integrated and easily -learned radio course,the "Edu-Kit" includes practical work as well as theory.; troubleshooting in addi-tion to construction; training for all, whether your purpose in learning radio befor hobby, business or job; progressively -arranged material, ranging from simplecircuits to well -advanced topics in Hi-Fi and TV. Your studies will be further aidedby Quiz materials and our well-known FREE Consultation Service.

THE "EDU-KIT" IS COMPLETEYou will receive all parts and instructions necessary to build 20 different radio

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In addition, you receive Printed Circuit materials, including Printed Circuit chas-sis, special tube sockets, hardware and instructions. You also receive a useful setof tools, a professional electric soldering iron, and a self -powered Dynamic Radio SiElectronics Tester. The "Edu-Kit" also includes Code Instructions and the Pro-gressive Code Oscillator, in addition to the F.C.C.-type Questions and Answers forRadio Amateur License training. You will also receive lessons for servicing withthe Progressive Signal Tracer and the Progressive Signal Injector, and a HighFidelity Guide and Quiz Book. Everything is yours to keep.

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ORDER FROM AD - RECEIVE FREE BONUSRADIO & TV PARTS JACKPOT WORTH $15.

13 Send "Edu-Kit" Postpaid. I enclose full payment of $26.95.0 Send "Edu-Kit" C.O.D. I will pay $26.95 plus postage.0 Send me FREE additional information describing "Edu-Kit."

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Progressive "EDU-KITS" Inc. 1186 Broadway, DN.

ept. 223GHewlett, Y.

(ATT. S. GOODMAN, M.S. in ED., PRES.)

(VERT OUTPUT)

from side to side.If a correctly recorded tape is played through the ma-

chine, the tabs on the speed control bracket can be adjustedwhile the tape is playing, and a fairly accurate adjustmentmade using the ear as a guide.-Max Alth

Heath CT-16dCapaci-tester"If this instrument gets knocked around hard and often,

the "eye" tube socket pins may touch the inside back of the

SOCKET PANEL OPENING

metal cabinet and short out. This can damage the device.Avoid the problem by sticking a 2 -inch wide piece of

adhesive tape on the inside of the case at the spot where thesocket pins may touch. Plastic electrical tape (several stripslaid side by side) will also do fine.-Allen Glaser

G -E 16T1, 16C103: No RasterSymptom: No raster, sound OK.Cause: Almost no accelerating anode voltage because of

excessive blanking amplifier conduction (see diagram).Cure: Replace shorted .0l -µ,f 1,000 -volt coupling capac-

I/212SN7-GTVERT ABLANKING

FROM12AU7-A 39K .01

PLATE1 KV

itor from vertical output plate. Note that there was no shortfrom A to ground, yet still point A was near zero volts. Boostand B -plus checked OK.- Warren Dere

Erratic Drift on AMThis set, a Truetone clock -radio model 2086A, would

shift frequency suddenly, and sometimes drift more gradu-ally. I traced the trouble to the wire connecting the oscillatorsection of the tuning capacitor to the oscillator coil. It wasabout 4 inches long and ran near a vertical shield. but withoutany support. When the wire shifted (with stress on the cabinet,or thermal expansion), the oscillator frequency would changebecause of the change in stray capacitance.

I replaced the wire with low -capacitance shielded cable.I grounded the shield at the tuning capacitor frame and tothe ground terminal of the coil. A touchup of the oscillatortrimmer completed the job.

Another possible cure is to fasten the wire along theshield and chassis so it can't possibly move. - Victor H.Boisseau

Substitute for 6M3The 6M3 damper tube designed especially for Philco

color sets and sold only by Philco have been failing prema-turely in their TV123 chassis. There was nothing wrong withthe circuit. Since this tube has no manufactured substitute,lists at $13.50 and can be obtained only from Philco, I setabout devising a substitute-which has been giving betterperformance for more than a year.

I wired a pair of 6AU4-GT tubes in parallel to a plug-in


6AU4 -GT 6AU4-GT

CAPFROMOLD6M3

6AU4-GT

LEADFROMCHASSIS

OCTAL SOCKETS

6AU4-GT

3/B" DIA SPACEROCTAL TUBE BASE

DRILL FOR6-32 BOLTTV CHASSIS

adapter. The drawings show how it was done. No changesare made in the circuit; the wire fuse in the heater circuittakes the extra 0.6 -amp drain without strain.

The top cap of the old 6M3 is removed and soldered toa 6 -inch lead which goes to pin 3 of the 6AU4's. The capthen plugs in to the existing cathode connector coming fromthe set.

This modification will end, once and for all, explana-tions about the short life of the tube, the wisdom of installinganother one just like it, the $13.50, and other embarrassingquestions. -John T. Hacker

Complex IntermittentWe had a 24 -inch RCA that would cut out and develop

an intermittent vertical roll. The picture would get snowyand the sound volume would drop whenever the set wastapped. Didn't seem to matter where it was tapped.

Suspecting tuner trouble, I began checking around andcame to a resistor I wanted to check. I unsoldered one endas usual, and the resistor just fell right out. Its other terminal,which passed through the hole in another solder lug, hadnever been soldered. But it had held out for 6 years, in the6X8 oscillator -mixer circuit.

The unsoldered terminal was hidden away where itcouldn't be seen until unsoldering the other end made theresistor drop out. -Harry J. Miller

Improve Small -Set SelectivityMany low-cost short-wave receivers suffer from bad

selectivity. This can usually be improved by inserting a low -value (50-500 pf) 200 -volt capacitor in the antenna lead.

ANT

FERRITE -CORE ANTENNA COIL=;;.:-1

veSHIELDI TO RCVR ANT

365PF (APPROX)

When trouble is severe, a wavetrap may be used, such as theone shown here. It really pepped up a Knight Space -Spanner.Circuit shown tunes out interfering AM broadcast stations.Other coil -capacitor combinations will he needed for otherfrequencies. -Allan Glaser

No Heater Voltage in MotorolaTS -449, TS -578

Cold tubes in these sets can be caused by an open groundconnection on the coax cable between tuner and chassis.

The CRT is the last tube in the string and is groundedvia the tuner. This approach simplifies adding a uhf adapter(which puts a 2AF4 in series with the CRT heater), but cancause an open heater string. -Havens Electric Co., via TSA(Albany, N. Y.) Newsletter END

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INSTRUMENTS IN ONE Out -of -Circuit.Trarisistor Analyzer

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Transistor Analyzer Model 212Factory Wired & Tested - $18.50Easy -to -Assemble Kit - $13.50

YOU DON'T NEED A BENCH FULL OF EQUIPMENT TO TEST TRANSISTOR RADIOS! All thefacilities you need to check the transistors themselves - and the radios or other cir-cuits in which they are used - have been ingeniously engineered into the compact,6 -inch high case of the Model 212. It's the transistor radio troubleshooter with all thefeatures found only in more expensive units. Find defective transistors and circuittroubles speedily with a single, streamlined instrument instead of an elaboratehook-up.Features:Checks all transistor types - high or low]power. Checks DC current gain (beta) to200 in 3 ranges. Checks leakage. Uni-iversal test socket accepts different baseconfigurations. Identifies unknown tran-sistors as NPN or PNP.Dynamic test for all transistors as signalamplifiers (oscillator check), in or out ofcircuit. Develops test signal for AF, IF,or RF circuits. Signal traces all circuits.Checks condition of diodes. Measuresbattery or other transistor -circuit power -supply voltages on 12 -volt scale., No ex-ternal power source needed. Measurescircuit drain or other DC currents to 80milliamperes. Supplied with three exter-nal leads for in -circuit testing and apair of test leads for measuring voltageand current. Comes complete withinstruction manual and transistor listing.

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JULY, 1964 65

SOUND SYSTEM LECTERN, Ampli-VoxSound Column Lectern. 25 -watt all -transistorpush-pull amplifier handles 40 -watt peaks. 6 built-in speakers in sound column; cardioid micro-phone; goose neck and lavalier cord. Powered

by 10 flashlight batteries, ac adapter available.Height adjustment from 36 to 46 in. Wood cov-ered with Texolite, retractable wheels. 40 lb.-Perma-Power Co., 5740 N. Tripp Ave., Chicago,Ill. 60646.

PROFESSIONAL MIKES. 2 low -impedancemodels, Nos. 802 and 803, and one high -impe-dance, models 801. 802: omnidirectional pickup

pattern. 803: cardioid type mike and recom-mended for use where external noise excessive.-Ampex Corp., 401 Broadway, Redwood City,Calif.

FILTER CHOKE, No. C-4133, exact re-placement for Admiral 74B24-2, Dumont, Emer-son R102134, Magnavox M105195, RCA 102134,112829, Travler, Truetone FC-23 and others. Elec-trical specs: 0.32 henry, 600 ma, 10 ohms. Ship-ping weight 1 tb, 4 oz.-Merit Coil & Trans-former Corp., Merit Plaza, Hollywood, Fla.

VARIABLE -FREQUENCY OSCILLATOR,model HE -89, for 6 and 2 meters. Operates withcrystal oscillators in 8-9-mc region. Output 10-20v rms. 117 volts 50/60 cycles. Tubes 6BA6, OB2

voltage regulator, silicon rectifier, 24 -in. low -losscoaxial cable-Lafayette Radio Electronics Corp.,111 Jericho Turnpike, Syosset, N.Y.

MYLAR-PAPER BYPASSTUBULAR CAPACITORS,type DBE. Mylar, quality ca-pacitor kraft tissue, and solid -setting thermo impregnant. Willnot crack, soften or flow withintemperature range of -55°C to+125°C. Standard capacitancetolerance of -H10% meets MIL -C -25 requirements. For 200, 400 -and 600 -volt ratings.-AerovoxCorp., Distributor Div., NewBedford, Mass.

DUAL -SPEED MOTOR UNIT. model 42.For chart drives, control devices and timers wherefinite reset required. Choice of 3 output speedsby electrical switch control off 2 different -speedmotors which can rotate in same direction oropposite at 180 rpm to 1 revolution per monthor less. Standard output shaft 1/2 -in. diameter by

length.-Bristol Motors, Div. of VocalineCo. of America, Old Saybrook, Conn.

OMNIDIRECTIONAL FM ANTENNA,Rondo model 4407G, said to outperform turnstileand S types. With tri-dipole system, antenna up to2.5 db better than turnstile on turnstile's strongest

sides, to 7.4 db than turnstile on weak sides. Infringe areas, Telstar FMX booster can be addedto make installation equal to 5 -element Yagi onrotator. Gold -color finish. -Channel Master Corp.,Ellenville, N.Y.

HAM ANTENNA, Mark ABB-6,omnidirectional fixed -station antennafor 50-54 mc, 6 -meter amateur radioband. 1/2 -wave radiator, low angle ofradiation gives gain over ground -plane antenna. Voltage -fed at bot-tom through 1/4 -wave section of RG-8/U. Vswr less than 1.5:1 over 49-55-mc band. No radials, fiberglass-nsulated aluminum, 10 ft.-B & K/Mark Div. of Dynascan Corp., 1801W. Belle Plaine Ave., Chicago, Ill.60613

BOOSTER -COUPLER FOR TV AND FM.BC -208 drives 1 to 4 TV or FM sets; 8 db gain

to each output. Takes up to 350,000 my of signalinput. No -strip terminals. Unused terminals neednot be terminated. Isolates sets in system, pre-venting any interaction.-Winegard Co., Burling-ton, Iowa

DETENTED UHFTUNER. Afc preventssignal drift. Indexinglets TV viewer snapin 70 channels on uhfband, in contrast withcontinuous tuning ason radio dial. - OakManufacturing Co.,Crystal Lake, Ill.

WALL TAPS. Versa -Taps install in apartmentand hotel MATV systems before rooms are painted.Standard ac wallplates cover flush -mounted tap-offs.-Blonder-Tongue Labs, Inc., 9 Ailing St.,Newark 2, N.J.

SELF -MOUNTING CLAMPS. Ty -Rap TC-116, TC-118, TC-120 reduce installation time ofcables, wire bundles and harnesses by eliminatingscrews or other fasteners. For Ty -Rap cable ties,

all -nylon clamp has expanding post, installs inmounting hole without special tools. 3 sizes fitNos. 6, 8, 10 holes. Color -coded, pull-out strengthfrom 25.5 to 35 lb. -Thomas & Betts Co., 36 ButlerSt., Elizabeth, N.J.

CB TRANSCEIVER, model 777. Transmitterinput 5 watts to final amplifier plate, frequencyrange 26.965-27.255 mc. 6 crystals selected byfront panel switch. Oscillator circuit factory pre-set and sealed. AM plate modulation automaticallylimited to less than 100%. Variable pi networkmatches most popular antenna types. Dummy an-tenna load for off -the -air tuning. Ceramic micro-phone has push -to -talk switch. Double -conversionsuperhet receiver: rf stage, automatic noise limiter,adjustable squelch, spotting switch and S -meter.


Continuous tuning with vernier drive, or crystal -controlled reception. 6 crystals selected by front -panel switch. Better than 1-Ltv sensitivity for 10-dbsignal-to-noise ratio. Power supply for 6 and 12vdc, 117 vac. 6 x 81/2 x 10 in., 15 lb.-Eico Elec-tronic Instrument Co., Inc., 131-01 39th Ave.,Flushing, N. Y. 11352.

ALL -TRANSISTOR TRUCK RADIO, ATRTruck Karadio. 5 transistors, 2 diodes. 5 x 3 -in.

elliptical speaker built in. 1 -

hole mounting in cab roofwith continuous ventilation.Yoke -antenna assembly andinterference suppression kit.Available for 12 -volt systemswith either negative or posi-tive ground. 33 -in. stainlesssteel antenna. Adaptable toboats or station wagons.-ATRElectronics, Inc., St. Paul,Minn. 55101

CB TRANSCEIVER, model HB-222, featurestunable receiver with 23 -channel crystal control.Dual conversion receiver uses 1650- and 262-kci.f. system. Better than 1 Ltv sensitivity. Audiooutput 3 watts to PM speaker. Illuminated metercalibrated in "S" units, relative power outputand modulation percentage. Push -to -talk noise -

cancelling ceramic microphone: relay switching,illuminated channel selector dial. Pi -network out-put matches 30 -100 -ohm antennas. Front panelphone jack. Built-in 117-v ac and 12-v dc tran-sistorized power supply. 10 tubes, 3 silicon di-odes. 12 x 5 x 81/2 in.-Lafayette Radio Electron-ics Corp., 111 Jericho Turnpike, Syosset, N.Y.

2 -WAY SPEAKERSYSTEM. Model SRINewport: 10 -in. high -com-pliance woofer with single -roll suspension and long -throw voice coil. A 4 -in.combination mid -range andtweeter speaker handlesmiddle through super -highfrequencies. Overall re-sponse: 53 cycles to 17,000+21/2 db. Crossover at1,800 cycles. Handles 45watts of program mate-rial. Minimum drive 10watts. Walnut veneer withcane grille, 24 x 13 x 91/gin. - Sherwood ElectronicLabs, Inc., 4300 N. Cali-fornia Ave., Chicago, Ill.60618

AM/SSB TRANSMITTER -RECEIVER,Comco model 606-SSB operates on up to 6 selectedchannels in 1.6-16.0-mc range in either SSB mode(A3a emission) with carrier suppressed or in com-patible -AM mode (A3h emission) with carriertransmitted. Upper sideband transmitted and lowersideband suppressed 50 db. Power output 100 wattsp.e.p. for A3a emission or 30 watts carrier for A3hemission. Sensitivity better than 0.5 Liv for 10 dbsignal -noise ratio for SSB signals, 1.5 Liv for 10db signal -noise ratio, 30% modulation when re-ceiving AM signals. Frequency stability better than+2 ppm. Agc threshold 5 vv. Audio bandwidth 350

to 2450 cycles. Receiver audio output 1.5 watts.Takes tip 834 in. rack space. -CommunicationsCo., Inc., 300 Greco Ave., Coral Gables, Fla. 33134

FOOT SWITCH, model 111, 5 x 2 x 1/4 in.Easily taped or cemented to floor. Electrical rating1 ampere at 117 volts ac (or 28 vdc) for loads

up to 100 waits. Ribbon switch element sealed invinyl envelope.-Tapeswitch Corp. of America, 545Meacham Ave., Elmont, N. Y. 11003

SOLID-STATE POWER CONTROLS. PDseries Powerdials use silicon controlled rectifiers.

Half the size and 1/10weight of conventionalvariable transformer con-trols. 120 volts ac input;outputs 0 to 120 volts acand 0 to 85 volts dc, bothat 0 to 5 amps, 2PD se-ries: 240 volts ac input,same output as PD series.41/2 x 41/2 x 21/2 in. alumi-num housing. Slow blowfuses, 3 -wire cords withreceptacle, polarized out-lets. For resistive and

mildly inductive loads-International ResistanceCo., 414 N. 13 St., Philadelphia, Pa. 19108

UNIVERSAL AM CAR RADIO. AutovoxBikini. 2 small units can be connected in variousways in autos with limited dashboard space. Power

output 2 watts. Illuminated dial. For 12- or 6 -voltsystems. Shortwave adapter or phono input.-Autovox Corp. of America, 250 W 57 St., NewYork, N. Y. 10019

TRANSISTOR IGNITION SYSTEMS. 4 basickits: 1 each for 6 and 12 volts and positive andnegative grounds. Installs in 1/2 hour with no en-gine or vehicle wiring modifications. Distributorpoints handle current of only 'A to ii/2 ampere.Output voltage approximately 30 kv to the spark

plugs; speeds up to 10,000 rpm. Special coil, tran-sistor circuit with heat sink and ballast resistor.Adapters for voltage or polarity change when sys-tem transferred to another car.-IgnitioneeringCo., 84 Borglum Rd., Wilton, Conn.

POLYSTYRENE CAPACITOR KIT, CPK-150. 150 sealed polystyrene foil capacitors, ratedat 500 volts, +5% capacitance tolerance. 17 se-lected values from 22 pf to 0.1 (if, with 5 to 20

pieces per value. In 1 -drawer blue -enameled steelcabinet. Replacement capacitors for radio, TV,industrial, research and development applications.-Centralab, Electronics Div. of Globe -Union Inc.,Box 591, Milwaukee, Wis. 532(11

ELECTRONIC MA-NOMETER system to re-place liquid manometers.for checkout of altimeters,pressure measuring devicesand air -speed indicators.Accuracy of ±0.15%.Transducer has infiniteresolution; repeatability.063%. Standard pressureranges from 0-20 in. ofwater to 0-600 psi. Powerrequirements 115 volts, 60or 400 cycles - Interna-tional Resistance Co., 401Broad St., Philadelphia,Pa. 19108

PORTABLE LINE TESTER, model LT -1, iso-lates common trunk anddistribution line troubleswith direct -reading port-able meter. Tests for linetermination, line splitting,open and shorted line.Self-contained power sup-ply, pushbutton operation.7 x 21/2 x 27/8 in.; 1 lb. 9oz. - Entron Inc.. SilverSpring, Md.

PORTABLE TAPECORDER, Sony model801-A. Battery -powered. 33/4. and 17/8 ips, dual -track monophonic, 5 -in. reel. Pushbutton opera-tion, self -storing microphone with remote stop/start switch, built-in amplifier and speaker, VU

meter indicating record level or battery condition.and variable back -spacing lever for repetition ofword, phrase or paragraph. 1.5 watts, 9 volts dc(6 size -D flashlight cells). Response: 90-9,500

cycles at 71/2 ips. Inputs: external mike and auxline. Output, earphone monitor. 13 lb. 124/5 x104/5 x 317/2i, in.-Superscope, 8150 Vineland Ave.,Sun Valley, Calif.

BOLT -SLICING CRIMPING TOOL slicesthrough 6 sizes of bolts. Wire cutter at tip strips

JULY, 1964 67

Rake This Your Lai2st, Dag

How TO Ft

TRANsISTORRADIOS

ANDIJITSED ciRC

Join the Gernsback Electronics Book Club today,and get this outstanding practical two -volume work

... with your first selection. You agree to buy only threeadditional books during the next 12 months at low Club prices.

A $9.90 Value ...Originally a $25 Training Course!How to Fix Transistor Radios and Printed Circuits! by Leonard C. Lanewas originally prepared as a complete course in servicing transistor radios. This twovolume version treats every aspect of transistors, much of it new, original, unavail-able anywhere else in book form. Hundreds of illustrations aid understanding. Com-pletely covers semiconductor fundamentals, how transistors work, transistor types,amplifiers, RF and IF stages, printed circuits, specific servicing methods and tech-niques, and many, many more subjects.

Here is a fabulous offer to introduce you to Gernsback Li-brary's famous Electronics Book Club, specifically designedto help you increase your knowledge and earning power.

WHY YOU SHOULD JOINWhatever your interest in electronics - radio and TV servicing,audio and hi-fi, industrial or defense electronics, electronics as ahobby - you'll find that the Electronics Book Club will help youget the job you want, keep it, improve it, or make your leisurehours more enjoyable. By broadening your knowledge and skills,you'll build your earning power and electronics enjoyment as well.

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GERNSBACK LIBRARY, INC.154 West 14th Street, New York, N. Y. 10011 74 BPlease send me the two -volume set HOW TO FIX TRANSISTOR RADIOSAND PRINTED CIRCUITS entirely without charge and enroll me as amember of the Electronics Book Club. My first selection at the specialreduced member's price (plus a few cents postage) is noted below. Iunderstand that I need accept only as few as three additional selectionsin the next.12 months, and I may cancel my membership any time afterthat. Send as my first selection

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INTRODUCTORY SELECTIONS AVAILABLE:Television Simplified by Milton S. KiverMost complete book on TV written. Everystage and part of receiver carefully ex-plained. 637 pages of updated data.Graphs, diagrams, giant charts.Regularly $9.95 Club price $7.95Basic Transistor Courseby Paul R.KenianTeaches you transistor fundamentalsclearly, simply. Discusses transistors allthe way from elementary circuits toradio receivers.Regularly $5.75 Club price $4.50Horizontal Sweep Servicing Handbookby Jack DarrFast, simple methods of locating and re-pairing troubles in the sweep system.Lots of practical shortcuts, developedand proved on the bench.Regularly $5.75 Club price $4.50

Basic Radio Course (revised and en-larged) by John T. FryeThe original sold out through eight print-ings! This lighthearted course in practi-cal servicing techniques is now com-pletely revised and updated.Regularly $5.75 Club price $4.85

Basic TV Course by George KravitzUp-to-the-minute television-even coverstransistorized portables! Presents techni-cal detail in easy -to -follow writing style.A must book.Regularly $5.75 Club price $4.95Basic Industrial Electronics Courseby Alfred HaasA practical, simplified approach to in-dustrial electronics - the branch whereearnings are nearly limitless; opportuni-ties always open to skilled technicians.Regularly $5.95 Club price $4.70

Basic Electronic Test Proceduresby Rufus P. TurnerSolves test and measurement problemsin every phase of electronics-from radioto rockets. Practical course and refer-ence for student. teacher, and technician.Regularly $8.50 Club price $5.95Practical Television Servicingby Richard JohnsonExplains everything necessary for rapidlocation and remedy of receiver troubles.Theory included only when it makesservicing easier, faster, more profitable.Regularly $7.95 Club price $6.75


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Transistor Reference BookContains the most complete and up-to-date listing of semiconductor types avail-able, with comprehensive specificationson each type.Regularly $6.00 Club price $4.50

Semiconductor Devicesby Rufus P. TurnerExplains the theory of semiconductor de-vices in simple language and shows nu-merous applications. Profusely illustratedwith hundreds of drawings and photo-graphs.Regularly $6.00 Club price $4.80

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Radio Servicing Made Easy(2 vols.) by Leonard C. LaneGet the latest servicing information onnew radio types. Full instructions on howto fix FM, M, AM -FM communicationsreceivers, marine radios, transistors.Regularly $9.95 Club price $7.75

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insulation from 10 to 22 -gauge wire, crimps insu-lated and noninsulated terminals. In plastic pouchwith supply of insulated and noninsulated termi-als.-Vaco Products Co., 317 E. Ontario St., Chi-cago, Ill. 60611

PHOTOCONDUCTOR KIT for electronichobbyists. 3 photoconductors, a Sigma ac/dc relay,22,000 -ohm 1 -watt resistor, mounting bracket, and

52 -page circuits booklet describing variety of ap-plications.-Electronic Tube Div., Sylvania Elec-tric Products Inc., Emporium, Pa.

SOLID-STATE STEREO AMPLIFIER, Cita-tion B. 40 watts per channel continuous power.Bandwidth at full power output 10-60,000 cycles.Frequency response flat from 1 to 100,000 cycles.Wiring harness couples all stages and silicon out-put transistors with casings fastened to heat sink,both channels mounted on epoxy boards. Outputcircuits safe even under direct shorts.-Harman-Kardon Inc., Ames Court, Plainview, N. Y.

HAM AND CB SPECTRUM MONITOR KIT,Ham -Scan panoramic adapter allows visual obser-vation of band activity up to 50 kc above and

orfr

below frequency to which receiver is tuned. Iden-tifies signals as to SSB, AM or CW types, spotsband openings or clear portions of band, iden-tifies splattering signals. As receiver is tuned, fre-quency you hear remains centered on screen.-Heath Co., Benton Harbor, Mich.

REPEATING TAPE PLAYER. Repeater ac-cepts programs of from 20 sec. to 8 hr., recorded on1/2 -track recorder at 17/8, 334 or 71/2 ips. Programstarted with external momentary pulse of 1 to 12

volts ac/dc to player via built-in connector. Pro-gram plays to end of recording, tape reverses andshuts off. Portable, rack mounting and consolestyles, mono or stereo.-Tape-Athon Corp., 523 S.Hindry, Inglewood, Calif.

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JULY, 1964 69

NATESA Clarifies PositionOn FTC Consent OrderThe National Alliance of TV &

Electronic Service Associations has de-tailed the circumstances under which itagreed to the Federal Trade Commis-sion consent order dated Jan. 22, 1964.That order cited practices in restraintof trade on the part of NATESA andof TESA-Green Bay, Wis., concerninglocal parts wholesalers. (See "NATESABows to FTC Restraint Order," Techni-cians' News, RADIO -ELECTRONICS forApril 1964.)

In an article in the April 1964 issueof the NATESA Scope, this explanationappeared: ". . . because we have not andpositively will not knowingly violate lawsit made better sense for NATESA toenter into a consent order with the FTCfor settlement purposes only." Accord-ingly, the article continues, "The agree-ment between NATESA and the FTCprovides in part that: 'This agreement

is for settlement purposes only and doesnot constitute an admission .. . that thelaw has been violated ...' "

Since, even so, the order is legallybinding on NATESA and on each ofits member organizations, the article re-minds all affiliates that they must be "ex-tremely careful to avoid actions whichmight be interpreted as being in viola-tion of the FTC consent order."

Pa. Licensing BillStill Major Issue

Although the Pennsylvania Federa-tion of Television & Radio Service Asso-ciations was unsuccessful in pushingthrough its licensing bill during the 1963State Legislature session, strong effortsare being made to enact the bill duringthe next session.

According to Leon Helk, secretaryof the FTRSA, the bill was all ready tocome out of the committee. Strong oppo-sition from certain distributors and man-ufacturers in the Philadelphia area appar-ently prevented passage. Meanwhile,local licensing is being encouraged asa stopgap measure.

Mr. Helk stated that there has alsobeen substantial opposition from theHarrisburg (Pa.) chapter of the AFL/CIO, which has mailed out flyers oppos-ing state licensing on the grounds thatit would be unenforceable and ineffec-tive. Mr. Helk was unable to say pre-cisely what the union's motives are.

The bill that the FTRSA wantspassed is much the same as others alreadyin effect in other states. The federation

favors licensing as a means of haltingthe operation of "moonlighters", on thegrounds that their work breeds com-plaints against the TV service trade asa whole. The proposed law would makeit possible for the state to bar from do-ing business anyone not qualified accord-ing to certain regulations.

NARDA-NEA MergerAttempt Fails

Indianapolis-The possibility of amerger between the National ElectronicsAssociation and the National Appliance& Radio-TV Dealers Association hasapparently ended.

At a meeting in Chicago in April,the executive committee of NARDAand officials of NEA failed to agree onplans for merging the groups. Accord-ing to a spokesman, NEA, which origi-nated the merger idea, will not pressfurther.

The basic area of disagreementseemed to be that NARDA was unableto accept the group membership of NEA.NARDA wanted NEA members to joinNARDA "as is" without NEA having adistinct voice on the NARDA board.That idea was unacceptable to NEA.

Local members expressed disap-pointment at the failure of the merger tocome about.

Florida Group LaunchesLicensing Drive

The first official directors' meetingof the recently formed Florida ElectronicService Association early this year cul-

61AiWrii41,.. DEAL EVER

RCAIlligtelfEWIt OFFERED!1 DOLLAR BUY

n $17.50 WEBSTER DIAMOND $ 1CARTRIDGE #SC2-D Stereo ..RONNETTE DUAL SAPPHIRE $2CARTRIDGE alPover typeDIAM. NEEDLES Ronette BF4O, $ 1Sonotone 2TS, Monarch, Vaco ea.

UNIVERSAL 5" PM SPEAKERAlnico 5 magnet, quality tone..

UNIVERSAL 4" PM SPEAKERAlnico 5 magnet, quality tone..

3 - $2.50 SAPPHIRE NEEDLESguaranteed 5000 playings

2 - UNIVERSAL 21/i PMSPEAKERS for Radios, Intercom,as multiple Speakers, etc3-SAPPHIRE STYLUS NEEDLESfor all type pickups

3 - AUDIO OUTPUT TRANS-FORMERS 501.6 type

3 - AUDIO OUTPUT TRANS-FORMERS 3V4, 3Q4, 3S415 - RADIO OSCILLATORCOILS standard 456kc

4 - I.F. COIL TRANSFORM-ERS 456kc, most popular type3 - I.P. COIL TANSFORM-ERS 262kc, for auto radios

3 - I.F. COIL TRANSFORM-ERS 10.7mc for FM

3-1/4 MEG VOLUME CON-TROLS with Switch, 3,, shaft

5 - ASST. 4 WATT WIRE -WOUND CONTROLS

10 - ASSORTED VOLUMECONTROLS less switch

1-15-ASSORTED VOLUME CON- $ 1TROLS with switch

BROOKS RADIO &

#CTC-11 COLOR TV CHASSISWe scooped the market-Wired complete (less Tubes & CRT) Ivneed minor finishing touches or parts, incl. SchematicIncluding full Set of Tubes (less CRT) $99

FREE WITH EVERY 10 ORDERED - PLUS FREE GIFT50-G.E. FLASHLIGHT BULBS $$PR -9, 2.7 volts

3-ELECTRIC MOTORS 1t/2 Volt $1wonderful experimenters item sa.

5-ASST. SIZES RADIO CHAS- $ 1S IS PANS drilled & plated .

5-VARIABLE CONDENSERS $ 1asst. popular super -het types

50-ASSORTED PRINTED CIR- $ 1CUIT SOCKETS best types

100-ASST. RADIO KNOBS $ 1all selected popular types

20 - INSTRUMENT POINTER $KNOBS selected Popular types

1000-ASST. HARDWARE KIT $ 1screws, nuts, washers, rivets, etc. A.

100' - FINEST NYLON DIAL $CORD best size, .028 gauge ..

20-ASST. PILOT LIGHTS$ 1$44, 46, 47, 51, etc.

20 - PILOT LIGHT SOCKETS $ 1bayonet type, wired

3 - ELECTROLYTIC CONDEN- $ 1SERS 50/30-150v

3 - ELECTROLYTIC CONDEN- $ 1SERS 40/40mfd-400 volts.

10 - ASST. RADIO ELEC- $TROLYTIC CONDENSERS

5 - ASST. TV ELECTROLYTIC $CONDENSERS

5-CD ELECTRO CONDENSERS $ 110/10/10-450 volts

r--1 6 - ASST. SELENIUM RECTI- $ 1I-I plus 65ma, 100ma, 300ma, etc. W6

L-1- CRYSTAL LAPEL MICROPHONE $1

High impedance, 200-6000 cps A.

i 5-IBM COMPUTER SECTIONSL.-I loaded with valuable parts .... $1I-I 100 - ASSORTED 1/2 WATT $ 1'-' RESISTORS some In 5%n 100 - ASST 1/4 WATT RESIST- 1

ORS choice ohrnages, some 5% As1-1 70 - ASSORTED 1 WATT $ 1

RESISTORS some in 5%17 35 - ASSORTED 2 WATT $ 1'-' RESISTORS some in 5%n 50-PRECISION RESISTORS $11asst. list price $50 less 98%n 20 - ASS'TED WIREWOUND $

RESISTORS, 5, 10, 20 wattri 50 - ASST. DISC. CERAMIC $1- CONDENSERS popular numbersn 50 - ASST. MICA CONDEN- $

SERS some in 5%El 10-DIODE CRYSTALS 1N34 $ 1

10-ASST. DIODE CRYSTALS5-1N60 and $ 1

750ma, 400 PIV2-SILICON RECTIFIERS $1

5-PNP TRANSISTORS 1general purpose, TO -5 case

i 20 - PLUG & JACK SETS $1- with wired leads, 101 uses sm.

5-NPN TRANSISTORSgeneral purpose, TO -5 case

n 50 - ASST. TUBULAR CON- $1- DENSERS. .001 to .47 to 600v An

ElCONDENSERS 047-600v $120-GOODALL TUBULAR

CHAPT ZU DI MITZIA "JACK- $11.--1 Km, double your money backif not completely satisfied

MARKET SCOOP COLUMN

F-1 STEREO PHONO AMPLIFIER Sii--I wired-each channel 3 watt ...

'-' 2-25BK5 TUBES & 2 -OUTPUT S2TRANS completes above Amp

n STARLITE 8 -TRANSISTOR RA- $aDIO complete needs slight adjust %dr

I-I $200 SONOTONE HEARING $gAID less Earpiece & Batteries ..

El $27 MERCURY RECTIFIER'---' TESTER $600 in sealed cartons lhal

7 BATTERY CHARGER 9 -VOLT$- Mel trans chargeable battery ..

I-I nSTANDARD TV TUNER 41mc s1_1 Comp. with Tubes & Schematic -

ri STANDARD TV TUNER 21mc $CL_J Comp. with Tubes & Schematic ea,

I-I 50-RCA LUCITE RADIO KNOBS $11--1 popular type w. indicator pointer

I-1 40-ASSORTED TV KNOBS $1all standard types, $40 value .. ib

7 10-ITT SELENIUM RECTIFIERS $1- 65ma-14v brand new fact. stock ra

Fl 8-ITT SELENIUM RECTIFIERS $100ma-14v brand new fact. stock

n 2-ITT SELENIUM RECTIFIERS $ 11_1 500ma, nothing finer made ...

5-ASSORTED TRANSFORMERS $ 11_1 Radio, TV and Industrial

i $12 TALKING DOLL 25" TALL $IM 0 $1900 IBM RATIOCOUNTING SCALE $2501--I sophisticated - blonde, brunette ea, in perfect condition....or redhead, 11 cute recitations TO

-2NETV CORP., 84 Vesey Dept. A, New York 7, N.Y. COrtlanELE PHdt7359


In 1 -LB SPOOL ROSIN -CORESOLDER 40/60 top quality

minated in a unanimous decision to pressfor statewide licensing of TV and elec-tronic servicers.

In an editorial in FESA News, for-merly the TESA-MIAMI News, A. Ed-ward Stevens, president of FESA, wrote:"Licensing was enacted there [in otherstates] not as a means of 'cornering' theservice market for the politically favoredfew, but as a safeguard to the public. Ex-isting laws do not cover fully the situa-tion at hand . . . When pushcarts ruledthe streets, traffic signals were few.

"With licensing comes the dignityof a recognized profession. As tinkerersand hobbyists we remained a mild sortof 'freak', . . . treated with no more re-spect than . . . the court jester."

NARDA TacklesIndustry Problems

The National Appliance & Radio -TV Dealers Association has "launched amajor offensive" against two of the big-gest problems facing appliance andradio-TV retailers: direct sales frommanufacturers, and the decreasing shareAmerica's "disposable income" comingthe way of appliance dealers.

Because the industry could notagree on a one -price policy to buildersand dealers, the Government has beenasked to step in as arbitrator. Specifi-cally, the Executive Committee ofNARDA has asked the Federal TradeCommission to set up a Trade PracticesConference to resolve the issues andfactions. END

NARDA Hopes to BoostAppliance Sales

Taking steps to combat what seemsto be a decline in appliance sales, or atleast a decreasing share of America's"disposable income" going for appli-ances, National Appliance & Radio-TVDealers Association president Earl T.Hoist has called on members of thetrade to launch a drive to improve theconsumer's image of the appliance-radio-TV industry.

One of the most delightful of Mr.Hoist's ad campaign ideas was to stressthat too many people turn summer va-cations into nightmares "by loadingfamilies into hot stuffy cars, caught inholiday traffic jams, for a few days ofsupposed rest." In contrast, he feels that"the family who vacations at home inan air-conditioned apartment in frontof a color television set obviously getsmuch more enjoyment."

Possibly those diehards who stub-bornly insist on traveling could packalong a few of the family's home appli-ances and plug them in from time totime along the way.

ANTARCTIC ANYONE?Engineers interested in joining the

team from the Boulder Laboratories ofthe National Bureau of Standards to theAntarctic (summer and autumn train-ing in Boulder-the Antarctic in Decem-

ber as summer starts south of theEquator) may write to the PersonnelOffice, National Bureau of Standards,Boulder, Colo. These projects constitutean exciting study of electromagneticphenomena, characteristics and behaviorof the ionosphere, and the effects ofsolar activities on radio transmissions.

50 Igears cAguIn Gernsbock Publications

HUGO GERNSBACK, FounderModern Electric& 1908Wireless Association of America 1908Electrical Experimenter 1913Radio News 1919Science & Invention 1920Practical Electrics 1921Television 1927Radio -Craft ...1929Short -Wave Craft 1930Television News 1931

Some larger libraries still have copies of Modern Electricsand the Electrical Experimenter on Ste.

In July, 1914, Electrical Experimenter

The Speaking Arc Light, by H. WinfieldSecor.

Experimental Electricity Course, by S.Gernsback and H. Winfield Secor.

Progress in Radiotelegraphy.Radio -Transmission and Weather, by A. H.

Taylor.A Vacation Radio Pocket Set, by Harry V.

Johnson.A Laboratory Switchboard, by Godfrey S.

Bloch.A Novel Detector Switch, by Albert St.

Cyr.A Looped Aerial Switching Scheme, by

Thos. N. Benson.

IMMEDIATE DELIVERY...SCIENTIFIC LIGHT PACKING for safe delivery at minimum cost. HANDY WAY TO ORDER -Pencil mark items & enclose with

check or money order, add extra for shipping, excess refunded with advantage to customer. Tearsheet will be returned with order, as your packing slip.

rIESTERN, PieceEL,EhCTRilCbieparts of $1$1

250 -ASST. WOOD SCREWS $1--1 finest popular selection

El 250 - ASST. SELF TAPPING $- SCREWS =6, r8, etc.

I-1 150 -ASST. 6/32 SCREWS1-1 and 150 6/32 HEX NUTS

150 -ASST. 8/32 SCREWSI-I and 150-8/32 HEX NUTS

$1

$1

El 150-6/32 HEX NUTS $

1---1 and 150-8/32 HEX NUTS ".

I -I 500 - ASSORTED WASHERS $ 1most useful selected sizes .

ni 500 - ASSORTED RIVETS1--1 most useful selected sizes . 1

El 4-TOGGLE SWITCHES- SPST, SPDT, DPST, DPDT $ 1

15-ASST. ROTARY SWITCHES $- all popular types $20 value ..

In 100 - ASST RUBBER & FELT $ 1'-' FEET FOR CABINETS best sizes

In SO-ASSORTED # 3AG FUSES $ 1- Popular assorted ampere ratings A.

250-ASST. SOLDERING LUGS $ 11-1 best types and sizes

I-1 50 - STRIPS ASSORTED SPA- $GHETTI handy sizes

I-1 100 - ASSORTED RUBBER $ 1GROMMETS hest sizes

i 10 - SURE -GRIP ALLIGATOR $ 1CLIPS 2', plated'-'

1-1 10 - SETS PHONO PLUGS & S 11-1 PIN JACKS RCA type

BROOKS RADIO &JULY, 1964

1-7 WESTINGHOUSE TV TUNER $ 141 me, brand new (less tubes)

1-1 MAGNAVOX PIECE OF EQUIP- $- mENT loaded with deluxe parts

1-1 MAGNAVOX SET OF TUBES S1_1 A.12AI:7 and 2-I2AX7, for above

1-1 4 - TRANSISTOR EARPHONES $ 11)-1 15 ohm standard for Radios, etc

1-1 $15.00 TELEVISION PARTS $ 1'-' "JACKPOT" best buy ever ..

17 4 - TV ALIGNMENT TOOLS $most useful assortment

'-'50-ASSORTED TV PEAKING $ 1COILS all popular types

REGO INDOOR TV ANTENNA $1hi -gain, 4 section, tiltproof

I-1 10 SETS - DELUXE PLUGS &- JACKS asst. for many

20 -ASSORTED TV COILSI.F. video, sound, ratio, etc. ..

I-1 20 - ASSORTED GRID CAPS S1--1 for 1133, 1X2, 6E06, 6E06, etc. A.

100' - TWIN TV LEAD-IN $1WIRE 300 ohm, heavy duty ..

El 5-TV CHEATER CORDS $ 11.-1 with both plugs

ri 10-6' ELECTRIC LINE CORDS $11--1 with plug standard brands ....

n 4 - 50' SPOOLS HOOK-UP $ 1WIRE 4 different colors

1--1100'-MINIATURE ZIP CORD $12 conductor, serves 101 uses Ai

32'-TEST PROD WIRE- deluxe quality, red or black .. $1

'-'$15.00 RADIO PARTS "JACK-POT" handy assortment ..

I-1 30 -BALL POINT PENS- retractable, assorted colors

25 - 2 TERMINAL PIN JACKSasst types for various uses ...

IT ELECTROSTATIC 3" TWEETER'-' SPEAKER for FM. IIT-111, etc. ..

(-7 20 - STANDARD FUSE HOLD-- ERS for 3AG fuses, easy mount

1--/5-I.F. COIL TRANSFORMERSsub -min for Transistor Radios .

$1

El 5 - AUDIO OUTPUT TRANS- S 1- FORM sub-mM for Trans Radios

1-1 20-BENDIX BUFFER CONDEN-SERS'-' .007-2000v $15 value ..

El 25 - SYLVANIA HEAT SINKS- for Transistors, etc.

El 50 -RCA PHONO PLUGS1-1 Standard for phonos, male ....

El 10-TOGGLE SWITCHES SPST1-1 deluxe U.L. approved, 101 uses

Fl 1 - SQ. YARD GRILLE CLOTHt.--1 most popular brown & gold design

Fl 100 -MIXED DEAL "JACKPOT" $11-1 Condensers, Resistors, Surprises di

1--1BONANZA"JACKPOT"fiut gold, 5Mnot oil, but a wealth of Electronic eaItems-Money-Rack-Guarantee ..

2 -EMERGENCY AUTO LAMPS $ 1Red dome blinker, incl Battery A.saves lives on highway stops ..

El 100 - CERAMIC CONDENSERS S 1Erie 50mmf-500v. 5%

ni 30 -GOOD -ALL CONDENSERS S1LI .19-600v (tests .25-1000v) ...

MARKET SCOOP COLUMN

20 -RCA 954 TUBES$ 1

20-SYLVANIA 2C4 TUBES $

10 - ASSORTED TUBESRadio, Television and Industrial $

10-SYLVANIA 1U4 TUBES S 1brand new Jan.. individual car- A.tons also serves as IT4

E ALL AMERICAN TUBE KIT $2Top Standard Brand - 1211A61213E6. 12AV6. 5005, 35W4 :

3 -TOP BRAND 35W4 TUBES $ 1

El $12 TV FLYBACK TRANS 90° $ 1for all type TV's Inc) schematic As

E7 3 -TV VERT OUTPUT TRANS $Li A.universal 10:1 ratio for all TV's

in 3-DUMONT VERT OSC TRANS S 1 Mel schematic for many TV use, as

1-1 100-RADIO & TV SOCKETS S1_1 all type 7 pin, 8 pin, 9 Pin, etc.

1_1100-ASST. TERMINAL STRIPS $ 1all types I -lug to 13Ing

1-1 100 -ASST. CERAMIC CON- $L -I DENSERS some in 500

ri 30 -ROTARY SWITCHESL_J popular DPST, 1/2" flatted shaft $ 1

1_1100-IRC 1W RESISTORS $ 14700 ohm, 10%

ri 4 - AUDIO OUTPUT TRANS. 11_1 standard for 50L6 latest type.. A.

TV CORP., 84 Vesey St., Dept. A, New York 7, N.Y. coTrtEZ74235971

ALL MAKESALL. LABORAND PARTS(EXCEPT TUBES)*

ONE PRICEONE LOW PRICE INCLUDES ALL UHFVHF AND UV COMBINATION TUNERS

Fast Service . . . Simply send us yourdefective tuner complete; includetubes, shield cover and any damagedparts with model number and com-plaint.

90 Day WarrantyExact Replacements are available fortuners unfit for overhaul. As low as$12.95 exchange. (Replacements arenew or rebuilt.)CASTLE TV TUNER SERVICE, iNC.5715 N. Western Avenue, Chicago 45, Ill.

New Eastern Location41-96 Vernon Blvd., Long Island City 1, N.Y.In Canada: 136 Main St., Toronto 13, Ont.

*Major Parts are additional in Canada

NEW! LAFAYETTE1 -WATT 2 -CHANNEL

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External 12 VDC Supply Complete with 2 -Pair Transmit/Receiver

Crystals Imported- -'77,,ed Lafayette's 1964 Catalog No. 640

422 Giant -Size Pages Everything in Electronics, Hi-Fi,C.B., Test Equipment, Amateur Gear, TV and RadioParts, and much more.

LAFAYETTE Radio ELECTRONICSDept. JG-4 P.O. Box 10,Syosset, L.I., N.Y. 11791

El Rush me FREE Giant 422 Page 1964Cat. 640

HA -150L Walkie-Talkie $ EnclosedShipping Charges Collect

NAME

ADDRESS

STATE__ __________ .....ZIP

noteworthy Circuits

Two -TubeI built this 2 -tube superhet for bed-

side use. Being interested only in localreception, I decided that a 6BE6 con-verter and a 6AU6 grid -leak detectorwould be adequate. Oscillator pullingwas a problem in the original version-even after the detector was converted to

4 FT ANT 1 FTFOR WEAK 613E6 (SEE TEXT)STATIONS 5

,

FERRITEROD ORLOOPANT

TUNE

22K

100PF ADJSLUG

1

Superhetfrom the secondary winding until it tunesto 900 kc. Align both windings on a 450-kc signal. The secondary will peak at900 kc.

The converter runs wide open andthere is no need for a volume control onmy set. If the converter overloads on a

6AU6 .001

100PF5

2

TO MEG17

MAGPHONES

2K ORHIGHERHTRS

PWR I5 MATRANS 2.2K

1I7VAC

a regenerative type.I solved the problem by using a

900-kc i.f. (There are no stations on900 kc in this area so i.f. interference isnot a problem.) The i.f. transformermust be modified. Using a grid -dip meteras a resonance indicator, remove turns

Simple Noise ClipperThis simple noise clipper and vol-

ume limiter can be added to most re-ceivers without drastic circuit modifi-cations. It is inserted between the voltageamplifier and the output stage or be-tween the receiver and the headphones.It prevents signals from exceeding a pre-set level.

The author, G3OGR, says in ShortWave Magazine (London, England) :"Set the clip control for maximum volt -

6H6 OR

6AL5

FROM .01

AMPL PLATEOR PHONEJACK

220K-5%

age on the diode plates and adjust thereceiver's volume control to the levelthat you don't want to exceed. Now,adjust the clip control until the volumejust begins to drop. The volume will notexceed this level."

CLIPCONTROL100 K 8+

47K8tif

TO OUTPUTOR

.01 PHONES

62K 250K

20/150V

ADJ TO50V

strong signal, apply fixed or variablenegative bias to the signal grid. Thepower transformer came from an oldTV booster. Any small half -wave powertransformer will work. Select the tuningcapacitor to match the antenna and oscil-lator coils.-Robert E. Flanagan

Improving theCascode Circuit

The reliability of the series -con-nected cascode circuit can be consider-ably improved by the simple addition ofone resistor. The circuit commonly em-ployed is shown in Fig. 1. Here the inputand agc voltages are applied to the gridof the first tube, while the grid of the

ti

RFINPUT

AGC Z 8+(ORIGINAL CIRCUIT)

Fig.I

second tube receives grid -leak biasthrough R. When a strong signal is beingreceived, the agc increases the negativebias on the first tube, and reduces theplate current. However, the bias on thesecond tube does not change. For thegiven plate current, then, the voltageacross the first tube becomes muchgreater than the voltage across the sec -

NEXTSTAGE


ond. Since the heaters are near groundpotential, the heater-cathode voltage ofthe second tube is greatly increased.Although the tubes normally used forcascode service are rated to withstandthis increased voltage, reliability is ob-viously better served if it can be avoided.

This can be done by adding a re-sistor equal in value to R, and connect-ing the two resistors as in Fig. 2. Herethe grid voltage on the second tube isheld fixed at one-half the B -plus voltage.

RFINPUT

tf, NEXT

STAGE

AGC B+(IMPROVED CIRCUIT)

Fig.2

Now, when the agc voltage on the firsttube increases, and its plate voltagerises, the negative bias on the secondtube will increase, and the voltage dropsacross the two tubes will be equalized.The increase in the heater -cathode volt-age of the second tube will thus bealmost completely eliminated.-CharlesErwin Cohn

Rf Output IndicatorThis device indicates when your

ham rig is on the air. No direct couplingis needed. The components are few.

The silicon controlled rectifier(SCR), a G -E type X-5, is energized by6.3 volts ac. It conducts and lights thepilot when sufficient rf is picked up atthe gate element. The potentiometerwhich controls the firing point (without

ANT

GE -X5

10K

IK

82K

GATE

C 6.3V

N°47

(0)ANODE

IIII7VAC

GE -X5CATH

rf pickup) is set just under the firingpoint. Then the rf fires it. To increasesensitivity, tie a metal plate or can cover(about 2 inches in diameter) to thejunction of the pot and the two resistors.

I use this arrangement in connec-tion with a 40 -watt transmitter usingpi -network coupling to a single -wire an-tenna. The indicator is about 4 feet fromthe antenna terminal, and operates wellon all bands from 15 to 80. Not onlydoes it remind me to throw the antennaswitch, it can be used to check keying,and to some extent can be used to tunethe antenna. Brightness of the lamp var-ies somewhat with rf output.-I. Queen,W2OUX END

u need to know aboutSERVICINGCOLOR TVBy Robert G. Middleton. A practical book that tells howto service color TV sets and make money doing it. Packedwith information. Illustrated with hundreds of photos,drawings and troubleshooting charts. 224 pages.

G/L No. 65 $2.90

and then some...RAPID TV REPAIRBy G. WarrenHeath. Lists over500TV troubles al-phabetically. Helpsyou fix the tough-est troubles fast.Cross-referenced.224 pages.G/L No. 60 $2.90

NEW SHORTCUTS TOTV SERVICINGBy Leonard C. Lane(2 vols.) A practicalservicing speed-upcourse. No theory ormath, but heavy ontest and repair tech-niques that save timeand help you getthose sets off yourbench. 320 pages.G/L 95 set /$5.90

BASIC TVCOURSEBy George Krav-itz. A book onTV as it is to-day. Technicaldetails presentedin easy -to -followwriting style.

G/L No. 105$4.10

BOOKS PURCHASED FOR PROFESSIONAL PURPOSES ARE TAX DEDUCTIBLE. Buythese books from your electronic parts distributor or send in the coupon below.

GERNSBACK LIBRARY/154 West 14th Street, New York, N.Y. 10011

ENCLOSED is $Please send me the booksindicated.

Write book number:

11

Name

Street

City State Zip Code

Z I P stands for the Post Office Department's new Zoning Improve-ment Plan. When renewing your RADIO -ELECTRONICS

subscription, or sending us a change of address, please let us know whatyour MP Code is. We'll add it to your address mailing plate ... and you'llget speedier delivery service from the Post Office. By the way, whenwriting to us, address: RADIO -ELECTRONICS, 154 West 14th St.,New York, N. Y. 10011.

ELECTRONICSEngineering -Technicians

The Nation's in-creased demandfor Engineers,

Electronic Technicians, Radio TV Technicians is at anall time high. Heald Graduates are in demand forPreferred High Paying Salaries. Train nowfor a lucrative satisfying lifetime career.

HEALD'SENGINEERING COLLEGE

Est. 1863-101 YearsVan Ness at Post, RESan Francisco, Calif.

Bachelor of Science Degree, 30 MonthsSave Two Years' Time

Radho-Television Plus Color Technician (12 Months)E1 Electronics Engineering Technology (15 Months) Electronics Engineering (B.S. Degree)

El Electrical Engineering (B.S. Degree)Mechanical Engineering (B.S. Degree)

CI Civil Engineering (B.S. Degree)LI Architecture (B.S. Degree)

(36 Months)

Approved for VeteransDAY AND EVENING CLASSES

Write for Catalog and Registration Application.New Term Starting Soon.

Your Name

Address

City

State

JULY, 1964 73

Handy Radio ToolSlip a Mueller No. 60 alligator

clip over the tapered tip of an artist'sbrush to make a handy home-made radio

tool. Use the clip end to hold parts orwires while soldering them in and outof circuits. Use the same end for string-ing dial cords and starting nuts andscrews. Solvent and lubricant applica-tion is easy with the brush end.-AllenC. Johnson

Ring of "Plastic Metal"Prevents Cord Pull -Out

To prevent a cord from pulling outof a phone plug, a ring of Duro "Plas-

tic Aluminum" or steel daubed aroundthe cord as shown makes a good stop.This idea is also applicable to manyother types of electrical connectors.-John A. Comstock

Anchoring and ShieldingSubminiature Tubes

When you breadboard circuits withsubminiature tubes, hold them in placeand shield them as well with strips ofcopper tape as shown in the drawingbelow.

Lay a strip of the tape down on thebreadboard where you want to put the

tube. Position the tube over it and tapethe tube down with another strip. If youlet an edge of the lower strip stick out,you can bond the two electrically withan overlapping blob of solder, and at-tach a ground wire.

If you can't get adhesive coppertape, strips of copper foil coated withrubber cement will work as well.-TomJaski

SolderingTo save time and do an extra -neat

job when you have a number of phone

Fig. 1

tips to solder, adapt an old solderingiron point by drilling a hole through it.This hole should slip over the soldercup easily.

Fasten an extra phone tip firmly in a

COPPER TAPE STRIPS

GROUND CONNECTION

Phone Tipsvise to serve as a holder (Fig. 1). Putthe tip to be soldered in the holder, slipthe iron over it and melt solder into thecup. Insert the end of the wire, dropthe iron down over the holder, and lift

Fig. 2

the wire away as soon as the solderhas cooled sufficiently (Fig. 2.) The re-sult is a clean job without the usuallittle globs of solder on the outside.-Hugh Lineback

Make an Allen -WrenchThis tool will get your Allen

wrenches into tight spots and also storethem all together inside itself!

Get an old socket wrench (nutdriver) whose business end can take a1/4 -inch spacing nut. Bore out its handleto as large a diameter as possible and

DRILL OUT

1/4" SOCKET

PIPE CAP

HANDLE

2" APPROX

l'

SPACER NU!

0)

,0"--f-BRAZED

AS LONG ASHANDLE HOLE

(MAKE 5 WITH DIFFERENTSIZE WRENCHES)

-c--THUMB SET -SCREW

Kit

about 2 inches deep. Anneal the socketend (if necessary) and drill and tap an8-32 hole for a setscrew or thumbscrew.

Fit the ends of your Allen wrenchesinto 1/4 -inch spacing nuts and braze orsilver -solder them in. To use them, slipthem into the socket of the nut driverand tighten the setscrew. When you'rethrough, slip all the wrenches into thedrilled -out handle and close the end witha pipe cap.-Peter Legon


Tube and Bottle CapsMake Control Knobs

Toothpaste tubes, medicine bot-tles, hair tonic bottles and many othersources will provide you with an un-limited variety of colorful and modern

control knobs for your electronicequipment.

The first photograph shows a fewof the products that come in tube formand the different styles of caps available

from them. The second photographshows how the hollow part of the cap isfilled with a quick -setting metallic plas-tic and is then pressed onto the shaft ofthe control. When the plastic has set, a

hole is drilled through and tapped sothat a control knob setscrew can beinserted.

The last photograph shows a com-pleted knob mounted on the gain con-trol of a transistorized receiver.-Capt.Rene E. Pittet, Jr.

Nail Clippers Trim LeadsA pair of fingernail clippers will

snip wires in tight chassis corners anddo an exceptionally neat job of nippingoff the ends of leads on printed circuitboards.

Smaller than "dykes," they make acleaner cut and a Much closer one. They

BRAND NEWUNITcD'S FIRST QUALITYTUBES DISCOUNTS up to

%U OFF

GUARANTEED ONE FUL?. YEAR! NOT USED! NO PULLS! WHY PAY MORE ?Tube

C195

Price Tube Price043 .....90 3DZ4

341305...79...970A40 .1.35082 .....80 31158

3Q4 .. .1.29..79063 ...1.20

003 75354 ..3V4 .. ..73..6I003 .80003 ..2.75 4AU64AV6

.94. .1.150Y4

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..7745A64805

..85.95.143

145....70....75 4508

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. ..901461A7

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1.35.9914F4 ..1.30

1404 .1.25 405848U8

. 1.351.2914X2 4626

4BZ7. ..95. ..99105

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164 40354DE6

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..902B7 .....702654 ...952035 ..95 534 i:41o5

1.002021 ...702X2 ....60.

524 1.402X2A .1.303A2 ...1.55 6A4

646.80

1.003A3 ....743A4 .....74 W. 2.251.453A5 ...1.103AF4 ..1.50 6464

6465.45.

1.953415 ...44.3472 .1.25 6A876405 1.00

1.9534U6 ...523436 ...40 6407

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64 F32.001.0031346 ...88

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. ..99..99

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3066..83..58 6AN6 2.453076 ..52 BANG

Tube Price Tube Price Tube Price7HG8 1.67 1204 ...67 17H3 . .957J7 ...1.5078 12085 1.0512068 ...31

17)28 .1.9817L6 .1.25

7L77N7 1.25

1:22 12088 ..85121706 1.02

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113FX6 ..51I8FY6 ...481941J4 ..85

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19866 1.3519E48 .777%7

7X7 1.2512DW7 1.2012038 1.75

19H38 1.4419J N8 .1.20734

7Z4 .

..95..95 120158 ..87

120Z6 ...GO1978 ...8321EX6 1.47

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..93

..9612E46 .9912E08 .1.713

21035 .1.92254144 -66813135 ....63

8CG7 ..66 I2EDS ..6012E66 ..60 254X4 ..68

25E185 1.358CM78CN7

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12EK6 ..6012EL6 ..48 25C5 ....51

25CA5B8CESB7B :9777 12EL8 ..86

12E26 ..55. ..57

25006 1.5025DK4 1.058EM5

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9A8 .941179687n4;8

.

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100E710E0710E8710014810.148

1.581.101.601.191.32.77

1.641.351.751.751.451.30

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1207.1235 .

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1.111.25..78..63..67..79..79.75.93

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....5835W4 ...403525 ....58364513 ..785045 .1.7050135 ....675005 ...51501304. ..71SOEHS ..5350HC6 ..8650L6 ....595036 ...95117L7 .3.95117N7 3.95

124F6 ..6512806 1.50124.16 ..60124L5 ..451241.8 ..9312405 ..5812476 ..4812477 ..74124416 ..49

125070-7.89125137 _9812U7 ...601236 ....6212W6 ...6912X4 ..241313E7 1.2413E87 1.9514A4

117Z3 ...8322 9524A 8526 .9527 ....1.502807 .1.5030 ...1 1532 033 -123

120.37 ..5912435 1.30 1447

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124X3 1.04 14881405

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..9838 9039/44 85124X4 ..65

124X7 .61.12437 1.4212427 -84

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41 95 -42 .. 9043 ....1.2045 .. .2.00

112213546 .65 140814117

1.20 46 9547 ....1 9512847 1.30.4812606 14J7 .

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1.30 48 ....3.5050 ....1.451213E3 .1.39..51111n

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12806/ 154011 1.951SCW5 1.15

... .2.0071A ..75 ...1.90CUB .1.09

12687 ..72 15FY7 1.29151166 1.28

76 ...1.4077 ...1.05

. 1.0974 164Q3 1.421743(3 .1.65

78 ...1.1580 ...1.25

.3.22.1167 ...:8749 17AX4 .6517E1E3 .1.84

81 ....1.2583 ....1.6512827 ...84 1713483 1.041705 .2.35

84/624 .9585 .., 98CUS ....5612055 ..54 1713E4. 1.2917084 1.22 84/6224 .98

5881 .. 2.9512086 .65.121778 1.60

171836 1.0417007 1.85 5881MP 5.75

6146 .3.9512006/806 1.10

170E5 1.7017G1/5 1.73

6336 .5.956550 .3.75

120346 ..52 1761/V6 1.64 807 70

SOLDER

Tube Price Tube Price6405 . 5, 6C-`13 661(6 ...9264Q6 . ,..69 6086 66X8 ...9264Q7 ..1.55 6C$6 6036 ...926808 1.20 6057 6625 .94(CARS ...84 6CUS 6HF5 .264136 ...95 6CU6 .1.05 6HF8 .1.51BARS .2.19 6CUS .1.75 61168 .1.6564R11 1.64 130,4/46455 .. ..59 6CW5 .1.10 22i2 :1.136456 .. 1.00 60)(8 .1.52

6)4646..2...9556

6458 . 1.20 60376457 . .2.75 6CY5

6J4WA 3.6564511 1.87 6025 .1.40 6.1136 . ..986476 . ..47 6CZ7 .1.75 6.1E6 ..3.256AT8 . ..84 604 . .1.75 6.1E8 -1.50611U4 .33 606 . .2.50 6JSM . ..9264115 1.75 6010 .1.66 6)5076AU6 ..50 6044 6J6 .64U7 ..54 6DA5 .1.19 6J7 . .1.6S64U8 .09 6085 .2.25 6.18 . .1.40

.

6AVS 1.75 6006 .1.201.2B 6).18181 8.11..83B6436 .3964311 1.49 6DE4 ..1.09 614664W8 ..88 60E6 . -59 61(769X3 ..92 6.1E7 ... 1.29 668 .1.4564)(4 ..64 6006 ...GO 6811 .1.5064X5 ..73 6DJ8 . . 1.17 680860.X7 .95 60146 ...57 6LS ..641(8 1.30 60N6 .1.48 6166 .1.456433 .99 6057 .1.35 6L6 -M .1.956428 1.75 60Q5 .2.95 6L7 ..1.05 1.3043.80 6006 .1.05 6M11 .1.856610 1.34 6087 .1.25 6N6 ..1.456643 1.15 6064 .. 2.12 6N7 .. ..986646 ..48 6065 .1.5 6P5 .....9526647 ..92 6D75 ...79 607-07 ..9861348 1.50 6076 ...61 607-51 .1.4561304 2.00 6078 ...9261305 .59. 6034 . 2.99 687 ....90654 .....496607 1.25 6"4 . 1.90 657 . . ..906808 1.00 6E5 .. 1.95 6S8 . .1.156606 . .95 6EA7 1.4568E3 1.15 6E48 65470.

.

7 .9768E6 ..53 6685 65/17-M 1.25

65873 1.1568F5 ..88 6E138 , .90 65C7 . .1.35136F6 ..42 6EH5 1.10

613F8 1.66 6EH7 1.55 6507 ....708505 ....756806 1.60 6E.17 1.1768146 1.00 GEMS

65F7 . .1.0068418 ..94 6EM7 : :i3g 6507 .. _85-80613.16 . ..63 6EQ7 1.05 65H7 .

65.1767 ..86611.17 . ..77 6E85 1.47 65.17-M ..9568.18 . 1.45 6655 1.256864 3.39 2

651(707 .90.79 65147-M 1.256E65 1.50 03EL17 1.00 651.707 .85

6BK7 ..84 6EU8 ..77 65N7 ...636BL7 . 1.05 6EV5 ..73 6507 ,92631.8 . 1.49 6E156 -55 R .1.00613144 1.00 6EW7 ..786658 1.03

.73.32;(4 3.65 3-7-2

61356

..95 6E25 1.4061306/ 6E28 1.75 678 . ...84

6U5

61358

1.05 6FA7 1.85.98 6FD7 1.55 6U8

86res7

6BU81.40 6FJ7 . 1.891.25 6F5 .. -130 666.14360.T ;111.20 6F6M 1.25..68 6F6 .. 1.05 6V6M 2.50

6W4 ..1306BW8 1.25 6F7 .. 2.50 .39

Tube Price

613K7..:77856835 2.19 6005 . 2.05

6638 1.07 6F08 -65 ilia . 1.1512561326 ..54 6FM7 ..77 .956627 .99. 6007 ..94 ill61328 1.25 6FSS . 1.20 1.15

1.156C4 . .43 SFS° . 1.15 748 6606 . 2.00 6FV8 . 77 1.156C5 . 1.40 6FV6 . 1.31

72%14g%; 1:156010 1.45 6FW8 3.556C8 . 3.25 6FW5 .1.96

-956C44 6FY5 1.10 7AH7.79 .

6CF6 ..95 60148 ..78 ...1.,9?6CG8 .78 60146 .77. 70

6CBS 3.24 60130 1.006086 .53 60E5 .91.60086CG7 ..59 6GKS ..59

1.45 6GFS 1.39

7C6 2.49

785786784

BU7

1.251.45

1.35

.63.1.21 605 .. 2.506CAS1.056056

1..44 6GL7 . 1.95.77 6GM5 1.27 7E7 ..95

707 1.45130L6601.8

60871.24 some ..95 7E36 .73.

6CM8 1.60 6075 1.70.67 60418 ..92 7F7 1.75

6C57 . ..68 V ..98 708 ...1.756C4 . 6GW6 1.65 707 , .95. 1.80 6GW8 1.40 7417 1.37

SEND FOR COMPLETE PARTS CATALOG WITHOUT COSTTERMS: Minimum order $5.00 exclusive of postage. Remit full price plus postage NOC.O.D. The above list does not reflect our entire stock as we hove one of the largestSelections of SPECIAL PURPOSE, BROADCAST & TV TUBES in the U.S. Write for quotation.

UNITED RADIO CO

ABOVE PRICESSUBJECT TO CHANGE

WITHOUT NOTICE

ESTABLISHED 1920

BOX 1000R, NEWARK, N.J.

CHISEL -POINT PRODUCED WITH DIKES

FLUSH END PRODUCED WITH CLIPPERS

WIRE LEADS

PRINTED CIRCUIT BOARD EYELET RIVET

will actually nip a wire off below thesurface where eyelet rivet contacts areused.

My clippers have been in use forthree years and show no appreciablewear. -W. E. McCormick END

"The lower half of your picture was morehazy than the top half because peanut

butter is more opaque than jelly."JULY, 1964 75

SAMS Best SellersLATEST EDITIONS OF TWO FAMOUSHOWARD W. SAMS HANDBOOKS!

Tube Substitution Handbookstill the Leading Reference-lists10,000 Tube SubstitutionsAbsolutely indispensable! 7 Sec-tions cover: Cross-reference ofAmerican Receiving Tubes; Cross-reference of Subminiature Tubes;Industrial Substitutes for Receiv-ing Tubes; Communications and

Special -Purpose Tubes; Foreign Substitutesfor American Types; American Substitutesfor Foreign Types; Picture Tube Substitu-tions. 128 pages; 534 x 834". $150Order TUB -7, still only

Transistor Substitution HandbookComputer -Selected Substitutes forOver 5,000 Transistors-Updated!Lists over 40,000 direct substitu-tions, including all popular typesused in transistor radios and sim-ilar equipment. Shows basing dia-grams, polarity identification andmanufacturers for over 5,000 types.Special section lists more than

15,000 American replacements for foreigntransistors-plus a semiconductor and diodeguide containing 800 substitutions. 128 cipages, 534 x 834". Order SSH-5, still only 41'

Transistor Ignition Systems Handbookby Brice Ward. Transistor ignition systems are revo-lutionizing the auto industry. This new book clearlyexplains the principles of these highly efficient sys-tems-how they work, how to install them, how totune them up. Describes typical systems now in use;provides complete data on installation.

$250128 pages; 534 x 834". Order IGS-1, only . .

Color TV Servicing Made Easyby Wayne Lemons. Written in "make easy" style.Takes the mystery out of color TV servicing. Intro-duces you to color principles and setup adjustments;thoroughly covers color circuitry, adjustments, andservicing of all color TV sets produced to date. Thisbook will help to put you into this fast-growing,profitable service work. 128 pages, 534 x 834". s295Order CSL-1, only

PHOTO FACTby Herrington & Oliphant. Contains over 240 photosof actual TV picture troubles, keyed to defectivecomponents in typical circuits. Shows exactly whathappens to picture tube display when any compo-nent becomes defective. By making the quick checksrecommended in special charts, troubleshooting isreduced to minutes. 160 pages, 534 x 834". $r,Order PFG-1, only

Troubleshooting with the Oscilloscopeby Bob Middleton. Explains how you can best usethe scope to actually view and analyze electroniccircuit actions, and apply what you see to moreeffective TV and radio troubleshOoting. Practicalchapters on scope operation, use of probes, signal -tracing, visual alignment, signal testing, circuitanalysis, and troubleshooting TV, Radio, and (ricoHi-Fi. 128 pages; 534 x 8 W. Order TOS-1, only 4e

Troubleshooting with the VOM-VTVMby Bob Middleton. Shows how to use these instru-ments for troubleshooting TV circuits. Tells how tocheck and interpret voltages; gives step-by-step pro-cedures for analyzing every type of TV circuit. Alsodescribes measurement and analysis of both AC andDC voltages, resistance, capacitance, and RF sig-nals. 160 pages; 534 x 834".

$250Order TWV-1, only.

Phonograph Cartridge & Needle Replacement Guideby the Howard W. Sams Technical Staff. Most com-prehensive guide available to replacement cartridgesand needles. Listed by original parts numbers andby equipment manufacturers' model and part num-bers. Fully cross-referenced. 96 pages, 534 x834". Order RCN -1, only

HOWARD W. SAMS & CO., INC.r er from your Sams Distributor today, or mail

to Howard W. Sams & Co., Inc., Dept. RE -74300 W. 62nd Street, Indianapolis 6, Ind.Send me the following books:

TUB -7 0 IGS-1 PFG-1 TWV-10 SSH-5 0 CSL-1 TOS-1 0 RCN -1

enclosed 0 Send FREE Booklist

Name

Address

City Zone State

My Distributor isL mo IN CANADA: A. C. Simmonds & Sons, Ltd., Toronto 7 ....I

Stereo TelevisionPATENT No. 2,955,156

Morton L. Heilig, New Yolk, N.Y.

Many feel that the best audio stereo effect through optical systems. The case also holds twois obtainable from phones rather than speakers. earphones connected via separate audio channels.Likewise, 3-D pictures look more natural through a Various controls are included for focusing anddirect viewer than through a projector. adjusting the picture and sound.

STRAP

EYEPIECES

STRAP

EARPIECE RODS

NOZZLE TUBING

These principles are applied here to TV. Two For added realism, small nozzles, connectedsmall kinescopes within a small case are strapped via external tubing, send air streams to the viewer'sto the head of the viewer. The tubes are energized nostrils. They may bring scents, breezes, or tern -by separate video channels, and the pictures focused perature changes as desired.

Wireless MicrophonePATENT No. 3,105,938

Peter K. Onnigian, Sacramento, Calif., andKeith Kirstein, Sacramento, Calif.

This radio transmitter is designed especially modulated rf is further amplified by Q4, then ra-for TV studios. In the diagram, Q1 and Q2 are diated from a ferrite loop antenna.audio amplifiers, and the output is fed through an The FM signals override static and manmade

®BATT 2

72. BATT I--E4§) ®

RF OUTPUT04

FM OSC

Q3

1ST AF AMPL 2ND AF AMPL

Q2

rf choke to C, a voltage -controlled capacitor. As noise. The entire circuit may be constructed as aits capacitance changes (at the audio rate), it self-contained, sealed module, with batteries ac -frequency -modulates crystal oscillator Q3. The cessible for replacement.

76RADIO -ELECTRONICS

SCHOOL DIRECTORYB. S. Degree in 36 monthsSmall professionally -oriented college. Four -quarteryear permits completion of B.S. Degree in threeyears. Summer attendance optional. Engineering:Electrical (electronics or power option), Mechan-ical, Civil, Chemical, Aeronautical. Business Ad-ministration: General Business, Accounting, MotorTransoortation Administration. One-year Drafting -Design Certificate program. Outstanding placementof graduates. Founded 1884. Rich heritage. Excel-lent faculty. Small classes. 200 -acre campus. Wellequipped labs. New library. Residence halls. Modestcosts. Enter Sept., Jan., March, June. For Catalogand View Book, write J. G. McCarthy, Director ofA dmissions.

itII

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EARN Engineering DEGREEYou can earn an A.S.E.E. degree at home. Collegelevel HOME STUDY courses taught so you can under-stand them. Continue your education, earn more in thehighly paid electronics industry. Missiles, computers,transistors, automation, complete electronics. Over27,000 graduates now employed. Resident schoolavailable at our Chicago campus-Founded 1934. Sendfor free catalog.American Institute of Engineering & Technology1139 West Fullerton Parkway, Chicago 14,

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PHILADELPHIA WIRELESS

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CAS Zone State

Antilog CircuitPATENT No. 3,089,968

Dale W. Dunn, Van Nuys, Calif. (Assigned toGeneral Precision, Inc.)

2N336(2)

10p.f

.2 -1.I VINPUT

21.6V

.046 -2.5VOUTPUT

With very low inputs, the resistance of acrystal diode varies logarithmically with respectto voltage. The resistance drops sharply with risingvoltage. When a diode is connected in the emitterreturn of a transistor, the voltage gain of the stagebecomes proportional to the antilog of the signal.With larger signals, the gain rises sharply.

This circuit provides true antilog outputs overthe voltage ranges indicated. Diodes are connectedin series to extend the logarithmic range. Zenersprevent current flow until a critical voltage isexceeded.

This circuit converts any log to its originalnumber or antilog. It is useful in computers wherenumbers are multiplied by adding their logs.

oV

0 B-

0

°---:

I

FILM

CAMERA TUBES

FILM DRIVE

Narrow -Band TVPATENT No. 3,108,155

Jacob Rabinow, Takoma Park, Md. (Assigned toRabinow Engineering Co., Inc., Takoma

Park, Md.)This patent suggests transmitting only 6 frames

per second to save bandwidth. The receiver re-peats frames to make a total of 30 per second asusual. To avoid jumpiness (resulting from so fewdifferent frames), two successive frames, say Aand B, are stored at the receiver, while A is fadedout and B faded in.

One possible method (see drawing) utilizesimage orthicon tubes to scan identical portions ofA and B. Outputs appear across the tapped po-

tentiometer. A rotatingwiper arm stays on each

VERTICALDEFLECTION

HORIZONTALDEFLECTION

FADER

-1 -,ter SYNCHRONIZER

TRANSMITTER

tap for the duration of aframe. Thus on the firsttap, the output will bethat of A alone. On thesecond tap, the outputwill be 80% of A and20% of B, and so on.When the wiper reachesthe last tap, the systemis blanked out and thefilm moved one frame.When it reaches the firsttap again, the outputwill be that of B alone,and then an increasingamount of C will beadded.

The film is movedat the relatively slowspeed of 6 frames persecond.

JULY, 1964 77

new ooks

BASIC JUNCTION DEVICES AND CIRCUITS, byRoy H. Mattson. John Wiley & Sons, 605 3rd Ave.,New York 16, N.Y. 53/4 x 9 in., 460 pp. Cloth,$9.75.

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Problems in correlating research, pro-duction and management, written from thestandpoint of the project leader and hisengineers.

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ELECTRONIC ENGINEERS AND TECHNICIANSREFERENCE HANDBOOK, by Electronic TeachingLaboratories. Howard W. Sams & Co., Inc., 4300W. 62 St., Indianapolis 6, Ind. 51/2 x 81/2 in., 224pp. Cloth, $4.95.

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TELEVISION SYSTEMS MAINTENANCE (Vol. 4 ofBroadcast Engineering Notebooks), by Harold E.Ennes, Howard W. Sams & Co., Inc., 4300 W. 62St., Indianapolis 6, Ind. 51/2 x 81/2 in., 288 pp.Paper, $5.95.

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CLASSIFIED 81Cleveland Institute of Electronics 11, 79Coyne Electronics Institute 69DeVry Technical Institute 7EICO Electronic Instrument Co., Inc 16Electronic Measurements Corp. (EMC) 65Gernsback Library, Inc 68-69, 73, 78Grantham School of Electronics 9

Heald's Engineering College 73Heath Co. 55International Crystal Manufacturing Co., Inc 15Johnson Co., E. F 63Lafayette Radio Electronics Corp 72Mallory & Co., Inc., P. RMARKET CENTERNational Radio InstituteNational Technical SchoolsP&H TV Tuner ServicePerma-Power Co.Philco-Techrep Division (Subsidiary of

Ford Motor Co.)PolypaksProgressive "Edu-Kits", Inc.Quam-Nichols Co.Quietrole Co.Rad-Tel Tube CoRaytheonRCA Electronic Components &

Devices Fourth CoverRCA Institutes 23Sams & Co., Inc., Howard W 25, 76Sarkes Tarzian, Inc. (Tuner Service Div.) 8

Schematic Library 65

SCHOOL DIRECTORY 77Scott, Inc., H. H 22

Sencore 61

Sonotone Corp. 14

Sylvania (Subsidiary of General Telephone& Electronics) 12

Tarzian, Inc., Sarkes (Tuner Service Div.)United Radio Co. 75Weller Electric Corp 17

Winegard Co. 18-19

MARKET CENTER 79

A. B. EngineeringCleveland Institute of ElectronicsEdmund Scientific Co.Fair Radio SalesOelrich PublicationsStereo-PartiTabTransistors Unlimited Co.Valley TV Tuner ServiceWarren Electronic ComponentsSCHOOL DIRECTORY 77

American Institute of Engineering & TechnologyElectronic Technical InstituteMilwaukee School of EngineeringNorthrop Institute of TechnologyPhiladelphia Wireless Technical InstituteTri-State CollegeValparaiso Technical Institute

69

59

Third Cover79

3, 775

6024

62806410608263

80RADIO -ELECTRONICS

Classified Ads 4-COMMERCIAL RATE (for firms or individuals offering commercial products or services): 550per word ... minimum 10 words.NON-COMMERCIAL RATE (for individuals who want to buy or sell personal items): 30f perword ... no minimum,Payment must accompany all ads except those placed by accredited advertising agencies.10% discount on 12 consecutive insertions, if paid in advance. Misleading or objectionableads not accepted. Copy for September issue must reach us before July 14th.WORD COUNT: Include name and address. Name of city (Des Moines) or of state (New York)counts as one word each. Zone or Zip Code numbers not counted. (We reserve the right toomit Zip Code if space does not permit.) Count each abbreviation, initial, single figure orgroup of figures or letters as a word. Symbols or groups such as 8x10, COD, AC, etc., countas one word. Hyphenated words count as two words. Minor over -wordage will be edited tomatch advance payment.

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SAVE 30-60% Stereo music on tape. Free bar-gain, catalog / blank tape / recorders / Norelcospeakers. SAXITONE, 1776 Columbia Road,Washington. D. C.

SALE ITEMS - tapes - recorders - componentquotes. BAYLA, Box 131 -RE, Wantagh, N. Y.

WRITE for highest discounts on components,recorders, tapes, from franchised distributors.Send for FREE monthly specials. CARSTON,125-R East 88, N.Y.C. 10028.

RENT STEREO TAPES-over 2,500 different-allmajor labels - free brochure. STEREO-PARTI,811 -RE, Centralia Ave., Inglewood 3, Calif.

HI FI, Ham Equipment, Discount Catalog,MENDOTA CAMERA SHOP, Mendota, Minn.

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SLEEP LEARNING. Hypnotism! Tapes, records,books, equipment. Details, strange catalogFREE. RESEARCH ASSOCIATION, Box 24 -RD,Olympia, Wash.

HOW COMPUTERS WORK. Send $2.00 for thiseasy to understand bulletin. ELECTRONICS RE-SEARCH LABORATORY, Box 154, Colonial ParkStation, New York, N.Y. 10039

HIGHLY-effective home study review for FCCcommercial phone exams. Free literature!COOK'S SCHOOL OF ELECTRONICS, Craig-mont, Idaho 83523.

TECHNICAL WRITING. Personal instruction byprofessional writers. Free lesson without obliga-tion. CENTURY CORRESPONDENCE SCHOOLS,1186A Fay, Largo, Florida.

BUSINESS AIDS1,000 Business Cards, "Raised Letters" $3.75postpaid. Samples. ROUTH, RE7, 2633 Randle-man, Greensboro, N.C. 27406.

JUST STARTING IN TV SERVICE? Write for FREE32 PAGE CATALOG of Service Order books,invoices, job tickets, phone message books,statements and file systems. OELRICH PUBLI-CATIONS, 6556 W. Higgins, Chicago, III. 60656.

ElectronicsPROFESSIONAL ELECTRONICS PROJECTS -Organs, Timers, Computers, etc.-$1 up. Cata-log free. PARKS, Box 1665, Seattle, Wash. 98125.

C-B'ERs-Ground Plane Antennas. List $9.95and up. Dealers wanted. Write circular. KOMETELECTRONICS, P.O. 222RE, Tilton, N. H. 03276.RADIO & TV TUBES 330. Free List. CORNELL,4217-E University, San Diego, Cailf. 92105.BEFORE You Buy Receiving Tubes, Test Equip-ment, Hi-Fi Components, Kits, Parts, etc....send for your Giant Free Zalytran Current Cata-log, featuring all STANDARD BRAND TUBES allBrand New Premium Individually Boxed, OneYear Guarantee-all at BIGGEST DISCOUNTSin America! We serve professional servicemen,hobbyists, experimenters, engineers, techni-cians. WHY PAY MORE? ZALYTRON TUBECORP., 469R Jericho Turnpike, Mineola, N. Y.JIFFY -MAST No holes, clamps, brackets; justslip into chimney. Ideal for light weight T.V.,F.M. antenna. Adjustable, fits openings to prox11 x 11". Send $1.95 plus .25 postage USA.VAN ALLAN CO., P.O. Box 8246, Cleveland,Ohio 44133.PRINTED CIRCUIT BOARDS. Hams, Experi-menters. Catalog 100. P/M ELECTRONICS, Box6288, Seattle, Wash. 98188.TRANSISTOR TELEVISION TRANSLATORS. Re-broadcast 25 miles, meets F.C.C. specifications,Battery powered. KEITH ANDERSON COMPANY,Piedmont, So. Dak.TRANSISTORIZED Treasure Detectors Findburied gold, silver, coins. $19.95 up. Kits avail-able. Free catalog. RELCO-A25, Box 10563,Houston 18, Texas.7" TV TEST TUBE-$6.99. Tubes 6146-$2.95;6211 (12AIJ7 equiv.) 390, 3 for $1. Germaniumdiodes, tested, equiv. 1N34, 1N60 etc., 30 for$1. Tophat silicon rectifiers, 750MA-1000 PIV750. Transistcrs, tubes, resistors, condensers,etc., bargain priced. Free catalog. ARCTURUSELECTRONICS, Dept. RE, 502 -22nd St., UnionCity, N. J. 07087.DIAGRAMS FOR REPAIRING RADIOS $1.00. Tel-evision $2.50. Give make, model. DIAGRAMSERVICE, Box 1151 RE, Manchester, Conn.

FREE ELECTRONICS CATALOG. TremendousBargains. ELECTROLABS, Dept. C -224-G. Hew-lett, N. Y. 11557.GOVERNMENT SURPLUS, jeeps-$62.50, Volt-meters $1.05, Transmitters $6.18, Oscilloscopes,Multimeters, Speakers, Parts, Typical surplusprices. Exciting details, FREE. Write: ENTER-PRISES, Box 402-F18, Jamaica 30, N. Y.IGNITION! Transistor, Coil, Ballast $7.50. FreeParts List. TRANSFIRE, Carlisle 20, Mass.WHOLESALE prices on TV cameras, transmit-ters, converters, etc. direct from factory. Cata-log 100. VANGUARD, 190-48 99th Ave., Hollis,N. Y. 11423

TRANS-NITION Electronic Ignition parts kit,Negative ground $20. Coil, Manual SPECIAL$8.50 Manual $2. ANDERSON ENGINEERING,Wrentham, Mass.TRANSISTOR IGNITION COILS-lowest prices,guaranteed. Information free. ELECTROSPE-CIALTIES, Box 548, Trion, Georgia 30753.

FREE CRYSTAL with 12 sensitive crystal setcircuits 500 KTB-1, 3524 Farm Hill Blvd., Red-wood City. Calif.DIAGRAMS for 1923 to 1952 radios $1.00, con-densed television diagrams $1.00. Give model.DIAGRAMS. Box 55. Williamsport. Pa."COIL WINDING METHODS" Handbook -500.Experimenter's catalog 250 exclusive items -250, refundable. LABORATORIES, 1131-B Va-Iota. Redwood City. Calif.TRAN-UNIT TRANSISTORIZED IGNITION, Zenerprotected, coil, mounting hardware, 12 V nega-tive ground. Free information. $21.95 Guaran-teed. TRANS -UNIT, 3700 Lincoln, El Paso, Texas79930.CONVERT any telivision to sensitive, big -screenoscilloscope. Only minor changes required. Noelectronic experience necessary. Illustratedplans $2. RELCO. Box 10563. Houston 18. Tex.TRANSISTORS, SCR's, diodes, nickel -cadmiumbatteries, meters, crystals, components. Qual-ity guaranteed. Send 100 for catalog. ELEC-TRONIC COMPONENTS CO. P.O. Box 2902B,Baton Rouge. La. 70821.ANSA FONE schematic, your money back onfirst service call. $1.00, JERRY REEVES, 18154th Street. Seabrook. New Jersey 08303.TRANSISTOR circuitboard semikits CB, 2M,6M, Police/Fire converters $1.00 each. Sweepgenerator 100 kc to 100mc $2.00. Many otherprojects. Free catalog. PAULIN SALES, Box122B. Upland, Calif. 91786.TRANSISTORIZE your television! Free details.Write to: P.O. Box 2498, Gardena, Calif. 90247

GeneralTV SERVICE ORDER BOOKS for use with yourrubber stamp. Duplicate or triplicate. Low cost.Write for FREE 32 PAGE CATALOG and SpecialRubber Stamp Offer. OELRICH PUBLICATIONS,6556 W. Higgins. Chicago, III. 60656.

CanadiansGIANT SURPLUS BARGAIN PACKED CATA-LOGS. Electronics, Hi-Fi, Shortwave, Amateur,Citizens Radio, Rush $1.00 (Refunded), ETCO,Box 741, Dept. R. Montreal 1, Can.CANADIANS Have you seen ELECTRON, Cana-da's own Service and Hobby magazine? Sub-scription $3.50. ELECTRON, Box 796, Montreal,Canada.

1ANTEDG -R, H -P, L&N, etc.. Special tubes, manuals,military electronics. ENGINEERING ASSOCI-ATES. 434 Patterson Road. Dayton 19. Ohio.QUICK CASH ...for Electronic EQUIPMENT,COMPONENTS, unused TUBES. Send list now!BARRY, 512 Broadway, New York, N. Y. 10012,212 WALKER 5-7000.PHOTOGRAPHS and COLOR SLIDES Wanted.To $500 each. Free information write PICTURE.Box 74607, Hollywood 90004.NEW DISTRIBUTOR now buying CRT's fromreliable manufacturers. Send complete details.BEDNARCHUK SALES, 517 Sand Creek, CoonRapids, Minn.. 55433

SERVICESMETERS-MULTIMETERS REPAIRED and cali-brated. BIGELOW ELECTRONICS, Box 71-B,Bluffton. Ohio.TRANSISTORIZED products dealers catalog, $1.INTERMARKET, CPO 1717. Tokyo, Japan.SF'EAKER RECONING. Satisfaction Guaranteed.C & M RECONE CO., 18 E. Trenton Ave., Mor-risville. Pa.ALL MAKES OF ELECTRICAL INSTRUMENTSAND TESTING equipment repaired. HAZELTONINSTRUMENT CO., 128 Liberty St., New York,N.Y.INVENTORS. We will develop, help sell youridea or invention, patented or unpatented. Ournational manufacturer clients are urgently seek-ing new items for outright cash sale or royal-ties. Financial assistance available. 10 yearsproven performance. For free information, writeDept. 53, WALL STREET INVENTION BROKER-AGE, 79 Wall Street, New York, N. Y. 10005.

HELP WANTEDTELEVISION TECHNICIAN for new communica-tion center on campus of dynamic, expandingmidwestern college of 9,000+ enrollment. Com-plete benefit program. Experience in closed-circuit and broadcast engineering. FM and 10TV. First class FCC license required. Salaryfrom $6,000. Maximum age 55. Contact Wil-liam R. Freed, Personnel Officer, Room 8,Administration Building, BALL STATE TEACH-ERS COLLEGE, Muncie, Indiana.

JULY, 196481

RAD -TEL'SAMAZING. OFFER...

YOUR CHOICE

1B3 -1G3 -1K3 -1J3

HURRY OFFER EXPIRESAUGUST 31, 1964

C. YEAR UUARA[ TEEftad-Te( vVtl! eplaCe arty tube that does not giveefftctept performance far 1 year fron' date of purchase.

EACH TUBE INDIVIDUALLY & ATTRACTIVELYBOXED & BRANDED RAD-TEL

ONE TUBE FREE1B3 -1G3 -1K3 -1J3

with the purchase of every io Rad-Tel QualityBRAND NEW TUBES

Qty. Type Price Qty. Type Price Qty. Type Price Qty. Type Price

_024 .79 5AQ5 .54 _6AX5 .74 _60A4 .68

_1AX2 .62 _5AT8 .83 6BA6 .50 _613E6 .61

_183 .79 _5BK7 .86 _68C5 .61 _6D66 .62_10N5 .55 _5B07 1.01 _613C8 1.04 _61318 1.21

_103 .79 _513R8 .83 613E6 .55 __613K6 .59

_1J3 .79 _5CGB .81 _68F5 .90 _601,16 1.55

_1K3 .79 _5C L8 .76 6BF6 .44 _6006 1.10

_1 R5 .77 5CQ8 .84 6BG6 1.70 _6075 .81

_155 .75 5EA8 .80 6BH8 .98 _6076 .53

_174 .72 _5EU8 .80 _6BJ6 .65 _6078 .94

___1U5 .65 _516 .72 6B17 .79 _6EA8 .79

1X2B .82 _5T8 .86 6BK7 .85 _6E135 .73

2AF4 .96 5U4 .60 6BL7 1.09 _GEB8 .94

_3AL5 .46 _5U8 .84 6BN6 .74 _GEMS .77

_3AU6 .54 .56 _61306 1.12 _6EM7 .82

_3AV6 .42 _5X8 .82 _61307 1.00 _6EU8 .79

_3BC5 .63 _5Y3 .46 _6BU8 .70 _6EV5 .75

_3BN6 .75 6AB4 .46 _613X7 1.11 _66W6 .57

_3BU8 .78 _6AC 7 .96 _6BZ6 .55 _6EY6 .75

_313Y6 .58 _6AF4 1.01 6BZ7 1.03 _6FG7 .69

-3626 .56 _6A05 .70 _6C4 .45 _6FV8 .79

3C B6 .56 _6AH4 .81 _6CB6 .55 _6GH8 .80

_3C 56 .58 _64H6 1.10 _6CD6 1.51 _6GK5 .61

_3DG4 .85 6AK5 .95 _6CG7 .61 _6GK6 .79

_313K6 .60 _6AL5 .47 _6CG8 .80 _66 N8 .94

_3076 .54 _6AM8 .7a 6CL8 .79 _6H6 .58

_3GK5 .99 _6AQ5 .53 _6CM7 .69 __615GT .51

--_304 .63 _6AS5 .60 _6CN7 .70 _6J6 .71

_354 .75 _ GAT 6 .45 _6CQ8 .92 _6K6 .63

_3V4 .63 GAT8 .86 _6CR6 .60 _654 .52

_41303 1.01 _6AU4 .85 _6CS6 .57 _65A7G7 .99

4C56 .61 6AU 6 .52 6CS7 .69 _6SH7 1.02

._41376 .55 _6AU8 .87 _6CU 5 .58 _6517 .88

_4G M6 .60 _6AV6 .41 _6C1.16 1.08 _65K7GT .95

5AM8 .79 _6AW8 .90 _6CY5 .70 _651_7G .84

_5AN8 .90 AX4 .66 _6CY7 .71 _65147 .65

Easy o work on

,,....ciazzaa&--033 CHEATER CORD set while panel is off.

6 ft., No. 154 29{ ea. Lots of 3-25a ea.

TUBE SUBSTITUTION BOOK Over 11,000 direct tube

substitutes Only all-inclusive directory of

electron tube equivalents:- For USA electron tubes- Substitutes for foreign tubes- Picture tubes, newer models- Picture tubes, older models- transistor replacements- Army -Navy, V.T. substitutes

$ 25No.

X193,

RAD-TELTUBE, RA

CO.m

T

AND HIDFIO

55 CHAMBERS STREET, NEWARK, NEW JERSEY 07105DEPT. RE

MAttutatturersSum?. tecl 1.41 Pv

RAD-TEL TUBE CO. NOT AFFILIATED WITH ANYOTHER MAIL ORDER TUBE COMPANY

Qty. Type Price Qty. Type Price Qty. Type Price Qty. Type Price

_650767 .94 12AL8 .95 _121375 .76_6T4 .99 _12AQ5 .60 _12077 .79_678 .85 _12AT6 .50 _12078 .78_6U8 .83 _12A77 .76 _12DW8 .89_6V6GT .54 12AU6 .51 _12026 .62_6W4 .61 1 2AU7 .61 _1 2E05 .62

6W6 .71 _12AV6 .41 _12EG6 .626X4 .41 _12AV7 .82 12EK6 .62

_6X8 .80 12AX4 .67 _12EL6 .50_7A8 .68 12AX7 .63 _12E26 ,57

7AU 7 .65 12AY7 1.44 12F8 .66_7EY6 .75 _12AZ7 .86 _12FA6 .79_7Y4 .69 _12134 .68_8AU8 .90 _121306 .50_8AW8 .93 _126E6 .53_8E105 .60 _1213F6 60

8CG7 .63 _12BH7 .778CM7 .70 _126K5 1.00

_8CN7 .97 _12131_6 .56_8C57 .74 _121306 1.16_8E88 .94 _12BR7 .74_8107 .56 ._1213V7 .76_9C L8 .79 _12BY7 .77_11CY7 .75 _12827 .86_12A4 .60 _12CN5 .56

12AB5 .60 _12CR6 .67_12AC6 .55 _12CU5 .58_12/306 .57 _12CU6 1.06_12A E6 .50 _12CX6 .54

1 2AE7 .94 ._12134 .69 17AX4 .67_12AF3 .73 -1213E8 .83 _17D06 1.06_12AF6 .67 -120L8 .88 -18FW6 .49____12A16 .62 _12006 1.04 18FX6 .53_12AL5 .47 _12057 .84 _18FY6 .50

_12FM6_12FR8_12FX8_12GC6_12.18_12K5..._12L6_125F7 .69_125K7G7 .95_12SL7 .80_1251,17 .67_1250.767 .91_12U7 .62_12V6 .63._12W6 .71_12X4 .47

.50

.97

.901.06

.84

.75

.73

ORDER TYPES NOT LISTED

FREE

TERMS 25% deposit must accompany all orders, balance C.O.O. Orders under $5add Si handling charge pluspostage. Orders over $5 plus postage. Approx 8 tubes

per 1lb. Subject to Ruin sale. No C 0.D. 's outside continental U S A

_19AU4_19BG6__19EA8_1978_21 EX6_25AX4___25C5_25CA5_25C06_25C U6_25DN6

25EH5_25L6_25W4_32E75_35C5_35L6_35W4_35Z5_36AM3_5085_5005_50EH5_50 L6_70L7_11723_807

.871.39

.79

.851.49

.70

.53

.591.521.111.42

.55

.57

.68

.55

.51

.60

.42

.60.36.69.53.55.61.97.85.75

OUR16th

YEAR

I Send For New Tube & Parts Catalog Send For Trouble Shooting Guide

Fast, Dependable service - Selling direct by mail for over 16 yearsTotalTubes $TotalPart (s) $

Postage $

GrandTotal $

Please rush order.TUBE SUBSTITUTION BOOK, No. 193 e, 1.25Cheater Cord 29c ea. Lots of 3 25c ea. #154

I Orders under $5.00 - Add $1.00 handling charge - plus postage

FREE'Send FREE Tube and Parts Catalog

Ei Send FREE Trouble Shooting Guide

NAME

RAD-TEL Tube Co.Dept. RE

55 Chambers StreetNewark, New Jersey 07105

I ENCLOSED IS $

I SEND:

I ADDRESS

I CITY..

EACH

ZONE STATE


Tips forfor TechniciansMallory Distributor Products CompanyA division of P. R. Mallory & Co. Inc.

Indianapolis, Indiana 46206

New Kind of Zener Diode

REVERSE VOLTAGE

.Ell IZT

EMU - ME1 ZM

Iz-zener currenlzk-zener current near knee

Input .

lzt-zener test currentlzm-maximum zener current

V1* 0V,')

Output

00Typical shunt overvoltage protection circuit usingzener diodes. Output is controlled between VI and V2.

IMIIMMINIENEIMMO

A zener diode, as you're probably aware, is a specialkind of semiconductor which has excellent voltageregulating characteristics. It's the solid-state suc-cessor to the gas discharge tube. It acts like a rec-tifier diode, blocking current in the reverse direction,until the "zener voltage" is reached-then it startsto conduct with a capital C. The zener diode cancarry appreciable current continuously. So this makesit a fine regulating device. You can use it in powersupplies where you need highly accurate output. Oryou can use it in clipper or clamper circuits, bybiasing the diode negative.

The big news in zener diodes is that you can now getthem from Mallory at a price which makes thempractical for service work, experimentation, or com-mercial circuitry. The news -maker is the new MalloryType ZA molded -case diode. Its electrical propertiesand reliability record are comparable to those ofmilitary grade units. In fact, we use the same siliconcell in the ZA as in the zener diodes we make formilitary requirements. But the price is only abouthalf that of hermetically sealed diodes.

The ZA is rated 1 watt at 25°C. If you install it ina hot spot, you can use it at ambients up to 100°C,derating linearly to 0.5 watt. Voltage ratings go from6.8 to 200 volts, in small increments so that you canget exactly the regulating voltage you need. Standardtolerances are 20%, 10% and 5%.

You'll like the cold -case design of the ZA. No needfor insulating sleeves when you squeeze it into tightlayouts. It's so small-only ''s" long by 0.220" indiameter-that it fits practically anywhere.

Your Mallory distributor has the Type ZA in arange of ratings. He also stocks Mallory silicon rec-tifiers . . . including handy packaged doubler, bridgeand center -tap circuits. See him soon!

At top, you're looking into the RCAReceiving Tube Reliability Laboratory-a most important factor behind theexceptional reliability of RCA receiv-ing tubes, and one more plus -value thatyou have in RCA tubes.

Here in two -hundred TV sets of allsizes-black-and-white and color-samples of each week's production ofRCA receiving tubes are subjected toextensive tests under actual field con-ditions. The operating conditions forthe TV sets vary from low -line to high -

Work Well Hereline voltages. And the sets are regularlycycled on and off to check the effects okheating and cooling on the tubes.

The Tube Reliability Laboratory re-veals-and allows us to eliminate-prob-lems that do not show up under normalproduction life testing. It also permitsus to conduct pre -production tests ofnew tube designs to make certain thatthe RCA standards of quality will befulfilled before the new tubes aremarketed.

Testing in the Tube Reliability Lab-

oratory enables us to verify the con-sistent high quality of RCA receivingtubes-to maintain uniformity of char-acteristics from tube to tube andthroughout life. It is another exampleof the care we take to assure that RCAreceiving tubes give RELIABLE PER-FORMANCE where it really counts-in your customers' sets.

SEE YOUR AUTHORIZED RCA DISTRIBUTOR

FOR TOP-QUALITY RCA RECEIVING TUBES

RCA ELECTRONIC COMPONENTS AND DEVICES, HARRISON, N.1.

The Most Trusted Name in Electronics

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