wttieles's, deeet111,(. 3rd, 1927. rfsiis*t111117.1) at the - 9 a ..tatsiapeit a new constant...

wTTIELEs's, Deeet111,(. 3rd, 1927. RFSIIS*T111117.1) AT THE - 9 A ..TATsiApEit

A NEW CONSTANT -REACTION CIRCUIT (Sep lane)

No. 287. Vol. XII.

°pular Every Thursday

PRICE

3d.

irolossINCORPORATING "WIRELESS" December 3rd, 1927.

'1

Special Features In This Issue

Measuring Your Eliminator Voltag e. H.T. Economy"Why I Don't Broadcast!" B y Chaliapine

THE "PROGRESSIVE" TWOThe R.S.G.B. and "Q.S.T."

Are Reflex Circuits Fundamentally Unsound ?An interesting sidelight on radio conditions in Germany is afforded by our cover photograph. Here is shown the wiroless set

testing laboratory installed in the offices of one of Berlin's weekly journals.

fi POPULAR WIRELESS December 3, 1, 1327,

An outstanding successAmple volume and clear, distortionlessreception have delighted the thousandsof users of the Dubilier R.C. CouplingUnit.This proves conclusively that theDumetohm is the Resistance which ispre-eminently suitable for R.C.Coupling.It consistency, noiseless working, non -inductive properties, and, above all, themanner in which it retains thesequalities, are now a by -word amongWireless men.A great advantage of this coupling unitis that Dumetohms of various valuescan be inserted to suit your own re-quirements.And the greatest advantage of all is thatyou can get this Dubilier R.C. Unit, with-out doubt the finest obtainable, for 7/-.

There is a wealth of information in the bookletshown here. In addition there are full instructionson how to make up five different valve circuitseach possessing unique advantages. Don't bewithout your copy. Your dealer will hand youone, or if he is cut of stock, we shall be pleasedto send you one, post free 3d.

DUBILIER

DLIBILIERDICTA

No. 3.

*Several people have written toask us whether the Dumetohmwill lose its resistance " if theair is allowed to get in." Theanswer is, of course, that theair was never taken out. TheDumetohm does not dependupon atmospheric pressure,negative or otherwise, for itsefficient working, nor areclimatic changes likely toaffect it.

Incidentally, since Messrs. A.C. Cossor included it in thespecification of their mostsuccessful set " The MelodyMaker," the popularity of theDumetohm has gone up stillfurther, and. if final proof ofthis popularity be required, itis surely to be found in thesincerest form of all flatterieswhich have latelybeen hedon this wonderful little re-sistance.

Whilst on the subject ofResistances, have you a selec-tion of Dubilier FilamentResistors by you? If you doany experimental work youwill find them invaluable, Theyonly cost 1/- each and theyclipneatly into the DumetohmHolder, which also costs 1/-.

*One of these Dumetohm Hol-ders connected into each fila-ment lead of that new set youare building, will enable youto make comparative testsbetween the results given byvalves of different filamentvoltage without changing yourL.T. Battery.

*Perhaps you are using four 6 -volt valves and want to put ina 2 -volt H.F. valve to compareit with the one in use. In thatcase you clip in a Resistor ofthe value necessary to bringdown the current from your 6 -volt accumulator to the normalfilament consumption of your2 -volt valve.

It is easy to calculate theResistor to use, but for con-venience we reproduce twocharts on p. 16 of our Cataloguewhich give the information ina handy farm. Remember tochoose a Resistor which willpass a current that the filamentcan handle in safety.

Advt. 7. Dubilier Condenser Co. (1g25) Ltd., Ducon Works, North Acton, London, W.3.TC80

Popular Wireless, December 3rd, 1:27.

FREECONSTRUCTIONAL

BOOKLETincluding blue printand full details willbe supplied for anyone of these receivers.Booklets, includingblue print of the otherfive receivers, 6d. each.

BATTERY -LESSRECEIVERS

For A.C. Mainsploying the famousK.L.1. valves.

K.2. Similar to K.1, but inaddition incorporatesan H.F. stage.

For D.C. MainsD. P.1. 3 - valve receiver-

simple to construct.D.P.2. Similar to D.P.1, but

gives greater range andselectivity by means ofa neutralised H.F.stage.

If you wantdistance

there are two specialcircuits incorporatingthe Marconi S 6 2 5Shielded Valve.T.1. 4 -valve receiver,including 1 H.F. stage,with 5625 valve.T.2. 5 - valve. TwoH.F. stages, with 5625valves. Stations hun-dreds of miles awaycan be tuned in withcomplete stability.

Forconvenience and economy

build this battery -less receiver

Model K.2 (for A.C. Mains)

BUILDfor yourself a receiver that needs no batteries-no

accumulators; that costs next to nothing to run; thatwill always spring to life at the turn of a switch. Build nowfrom the free Marconiphone circuits. Full constructionaldetails and full-size wiring plan are provided. You cannotgo wrong.

The receiver illustrated-the K.2, a 4-valver, in addition tooperating entirely from A.C. Mains, is fully as efficient asthe best four -valve circuits. And remember, in addition totaking all maintenance worries from you, it also lightensmaintenance costs to an amazing and welcome degree. TheK.2, used every day for a year, costs, at most, 35/-, and aslittle as 10/- or less if a power supply is available. Comparethis with the annual cost of H.T. batteries and accumulatorcharging.

MARCONIPHONETo the MiIRCONIPHONE CO. LTD., 210-212, Tottenham Court Road, London, 117.1.

Please send me FREE constructional booklet, including blue -print for circuit

I am also enclosing for the following booklets

NAME TOWN

ADDRESS COUNTY

co..le III -4

Of* it.)UtAA3NS001

SVEC ir-°4-

,40

Popular Wireless, December 3rd, 1927.

A FULL SIZE

BLUE PRINT

FREEWITH EVERY

ISSUE.

SPECIAL CHRISTMAS DOUBLE NUMBEROn Sale December 1st. Price

THE VIKING IV.WITH FULL SIZE BLUE PRINT.

a C9

THIS YEAR'S SOLODYNE.First details of a New Solodyne Set. Special and exclusive arrange-ments with Mr. John Scott -Taggart, A.M.I.E.E., F.Inst.P., have beenmade for the publication of details about a New Solodyne Set.Dozens of other fine features also appear in the "MODERNWIRELESS" CHRISTMAS NUMBER-features which will appealto every amateur.

Order your copy NOW and avoid disappointment.

Popular Wireless, December 3rd, 1927. 6S7

"Come on-- aCharleston

ED

"Isn't it clear ? Wonderful, eh ?Made it myself. Marvellous !Come on-shake a leg there!"

" Mind the valves, John ! ""That's all right: You can't bustEdiswan Valves! "

Have you made the NewR.C. Threesome-thenew model brings inmany additional stationswith all the quality ofthe original receiver. Twohours work. 50'- for parts.Only 5 simple connec-tions. Anyone can makeit. But you must useEdiswan valves to get out.of the set all it is plannedto do.

I EDISWANVALVES

ClearestStrongest

Last the LongestA type for

every purpose

SWANNEW R.C.

THREESOMESEND THIS COUPON P.W. 3.12.27.

To THE EDISON SWAN ELECTRIC CO.,. LTD.(Publicity), 123/5, Queen Victoria St., London, E.C.4.

Please send, post free, presentation copies of the NewR.C. Threesome Instruction Book and Blue Print.

NAME

ADDRESS

C -S8Popular Wireless, December 3rd, 1927.

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PopularWirelessAltlit,

Pure

Scientific Adviser :Sir OLIVER LODGE, F.R.S.

Editor :NORMAN EDWARDS, M.Inst.R.E., F.R.G.S

Technical Editor : G. V. DOWDING, Grad.I.E.E.Assistant Technical Editors : K. D. ROGERS, P. R. BIRD

G. P. KENDALL, B.Sc., A. JOHNSON RANDALL.

RADIO NOTES AND NEWS.Brass-The All -Black Route-P C J J-Broadcasting Times-Transmitting Notes-

An Astounding Admission-Less Than Nothing.Pure Brass.

FOIL pure untarnishable brass I recom-mend you to a gentleman whose letterI have seen in a North Country news-

paper. He has a crystal sot, but threatensto let his licence lapse because of thebehaviour of niggardly valve -set ownerswho are low-down enough to tune away friamthe local station, thus depriving him of thebenefits of re -radiation. The remedy is the

P. \V." " Every Purpose."

The All -Black Route.WH. B. (Heathfield), who gets Sydney

. (N.S.W.) on the above set, whichvotes " the best ever," winds up his

letter with a poser.- If all his questions areequally nasty, I fear he will be hounded outof society. " Which way round doesSydney come ? " It would take a clevererman than Arid to say, but my understand-ing is that it comes all ways at once; but somuch more strongly over that .part of theearth which -is in darkness that the otherways don't count. Hence, generally speak-ing, it comes round one way by day andthe opposite way by night. .

The Radio Car Returns.GLAD to hear that Captain L. F. Plugge

has returned safely from his motortour through France, Portugal, and

Spain. A good example of the advantage ofa radio -fitted cast was supplied -by the factthat whilst en rolte,he picked up an S O.S.for one of his party whose father wasseriously ill, and who .was thus warnedto return without the delay which, but forthe radio, would have occurred. CaptainPlugge thinks the Portuguese roads need

. plugging. They do.. They are simply astung of p6t-holes joined by _mid andstones. '

The League and Radio.

1Tis not surprising that the League ofNations has felt the need Apf its ownwireless station, radio being such a

fine instrument f6r propaganda. I under-stand .that the Swiss Marconi Company hasdecided to build a new high -power station,50 kiloWatts to the anodes, capable of reach-ing.all places in Europe, North Africa and theEast.- I expect this will interest ex -UncleArthur 'R. Burrows, who is now posted inGeneva.

PCJJNOW that this famous station is: beim;

dismantled and re -erected at Hilver-sum; a brief review of its work may not

be amiss, for it -has Certainly made radiohistory and given the B.B.C. the -jog of itslife. It'began by working on 30.2 metres,when Australia spoke very well of itssignals. _ Then, on May 20th, 1927, it had theaudacity to relay Daventry, its signals beingwell received in Australia, New Zealand,India and South Africa.

The Great Debt.transmitted a special Beethoven

programme which was received allover the world and was even relayed

by other stations. On March 11th, 1927, itestablished telephonic communication withBandoeng, Java, and on May 31st, 1927,

Queen Wilhelmina and. Princess Julianaaddressed the DutchIndies through P C J JFinally, on August 14th, 1027, theAustralian High Commissioner in Londonspoke to Australia through Eindhoven, wherethe Philips' ::experimental station - was atthat time. But ithe .great -,debt owing toPCJJ is that it woke up the B.B.C. witha start, because it showed what could bedone.

News from Ireland.OFFICIAL figures show that the value of

Irish imposts of sets and parts for thehalf-yest ending June 30th was

£35,307, as against £58,662 for the sameperiod last year. Of these imports Englandsupplied £33,730 and Nokhern Ireland£549.

(Continued on next page.)

WIRELESS ON AN INLAND WATERWAY.

Mr. Percival Westerman (right), the author of many popular sea stories, has radio fitted upon the bargein which be traverses the inland waterways.

NOTES AND NEWS.(Continued front precious page.)

The Washington Conference.IHAVE received pews that the Conference

decided to abolish spark transmitters.I do not know what period will be

allowed, but anyhow, it is good news formany Morse -haunted listeners. The wave-bands elicited to amateur transmitters are_(in metres) : 150 to 174-927 ; 75 to 85-714-;41.096 to 42-857 ; 20.833 to 21.429 ; 10 to10.714 ; 5 to 5-37. The band 0 to 5 isallotted to no one in particular.

Broadcasting Times,1T is extremely difficult to get infor-

mation about short-wave transmissiontimes, probably because so many of

the stations are experimental. However,here goes ! Cincinnati, NV L W, 52-02.Relays programme at 11.5 A.M. G.M.T.2 X A D, 21.98, Tuesday, 9 to 9.40 A.M.Also transmits evening programme of W G Yon Sunday, Monday, Wednesday andFriday. Rocky Point, 2 X G, 16-02,Monday and Friday, after 5 P.M. RadioMalabar, A N H, 17.3, Monday, WednesdayFriday, 7 A.M. to noon ; Tuesday, Thursday,Saturday, noon to 5 P.M. (E H 9 OC relaysBerne programmes at 7.30 P.M. and 9.45 P.M.)

Station News.ANEW station at Laibach, Jugo-Slavia,

is expected to be ready by Easter.In due time you can Laibach and

tune for it. In order to minimise the inter-ference from Australian stations and thenew high -power station at Wellington, newwave -lengths have been allocated to theNew Zealand broadcasting stations, asfollow : 1 Y A, 333 metres ; 2 Y A, 420metres ; 3 Y A, 306 metres ; 4 Y A, 363metres.

North London Club.Awireless club is to be formed at the

Holloway Literary Evening Institute,Holloway County Secondary School,

Hilldrop Road, Camden Town, N.7, meetingon Mondays at 7.30 p.m., and conductedby Capt. Jack Frost, formerly of the B.B.C.Membership fee, 4s., November to Easter.This is going to be a live affair, with lanternlectures and demonstrations galore, andwill Iook after beginners as well as experts.So pack up your radio troubles in your oldkit bag-and go to Holloway.

Birmingham Club.AWIRELESS society, " Slade Radio,"

a branch of the Wireless League, hasbeen formed at Erdington. Member.

ship includes that of Wireless League.An experimental station is being provided,besides lectures and demonstrations. Hon.Sec., Mr. H. Clew, 52, St. Thomas Road,Erdington, Birmingham.

Another Society Note,THE Southport and District Radio

ty (Hon. Sec., Mr. E. C. Wilson,Hampton Road, Southport) held

its third annual exhibition from November7th -November 12th. Somehow or otherI did not receive sufficient notice of this topermit me to publish the news in advance.Club secretaries will take warning by this,and let me know about their special" doings " as far in advance as possible. Thisclub is not a dull emitter by any means,

and judging by its exhibition programme itis run by what Uncle Sam would call " gogetters." The fee is 5/- per annum and thepresent session alone is worth double.

Transmitting Notes.STATION 6 Y F is now on the ether, 45

metres. The owner would welcomereports, particularly about his "key-

ing chirp." Address, 6 Y F, 38, Barrow HillRoad, St. John's Wood, N.W.8.. Mr. J. N.Roe, " Mirydon," Ridgeway Road, Farn-ham, Surrey, is now operating RadioG-2 B U W on an artificial aerial. He is anice man, because he says ho reads "Notesand News" first, and because he wants tohelp anybody with tests, especially on.short waves. On a modified " Simmonds "he gets 2 M E and 2 F C, at R 5 in thephones.

Changed Call -Signal.SIR. H. T. HUMPHRIES, Carrick House,

7, Elmwood Road, Herne Hill, S.E.24,states that he has changed his call -

signal from 2 Z W X to 6 Q J. He trans.

E SHORT WAVES.E == " How to obtain volume on your wireless." === Place a book on it.-" Daily Mirror." =_= * =

A PICK-ME-UP." I'm feeling very run down,"

accumulator.E " Well, come and have a spot," i.

said the

said the9 crystal, s:

* * E.'.

Wireless beats time, not with the baton, but EE by the variation of the clock every time listeners E.-.

E in Great Britain hear the relay of a programme Efrom Australia.-" News of the World."

Old Lady" . . . and will you please send me the pamph-let telling me bow to osculate."-" WeeklyRecord and Mail."

THE BLESSINGS OF RADIO.An intelligent appreciation of radio is shown

in a letter received recently by the B.B.C. :" And the classical music is so soothing.Grandma. sleeps peacefully through it everyevening, so I do not have to stay with her butcan go out for a game of billiards."

Once people who talked to themselves werethought to be evincing the first signs of insanity.Nowadays they're known as radio lecturers.

A STANDING BUY.Teacher : "If your father bought a sixty -

dollar radio set on the instalment plan, andpaid off two dollars a week, how long would ittake him to pay it off?"

Jimmy " Ten years."Teacher : " Sit down, you don't know the

lesson."Jimmy : " You don't know my father !"-

"Radio News."

A thought for to -day : To be successful in =life you must keep on climbing, and when you =have reached the top of the ladder you will Hprobably remember you left the aerial wire Hdown on the ground.

mits on metres 45, 90, 150 and 200 and willbe pleased to arrange ,tests with any othertransmitter in the British Isles.

Correct Dress for Amateurs.AWRITER of wireless notes in a very

well-known " daily," in dealing with"hand -capacity" effects, recommends

the wearing of rubber gloves when tuning.This is very old-fashioned. Everyone knowsthat the proper costume is a straw hat,morning coat, flannel bags, carpet slippersand calabash pipe ; spats optional. But,joking apart, for the information of technicalreaders I would ask my friend, who is, Isee, an A.Rad.A.-nothing to do withradishes-why he prefers to use a rubber

Popular Wireless, roosember 3rd, 1927.

dielectric for his " hand capacity " ratherthan the more usual dielectric of air. It'smuch more expensive and the results areno better.

Less than Nothing.JUST one more technical hint, this time

from a Leeda paper. The expert,trying to explain an oscillating current,

says, "That is how the current continues.From zero, it continues its progress until itreaches its lowest power (minimum potential),which is just equal and opposite in value toits highest power." The italics are mine,because I want you to note that when thecurrent has a minimum value, lowerthan zero, it is equal in power to its highestpower. Gentlemen, bare your heads, forthis is a miracle. Zero will have to pack upand go out of business.

Three Items to Note.DECEMBER 2nd, Comic opera, Rose of

Persia," by Sullivan. 2 L 0 and5 X X. December 6th, A party of

the Victorian days, from Birmingham.Shades of musical chairs, Family Coach andPostman's Knock ! December 7th, Theopera, " The Travelling Companion,' by C.Villiers Stanford, from Cardiff.

An Astounding Admission.WHEN I read that, speaking at Man-

chester on November 10th, Sir JohnReith admitted that the " Children's

Hour " and Variety Entertainments (by theB.B.C.) tare " dreadful," I oscillated soviolently that my equilibrium was half adegree to starboard for several days. Ihope Sir John was correctly reported andthat his utterance is proof of heart-searchingby the B.B.C.

The Public Knows.INTERESTING results have come from a1 questionnaire circulated to listeners in

America, with the object of finding outtheir favourite composer and type of music.Beethoven was top of the list and Schubertsecond ; the third was Victor Herbert, anAmerican composer. Well, if a publicthat puts Beethoven first puts Herbertthird -we ought to hear Herbert. Has theB.B.C. ever broadcast any of his work ?The overture -to " Tannhauser " -came firstfor the second question, " Poet and Peasant"(Suppe) second, with " Marche Militaire "(Schubert) third. No English composerwas mentioned, though " H.M.S. Pinafore "was ninth of ten favourite pieces.

American Radio Fun.FROM " Radio News." Neighbour i

" How many controls are there onyour radio set ? " Owner : " Three ;

mother-in-law, wife, and daughter." Andagain. Sonny : " Daddy, mother wantsyou to look at a spider's 'web before shebrushes it away." Daddy : " What'swonderful about it ? " Sonny : " She'safraid it's a part of your radio set."

Talks from Paris.THE University Extension of the " In-

stitut Radiophonique," Paris, hasarranged a weekly talk from Eiffel

Tower and P.T.T. on " New Books inEnglish," given by Miss Golda M. Gold-man As these talks are under the auspicesof the Sorbonne they are almost certain tobe worth while, and may repay you fortroubling to pick up Paris. The talks arein English. ARIEL

Popular Wireless,' December' 3rd, l927.

EVER since the valuable properties ofreaction were first made known therehas been a constant endeavour to

evolve a circuit which would give constantreaction over the whole tuning scale, inother Words, a circuit in which a reactionsetting for maximum sensitiveness made

at any one poidt of the tuning scale would.remain unchanged for any other tuningposition.

With all ordinary reaction circuits, morereaction is required at the top of the tuningscale than at the bottom, and as we increasethe wave -length setting of our receiver, wemust steadily increase the reaction couplingto maintain the same sensitivity,

Although many attempts have beenmade to evolve constant reaction circuitscomparatively few have had any practicalvalue. Certain mechanical arrangementsin which the coupling between the reactioncoil and the grid coil has been continuouslyvaried as the tuning condenser spindle isturned, have proved fairly suecessful, butrequire special apparatus' and have beennone too easy to manufacture.

Resistance Coupling.One of the most successful of the non -

mechanical schemes is that put forward byLoftin and White, and previgusly describedin this journal. In this, the increasingefficiency of capacitative coupling withincrease of wave -length is balanced againstthe decreasing efficiency of inductivecoupling with increase of wave -length, anda fairly constant feed -back of energy overthe whole scale can be obtained.

The Loftin - White constant - reactionscheme, although giving great promisewhen first tried, has proved in practice tobe rather troublesome and has not achievedany great popularity.

My new constant -reaction scheme isquite different from the Loftin and White

A NEW CONSTANT--E CTION CIRCUIT

* A0000000 -0-4,- -*-0- +P- -0- ..... *+ Mr. P. W. Harris here gives the first published description of a t

new and very interesting circuit. It has been tested thoroughly +,+ and would appear to be the most practical solution of the T

problem of " constant sensitivity " yet brought forward. Next T+ week a simple two-vaiver incorporating this novel scheme will 7

be detailed in full.By PERCY W. HARRIS, M.I.R.E.

* -40-- *

method. It is the result of a number ofexperiments conducted to find methods ofapplying the new high -magnification R.C.valve to high -frequency work. An articleon this subject has appeared in POPULARWIRELESS, No. 266, under the title,." Bringing in Daventry and Co." Here I

showed that a verygood .measure of suc-cess was obtainableon the DaventryRange and that dis-tinct amplification,although of a smallerorder, was also obtain.able on the broadcastrange.

If readers will referto this article they willfind a detailed de-scription of experi-ments with reactioncontrol from the plateof the detector valve

to the grid circuit of . the high -frequencyvalve, extremely small capacities beingsufficient to feed back the energy requiredto produce oscillation.

The continuance of these experimentswith the object of finding some method ofobtaining sufficient feed -back to producesmoothly -controlled reaction on the broad-cast band has had very interesting results,and has led -to a new circuit being evolvedusing a high -frequency stage, and a de-fector (followed, of course, by one or twostages of note magnification, if desired),

Here is one of the experimental receiverswith which Mr. Harris carried out theresearch necessary for the practical appli-

cation of his invention.

with only one tuning condenser and areaction scheme which gives .constant re-action control over the whole tuning band._This means, of course, that we have nowthe true . single condenser, single -dial set,including a stage of.high frequency-a mostdesirable state of affairs.

The circuit itself, for which. a patentapplication -has been filed, is shown inFig. 1. It is made up in this -case, as athree -valve set. The high -frequency valveis coupled to the aerial with a standard sixpin Reinartz transformer, reaction beingobtainer} with the aid of the winding L3,and the condenser C2. This high -frequencyvalve is coupled to the detector Valve bythe resistance Ra. and condenser 4 , thegrid leak R, being joined to the poSitiveleg of the valVe in the usual way. FolloW-ing the detector valve we have a radio- -frequency choke, anode resistance RI, andcoupling condenser C, with the grid leak

Constant- Sensitivity.- The interesting part of this circuit is, of

course, that which gives the constantreaction coupling. This is the combinationof condenser 0,- joining the plate of the -

detector valve to the grid of the -

frequency.- valve and the condenser 02,with the winding La. Ignoring the coup. -hag givenby the condenser C,, and con-sidering on!.- the ordinary reaction controlon the high -frequency valye, consisting ofthe condenser C, and the coil L, we shallfind that if the circuit is arranged so as tobe just on the oscillation point when thecondenser Cr is at its minimum, a steady

(Continued on next page.) -

692 Popular Wireless, December 3rd, 1927.

A NEW CONSTANT- I4 REACTION' CIRCUIT.

(Conlineted front previous page.)

increase of capacity of 02 will be requiredto bring the set to the .point just belowoscillation as we increase the reading of0,:. Briefly put, we can say that we mustincrease reaction as we increase wave-length for this circuit.

Now consider the radio -frequency coup-ling produced by the resistance R3 and -thecondenser CI4. It is well known that theefficiency of resistance coupling goes up aswe increase the wave -length. We shall,therefore, get a greater step up in areplifica-lion as we increase the wave -length towhich the set is tuned, the - sole tuningcontrol in this case being the condenser 01.in the first grid circuit.

For a given setting of 03 there will be acertain amount of feed -back . from thedetector to the first valve. Owing to theincrease of amplification as we increase thewavelength of the circuit, an increase infeed - back will be applied through thecondenser 03 to the grid of the first valve.There are one or two other effects to betaken into account, such as the varying

reactance of '3, but these do not substan-tially effect the general working. :

If, now, we adjust, the values of 02 andC3 so that the increase of feed -back by oneis balanced by the decrease of feed -back ofthe other, we shall have achieved constantreaction. This is what we do. Such anadjustment is quite simple to effect inpractice, as will be explained later. Theresult is that we have a sharp tuning circuitpossessing high selectivity and sensitivity,with a single - tuning control, using noganged condenser or other complication.Low Cost.

If the set is made up with a resistance -coupled andiosfrequency stage, as well asresistance -coupled radio frequency 'stage,the cost is extremely low, for the resistancesR3 and R4 need only be }-megohm gridleaks of good quality. In fact, the re-sistance R4, condenser Cs, and grid leakR2 can, in combination, be one of the veryinexpensive R.C. units now sold.

It is not possible to use such an R.C.unit for the radio -frequency stage, as thevalue of the coupling condenser in such apnit is designed for audio: frequency workand not for radio -frequency coupling. R3can be a 1-inegehm grid leak, and Rr a2-megohm leak, while 04 can be the usual.0003 mfd. grid condenser.

L1, L2 and L3 together, form a standard.six -pin Reinartz transformer for the lowerbroadcast band, and the condenser Csshould be a smoothly adjustable neutrodynewith a very low minimum. C. should be a.0001 mfd. maximum variable condenser,one of the midget types suiting excellentlyfor this purpose, although the maximumvalue of some of the neutralising condenserswill be sufficient for this.L.F. Easily Added.

The condenser Ci should have a value of.0005 mfd., and both first and second valvesshould be of the R.C. type. The thirdvalve should be a small power valve orbetter, a super -power valve, if yen havevery loud signals to deal with. Only onehigh-tension tapping is required for such acircuit, which, again, makes for simplicity,

Another view of the experimental Harrisreceiver. Although a stage of high -frequency and the constant reactionscheme are included it will be seen thatthe " h3ok-up " is of a very simple nature.

and one Mansbridge condenser is sufficientto shunt the battery.

A few experiments with a set which caneasily be made up on a board in an ex-perimental form, and will soon show theremarkable capabilities of the set. Theexperimental board used for trying out thearrangement described is shown in thephotographs, although it is not wired upin the final form which has been discoveredto be best. A theoretical diagram of howto connect up your components is given inFig. 1, and having grasped the principlereaders may like to devise sundry modifications to suit their own conditions. Veryshortly I will give you a design for a finishedset, using this circuit.

Of course, it is a simple matter to add afurther stage of note magnification to thecircuit given, and this should preferably hatransformer coupled. It is not recom-mended to follow the detector -valve ar-rangement with transformer coupling, as itis obviously advisable to use a high -im-pedance R,C. valve for the detector.

* eeeee *MAKING RADIO

CABINETS. -

f*

T" problem of making cabinets forwireless sets and other apparatusis not easily solved, for when made

the trouble is not ended-how is it to befinished, what varnish, what stain ?

I always make my cabinets from I -in.mahogany. This wood I find is mostsuitable, being not too hard to workwith ease and yet capable of taking anice finish. The corners are halved, gluedand nailed with oval brads which canbe punched out of sight. The reader willknow' what he should make the lengthof the pieces of wood which are to formthe sides of the cabinet. The bottompiece of wood is made }-in. bigger all roundthan the bottom of the cabinet, and theedges are bevelled before fixing. It isadvisable to smooth all the faces and edges,that will be exposed, with fairly coarseglass-paper before assembling. When theglue has set hard, the corners are trimmedfirst with a rasp and then with a file, thenails punched below the surface, and theholes stopped with bees -wax. Finally, thewhole is smoothed with fine glasspaper.

Finishing Off.The first coat to be given is one of gold

size, obtainable at any paint merchants.This brings the colour of the wood out andfills in the pores of the wood. When this ishard the cabinet is smoothed with the fineglasspaper again, and another coat of thesize given. This is followed by two coatsof colourless varnish, the wood beingsmoothed before 'each coat.

Mahogany treated thus will have a lightbrown colour and a good surface. It willnot have the dark japanned " look of thebought cabinet. If _the reader desires to

adarken the wood, coat of stain (blackenamel diluted with turps put on verythinly will do) should be applied before thegold size. C. M. B.

....... *R.C. & SELECTIVITY

*Neese -4-4- -0- -4.- 4. -4.-4.*

PROBABLYnot many realise that the

use of resistance -capacity amplifica-tion after the detector valve (in sets

which incorporate no H.F.) materially im-proves selectivity. One sometimes finds aset with a very high magnification valve asdetector (on account of the use of resistance -capacity amplification) which, with a direct -coupled aerial and no reaction, is moreselective than the average oscillating de-tector. This is, of course, on account of thevery high grid -to -filament impedance ofvalves of this type. which therefore con-stitutes a much smaller source of dampingacross the secondary or A.T.I.

It often pays to change the first L.F.from transformer to resistance coupling,simply so that one can profitably use oneof these high -impedance valves (60,000ohms Or so) and obtain the resultant im-provement in selectivity.

T.

Popular Wireless, December 3rd, 1927. 693

X2 PR

WELL,have all you constructors had

that one-valvet going really well ?If you have, then You can carry on

with this week's work and bring the set upto the full two -valve stage. Not a singlecomponent will have to be moved andnot one of the leads will have to be replaced.Everything is purely addition and you willhave the satisfaction of knowing that the

efficiency of the detector stage will be unim-paired. Your H.F. stage will not be camou-flaging any faults, and when it is operatingproperly you will have a real " DX " two -waiver going.

Have a look at the accompanying theo-retical diagram. You will see that the presentaerial coil becomes a tuned grid coil. A newcoil is brought in to tune the aerial andthis is connected to the grid of the high -frequency amplifying valve. To this newcoil the flexible wire connected to theaerial terminal is new joined, a fresh flexiblebeing introduced to take its place on thegrid coil.

Sensitive, Selective and Stable.This H.F. coupling method is sometimes

alluded to as the " tuned grid " and some-times as the " shunt" system. Actually,of course, it is a choke -capacity coupling-with the addition of a tuned grid circuit inthe detector input. It is a very efficientmethod and is particularly suitable for sucha set as this. It is sensitive and selectiveand distinctly stable. I am not going to -saythat it is preferable to some of the modernmethods from every point of view although,undoubtedly, its simplicity makes it moregenerally reliable.

NS

*A- ..... *; Last week's one -valuer becomes a two-/ valuer without altering any of the

existing Leeds or components.By G. V. DOWDING, Grad.I.B.E.

(Technical Editor.)

It is debatable whet her the results givenby- that type of circuit in which something

is introduced to overcome something andsomething else brought in to overcome someeffects due to the use of the first something,and so on, are really so wonderful after all.It is my opinion that many technicians are

?..111111111111111111111111111111111111111111111111111111111111111111111111111111

COMPONENTS REQUIRED.The additional components you will

E need in order to add an H.F. stage to theE " Progressive " One are as follows :- 1 '0005 MM. variable condenser (pre-= ferably with a slow-motion control,= although this is not essential). (AnyE good make. -Original was a Brandes.) 1 H.F. choke ,(Any good make).

1 Baseboard -mounting single -coil holder 1'E (L. & P., Lotus, Peto-Scott, etc.). 1 Valve holder for baseboard mounting IE.

(Any good make).1 '0002 mfd. fixed condenser (Clarke,

E. Dubilier, Lissen, Mullard, T.C.C., etc.)E Terminals, wire, etc.- You should read the article carefully

before purchasing any of the above parts.

in danger of losing their heads with suchintriguing complications, and it is a east -ironfact that "a very high percentage of tipmore spectacular performances recorded ny


The high-Trequency components are well spaced out and the leads widely separated. The threw Aextblascan be seen clearly.


*....... .*

1TIE /" PROGRESSIVE" TWO.(Continued front previous page.) 1

*----...-4-4,4-4,---.--4.-4---4-4-4--*

readers are achieVed with the simplest ofapparatus.

However, with one stage of high -frequencyamplification, problems which have to befaced in the ease of multi -stage amplifiersdo not have to be taken into consideration.Stray capacities and weird coupling effectsare seldom troublestime, and stability doesnot have to be obtained by the sacrifice ofsensitivity. And the circuit employed in ourtwo -valve "Progressive " is a happy onejudged from these angles, inasmuch as theplates of bOth the valves are isolated from'the common H.T. supply by the inter-position of 1LF. chokes necessary for quiteanother purpose. This is going to help usconsiderably on our L.F. side, too; and willmake for_purity of reproduction.

WIRING INSTRUCTIONS.Join a flexible lead to one terminal of F_

11002 mid. fixed condenser (19).= Join one terminal of new H.F. choke :E to H.T. -F terminal (20).E Join one terminal of new 0005 mfd.

variable condenser to one side of new FE-.7; coil holder (21).:14 Join same side of new coil holder to E

grid socket of new valve holder (22).= Join one filament socket of new valve =_FE holder to terminal of filament resistor E

nearest other valve holder (23).E Join remaining side of H.F. choke to= remaining side of .0002 mfd. fixed -f.-== condenser (24), this same side of fixed

condenser is then connected to plate FEE socket of valve holder (25). (In suchE cases the one piece of wire can be carriedF.:. on to make the two leads.)

Join the Earth terminal to remainingfilament socket of new valve holder (26)

E and carry lead on from this point to remain-ing side of new 0005 mfd. variable (27).

Join a short lead (28) to other sideof new coil holder and to lead No. 27.

You will not require much stuff for thisH.F. stage. Another .0005 mfd. variablecondenser is required, and this shouldpreferably be fitted with a slow-motioncontrol. Then one more H.F. choke isneeded, and this can be of any good make.The baseboard-mountinf, coil holder, valveholder and 0002 mfd: fixed condensercomplete the list and are items of a verysimple, straightforward nature.

Very Simple Task.Constructionally speaking, this week's

labours are so easy that you will almostbe able to carry on without any furtherassistance than that provided by thediagrams and photographs. One light andinteresting evening's work should see thetask comfortably concluded.

One hole must be bored in the panel for thevariable condenser in the position indicatedin the appropriate diagram. Now f mustpoint out here that if you buy condensers ofa different type to those used in the photo-graphed set, it may be necessary to vary the


V14

THE"PROGRESSIVE'TWOWIRING DIAGRAM

O®®@@ee@@@)

/ANEW LEADS


* -0- 0-4,-4.1^ *f THE

PROGRESSIVE " TWO.(Continued from previous page.)

panel drilling slightly in order to retainuniformity. But you will see this for your-selves. The only essential thing to note hereis that the vanes of the variables must clearthe adjacent variables by at least an inchand must also clear the wiring and any ofthe other components.

Having fixed the new variable in position,the other four new components can bescrewed down on the baseboard in theapproximate positions shown in the photo-graphs.

The New Leads.You will notice that the wiring diagram

has been drawn so that the additionalcomponents and wiring stand out muchblacker than the existing parts. The num-bers carry straight on. No. 18, the flexiblelead attached to the aerial terminal, re-mains so connected, but this will be joinedto the aerial coil instead of to what nowbecomes the grid coil. A new flexible

(shown as No. 19) is joined to one terminal' of the .0002 mfd. fixed condenser and this isconnected to one of those points on what isnow the grid coil and to which formerly theNo. 18 lead was taken. I hope I have madethis quite clear, because this is the onlypoint which can possibly cause confusion.

The one filament resistor is going to bemade to serve both the valves, so that a lead(No. 23) is taken from one of the filamentsockets of the new valve holder to Oneterminal of the filament resistor: No. 27lead, whickjoins brie terminal of the variablecondenser to the other filament socket ofthe valve holder, carries on as No. 26 leadto the earth terminal. The earth terminalis joined via another lead to the H.T.minus terminal, and in this way the filamentcircuit of the H.F: valve is completed withan economy in leads.

The longest lead is No. 20 and as thiscarries high.tension current, care should betaken that it is clear of everything else onits route and has, in the bargain, nicemargins. Make sure that even should theset receive a heavy blow, this lead will notsway into contact with anything, moreespecially other leads connected with eitherof the L.T. terminals. Again, I would advise-

, yOu to keep the wiring low down, but notso low that- it touches the baseboard. Lowwiring is both neater and safer.

Don't forget to cross out the appropriatenumbers in the left-hand corner of the

Here the " Progressive " Two is shown with its coils and valves in position.

wiring diagram as the leads are joined up,for by so doing you will automatically bechecking your work.

You will want another coil to occupy the

new coil holder. A Lissen " X " No. 60or an " Atlas " No. 60 tapped coil will coverthe lower wave -band .while 5 X X coils inboth types are available. The flexible leadjoined'to the aerial terminal is taken to theterminal fitted on the aerial coil. A.60 -turn

spiderweb coil can be wound by the con-structor himself quite easily. A tappingshould be taken at a central point. It maybe found that the flexible lead is rather longnow that it is taken to a somewhat nearerpoint. In this case it can, of course, boshortened.

Now, for the operational details of thistwo-valver. The same H.T. and L.T. willbe O.K. and a similar sort of valve to thatused in the detector will prove quite suitable.This, you will remember, was an H.F. valveof not too high an impedance. One of thesevalves ranging around 20,000 ohms functionadmirably. These are generally designatedas " H.F. and Detector " on their boxes.

Operating Notes.You may find that the set will oscillate

somewhat easier now that the H.F. stageis added, and it may prove necessary tolower the lead from the* reaction controlvariable to the tapping on the grid coil

- third or fourth from the top. Also, the- H.T. may, with advantage, be lowered- slightly.

(Continued on page 727.)

You should compare this week's photographs with those of the " Progressive " One in order clearly toidentify the new components.

dt)ti Popular Wireless, December 3rd, 1927.

* -:= ar 4. 4- 4-04- 4.-4 4- -- ..... *t CURRENT TOPICS. jjp

THE R.S.G.B. AND " Q.S.T." IAu Explanation-The Position of the Wireless Societies.

By THE EDITOR.

THE Secretary -Editor of the RadioSociety of Great Britain has for-warded us the November issue of the

T. & R. Bulletin. He draws our attentionto the editorial published in this number,which he hopes will clear up the matteron which an article in" Q.S.T." gave rise todiscussion some weeks ago.

The editorial points out that in the firstplace it must be clearly understood that theBritish delegates to the conference atWashington were Government officials and,as such, their utterances and representa-tions are those which might be expectedfrom official sources. The British amateurhad no place in 'the delegation, and wasnot invited to submit his views.

" Sadly Misinformed."

It appears that the President of theSociety was assured by the Postmaster -General's department that the needs ofBritish amateurs would be borne in mindat the Conference. The editorial seems tosupport the view that even if a Britishamateur of the Radio Society of GreatBritain had wanted to attend the Confer-ence he could not have done so.

We have no means at the moment ofchecking this view, but we feel sure that,just as Captain Eckersley visited theConference in an advisory capacity, socould a member of the Radio Society ofGreat Britain have attended the Conferencein an unofficial but advisory capacity.

As it is, the T. & R. Bulletin editorialstates that eventually it was agreed thatMr. Warner, secretary of the InternationalAmateur Radio League, and Mr. Maxim,the president of the League, should repre-sent British amateurs at the Conference.

The editorial continues as follows :" What cannot be understood, however,

are the statements made by the Britishdelegates at the preliminary meeting inCanada, which is reported by Mr. Warnerin his editorial. As predicted by Mr.Warner, the affected ignorance of thedelegation as regards the strength ofamateur radio in America and at home here' fair makes our hair stand on end.' Weknow that copies of the Bulletin find theirway into the office of the Postmaster -General and his assistants, and for thedelegates to display such ignorance merelyproves that the delegation has been sadlymisinformed as to the position both hereand abroad. . . .

R.S.G.B.'s Explanation." The blame for such a position entirely

rests with the authorities responsible, fornobody who has lived in this country forthe past ten years and who has beenassociated with radio can possibly havefailed to note the influence of the amateuron the progress of the art."

That, briefly, is the explanation offeredby the T. & R. Bulletin, published by theRadio Society of Great Britain, as to the

reason why British amateurs were notrepresented at the Conference.

We do not consider that the explanationfully exculpates the Radio Society of GreatBritain. If their request for permissionto attend the Conference officially wasdenied, then why in the name of-amateurradio, let us say-did they not have thesense to drag the matter out into the lightof day ?

If the Post Office has bamboozled theRadio Society of Great Britain into theacceptance of the view that the Britishdelegates chiefly sent by the Post Officewere sufficient to deal with matters at theConference, then the Radio Society ofGreat Britain took this dictum veryquietly, for it is the first we have heardabout it-and, we venture to say, the firstthe general public have heard about it, andthat includes many thousands of amateurs.

Not Strong Enough.The trouble is that the Radio Society of

Great Britain is not strong enough and notalive enough to press home its justifiableclaims ; and, in any case, the British Post-master -General has no power to preventa member of the Radio Society of GreatBritain from being present at the Con-ference, where a competent man in informaltalks with the other de7egates could havedone far more to make known the realposition of the British amateur and hisneeds than an Ameri-can amateur tem-porarily investedwith the right tospeak on behalf ofBritish amateurs.

As this article iswritten we. learnthat the WirelessLeague and thewireless Associationhave' amalgamated.That is good news ;it would be evenbetter news if theRadio Associationand "the WirelessLeague joined upwith the R.S.G.B.or if these societieswere put into themelting -pot, re -cast,and a new andenergetic societycreated.

Even with thenecessary funds, wedoubt whether theR.S.G.B. is com-petent to representthe British amateurmovement. Itswork, so far, hasbeen for the few :undue emphasis hasbeen laid- on theamateur transmitter,

and there has grown up a sort of legendthat the only bona fide experimenter inradio is the man who has a transmitter.

Nothing of the sort. There are manythousands of bona fide experimenters who donot own transmitting stations--eand theyare not catered for, in an adequate way, byany existing society.

Amalgamation Wanted.Insurance policies, legal advice, etc., are

no doubt very useful items in the service listof a wireless society, but by no means ofparamount importance ; and as there arecompetitive societies, each having its ownmethods and each claiming to represent thelistener and the amateur, the result is a lack-of unity among amateurs and a weak defencewhen dealing with questions of real import-ance to the status and privileges of ama-teurs.

We hope that the R.S.G.B., as the oldestwireless society; will take the lead in thismatter, and will open up negotiations withthe Wireless League and the Radio Associa-tion with a view to complete amalgamation.United they might be of some use, divided,they never will be.

Complete Re -casting Required.We suggest a round table conference and

the re -casting of the R.S.G.B., followed byan intensive campaign for the greater en-largement of the membership list, and aconsequent incrcase in the vitality, strengthand importance of the exeentik-e com-mittee.

We offer to help to the best of our ability,and the editorial -pages of " P.W." and itscontemporaries published at this office willbe open to the council of the R.S.G.B. forthe purposes of making known any attemptto be made to make the R.S.G.B. a real anduseful force existing for the avowed object ofserving the British amateur.

One of our !Winr amateur experimenters, Par. Gerald Marcuse, of 2 N 14 fame.


CHAMAPINE is, admittedly, one of thebiggest musical attractions in theworld. For this there are at least

two reasons. In the first place he iscertainly the greatest bass vocalist whichthis generation has produced and, secondly,he is a unique personality-a much -talked -of figure whom everybody wants to see andhear ; a man whose name is enough toattract thousands and thousands of peoplewho could not really be included in thecategory of music -lovers.

Mr. Cochran has told me so. The Londonmanager of the Gramophone Company hastold me so. And their judgment should begood enough for anyone. But, apparently,it isn't good enough for the B.B.C.

Only once in the whole history of broad-casting in this country has Chaliapine stoodbefore the microphone, and that over twoyears ago, in 1925.

" Why is that ? " I asked Chaliapine,when I talked with him the other day.

He smiled whimsically."There is .a very simple reason, my

friend," he replied. " Once here in yourLondon I broadcast. It was two yearsago, and I did it because they asked me to.I have not sung at Savoy Hill again justbecause I have not been asked again. Toyou, perhaps, it may sound incredible, butit is just the truth."

It is a simple reason, indeed, but onewhich raises an even more perplexingproblem. Why have the B.B.C. not invitedChaliapine to broadcast again this yearwhen his name has been on the lips ofeveryone in the country-when everynewspaper has been full of his praises, andwhen he had been in London for quite alengthy visit ?

After Due ConsiderationB.13.C. programmes, as we have been

informed, ad nauseam, are compiled afterthe programmes' committee have dulytaken into consideration the writtendemands of their correspondents. Are theyreally going to tell us that a good proportionof writers during the days followingChaliapine's broadcast in 1925 did notenthuse over his singing and ask for moreWould they have us believe that at leasta hundred-perhaps a thousand-requestsfor another wireless broadcast by Chaliapinehave not been received recently, followinghis tremendous success at the Albert Hall ?Has it never struck them that there are amillion listeners who would like to hearthis famous vocalist on the radio betterthan any other concert or opera artiste inthe world 7

*-0-0-s--4-4-0. -4-4-..--.--4-4--..--4.-*

An interesting explanation apd a few words aboutBroadcasting in general by MIALIAP/NE, the great

Russian basso, in an interview with " Ariel."*--------------4----4------4---4-4.-----4.---*

" Ah," Savoy II ill might object, " hisfee would be too big. We daren't invitehim because we know we shouldn't be ableto afford to include him in our programmes."

Not Wanted?I do not propose to deal with the question

of how much the B.B.C. can afford withoutgoing into bankruptcy, and it does not ariseas far as Chaliapine is concerned.

" But no," he said to me, " the questionof fee would not be an insurmountableobjection to my broadcasting, I am quitesure. I should not ask anything colossal.

Chaltapine, the great Russian singer.

All I should ask would be a fair remunera-tion, based on the value of my services.I am always prepared to be reasonable andfriendly. I want as many as possible ofniy 'British public to hear me sing, and Irealise that they can't all come to my fewconcerts.

" But the reason I have not been asked tobroadcast-perhaps that is something Ican tell you without too much guessing.When I was first asked to sing in 1925,then the wireless people needed me. Theyneeded my name and the name of everybig musician and singer they -could getin order to convince the people of thiscountry that broadcast music was realmusic, and not just a ' stunt,' as you say.

" I helped them gladly, and many ofmy fellow artistes helped them, too. Butnow we are not needed to attract peopleto listen -in. We have served our purpose,and are no longer wanted.

" In those days broadcasting was beingrun by a private company, which dependedfor its existence upon the pleasure of thepeople. It had to give them what theywanted or else close down altogether.But now your broadcasting is a governmentmonopoly, and who shall convince me thatthat corporation really care very muchabout what the people want to hear ?

" If they had one, or perhaps two. othercompanies competing with them, shouldI have been asked to sing ? Yes, and by allthree. But that is not the way ofmonopolists.

" ' Listen to what we give you,' they say.' We know what is best for you to hear,and what is most convenient for us to giveyou. If you don't like it, then don't listenat all.' The B.B.C. is a governmentdepartment now, and whoever heard of agovernment department who cared any-thing about music or art-or very muchfor the wishes of the people ?

Poor Results," Some may think it is a little unkind

of me. to say that. But it is the truth asI see it. And I do not complain-ah, no !Perhaps I, and other artistes like me, cando something for the B.B.C., but whatcan they do for Us ?

" Can they enhance our reputations ?Can they make us more popular ? Theycan't, and I doubt if it is to the advantageof any established artiste to appear beforethe microphone at all. It may be thattransmission as good as possible is madefrom Savoy Hill, but what of the sets uponwhich our voices are received at the otherend ? If I could hear my own singingthrough some of the loud speakers andheadphones I know of, I might say : Sothat is Chaliapine ! Is that the voice ofwhich everyone is talking ? I don't thinkso much of him ; I shall not go to hisconcert.'

" For myself, I have nothing to sayagainst broadcasting as broadcasting. Itis one of the most wonderful and amazingthings in this wonderful world. In the righthands it would do so much good both formusic and music -lovers. One day it may.But as a government department, thinkyou ? Ah, my friend, no wonder so manypeople are dissatisfied with your broad-casting."

698 Popular Wireless, December 3rd, 1927:

0

TECHNICAL NOTES By Dr. J. H. T. ROBERTS, Finst.P.

DETECTOR METHODSGRID LEAK OR ANODE-LOPTIN-WHITE COMPONENTS-CINEMA

BROADCASTS-RADIO BEAMS.

41.11. --4.-.11.-.1.4.-4.7.11.---.111.-40-4.--4.---4.-4.-4.+-

WHIGH is the best method of valverectification I This is a questionwhich has always been a favourite

subject of discussion amongst expg'rimenters.There is no doubt that the most popular

form at present is the grid -leak method ofrectification, as this produces the loudestsignals. The grid leak method, however,suffers from the fact that it readily intro-duces distortion which, of course, is par-ticularly undesirable for the reception oftelephony.

Anode rectification (or lower -bend rectifi-cation, as it is sometimes called), givesbetter signals, although, as mentionedabove, the strength of the signals is aptto be somewhat less than with -grid-leakrectification:

Where high -frequency amplification isused it is probably better to use anoderectification, thus ensuring the better qualityof the signals. Any fogs in signal strengthmay then easily be made up by the littleextra high -frequency amplification.

Grid Lsak or Anode.It is a comparatively simple matter to

change over from the grid -leak rectificationto the anode rectification. For simplicitywe will suppose that the set is a single -valveset. The grid leak and condenser shouldbe removed and the aerial end of the tuningcoil connected direct to the grid of the valve.A potentiometer of, say, 300 ohms shouldbe connected across the low-tension battery,and two extra terminals should bo providedon the panel.

The earth terminal should be discon-nected from the low-tension (positive ornegative, whichever it may be), and oneof the two extra terminals should be con-nected to earth. The other extra terminalshould be connected to the potentiometer.

A grid -bias battery should then be con-nected to the two extra terminals, thepositive of the arid -bias battery being con-nected to that -terminal which goes to theslider of the potentiometer, and the nega-tive terminal (wander plug) to the otherterminal which, as mentioned above, goesto earth.

It will be necessary, of course, to trydifferent tappings of the grid bias, or

. different maximum values of grid -biasbattery, in order to obtain the best results.

Liquid Condenser.I see the " mercury condenser " which

I described in these Notes some time ago,and which appeared for a short time on theAmerican market, is now advertised in theGerman radio journals. This condenseruses mercury as one electrode and into thisdips a vane (or vanes) coated with a verythin layer. of insulating material such ascelluloid or shellac varnish. The mercurylies at the bottom of the containing cell, andas the vane is rotated it dips more and more

t

into the mercury and so the capacity is,increased. Owing to the fact that the mer-cury makes contact with the outer surfaceof the di -electric without friction, it isquite possible to use an extremely thinlayer of di -electric, and consequently amercury condenser of given electrostaticcapacity may be made to occupy much lessbulk than a condenser of the same capacitybut of the conventional air -spaced type.The di -electric, in the German ".silver -" condenser is only 3 -100th of amillimeter in thickness. The condenser is_very light in weight and the price (in Berlin)is 15 marks.

Loftin -White Components.Those of you who made up and experi-

mented with the Loftin -White circuit willbe interested to know that in view of the

be adjusted with extreme accuracy. In theLoftin -White receiver the coupling adjust-ments need be made once only. Thesetransformers are made capable of accurateadjustment so that they may be simul-taneously tuned by means of a tandemcondenser. This means that for practicalpurposes their inductance values may; bemade accurately equal

The terminals are in the form of solderinglugs, as already mentioned, and these lugsare mounted upon the Bakelite strips whichalso serve the purpose of supports for thecoils themselves.

The three units thus furnish the completecoil equipment for the Loftin -White circuit,which includes two stages of tuned high -

frequency amplification and a tuned de-tector -input circuit.

Photo -electric Relay.How an almost infinitesimal amount of

power may be used by means of a relaysystem to control an enormously greaterpower was lately demonstrated in aninteresting test carried out in New York.By means of a photo -electric cell, a flash-.light of one candle power caused theswitching on of a great searchlight atCharlottesville, in Virginia, of nearlyone -and -a -half -million candle power. Whenthe flashlight beam fell upon the light-sensitive cell, an electric current was sentby a wire and actuated a relay, whichswitched on the power for the searchlight.In a similar way the first glow of the search-light at- Charlottesville operated a photo-electric cell that switched on a flood -lightin the City Hall, in New York City.

This beacon in Charlottesville is intendedas a guide for aero-planes and is believedto be the largestsearchlight ever con-structed.

A popular portable German receiver, with two carrying straps and accessiblecontrols.

great popularity of this circuit, especiallyin the United States, special Loftin -Whitecomponents are now available in commercialform.

A special set of three coils can be had, theaerial -coupling coil and two inter -stagecoupling coils. The aerial -coupling coilcomprises primary and secondary windingswhich are fixed in their coupling relation,mounted on a thin Bakelite strip which alsocarries lug terminals for soldering. Thewindings themselves consist of silk -coveredcopper wire which is wound upon a" former " and then impregnated with acellulose dope. The " former " is thenremoved and leaves a coil the efficiency ofwhich is high, owing to the fact that a verysmall amount of di -electric material is used.

Accurate Adjustment.The two high -frequency transformer units

are wound in a similar way, but each isequipped with a mechanical device whichpermits variation of the coupling betweenthe primary and secondary. This variationis controlled by hand and the coupling may

Cinema Broadcasts.A method has been

perfected in Germanyfor combining movieswith radio for thepurpose of illustrat-ing broadcast lectures.In each theatre orother building wherethe broadcast lecture

is to be heard, the films are run through aprojector which is driven by a motorsynchronised with the other motors in thesystem. The lecturer watches one of thecinema displays, or a private cinema dis-play in his own studio, and times his re-marks (which are being broadcast) inaccordance with the progress of the film.The system amounts, in short, to the syn-chronising or simultaneous display of thesame film in different theatres or halls andthe broadcasting of the lecture or commen-tary to correspond.

Radio Beams.Apropos the searchlight beacon for the

guidance of aeroplanes as mentioned above,I see that the radio beacon system for use in aerial navigation has been progressingunder the auspices of the U.S. Bureau ofStandards, and the system now incorporatesthree main radio devices. The first of theseis the directed radio beam, which sends outa special type of radio beam by which airpilots are able to follow their courses in fog



THE SOURCE Or ONVE12

THERE is limit- ess power in nature-in the vas:coal beds, mighty waterfalls, great oil wells.

There is great power also in the chemical genera-tion of energy in the Lissen New Process battery.Not only great energy, but energy which is longsustained and smooth flowing all the time youuse it, never a sign of ripple in it, and never a traceof noise. That is why you get such clear repro-duction when you use the Lissen New ProcessBattery, and that is why you find that your re-production is as true and clear at the end of thelongest programme as it was at the beginning,hours before. No other battery yields such power-no other battery in the same way yields suchoxygen for your valves, because no other batteryembodies the new process and chemical com-bination which Lissen alone uses. because Lissenalone holds the secret.Next time you want a good battery ask for LissenNew Process in a way which shows you will takeno other. Ten thousand dealers sell it through thecountry at a price which brings it within the reachof all.

60 volts (reads 66) .. 7/11100 volts (reads 108) .. 12/ 11

9 volts (grid Lias) 1,'6

ILISSENAA3ATTIFYLISSEN LIMITED, 8-16, Friars Lane, Richmond, Surrey.

L 51;Managing Director : TIIOS. N. COLE.


* -4. 4-6- -4-4-- ........ 4.4.-4-0-*

BRITISH BROADCASTING.No. 5.-SAVOY HILL AND THE PUBLIC.

By THE EDITOR.

THE B.B.C. professes to take endlesspains to test and gauge public opinionon programmes. The general view is

that Savoy Hill is making heavy weatherout of a comparatively simple problem.But let us begin by examining the variousprocesses employed by Savoy Hill.

First of all there are the letters fromlisteners-always numerous both in Londonand in the country stations. It is under-stood that as many as ten thousand lettersa week are addressed to the B.B.C. onprogramme matters. It is not surprisingthat the B.B.C. attempts to make capitalout of this tremendous volume of corre-spondence. For one thing, there is a gratify-ing preponderance of satisfaction andadulation. For another thing, there is sucha diversity of view, such degrees of praiseand blame for every item in the programmes,that there is at hand enough evidence foralmost any case to be convincingly sup-ported.

If talks are attacked, the B.B.C. can trotout correspondence statistics in defence.If symphony music is attacked, equallystrong refutation is taken from the letter -bag. If religion is attacked, then the answerof the correspondents is literally anni-hilating. '

The B.B.C. keeps on saying that religiousbroadcasts get more appreciative commentsfrom listeners than does any other item in theprogrammes. This means that more peoplewrite in insistently about the religiousservices than about jazz, for instance.

Alternative Sunday Programmes?And it is precisely on this ground of the

alleged popularity of the Sunday servicesthat we discover the danger and weaknessof trusting too much to letters from listeners.Religious -services have a specialist audience--no doubt considerable in extent, but alsonotoriously keen and coherent.

In other words, nearly everyone wholikes the religious broadcasting is so keenabout it that he or she is ready to write andsay so. This does not mean, however, thatthe vast majority of listeners, while readyto -tolerate and occasionally to enjoyreligious broadcasting, do not wish to be provided with a suitable alternative toreligious services. This principle of analternative to religion the B.B.C. will notconcede, in the belief that the denial is inaccordance with public opinion. If corre-spondence can be invoked to justify such apolicy, then correspondence is not aninfallible guide.

If the B.B.C. fails to find justification incorrespondence, they are apt to invoke theaid of the Press in support of any particularline of action. But it is notable that theyalmost always refer to the lay Press ratherthan to the specialist Press.

Now, the Jay: Press .looks upon broad-casting chiefly as a potential menace, andquite secondarily as a source of useful news.The bulk of the comment in the lay Press is,in fact, vitiated by policy considerationsor by some kind of control from the B.B.C.

It is clear, therefore, that the B.B.C.cannot claim to be consulting public opinioneffectively by a tendentious interpretationof lay Press comment on broadcasting.

I was extremely interested in followingthe progress of the experiment with pro-fessional critics undertaken last year by theB.B.C. In theory this has much to be saidfor it. The idea was to secure weekly reportsfrom a group of representatives of the mainclasses of listeners. These were to be paidand were to listen regularly. The con-sensus of their reports was to be regarded asa fair appraisement of current publicopinion. The plan was worked for a year.

Although for a time the B.B.C. pretended

A " Spanspace " Three built by one of our Bristolreaders. This set has proved very popular.

to regard it as a success, it abandonedthis attitude in the face of repeatedevidence of its failure. The professionalcritics listening regularly produced nothingupon which any programme policy couldbe built. The very fact that they weresuccessfully balanced meant that theiropinions and their judgments cancelledeach other out. The experiment wasreluctantly abandoned some months ago.

Parliament No Solution.The third instrument for registering

public opinion is the Wireless OrganisationsAdvisory Committee, which, under the ableguidance of Captain Ian Fraser, meetsmonthly at Savoy Hill. This committeenominally represents all the recognisedsocieties of listeners and experimenters.Its pretcntion to be a " listeners' com-mittee " in the sense that it reflects theaverage opinion of millions of listeners hasbeen seriously challenged, and with ameasure of justification.

The total active constituency composedby the paying members of the societiesconcerned would not be greater than fiftythousand, but the unexpected fact emergesthat this committee has been of real valuein keeping the B.B.C. on the right lines

on at least some programme matters. Itwould not be an exaggeration to say thatif this committee were strengthened bythe addition of a few representatives ofthe technical wireless Press it would go avery long way to establish effective andcontinuous contact between the B.B.C.and listeners generally.

What, then, is the essence of the problemwhich has caused so much anxiety atSavoy Hill and so much speculationigenerally ? Looked at from the repre-sentative angle, the only solution of theproblem is Parliament itself.

The new constitution of the B.B.C. wasdesigned so that the ultimate responsibilityfor the broadcasting service would reside-in Parliament. In tie representative sensethe House of Commons is the nearestpossible approach to the ideal listeners'committee. But, unfortunately, two factorsintervene to prevent the House from playingthis new role. The first is that there is notime. The second is that barely ten per centof M.P.'s either care or know anything atall about broadcasting.

Unfulfilled Promises.Therefore, Parliament offers no solution,

nor can any solution be found from therepresentative angle. The combinedmembership of wireless and listeners'societies is negligible. Plebiscites are in-conclusive. Their only uniformity, is theirfailure to attract general interest or toinspire general confidence.

The fact is that the representative angleis the wrong one. The reason why theWireless Organisations Advisory Committeeis helpful is not because it representssocieties, but because it is made up of agroup of common-sense individualS ready toapproach programme problems with a freshoutlook. The essence of the problem ofgauging public opinion is the intelligentconsultation of commonsense. The B.B.C.need seek no mysterious or elaboratemachinery. The man -in -the -street is nothidden in an inexplorable labyrinth, noris he too coy to resist all advances.

While I am on this subject of publicopinion, I must add something on a strangedevelopment of B.B.C. activity. Were weall to form our opinions of broadcastingfrom what we read of the B.B.C. in its ownnewspapers and in the lay Press I ventureto think that the voice of hostile criticismwould never be raised. The B.B.C, pro-pounds, outlines, apd explains its pro-gramme policy in a most convincing andreassuring manner.

The basic principles advanced are in-variably sound and usually agreeable.The contrast programmes from 5 G B, forinstance, were admirably explained, andinitiated with the customary torrent ofadulation from the lay Press.

But those of us whose business it is toexamine the actual results of B.B.C. policyfind many a slip in performance. The super-lative claims of policy announcements arenot fulfilled. Either these claims shouldhave been modified or the standard of per-formance improved.

The B.B.C. would be well advised toguard against any increase of the gapbetween promise and performance. I amoptimistic enough and confident enoughof the ability of the B.B.C. to believe thatthe gap may be considerably reduced, notby restraining the exponents of policy, butrather by improving the standard of output.


I I I Mr I I I 11... I I Ira

I

O

4

\\

I

Build youryour own Cone Loud SpeakerThe LISSENOLA is the essential sound -reproducing base which you convertyourself into a loud speaker of whatever type you please. Used in accordancewith the directions given with each instrument, the LISSENOLA yieldsresults equal both in quality and in volume to loud speakers selling at severalpounds. The secret of this remarkable efficiency lies in the effective mannerin which the electro-magnetic sound reproducing system is concentrated.

Compare the price last. Make this testbefore buying: Go to your dealer-askhim to put on the best loud speaker hehas in stock-then use the same hornon the LISSENOLA, and see if you cannotice any difference.A very successful type of speaker thatcan be made quite easily and cheaply fromthe directions given in almost any wire-less journal is the Cone Diaphragm.

Make theDiaphragm your-self-then fit the LissenReed to the LISSENOLAand clamp it to the centreof the cone by means ofthe two nuts provided.The purity of tone-and

the volume - obtained will surpriseand delight you. The illustration shows

one method of mounting a cone dia-phragm speaker.But for biggest volume ofall, build a big horn fromthe directions and full-size exact patterns givenwith every LISSENOLA.The illustration showsthis effective horn, whichcan be covered with fancy paper andpainted to resemble a factory article, andmade by you for a few pence.In addition, the LISSENOLA will fit thetone -arm of any gramophone, instantlyconverting it into a loud speaker.Your dealer will gladly demonstrate andsupply-or the LISSENOLA can be ob-tained post free by return atom the makers-price 13/6, or with Lissen Reed 1416.

THE LISSENOLA COSTS 13/6-but compare the price last

Lissen Limited, 8-16, Friars Lane, Richmond, SurreyP.'one: Richmond 2255 (4 lines). 'Grams: "Lissenium, 'Phone, London.

Via

7( Popular Wireless, December Vd, 1827.

veaWAtatN4'"

313t0W11 Universal.Your Dealer will he quite proud to,demonstrate it to you. Price £6.

ITis the easiest thing in the world, when lying

back in your chair with your feet on thefender and your eyes half closed, to imagine

your iSCOWit Loud Speaker is the singer himself.It is only when you rouse yourself and lookabout you that you are certain you are still alone.It is a habit of the 3rOW11 to make itself heardwithout making itself obvious. Some peoplecall it the loud speaker that isn't." They sayit is a loud speaker that doesn't let you knowit. Which, of course, is the highest tributethey can pay it.If you have never heard the krown UniversalLoud Speaker there is a thrilling experience instore for you. When, some evening you arealone, you turn out the light and draw yourchair to the fire, its uncanny realism will stiryour very soul.

S. G. BROWN, LTD., WesternAvenue. North Acton, Loudon,W.3. Showrooms : 19, Morti-mer St., W.1 ; 15, Moorfiehls.Liverpool ; 67, High St..Southampton. WholesaleDepute throughout theeountrY

MIca


AFEW years ago many people used tosay there was nothing quite so niceas a good reflex receiver, although

one must "admit that possibly an equallylarge number condemned them, saying theywould_not have one at any price. Of latevery few reflex receivers have been describedin the technical papers, and when they aredescribed no great entlnisiasm seems to bearoused, which surely is a pity, for to a fewof the,keener experimenters there is nothinglike a 'good reflex set, considered purelyfrom the point of view of economy.

Unreliable Sets.It will, therefore, be interesting to con-

sider for a moment whether all reflex circuitsare fundamentallyTunsound. We may aswell begin our inquiry by going back to thetime when reflex circuits were first intro-duced to the public, when, in fact, reflexreceivers were being pushed as the onlysets worth having. Some of us knew at thetime what many know to -day, that themajority of the reflex sets described werehorrid, nasty things. Chronic instability,buzzing noises, and wretched quality werethe main characteristics of such sets, whichone regrets to say were described in numbers.

Readers of the papers concerned who

Arc) oflrrxCircuitsFundamentallyUnsound ?In this article some definite opinions on the subject are offered, andthese are naturally very interesting in View of present-day knowledge.

4 -

By W. JAMES.

made up a reflex set were, it would appear,soon divided into two camps. On the onehand were those who felt thoroughly satis-fied ; on the other, those who did nothesitate to condemn them. To the satisfiedusers I have nothing to say beyond this-in those days loud speakers were bad, powervalves were expensive and bad quality wasacceptable to many.

I am sorry for those who made up whatturned out to be nothing but a faulty design,and who decided to turn their back on reflexsets for ever, for I believe that in so doingthey have denied themselves a good deal ofpleasure.

Two New Circuits.A good reflex set is -a most interesting

affair, even if one can hardly claim for it inthese days of reasonably priced valves thevirtue of economy.

The point is this, that we have to admitthat many of the reflex sets described in thepapers some time ago, were very unsatis-

(Continued on net page.)

The earlier reflex receivers incorporated very straightforward circuits. The one above merely had a crystaldetector and primary of an L.F. transformer connected across an anode -tuning coil. Ths secondary of tha

transformer was included in the grid circuit of the valve.


ARE REFLEX CIRCUITS tFUNDAMENTALLY +

UNSOUND?(Continued from previous -page.)

44

factory and as compared with the few who,.constructed a reflex set and found it useful,many found themselves burdened with quitea useless contraption. It would, therefore,seem that he is a bold man who is preparedto put forward a reflex set and say that itwill give good results, but I am preparedto do this-, provided those who try thecircuit stick to it and do' as they are told inthe matter of components, valves, andpower supply.

Two circuits are given ; that in Fig. 1

being of a two -valve receiver- and Fig. 2 athree -valve. The three -valve set is merelythe arrangement of Fig. 2 with a further low -frequency stage. - Referring to Fig. 1 we seethat the aerial can be connected to pointAl or A, and. that the secondary coil istuned with a .0003 mfd. condenser. 'Thetwo taps give a choice of selectivity. Thiscoil has a total of 75 turns of No. 22 D.S.C.wire, wound on a former 3 in. in diameterand 4 in. long ; 65 of the turns are includedbetween points G, and E, 5 between E andAl and 5 between Al and A,.

Constructional Considerations.In the anode circuit of the first valve,

V1, is the primary winding of the intervalvehigh -frequency transformer whose secondaryis connected to the detector V.- This istuned with a -0003 mfd: condenser, and it

N.C. is joined between the grid of the firstvalve and a tapping on the secondary of thehigh -frequency transformer. The secondarywinding of this transformer has 65 turns ofNo. 22 D.S.C. wire wound on a former 3 in:in diameter ; the tappings should be madeat the 10th' turn. Over the turns 1 to 10,8 or 10 pieces of ebonite or wood, i-in. thick

and 4 -in. wide, are placed. These may bestuck on the surface of the covered wire, orheld in position with a rubber band, while8 turns of a fairly fine wire such as No. 30D.S.C. are wound over the spacers, thiswinding being in the same direction to thesecondary.

The method of connecting this coil in thecircuit is shown in the diagram. One endof -the secondary is connected to L.T.-, andthe 10th turn from this end is connected tothe balancing condenser, the top of the coil,

re.,-aWunt, h' A - 3j."--0 H T +/

Readtion is obtained from the detector inthe usual way, using a .0003 mfd. -variablecondenser and a coil R. This coil is woundin the same direction as the grid soil, andhas 15 turns of a fairly fine gauge of wiresuch as No. 30 D.S.C. It should be placedabout 4 in. from the "end of the gridcoil.

To the anode of the detector is connecteda Marconi 2.7-1 transformer, whosesecondary is connected to the grid of V,through a :5 megohm grid leak. Shunting

2 f H.T+2. 3.

Elm5 f

/7.0 2.X 137

of course, going to the tuning condenserand the grid condenser and leak. It isimportant to join the primary correctly, andthe anode of V1 should be connected to thebottom of the coil.

If this high -frequency transformer is toodifficult to construct wind 65 turns of No. 22D.S.C. on a 3 -in. former, and then wind inthe same direction a separate coil of 8 turns

of the No. 22 D.S.C. Theend of the secondary adja-cent to the primary is thenconnected to L.T. whilethis end of the primary isconnected to one side of thelow frequency. transformer.

A popular reflex circuit is that due to Mr. Hale. The aboveis a receiver incorporating it, built by Mr. P. W. Harris.

it is a -0001 which tendsto stabilise the circuit.

One of the 'most important things aboutreflex circuits is that valves having suitablecharacteristics must be used. For thedetector in the Fig. 1 circuit, a valve havingan amplification factor of about 20 may beemployed, but the reflex valve must be oflow A.C. resistance. A valve of 6-10,000

- ohms will be satisfactory, and it must beused with ample anode voltage and grid bias.Preferably employ an anode battery of 120volts with a grid bias of approximately -9volts, depending on the valve, of course.

Good Quality. -

The quality given by this receiver will begood, because care has been taken to pre-serve the higher and the lower notes. andit will be just as stable as other receivershaving adjustable reaction. This receiverwill not give quite the same results as astraight three -valve set, because we aresacrificing a small amount of high -frequencyamplification by using a valve of the lowimpedance type at V1, and also because'of the method employed to feed the low -frequency currents to the first valve, butthis two -valve receiver will give more volumethan a straight two -valve set, and for anequal amount of reaction the quality willbe quite as good.

There is no need to desciibe the three -valve set in detail, except to point out thatthe power valve used at V3 should be a realpower .valve, and be supplied with ampleanode voltage and grid bias. If this set is tobe used at a place some distance from abroadcast station, valve V1 can be of thetype having an amplification factor of 15to 20, but its A.C. resistance should not bemore than about 20,000 ohms.


Met -Vick Components make the most of a Set

WTHETHER you are buildinL- the Met -Vick three or four Valve Sets or any

other set, you cannot fail to get successfuland satisfactory resultS if sour componentsare Met -Vick. Most of the lines shown -here -are already well known amongst enthusiasticConstructors and listeners; yet for thosewho have not yet used " Cosmos " Com-ponents, here are some details :-

,A.N.P. (Astatic.Non..Parasitic) Coils.-These newMet -Vick " products provide a clever solution of a difficult

problem. They overcome, simply and efficiently, the threedifficulties associated with H.F. amplification, namely :Magnetic coupling between coils, Stabilisation, and ParasiticOscillation. LiSt 4117/S.

Resistance Coupling Units .-" Cosmos.' (" Met -Vick ") Resistance 'Coupling Units are well known to allwireless enthusiasts. The " V " type can now be obtainedfitted with new " Met -Vick " A.C. Valve Holder. The latteris also supplied separately. List 7117/8.

Valves.-" Cosmos " (" Met -Vick ") SHORTPATH Valvesfor 2-v. and 6-v. battery working are available at the newreduced prices. The new " Cosmos " (" Met -Vick ")Valves are also available. These make possible the opera-tion of a set from the electric -light supply without any of theaggravating " mains noises." A special disc adaptor enablesa battery -set " to be easily converted without re -wiring.Lists 4117/3 and 7117/8.

Battery Eliminators.-" Met -Vick " Battery Elimina-tors are supplied in two models. The H.T.-G.B. Modelcan be used on various supply voltages of 40-100 periods.Grid Bias tappings are provided at 5, 10, 15, and 20 volts.A high voltage (up to 25o volts) can Jbe applied to the lastvalve. The L.T: Model gives an output of 5 amperes at4 volts without hum. List 7517/8.

MET-VICK(COSMOS)

For a complete description of the full range of Met-1",cle (Cosmos)Components, ask your dealer for a copy of Booklet No. 4517/6.

Metro -Vick Supplies Ltd.,155, Charing Cross Road,

London, W.C.2.PVti

Met -VickBattery

Eliminators

706 Popular Wireless, December 3rd, 1927,40.1. - - *I BROADCAST NOTES.

FROM OUR BROADCASTING CORRESPONDENTS.

Impromptu Concert at Blanchester-Microphone Agiin in Danger-A Two -Piano Spe.ciality-The Wireless Singeks Again -=-Bristol Opera for Cardiff-The Growing Generation ---Mr. Punch Disclosed-Sailors' Community Sing-

ing-Ireland's First Theatre Broadcast-Miss Bondfield to Broadcast.

Impromptu Concert at Manchester.SOME time ago four of the most pro-

minent musicians in Manchester metat the local studio, and over a cup of

tea played or sang or talked, according -toinclination. So successful was their pro-gramme that another is to be given in thesame informal and impromptu mannerto -morrow, Simday, DeCember 4th... On that occasion five musicians will meetin the studio, namely Kathleen Moorhouse,a gifted young 'cellist, Leonard Hirsch,principal second violin in the Halle Orches-tra and a member of the Latter_ all StringQuartet, Alec Whittaker, who at the age oftwenty-two found himself the principaloboist in the Halle OrcheStra, and ElsieBoardman, contralto, who distinguishedherself in the sole of " Carmen" at therecent Manchester . performance. Therewill also be piano solos by Eric Fogg, thestation accompanist, who was last yearmarried to Miss Moorhouse.

Microphone Again in Danger.The last occasion on which the Glasgow

Gaelic Musical Association gave a perfor-mance from the local studio the announcerhad to stop some of the impromptu dancingwhich began when a piper struck up, as thevibration caused the microphone to sufferinternal complications. The Association isgiving another " Gaelic Evening " onTuesday, December 6th, when the variousitenis-part songs, mouth music for dancingand bagpipe selections-will be introducedby Mr. J. N. McConochie.

A Two -Piano Speciality.Ethel Bartlett and Rae Robertson, -two

of the best-known two -piano artistes in --London, are giving a short programme oftheir interesting and varied repertoireduring the London programme on Tuesday,December 6th. In the same'recital SarahFischer will sing some of the _dainty folkSongs of whiCh she is so ideal an interpreter.

The Wireless Singers Again.Since their formation some months ago

the Wireless Singers, as a vocal combina-tion, have become recognised as one of.the most efficient and attractive organisa-tions of their kind in this country. Theyare trained by Mr.. Stanford Robinson,chorus master at 2 L 0, and consist ofeight performers, i.e. a double quartet.The little programme of madrigals whichthey are giving in the London studio onWednesday, December 7th, is certain tofind a welcome place in the programmes.

Bristol Opera for Cardiff.Cardiff Station will relay an important

-broadcast of the Bristol opera season onWednesday, December 7th, from theVictoria Rooms, Clifton,- Bristol. The workchosen is " The Travelling Companion,"by Charles Villiers Stanford, and the

principals are Steuart Wilson-, ArthurCranmer, Johnson Douglas, Louise Trenton,Dorothy D'Orsay, Judy Skinner, andLeyland White.

The Growing Generation.Those who can listen during the after-

noons should not miss the last talkin the series on " The Growing Genera-tion," which is to be given on Thursday,December lath, by Mr. Alec Patterson, oneof the Prison Commissioners. Mr. Pattersonis mainly responsible for boys in BorstalHomes, and has just published a littlepamphlet containing some biographies of

The new mechanised Army finds radio the most rapidof communication between units.

these youths, under the title of " A BadStart and a Good Finish." Recenty hemade an effort to raise funds to build achapel for the boys of Borstal, which it isproposed shall be dedicated to the memoryof those who passed through the variousBorstal establishments and made good inthe war.

Mr. Punch Disclosed.The true history of Mr. Punch and his

lamented wife Judy and the other membersof their family form quite an attractiveitem in the programme from London andother stations on Friday, December 16th.The entertainment, which has been devisedby Mr. W. S. Meadmore and Mr. L. de G.Sieveking and will be presented by their inco-operation, introduces an actual Punchand Judy performance by one of the oldestshowmen at the game.'

The average listener probably knowsnothing of the history of this famouscharacter,, who was originally a hunch-backed Italian actor whOse perforniancesbecame so famous that the puppet -shows,for which Italy is fainous, imitated andperpetuated him in the show which stillmakes the whole world laugh.

John Daniel : Gorilla.

The adventures of the famous gorilla,John Daniel, who for some time lived withhis owner in aristocratic Sloane Street,and whose premature death soon afterbeing taken across the Atlantic,. forms oneof the most 'Interesting animal -stories ofrecent times. Gorillas seldom survive longin captivity, and few people have had suchopportunities of studying their ways in theirnative haunts as Dr. Neville Sharp, whorecently returned from an expedition toCentral Africa. Dr. Sharp is giving a talkon his observations of these animals onSaturday, December 17th, and it will bebroadcast from most stations.

Sailors' Community Singing.Community singing by an audience

composed entirely of sailormen will herelayed from the John Cory Sailors' Rest atCardiff and broadcast to Welsh listeners onWednesday, December 14th. The concertis being arranged under the auspices of theBritish Sailors' Society by Mr. OliverS. Hopkins, the Port Missionary, and theprogramme will also include items by WillGriffiths (entertainer) and the Madame Ben

Davies' Tarbes' Choir,which will lead theaudience in popular oldsongs such as " The OldFolks at Home."

and reliable means

Ireland's First TheatreBroadcast.The first theatre broad-

cast in Ireland takes placeon Tuesday, December13th, when - at 8 p.m.

-listeners to Belfast andthe Dublin stations willhear half an hour's en-tertainment relayed fromthe Empire Theatre, BO -fast. The programmewill consist of excerptsfrom " Hip, Hip, Hoo-Radio ! ". a stage revueadapted from the RadioRevue of the same nameand presented entirely

by broadcast artistes.The principals are Grace Ivell and Vivian

Worth, Kitty Murphy, Marian Wright,Dorothy Camlin, Richard Hayward, J. R.Mageean, Jack Chambers,.Kenneth Coffeyand Jack Gavin, all of whom, with theexception of Grace Ivell and Vivian Worth," graduated " from 2 B E.

Miss Bondfield to Broadcast. .

Miss Margaret Bondfield, who isprobably the most, distinguished womanmember of the 1..alamir Party, and whoduring Mr. Ranagay MacDonald's Govern-ment was Parliamentary Secretary to theMinister of Labour,- la giving a talk in theLondon studio on Tuesday, December 13th.on the new Hostel which has just beenopened at Market Harborough by the Over-seas Settlement Department and theCommonwealth Government of Australia-.

The Hostel is intended for the use ofwomen who knoW little or nothing ofhousehold work; but who wish to settlein Australia and to whom the.courSe at theHostel is imperative before they are eligiblefor a free passage to " down under " underthe Empire Settlement Act. -


MEASURING YOUR,

An ordinary voltmeter is useless witha mains H.T. unit, but voltages can bedetermined in quite a simple manner if

you know the way to go about it.By G. P. KENDALL, B.Sc.

*

THERE can be little doubt that the set of thefuture will be operated entirely from the electricmains, both L.T. and H.T. being provided by

suitable eliminator circuits, and batteries will remainmerely for the use of those unlucky people, who -haveno electric light laid on. The reasons for theinevitability of the change are mainly that batteries,with their charging, renewals, and variations ofvoltage, not to mention their noisinessat times, are found by most people to be anuisance, and, further, that the, moderntendency in loud -speaker work is all in thedirection of larger and larger power valvesand higher and higher anode voltages, andhere batteries, even the largest, are oflittle use.

Measurement Difficulties,The change, then, is one which must

Come sooner or later, and the wise man isundoubtedly he who is changing over now,and reaping the advantages of no -troubleoperation, even if he does not yet feeljustified in launching out into the latestthing in super -power amplifying circuitsfor working his loud speaker. The change:over, so far as the H T. supply is concerned;is really a very much simpler affair thanmost people imagine, especially with anA.C. supply, but there are one or twopractical difficulties which must be over-come before the use of an eliminatorbecomes entirely satisfactory.

One of the most obstinate of thesedifficulties is that of measuring or estimat-ing the actual H.T. voltages being appliedto the various terminals of the set, anduntil it is overcome one is working in thedark in a very undesirable fashion.

The difficulty lies in the fact that theordinary voltmeter is useless with aneliminator, for the reason that its resistance

is low, and the current which it draws islarge enough to produce extra voltagedrops in the eliminator circuits whichcompletely upset the working conditionsand make the reading which 'is obtainedquite valueless.

Voltmeters of a type capable of givingaccurate indications can be obtained,. ofcourse, but their high cost puts' them outof reach for ordinary purposes, and mostpeople have to fall backmethod of estimating the voltage bycalculating the. voltage drop .across theresistance used in the eliniinator to reducethe pressure, nsing for the purpose aknowledge :of the. currents= flowing, thisbeing obtained by' the Use of a milliamineter.The process; is always troubleseine, and insome cases cannot be carried out at allbecause the values of the reSistahees'in theeliminator are not known,

A Simple Solution.It is far preferable to be able to read the

voltage directly by means of an instrument#and a simple scheme for doing this has nowbeen adopted in the " P.W." ResearchDepartment, which enables it to be donewith the aid of a special resistance and amilliammeter of a type which need not beat all costly if a very high degree of accuracyis not required. There is no particularnovelty in the method, which employs simpleand well-known principles, but it does not

A reading being taken with a mithammeter and resistance, as described in the accompanying article.

appear to have occurred to anyone toapply, it to the solution of this_ particularproblem before, possibly because it wasnot realised that the necessary specialresistance was ready to hand in the formof a cheap standard wireless component.

uurPurTiRM/NALS

OFELIMINATOR

2734,

/0q000'OR

4-RogowOHMS

411/4,sewerex,

-4--SevircH

Briefly, the method is this : A highresistance of accurately known value isconnected across the H.T. terminals, andin series with this is placed a milliammeterwith a suitable scale to measure the currentflowing. Then, by the simple applicationof Ohm's Law the voltage can be deter-mined, the arithmetic involved being of atrifling nature if the value of the highresistance has been wisely chosen.Simple Arithmetic.

An example will make this clear. Supposethat the resistance is of 100,000 ohms :a voltage of 100 across this will producea current of 1 milliamp, 50 volts will givea current of -5 milliamp, 40 volts one of4 milliamp, 25 volts one of .25 milliamp,

and so on. It will be noticed that there isa very simple relation between thesefigures ; the figUre for the current is exactlyone -hundredth of that for the voltage.Obviously, then, all that we need do is toread -the current flowing in milliamperesand multiply this by a hundred to get theH.T. voltage.

When this scheme is used the currentdrawn is quite small, as has been seen, andwith many eliminators it will only produce'quite a slight change in voltage when the


70S Popular Wireless, December 3rd, 1927.

4

-- ---- --- --- ......SIMPLE SWITCHES.

llsn ingenious improvisation which can be carried out verycheaply and easily.

By HUMPHREY PURCELL.

THE types of switch on the market. arelegion. . There are rotary switches,push - pull switches, throw -over

switches, and switches that are combinedwith rheostats and tuning units and whatnot. Most of them are excellent, and even

Two terminals, a strip of fibre and a short piece ofwire are the main items required.

where a rubbing contact is provided, itis seldom that any .treiible arises. Theyserve so simple a purpose that there couldbe no excAs6 'for inefficiency, and for thesame reason even the best of them functionsno better than a simple home-rade device.

Primitive. Types.The simplest home-made switch is that

which consists of two terminals...and. a pieceof wire, 'the' wire being inserted betweenthe terminals for the ON position, and

disconnected from one or both of theterminals for the OFF position. The wiremay be stiff or flexible, and the terminalsmay be of the pillar type or the telephonetype, mounted on the panel or above thebaseboard, or they may be the -terminalsof large components such as variablecondensers or resistances or L.F. trans-formers. If " Clix " terminals, or valvesockets, are used, the moving wire may beconnected at will to any one of a number ofpoints. There may be more than oneconnecting wire,

A Practical Scheme.

The only objection to these devices isthat when the switch serves an. ON -OFFpurpose, either a spare disconnected terminalmust be provided, or the connecting wiremust be removed, or left hanging loose.The photographs herewith indicate a methodof getting over this difficulty.

Two terminals of the pillar variety aremounted on the pane], or on a short stripof ebonite. These should have fairlylarge heads, and on one of them the portionof the threaded rod above the base shouldnot be too short. On this terminal a smalldisc of fibre or thin ebonite is inserted justabove the base. A piece of No. 16 tinnedcopper wire is then bent so that it is clampedsecurely in one terminal. (pliers being usedto tighten the head). .This is the -terminal'which does not contain the fibre disc. Onthe other terminal the wire lies on top of

. .

the fibre in a loop which encircles but doesnot touch the central threaded rod.

It will be seen that when the head of thesecond terminal is loosened, the connectingwire touches the fibre disc but does notmake contact with any part of the brass -work. The switch is thus in the OFFposition. A turn or . two of the head ofthe terminal will force it down on to thewire, and contact will be established.Connectiona are made to soldering tagson the other side of the panel or ebonitestrip.

One terminal remains screwed tightly down, theother being used to provide the switching action.

* *MEASURING -YOUR t

ELIMINATOR VOLTAGE.f (Continued from previous page.)

*" voltmeter '! is connected or disconnected.In the ease of the tapping for the L.F.valves, for example, where -the' Currentflowing to the, set will -be fairly large, theeffect of the. extra current drawn. by the" voltmeter ", will be. quite negligible.

There will be cases, however, whereeven this small current will be undesirable,and it' is therefore recommended that it becut down still further by the Use of a higherresistance, 200,000 ohms being a convenientvalue. When this is used it will be necessaryto multiply the milliammeter readings by200 to get the H.T. voltage. If this provestroublesome, simply make yourself out atable like the one shown in the nextcolumn, and keep it handy for reference.

Type of Meter Required. -

With this table at hand it is quite easyto read off intermediate voltages, assumingthat the milliammeter has a sufficientlyfinely -divided scale.

This latter point brings us to the first ofthe practical details concerned. namely,

Milliammeter . EquivalentReading. H.T. Voltage.

-1 15

-95

-35.4. 45.5.55.6-65

.75

2030405060708090100110

130140150

the type of meter to use. What is wantedis an'instrument with as large and open ascale as you consider yourself justified inaffording, the scale to run from zero to onemilliamp for preference.

Higher readings are unnecessary (thetable will show you why), and to use a meterreading up to, say, 6 milliamps merelymeans that the scale will be very crowdedand difficult to read. Evidently, then,it will pay to get a low reading meterspecially for this work, but it need not bea very expensive one, since a very highstandard of accuracy is not really required.

The special resistance can be dismissedvery briefly : an ordinary anode resistanceis used, several of the larger manufacturersbeing preparedto supply these to a certaindefinite standard of accuracy if this isspecified when ordering. Messrs. R. I. andVarley, for example, will supply theirstandard wire -wound resistance to anaccuracy of one per cent (or even nearer itdesired),. and this is quite close enough forall ordinary purposes.

An Exception.A final point : In most cases you will find

that the current drawn by this " volt-meter " is not large enough to have mucheffect on the H.T. voltage when the meteris put across the terminals, but an exceptionmay be found in the case of a positivetapping supplying quite a small current,perhaps to a detector valve operating onthe anode -bend principle.

So long as the currents involved arereasonably large, the device is quitesufficiently accurate, but this point shouldbe borne in mind. Fortunately, however,it is not of great importance, since it iseasy to adjust. the voltage on a detectorto the right value_ by audible indicationswithout using a voltmeter at all. It isreally in dealing with the H.F. and L.F.valves that the meter is so valuable.


FERRANTI

THE

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EXPONENTIAL HORN

THE

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FROM THE A.C. MAINS

FERRANTI LTD. HOLLINWOOD LANCASHIRE


This new AmplionCone is designedfor hanging froma picture rail orother suitablesupport, placingit out of harm'sway and in themost convenientand efficient posi-tion,

The rim is a dark;chocolate -co-loured mouldingwith cone tinted to match.is fitted,

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Separate adjustments to ,cone and unit.

Price only 37/6Ask your dealer for a demonstration.

AMMONJunior

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wo*

The famous Ericsson SuperSensitive Telephones are

reduced to 12'6 a pair v.

Adopted oy the B.B.C. for use in their studios. Used by all the D.Xexperimenters. Adopted as standard in 1909 by the Admiralty and in1917 by the Air Board. Three resistances, 120, 2000 and 4000 ohms-one price, 12,6. Get your pair to -dayEven if you have a multivalve zet nosy and again you'll need a goodcrystal set. Buy an Ericsson Crystal Set to -day. Sturdily and hand-somely made. A really sensitive instrument. A real snip at 1 5i --

At all our agents or direct from the Company.ERICSSON TELEPHONES LTD., 67/73, Kingsway, London, W.C.2

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Build the

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One -dial tuning-Razor-sharp Selectivity --Real Music -20 Stations on Loud Speaker-Cost of Components. £5 : 10 :0.

That's what you're looking for, isn't it? Andit's a straight, quick job for any beginner.

This amazing simple circuit is becomingthe rage of the season, and is already theenvy and despair of H.F. screening- andneutralising devotees.

Circuit and wiring diagram FREE in everybox containing the L. & P. Two-wayCoil Tuner. Obtainable from all goofWireless shops or direct from

LONDON & PROVINCIAL RADIOCOMPANY LTD., COLNE, LANCS.The L. & P. Variohm-the finest Resistormoney can buy - isincluded in above

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m 10

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Announcement of Graham Aritplion Limited, 25, Savile Row, Landon, Iv r

Popular Wireless, December 3rd, 1927. '711

RADIO IN NEW ZEALAND.The Editor, POPULAR WIRELESS.

Dear Sir,-You may welcome a letter from adistant reader, having been here about nine months.I feel compelled to write these few lines on N.Z. radio.

On the 16th of July last, 2 Y A (Wellington) wasofficially opened, to the delight of the fans. It isworking on 420 metres, with an'aerial output of 5,000watts, quite a change from 100 watts, which was thepower of the old station, 2 Y K. Of course, theprogrammes are not of the standard that London andthe Continentals put out.

I am at present using a five -valve receiver withmuch success, getting Australian stations on theloud speaker, the nearest being 2 B L and 2 F C(Sydney), a distance of 1,250 miles; and all the N.Z.stations --1 Y A (Auckland), 333 metres, 500 watts,300 miles ; 3 Y A (Christchurch), 306 metres, 500watts, 200: nines ; 4 Y A (Dunedin), 453 metres,500 to 750 watts, 375 miles. A slight difference topicking up the Continentals with their thousands ofwatts. Fading is very bad here, and in town electricalinterference is terrific, mostly caused by the overheadlighting system.

I have read with much interest your articles onEmpire broadcasting, and my opinion is that someenterprising radio firm should have taken the matterup if it was only for the advertising they would havegot, because since Philip's started this short-wavebusiness their name has become a household wordwith the fans. I am at present working at a dis-tributing agents for Philip's, and I guess by the quan-tity of valves, chargers and speakers that passthrough our hands, for such a small population, theymust well exceed the sales of any other manufacturer.British radio is poorly represented in the way ofmulti -valve sets, which seem very popular here, owingto the great distance of our neighbour, Australia.The majority of seta, and components are Yankee,although the Brownie crystal sets are very popularjust now. It is true there are some agents forBritish goods, but they give a very poor display. Idon't like to be personal, but, taking '( ..'s ) agentas an example, they do not stock half the goodsmanufactured by ( ), and I am sorry to sayit is inferior quality to that purchased in London ;et least, the articles I pnrchaaed were.

It may interest you to know that a receiverlicence is 30s. a year, and a dealer's licence is £7 orthereabouts ; also, that howling sets are banned,dealers have to submit new sets to the Post andTelegraph Department for examination, but never-theless there are some howlers.

Well, I think this is all the news for now, wishingyour papers every success in the future.

Yours truly,L. BEASLEY.

Wellington, New Zealand.

IMPERFECT R.C.The Editor, Pornian WritELEss.

Dear Sir,-Since the controversy regarding therelative merits of resistance and transformereoupling is still continuing in your columns, perhaps Imay be permitted to contribute a personal experience.

I went recently to see a friend who has just in-stalled a " Kone " speaker, and who had made Itperfectly clear to me that the detector and amplifierto operate it were to be, as near perfection as possible.We had, in fact, worked out together a completereceiver to give straight-line amplification from 20to well over 5,000 cycles, which was to end with a1,200 ohm output (2 L.S.5a's in parallel), to ensureplenty of low notes.

As soon as I came in he asked me, " Well, how doyou like it ? " I listened for a moment, and then,without seeing the set, asked, " But why in thunderare you using a transformer ? " " Chiefly," hereplied, "to see if you could detect it without directcomparison with resistance coupling." And he then

.,proceeded to remove the transformer and replace it,much to the relief of my ears, by a resistance.

The transformer he was using is made by one ofthe best-known wireless firms in the world, and is" guaranteed distortionless " by them , moreover,it was being used after a valve of the lowest impe-dance that was possible while still keeping short ofthe maximum safe primary current permitted by themakers.

The fact that the distortion introduced by _thetransformer was so completely unmistakable withoutany standard of comparison seems to me absolutelyirrefutable proof that even the best transformercannot approach the quality given by a properly -designed resistance amplifier. There are: however,two reasons why the opposite opinion is held bymany people.

The first of these is that properly -designed resist-ance amplifiers are not common, while badly -designedones are legion. One of the best-known and mostwidely -advertised commercial R.C.C. units, whenused with the valves recommended, gives qualityfar inferior to that of a really good transformer, thecut-off on both high and low notes being very badindeed. Obviously the makers have thrown awayhigh notes with both hands in the endeavour to gethigh amplification per stage, and then, finding thetone " woolly," have deliberately cut low notes (byjuggling with the grid condenser) to get the averagepitch about right. Tho result is that only middlenotes remain, so that music becomes a horribletravesty of its real self.

*CORRESPONDENCE.

RADIO IN

NEW ZEALAND.IMPERFECT R.C.-

RECEPTION IN EGYPT.Letters from readers discussing interesting andtopical wireless events, or recording unusualexperiences, are always welcomed ; but it mustbe clearly understood that the publication ofsuch does in no way indicate that we associateourselves with the views expressed by ourcorrespondents, and we cannot accept any

4 responsibility for information given.-Editor. 4* -4.--4. 4.-4,--4.--00-4,-4.--4.------...--4.--4,4,-4,*

Most users of resistance amplifiers are as far fromperfect quality as those who use transformers, so whywonder that so many still stick to the transformer,which offers fewer pitfalls to the unwary I

The other point is that unless the loud speaker isfairly good, small differences -in quality due to changesin the amplifier are not apparent. It is pure waste oftime to design an amplifier for a horn speaker ; anycollection of odd parts, moderately intelligently used,will give quality better than such a speaker canreproduce, so that improvements over this are simplynot heard. Most of the diaphragm or cone type,even, cannot discriminate between the best possibletransformer amplifier and a nearly perfect resistanceamplifier. But this is no reason for keeping thetransformers, but only for getting a better speaker.

Yours, etc.,A. L. M. SOWERBY (MSc.).

London, W.2. -RECEPTION IN EGYPT.

The Editor, POPULAR WIRELESS.Desy Sir,-In your lame of POPULAR WIRELESS for

October 1st, you publith a letter from a Turkishreader resident in Constantinople, giving the resultshe had obtained using a five -valve set with threestages of high frequency.

I thought that you might perhaps be interestedin a report concerning reception here at Aboukir.Using a four -valve receiver -1 high frequency,detector, and 2 low frequency-of which I onlyemploy the first three valves on account of the secondlow -frequency stage so greatly amplifying atmo-spherics, I regularly receive the following stations :

Strength.Daventry (5 G B) ; B.S.Daventry (5 X X) ..

Stamboul (our " local" station-distant $80miles)

Vienna R.S.Naples R.7.Paris (1760 metres) .. R.6.Rome . R.6.Latigenberg R..4.Keenigswusterhausen .. R.5.Berlin ..

(All above on 'phones.)

There are dozens of other stations that I receiveat irregular intervals. For instance, some time agoI tuned in an English (or Irish) station somewhereabout 300 metres-a gentleman singing " MotherMathree," the enunciation was perfect-it wasnight particularly free from atmospherics, I remember.It would be somewhere about the middle of September.Atmospherics are our bugbear out here. Some nightsthey are so bad that one can hear nothing, even fromour " local " station, Stamboul. To -night I have justtuned -in to a very powerful station-and an utterstranger to me-whose wave -length, carefully mea-sured, appears to he 1725 metres. The programmeup till now has compriSed nothing but speeches in aquite strange language, and apparently in a publichall, as the sound of applause can be heard. Thestrength-on three valves-is about R.8, so it mustbe a pretty powerful station. It is not Paris (1760),as not a word of French has been spoken.

Wishing you a very deserved success,Yours very sincerely,

GEO. BRUCE OSWALD.Royal Air Force Depot, Aboukir,

Alexandria, Egypt.

"DETECTING DISTORTION."Tho Editor, POPULAR WIRELESS.

Dear Sir,-In connection with Mr. W. James'article on Detecting Distortion in a recent numberof POPULAR WIRELESS, perhaps the results of someaural tests which I recently carried out would beof interest to some of your readers, particularly asthey seem to point the way to considerable economiesof H.T. current.

In the end, it is the ear which has to be satisfiedwith the quality of reproduction, and while it isimpossible accurately to judge the quality of ordinarymusic by ear, yet if a very nearly pure note can heapplied to the loud speaker and its strength suddenlyincreased, any serious distortion of the loud note incomparison with the softer one is readily detected.

I have set up an audio -frequency generator whichwill produce, as I believe, a very nearly pure musicalMate of any frequency. Experimenting- as outlinedin the previous paragraph, the conclusion I come tois as follows : The smallest flow of grid current intro-duces clearly andible harmonics, whereas a consider-able amount of bottom -bend rectification can beallowed without any noticeable change in the purityof the sound produced.

I am now using 36 volts grid bias on a D.E.5A.valve with only 120 volts H.T., the anode currentbeing about 8 milliamps or less, and I can get louderand purer signals than when I was using 20 voltsbias (which is in itself greater, I believe, than isusually recommended for this valve) and twice asmuch anode current. On loud bass notes the anodecurrent will increase by 2 or 3 milliamps but nodetectable distortion results.

The power valve is preceded by a Ferranti A.F.3transformer and followed by an output transformer ofthe same make, feeding a cone type Lissenola-drivenspeaker.

I should be interested to know whether any otherof your readers get similar results by using highvalues of grid bias.

Yours faithfully,A. K. G.

Blundellsands,Lancashire.

A DIALINDICATOR.

By M. B.

ASIMPLE dial indicator can be madefrom a piece of stiff, white paper.The paper is stuck on the panel so

that it comes just above the dial edge(see below). A pencil line is drawn downthe middle 'of this paper. It is foundthat the black line shows up very wellagainst the white paper.

A BATTERY TIP.

ALWAYS place your accumulators on an'old book or on a piece of wood.There is always a lot of loose acid

knocking about at a charging station, andhowever carefully the cells are wiped thereis a possibility that a very fine film of acidmay be left. Sulphuric acid is extremelycorrosive, and it does not take much of itto ruin an expensive carpet or damage theinside of a radio -set cabinet.

However, if the accumulator is alwaysstood on something, preferably an oldmagazine, stray acid will not be able tocause damage.


H. T. ECONOMY.o HOW LONG SHOULD THE H.T. BATTERY LAST ?

A PRACTICAL ARTICLE ON AN IMPORTANT SUBJECT.By I'ERCY W. HARRIS, IVI.I.R.E.

WHEN should we discard dry high-tension batteries and why ? Whatis the end of their useful life ?

Probably nine people out of ten use drybatteries for their high-tension supply,and anything that can be done for eco-nomy in this direction is well worth con-sideration.

Firstly, then, on the question of dis-carding the batteries. It is not merely thedrop in voltage that causes us to discardbatteries. One of the chief `reasons is thata three or four -valve set operating from acommon" high-tension dry battery becomesunstable, tending to howl, and gives dis-torted reproduction after a time. We there-fore conclude that as the signal strengthhas gone down at the same time, that anew battery is required, and on discardingthe old one and putting a new one in'place,we immediately get a return to our originalvolume and quality.High Internal Resistance.

Now, as a battery gets older its internalresistance goes up and this causes a dropin voltage. We will assume that we havea battery which, when new, gives 120 volts.When this has dropped to 90 volts we getall the troubles above referred to. It iseasy to prove that it is not merely thedrop in voltage that is the trouble, for ifwe take off the old battery now giving90 volts on load and substitute for it anew 90 -volt high-tension battery, we shallfind that, save, perhaps, for a reduction involume and a little blasting on the veryloud tones, the reproduction is almost asgood as before, and certainly there is noneof that distortion and tendency to howlwhich characterised the set with the oldbattery.

What, then, is the reason ? Simply this,that the relatively high resistance of thebattery, being common to each valve cir-cuit, forms a coupling between these circuitsand produces unwanted inter -action effects.In fact, many sets with high frequency arefound to oscillate badly on an old battery,whereas, with a new one they are perfectlystable. This common battery coupling i$a very frequent cause of trouble.

Causes Coupling Effects.Let us imagine, then, that we have just

discarded a 120 -volt battery which hasdropped to 90 volts and installed a new120 -volt in place of the old one. Theresults are, at the moment, good, and willremain reasonably good until the voltagedrops to round about the figure at whichthe old one gave trouble. What are wegoing to de With our old 'batteries ? "It's,nouse keeping them," you say !

Not at all ! A few minutes considerationwill show that not only can we maize use,of these batteries, but that we can causethem to effect economy in our general high-tension consumption.

Some experiments 'I performed a littlewhile ago indicated quite clearly that iffirst-class quality is sought in every regard

separate high-tension batteries for eachvalve are an advantage. The reason ofcourse, is that if each ° valve has its ownhigh-tension supply froin a separate battery,there is no resistance common to all thevalve circuits, so that no matter how highthe resistance of tho battery, so long asthe current supply is available for it atthe voltage we desire, it does not matterwhat its internal resistance may be.

Returning now to our set with the newhigh-tension battery, which is serving as acommon battery to several valves. Quitelikely one or more of the valves in yourset is resistance -capacity coupled, taking,individually, very little in the way of platecurrent. The demand of these valves isso small that the drain on the battery isnegligible. Take your old battery whichnow gives 90 volts and place in series withit any other old battery you may havewhich will give 20 or 30 volts more, andyou will obtain a high-tension supply at120 volts-with a very high internal re-sistance, it is true-but quite capable ofgiving you the current you require for theR.G. valve at 120 volts.

Two advantages will follow from thisarrangement. Firstly, you will reduce thedrain on the main battery by a smallamount, and secondly, which is much moreimportant, the R.C. valve will not haveeven the slightest battery coupling withthe other valve or valves.

To Eliminate the Trouble.Most experimenters have a number of old

batteries on hand, and if in a set you areable to bring together your old batteriesso that you .get a separate high,tensionsupply for each valve, leaving the newbattery to supply the output valve, youwill get a distinct improvement in quality,and you will be able to run the new batteryfor considerably longer than would -other-wise be the case.

To prove this, I recently ran a set con-tinually for six weeks after a commonhigh-tension battery had been discardedthrough the production of distortion fromcommon battery coupling, using old high-tension batteries to give a separate supply.This completelyremoved the distor-tion, and I got afurther run of life (1)out of a batterywhich would other-wise have been dis-carded, and..(?) outof a battery whichhad alreaclY beendiscarded.

Aruither way inwhich you caneconomise in high-tension .supply from'your batteries is tobe careful in choos-ing your valves.Many good modern

low -frequency transformers work betterwith what is generally termed a " high -

frequency " valve (having an impedance of15,000 to 25,000 ohms) than with a general-purpose for the detector valve, having animpedance of 7,000 or 8,000 ohms. Thehigh -frequency valve, in such circumstances.will take less current from your high-tensionbattery as well as giving better results inreproduction and volume.

The difference, however, is not so greatas might at first be imagined, for it mightbe thought, for example, that a valve of21,000 -ohm impedance would take only athird of the current of one of, say, 7,000-ohms when used as -a detector valve.When it is remembered that invariably apositive bias is placed on the grid of thodetector valve and that it is not workedat zero potential, it will be realised thatthere is not so big a difference as might

NEXT 11/STEEIK ! F.

There will be a special and= considerably enlarged ==

CHRISTMAS NUMBER

°POPULAR WIRELESS.PRICE 3d. AS USUAL

ORDER YOURYOUR COPY NOWJ11111111111111111111111111111111111111111111111111111111111111111111111111117

otherwise be thought. However, the differ-ence is worth while if you are trying toobtain economy in high-tension current.

Use Large Batteries.The biggest economy of all, of course,

is making sure that one uses an adequatesize of high-tension battery for the set towhich it is connected. A set that has threeor four valves is very extravagant to runon the small size of high-tension batteries.The larger sizes are more expensive as tofirst cost, but much cheaper in their " costper hour." Obviously, one should calcu-late one's high-tension expenditure accord-ing to the period of time over which thebattery is used. A ten -shilling batterywhich lasts, say, nine months is muchcheaper than a five -shilling battery whichwould only last three.

This point, however, has been stressedon many occasions, and I do not thinkthe same number of experimenters haverealised the really useful economy namedat the beginning of this article-the use ofold high-tension batteries in series and asseparate supplies for each individual valve.

The grid -bias battery plays a large part in the rutting down of plate current,besides making for pure reproduction.

Popular Wireless, December 3rd, 1927. 7l3

MARCONI rSHIELDED

LVViA EType

S 62 5The principal feature of the MarconiShielded Valve Type 5.625 is its elimina-tion of all capacity effects between grid andplate. It thus opens up a new era inhigh frequency amplification.In practice, this valve gives an amplifica-tion of 30 to 50 per stage with absoluteefficiency and complete stability over awide band of wave -lengths.The second grid of type 5.625 over-comes the capacity effects betwren gridand plate, thus preventing the ' feedba k' of energy which causes oscillationin an ordinary valve.Moreover, the arrangement of the elec-trodes and lea& makes it possible touse very simple and effective circuits.Approximately 120 volts of high tensionmay be appli:d to the anode and, owingto the great magnification and consequentlarge high frequency input to the detectorvalve, anode bend rectification maybe used.

to

..................m.........mmumm.11........ ...........m.... mum=IMINIERIMIE....0...m...mm...........wm....MEMMIIMMIWAMMEMMEMMIIIMIIIMI/41111MMEIM11111MMEMINMEMMEMMEMWIMMOMMAMEMEMEMMEagar 1111=111,1rfillinEIMIMMEIN

20 40 1.0 80 I . LOAVOOL" VOLTS

APPROXIMATE DATA-Filament Volts6.0 max. Filament Current 0.25 max.Anode volts120 max. Magnification factorand impedence values vary, but under

typical conditions, are as follows ;Screening grid volts - - 80

Grid VoltsMagnification factor - 110

Impedence175,000 ohms.

Price2216

et,z 0..?oz,_. ejj

goc, -(.2.?,`N464, 04), oe,

tk 0 2Bien ./.bad 42',5e,' b4+., -.414c4- csk. ottr. 4

z, cf. ..eor,

Address

. County r

Gettinvat the P

root of itTo get rid of the thistles in the delphiniumsyou don't cut them back with a pair of nailscissors-you grub them out by the roots.To eliminate grid -anode reaction effects fromhigh -frequency amplification circuits, it's nogood fiddling about with neutralisationcondensers.

Go to the root of the matter. Neutralise insidethe valve. Use the Marconi Shielded ValveType S.625.Like every other Marconi Valve, the S.625knows its job and does it-just because itwas designed and made for it.A Marconi Valve always is designed andmade-it never just happens. Try Marconiand see-or rather, LISTEN.

IA full description of Marconi Valvee,Marconi Sets, etc., is to be found inan amusing but informative freebooklet called " Back Chat" justpublished. To secure your copysend off the coupon below at once.

1. a valVALVES

ve should do

714

ApparatusTostod

Traders and manufacturers are invited to submit wireless sets and components to the " P.W:'Technical Department for test. All tests are carried out with strict impartiality in the "?.W."test -room, under the supervision of the Technical Editor, and the general reader is asked to notethat this weekly article is also intended to provide a reliable and unbiased guide as to what to

buy and what to avoid.-EDITOR.

A NOVEL COIL -HOLDER.ALTHOUGH there are rumours to the

effect that there are to be considerablewave -length Changes, it would appear

to be definite that 5 X X 'Daventry) is tocarry on, more or less indefinitely, at1,600 metres. In some respects this is goodnews, but from the point of view or setdesign it means that in the future we arestill to be faced with the problem of switch-ing from the high to low range. As ameans of doing this the London & Pro-vincial Radio Company, Ltd., have pro-duced a novel version of their scaledreaction two-way coil holder. The movingand fixed portions of this each carry twocomplete coil sockets. These are arrangedat' such angles that two pairs of coilscan be accommodated.

By means of simple switching either paircan be brought in or out circuit as desired.This ingenious coil holder will take practi-

cally any size of coil and, owing to a careful -design, is not bulky or awkward in appear-ance even when it has the coils fixed' inposition. The advantages of having theseparate coils both for aerial and, reactionare, of course, obvious, and they areefficiently disposed of in this L. & P. Coil

rliolder. As we have already indicated,the holder incorporates the scaled move-ment and this enables calibration to becarried out.

The geared movement is quite a goodone and the component seems to -be asound mechanical job. The price of thisL. & P. " High -Low " is 14s. 6d.

Another new component due to theL. & P. people is the Variohm. This is abaseboard -mounting filament rheostat. Itis not unlike an edgewise -mounted fixedcondenser in appearance. The adjustmentis carried out by means of a small beadwhich runs up and down a slit in the top.


Along this aperture is moulded a scalewhich enables vdefinite resistance settingsto be obtained.

The adjustment is smooth and we notethat an " off " position is provided. Theresistance range of the Valiohm which wehave had under test, is stated to be 0 to 10ohms, and we found that this was a veryclose approximation of the component'sactual characteristic. The Variohm is aneat, well -designed and, well -made littlecomponent and retails at 4s.

NEW " COSMOS " COMPONENTS.Some very interesting new components

recently arrived from Metro -Vick Supplies.Included in these 'were a number of theA.C. valves. These Cosmos A.C. valvesoperate directly from A.C. mains. Theyhave indirectly heated cathodes. The" raw " A.C. is taken to a heater whichtransmits its heat to a small metal tubecoated with a mixture of oxides of twocomparatively rare metals and from this theelectrons are emitted. A particular featureof the Cosines A.C. valves is that they caneasily be adapted to operate in any existingsets without wiring alterations.

For this purpose special five -pin capadaptors are available and these are ofquite a simple nature and comparatively in-expensive. The type A.C. Green Spot hasthe following characteristics : Heatervoltage, 4 ; Heater current, 1 amp. ;amplification fabter, 35 ; anode impedanceat 120 volts H.T., 17,500 ohms, mutualconductance at 120 volts H.T., 2 milliampsper volt. The price is 22s. 6d. The veryhigh amplification at a moderate impedance,


If your dealercannot supply

"111

C4gie>, (SISY

t LOU" Valves like we sendost free.

THE overburdening of Valves isA. so common, that the AshleyResistor method of preventionwhen adopted, not only takes theextra load from the battery butrelieves the burden of anxiety onthe minds of those who may haveto foot the bill for replacements.And similarly, each of the otherAshley components perform theirvarious functions reliably in theHome Set, so that nothing willgo amiss in the absence of the

person whose pet itmay happen to be.

Two fully descriptive leaflets.will be sent on request.

ASHLEY WIRELESS TELEPHONE CO.(1925)Ltd.Finch Place, London Road, LIVERPOOL

.c1

ANDRESISTORBASE

2/6state particulars of valve forwhich Resistor is requiredwhen ordering.

MULTIPLEFIXED

CONDENSER

5/6

15 various capacitiesfrom the one unit.

R.C.C. UNIT

5/6

Neatest and most reliableat lowest price obtainable.

GUA ANTEEDCOMPONENTS

Popular Wireless, Dc,:ember 3 -rd, 1927.- 715

Getbettera rice

LOPE

THE wonderful filament of specially treated nickelpossesses certain properties (essential to the perfectfunctioning of a valve) possessed by no other metal.

That is why, when these valves are used, broadcast pro-grammes become uncannily real, and are endowed withan atmosphere which has hitherto been lacking. Thisre-creation of the transmissions is yours simply bychanging over to these modern valves. It is surelygood to get theSe results. It is still better to know you cankeep them. You can, too-for a considerably long'..1-period than with any other valve. .

No doubt exists as to the superiority of NickelFilament Valves, but. we ask you to satisfy yourself bytrying them in your set. Your ear will do the rest.

B 210 HR.C. and H.F.

Fil. VoltsFit. Amps 0 10Max H.T. Volts 150

10s. 6d.

B 210 LGeneral Purpose.

Fit. Volts 2Fil. Amps 010Max H.T. Volts 120

10s. 6d.

B 215 PPower ,AmplifyingFil. VoltsFil. Amps.. 0.15Max H.T. Volts 120

12s, 6d.The above prim are applicable in Gre.4 Britain and Northern Irelan.1 only.

Your dealer holds adequate stocks of these valves.

ICKEL FILAMENT"L116 11/ 1161

Made at Rugby in the Mazda Lamp Works

rThe Brghle Thomson -Houston Co. Ltd. 2672A

V,P1

N

V4SCAPHONE SETS

The simplicity of the Efescaphone One DialReceiver and its extraordinary results makeit an Ideal Set for the man who is interestedin Wireless as an entertainment rather thana hobby. Its ease of tuning by a single slowmotion dial renders it suitable for quite non-technical users, while at the same time it iscapable in practised hands of performanceequal to much more complicated sets. In orderto bring the Set within the reach of all we haveinaugurated a Hire Purchase System wherebypayment may be spread over 12 months.The equipment is supplied complete and thebest material only is employed. StandardBritish Valves form part of the equipment.

Typical Setscomplete with Batteries, Battery Cable,Phones, Aerial Equipment, P.M. Valves andPuravox Loud Speaker, including Royalties.

CROMWELL WOLFE2 Valve £13 - 0 - 0 Cash 3 Valve £15 - 13 - 6 Cash

Or

£1 . 0 - 0 Deposit and12 monthly Instalments

of El - 1 - 0

or- 5 - 0 Deposit and

12 monthly Instalmentsof £1 - 5 - 3

Applicable only in Great Britain.

FALK, STADELMANN & CO. LTD.83-93, FARRINGDON ROAD

LONDON, E.C.1

GLASGOW, MANCHESTER, BIRMINGHAM, DUBLINNEWCASTLE and CARDIFF


01.1-

o APPARATUS TESTED.(Continued from page 714.)

giving the extremely favourable mutualconductance figure, is a special feature ofthese A.C. valves, and one which gives themdefinite advantages.

The Green Spot is an all-purpose valve, andmakes an excellent high -frequency amplifier,detector or first low -frequency magnifier.It gives very good results in any one ofthese positions. 'In comparison with ordi-nary valves we can almost say that it givesabnormally good results. Considerable am-plification with freedom from microphonicnoises and perfect stability is possible.

A.C. Red Spot is a power valve. Thecharacteristics of this type are as follows :beater voltage, 4 ; heater current, 1

amp. ; amplification factor, 10 ; anodeimpedance at 120 volts H.T., 3,000 ohms :and at 180 volts H.T., 2,500 ohms mutualconductance at 120 volts H.T.. 3.5 milli -amps per volt, and at ,180 volts H.T., 4milliamps per volt. The price of this isa!so 22s. 6d.

Here we have a tremendous " slope,"And one that in the usual way is not ap-proachable. Needless to say this is avery great advantage, particularly for avalve of the power type, and considerablemagnification can be obtained while a veryexcellent degree of grid swing can behandled. The makers claim that thisvalve requires only half the input to givethe same output as the best battery -operated

valve, and our tests would seem to indicatethat their claim is by no means exaggerated.

In fact. we were considerably impressedby the operation of both of these CosmosShortpath A.C. valves. They conclusively

A short-wave setdesigned to thespecial order of the SudanGovernment by the R.I.and Varley Co., Ltd. Its pur-pose is to receive radio time sig-nal.; for checking chronometers.

prove that there is nothing to be lost andeverything to be gained by changing overfrom batteries to the mains.

In regard to the H.T. supply, the MetroVick people supply an excellent full -waverectifier, the S.P. 42/11 Operated at 4volts and taking- two amperes, this valveenables a D.C. output to be obtained of 50milliamperes, which is quite sufficient forany but a very elaborate outfit, and it willstand up to 250 volts R.M.S. per anode,The price of the S.P. 42/U is 22s. 6d.

We have had -a receiver in operationusing these Cosmos valves throughout andderiving both its L.T. and H.T. from themains, and its performance was well abovethe average in respect of both sensitivityand purity of reproduction. The Metro -Vick people supply all the necessarytransformers, etc., at very reasonable prices.There is a complete L.T. battery eliminator

for these A.C. valves at £2 10s.The output is 5 amperes at 4 volts.As the makers say : " This unitmay be regarded as a substitutefor the accumulator as used withthe ordinary type of valve." Theinstrument is contained in a neatcase with a crystalline finish. andis fitted with ten feet of flexiblecable and an adaptor for plugginginto a lamp holder. There aretwo types available one for 100to 110 volt mains and the otherfor 200 to 240 volts. Either willoperate at any periodicity from

40 to 100. This unit, as with all the Metro -Vick mains supply apparatus is designed insuch a way that it can be safely operatedby inexpert listeners.

PateneAlo.269,388

y the RedfernPiteumatieValve Holdersupersedes all other designs

(1). It positively absorbs all shock and vibration.(2). Designed to dispense with spring suspen-

sion, it is entirely free from any naturalvibratory frequency.

(3). Electrically perfect, high frequency lossesnil, insulation resistance infinity, Self Ca,pacity immeasurable.TEST REPORTS ARE NOW AVAILABLE

ON REQUEST

Your dealer can supply you.

REDFERN'S RUBBER WORKS LIMITED,HYDE, CHESHIRE


Will you gagthe ChristmasProgrammes ?Christmas Eve !-everything overhauled-batteries re -charged --lovely new (ex-pensive) loud speaker that can also beused as a pipe rack-" NOW WE'REREADY ready ready

* * *

" I think we'd better play ' Hunt theSlipper,' Aunt, as you suggested, I'mafraid the atmospherics " (and hecan't even hear the atmospherics).

* * *

Not a bad set on the whole, but what area couple of headphones amongst so many(fifteen all told and the twins) now thatspeaker has again become a pipe rack.

ETHOVOXThe happiest homes this Christ-mas (from the wireless point ofview) will be the ETHOVOXhomes-where the loud speakerlooks like and speaks like aloud speaker.

*

And a round £3 will buy it-"this speaker that first madewireless popular." Go to yourdealer NOW or come to ourSHOWROOMS -15, BEDFORDSTREET, STRAND, for ademonstration.

BURNDEPTBLACKHEATH, LONDON, S.E.3

Save shillings onevery valve.

Compare our prices with those of otherwell --known valves and see what you save.Metal Valves are used in many Broad-casting stations exclusively, which is proofof their superiority, for Radio StationEngineers know from experience whichvalves are best.

Unlike some valves which only functionefficiently when used on certain circuits,Metal Valves are designed to suit allcircuits, and will get the best out of yourset. Try

MICTALRADIO VALVES

Dull Emitter, Type C.L. 124, Loud Speaker Power Amplifier, L.T.4 volts, 0'12 amp., H.T. 4o to loo volts. .. .. Price 8/6

Dull Emitter, Power Amplifier, Type C.L. 162, L.T. 2 yOlts, 0.16 amp.;H.T. 40 to 8o volts. .. .. Price 8/6

Dull Emitter, Type C.L. zoz, H.F., Detector and L.F., L.T. 2 volts,0.2 amp., H.T. zo to too volts. .. .. Price 419

Dull Emitter, Type 6'1oo, H.F., Detector and L.F., L.T. 4 volts,o'o6 amp., H.T. 20 to 8o volts. .. .. Price 6/-

POSTAGE FREE ::OTHER TYPES IN LIST.

If unable to obtain from your local dealer,send direct, with remittance, stating typeof valve required.

JOHN RAE, LIMITED,Sole Distributors,

60, Blackfriars Rd., London, S.E.1.

718 .Popular Wireless, December 3rd, 1927.

IOTAll Editorial Communications to be addressed to The Editor, POPULARWIRELESS, The Fleetway House, Farringdon Street, London, E.C.4.

The Editor will be pleased to consider articles andphotographs dealing with all subjects appertaining towireless work. The Editor cannot accept responsibilityfar manuscripts and photos. Every care will betakento return MSS. not accepted for publication. A stampedand addressed envelope must be sent with every article.All inquiries concerning advertising rates, etc., to beaddressed to the Sole Agents, Messrs. John H. Lile,Ltd., 4,'Ludgate Circus, London, E.C.4.

The constructional articles which appear frQnt time totime in this journal are the outcome of research andexperhnentat work, carried out with a view to improvingthe technique of wireless receivers. As much of theinformation given in the columns of this paper concernsthe most recent developments in the radio world, someof the arrangements and specialities described may -bethe subject of Letters Patent, and the amateur and thetrader would be well advised to obtain pehnission ofthe patentees to use the patents before doing so.

QUESTIONS ANDANSWERS.

BISCUIT TIN FOR SCREEN ?J. W. E. H. (Nr. Belfast):-" I intend to

build a set employing the circuit of the 4! Cube -Screen ". Three, given in "P.W." No. 280, -

pag 329, but using a cabinet large enoughto give plenty of room for modifications oflay -out. In connection with this circuit.could a small biscuit tin be used instead of acube screen ? "

No. The magnetic properties of an ordinarybiscuit tin would be quite fatal to its effective useas a screen in any circuit of this type.

HOLES IN ACCUMULATOR CAPS." DuNNo " (Redditch).-" What is the pur-

pose of the holes in the little caps that fit intothe tops of accumulators ? Does it matter ifthey get stopped up ? "

An active accumulator discharges a good deal ofgas, -especially when it is being charged, and the holesare there to allow this to escape. They should cer-tainly be kept open, for the pressure of gas in a cellis sometimes quite considerable, and might besufficient to cause the cell to burst if no outlet isprovided for it.

SPARK WHEN CONNECTING UP THE H.T.P. G. (Stepney Green, London, E.).-What puzzles me is that even before the

filaments are alight I get a little spark whenplugging in the H.T. battery lead. The

set seems to work all right-in fact, I am verypleased with it-but I can't understand acurrent flowing, as shown by the spark, whent!u-re is no -valve alight. What is wrong ?

Nothing is wrong if; as we expect, you have a large,fixed condensershunted across the H.T. The currentflow that is puzzling you is simply due to the factthat every - time you plug in, this "" reservoir" con-denser is charged up. When tbe set is switched offthe charge slowly dissipates,,so that the next timeyou connect up again -another .charging current flowsfor -a moment, thus causing another spark.

THE CARE OF AN ACCUMULATOR.R. (Cheltenham, Gjos.).-,-" My accu-

mulator stands in a corner beside the fireplitce,and although I have -only had it two or threemonthS, the acid seems to be running low.Can I put tap water in ? "' There is no doubt that you can put tap water inan accumulator, in just the same way that youcan put your money into a,pocket ;which has a holein the bottom. But if you take our advice you willdo neither. There are more ways than one of losiiigmoney, and one of the most certain is to treat anaccumulator badly. To get the best from such anaccessory Tou must treat it in -accordance Withthe makers instructions, and in nearly all Cases youwill find that the makers definitely recommend theuse of 'distilled -water and not tap water for refillingan accumulator.

We notice, too, that you stand the battery nearthe fireplace, which would account for the electrolyteevaporating quickly. This again is directly atvariance with the advice given by the manufacturers,who state that the cells should be " kept in a coolplace." Although the average accumulator willstand a lot of misuse, we are afraid that you are notgiving yours a fair chance, and we recommend youto adhere to the makers' instructions as closely aspossible.

If you have lost or mislaid these, no doubt yourdealer would be able to help you, or you could obtainthem direct from the manufacturers of the battery.

OVERHAULING A LOUD SPEAKER." TOMMY " (Coventry, War.).-" I have

had my loud speaker in use for just over twoyears, and although I do not use it very much


?or theCossor

AielodyMaker

REDFERN,SNEW SIZE

11Insist on Redfern's - Br/6/s!) 6, Tested,

REDFERNS RUBBER. WORKS LTD, HYDE, CHESHIRE

EBONITE LOW LOSSCOIL FORMER7" LONG 4"OUTSIDE DIAMETER

Your Dealer can supply you

719

RECUPERATING AGENTIN THE

HELLESENDRY BATTERIES

THE proof of a Dry Batteryis the number of hours of

efficient service you can get outof it for the money you spend.We are confident of the resultif you rely on a Hellesen DryBattery for your H.T. Supply.Get a smooth uniform H.T. Supplyat the minimum cost per hour froma sealed genuine Hellesen H.T.Battery with the quadruple insula-tion and the No. 7 RecuperatingAgent.

60 -volt "WIRIN " 12/699 -cat "WIRUP " 21/ -

(Postage Extra.)AB types, voltages, etc.. in Doulde andTreble capacities for 11.T. and L.T. Supply.Ask your dealer for the type to suit yourset and yet the maximuin service, tit. _writeus for full particulars.Obtainable at alt Radio, Electrical mad General Stores,

Harrods, Selfridges, etc., or direct from

A. H. HUNT, Ltd. ( °;ft. ), CROYDON, SURREY,


A new field ofexperiment for you !That old gramophone you have got tired of can hemade to give reproduction many times better thanit ever did before and all for a very small outlay.

Merely replace the soundbox with theIGRANIGPACENT

pHONOVOXand connect to the amplifier and loudspeaker ofyour wireless set. The result is far better qualitythan either of them gave alone. kVhat it amountsto is that you obtain electrical reproduction suchas is beings ued in all de -luxe gramophones.Get the Phonovox for Christmas and provideexcellent quality dance music for the family.Remember the volume is only limited by thecapacity of your amplifier.

THE PHONOVOX, Price 57,6The' following are optional:-

Plug Adaptor, 5/. Volume Control, 7:6Send for List No. R.7o for further particulars.

The range of Igranic Radio Devices is the mostcomplete in the world and they are always stockedby reputable dealers. All reports received by usof difficulty in obtaining them receive immediateattention.IGRANIC ELECTRIC CO., LTD.,149, Queen Victoria Street, London, E.C.4

Works: BEDFORD.

AAA/V\AAAAJAAAAAAAAAAAAAAAAAAAATWO WONDERFUL

LOUD SPEAKER SETSThese wonderful instruments incorporate all 1928 improve-ments, and are the finest sets money can buy.22 STATIONS on the two -valve and 46 STATIONS on thethree -valve have actually been received, and most of theseat good volume on the loud speaker.The latest all -wave tuner is used, thus eliminating coilsentirely, and any amateur can build these sets in two hours.NO SOLDERING - NO DRILLING -NO COILS TO CHANCE.

Booklet describing the -,Saxon " Booklet describing the Saxon "Two -Valve Loud Speaker Set, with Three -Valve Loud Speaker Setdiagram and full instructions. v.ith diagram and full instructions,

3d. post free. 3d. post free.

SAXON RADIO CO. (Dept. 14). HENRY ST. WORKS; BLACKPOOL.

o Lapacity ranges, and each inBaseboard and Panel models.22, CRICKLEWOOD LANE, N.W.2

'Phone: Hampstead 17E37.

FORMO-DENSERA sound variable condenserwhich fills a long -felt want.Specially designed to take theplace of the hitherto generallyused Fixed Condenser. Foruse as :

Neutralising CondenserAerial CondenserGrid CondenserReaction CondenserPhasing CondenserTone Control Condenser

BUY FORMO HANDBOOK. PracticalCircuits Blueprints of two sets, etc., It-.


RADIOTORIALQUESTIONS AND ANSWERS

- (Continued from page 71S.);

.

in the summer months, it sees a good deal ofconstant service one way -and, the other; Justlately it 'seems to be falling off- a good deal,and reception is not as pure as it was a fewmonths back Certainly not half as .cicar aslast year. My friend's loud speaker, which isof the same make but is ,a new model, seemsto have far more life and tone on my setthan -my own speaker. Does this mean it isveering out- and 1 shall have to get a new

one ?After two years of constant service your loud

speaker, needs an overhaul. Possbibly it may be alittle worn, eithet mechanically or electrically, andin any case, it 'probably has accumulated a certainamount -of dust whirls is interfering- with its properfunctioning. You should ask your, dealer if he cansend it back to the- manufacturers for a test, or,failing this, we should take the matter up direct withthe makers. '

'WHAT IS VERNIER TUNING ?"A NEW AMATEUR" (Crowmarsh, Oxon.).---

" I am afraid I shall sound an awful ignoramus,tut being buried away in the country here, Ido not often see a wireless shop and get veryout of touch with wireless terms. The onethat is puzzling me at present is " vernier."What is meant by vernier condensers andvernier tuning ? " -

The word vernier applied to wireless simply meansgreater fineness or accuracy. You probably- knowhow even a very slight movement of a variablecondenser will alter tuning, but sometimes the verysmallest movement of the main dial is an adjustmentwhich is too coarse. In -such cases the final adjust -meet is made on a separate control which is called avernier control. In most of the really modern con-densers the necessity for a separate vernier tuningadjustment is obviated by the use of some slow-motion device, such as gearing, which gives the sametine adjustment as a separate vernier effect.

. WHAT IS THE BEST ONE -VALVE SET ?J. N. (Wells -next -the -Sea, Norfolk).-" I

have been interested in wireless for years,and although funds will only allow me to

question which I have often wanted to ask,and that is-what is the best one -valve set? "

Your question is easily asked, but as one man'smeat is another man's poison, there are alwaysbound to be differences of opinion as to what consti-

tutes the very best methodof hooking up_ one valve.

WHAT IS WRONG ?

The above diagram is supposed to represent the connections of anH.F. and Detector receiver, with split -primary H.F. transformer andreaction on the secondary. But it is wrong, and would not work properly.

Next week the correct diagram will be given, and to test your skill -we shall continue to publish every week a diagram in which a mistake(or mistakes) has been inserted. The correction will be published thefollowing week, and the series will work up from a simple crystal setto multi-valvers.

No prizes are offered, but by following this series and trying to solvethe problems week by week the reader cannot fail to learn a lotabout radio circuits

have a crystal set, I always read about thevalve sets in the hope that one day I shallown one. Other people's troubles are veryinteresting to read about, but there is one

The most popular arrange -meld in vogue to -day, andone which gives'uncommon-ly good results, is thatknown as the straightone -valve detector withreaction. This latter can becontrolled by the swinging -coil method or by a con-denser. In either form thiscircuit is very simpleand reliable, and althoughrobust , in operation it isquite sensitive enough tobring in many long-distanceforeign stations undergood conditions. (In fact,with a straight one -valvecircuit many " P.W."readers have succeeded intoning in American broad-casting stations direct !)One advantage of this typeof receiver is that with themagnetic (swinging coil)reaction, it works as wellon the long waves, i.e.5 X X, as on the shorterwaves: used by 5 G B andthe other local stations.

On the other hand, thereare :some . experimenterswho prefer a circuit whichis decidedly more sensitive,even though it is a littlemore tricky in operation.Such a circuit as the Chitos,for instance, which wasintroduced to the publicthrough the pages of thisjournal. The Chitos setwill 'always find warmadherents amongst thoseWho prefer super -sensitive

circuits, even though these may be a little more diffi-cult to handle than the simple types already referredto. Nearly -everyone. who, has tried the Chitos hassaid that this receiver gives better results on the


the girlsmay win

iris good that girlsplay games andcompete for 'cups'

just as boys do. Thew'nners may seem towin by luck, but oftenwhat looks like good luckis simply good health.She who is healthy holdsvictory in her hand, sothe most valuable cupof all May be "TheHealth Cup."

There are severalways to win that. Goodfood, fresh air, exercise,early bedtime and oneother thing - food todrink. This means the`Bournville Cup' whichitself is a health cup-- wise economy because

it costs no more than ordinary drinks and issimply packed with nourishment. BournvilleCocoa has a delicious chocolaty taste which winsthe palate of everyone. Serve it with breakfastand supper.

Young Britain's Health Cup

BOURNVILLE COCOA

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'\.'?> '6°- t/'9te tot,

;101.%0ttlSt$0 t°011:0°

\t.Cto6 cc\N.1:19' %;'5 Ilift:i:csu:lars or apply to :

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give urdealerYufullest pr-

t",

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LE CARBONECOVENTRY HOUSE,

SOUTH PLACE,LONDON, E.C.2.


he pictureon the hoi

may not be the sign of a good cigar,but a gcod wireless cabinet is a suresign of a good set.Your set deserves a V. C. BondCabinet. It will not only add dis-tinction to your room as a piece offurniture, but wilt add to theefficiency of your apparatus.Our cabinets are made like that -experts in radio and cabinet-makingcontribute to the beauty of designand sound construction which hasmade them so popular.We have many designs from whichyou may choose, but we can makeone to your special requirements too.

This combined bedroom chair andtrouser -press solves the problem ofthe Christmas gift. It is not only apiece of good furniture, but a per-sonal servant any man wouldappreciate.For full illustrated particulars ofcabinets and chairs, write or'phone to

Actual Manufacturers:

V- C= BOND 6' SONS61, The Grove. Mare Street, Hackney, £.8.

reteph,n, : Clissold 0883. Est. 1899.T,tr grams " VeeCcel3ee London."

Racitio2mgass.4

Dundas Headphones,the finest value ob-tainable. 1 yearguarantee with every

pair. 3/11 pair.postage 65. extra.

TO CLEAR.A Quantity of 4-v. Powerand Ordinary FrelatMetal and Electric A/Valves, price cacti ---"rfCOSSOR MELODYMAKER. Write for dia-gram and prices of parts.All well-known makes ofparts supplied. lissen,all Valves. Benjamin,Igranic, Formo, EdisonBell, all Loudspeakers.Write for Lists or sendorder.

Everything is sold under guarantee to return yourmoney in fell if dissa, isti- 5. Goods value 20/. and ov,rsent carriage paid.

ASK FORNEW SEASON'S CATALOGUE

POST FREE.SPECIAL BARGAIN COLUMN.GOODS sent C.O.D.on r e q 11 es t. Please

state on Order.

Var. Neutralising Condensers, each 2/6. OxidisedPanel Brackets, pair, 8dBaseboard Var. Resista ncert, each 1).. Base-board Coil Plugs, each 9d.Variable Resistances, earl6d. Slow Motion Dialseach 3/6. Push -PalSwi tches, each 1/, ColouredInsulated Wire, 20 ft. for1,6. Large ShellInsulators,2 a ld. Neutron Crystal,7d. Permanent Detectors,-usually 3!6, to clear, 1,3.Voltmeters, 0-10, each 2/6. -Croix Transformers, 3-1 &5-1, each 319. VariableGrid Leaks, each 6d. Rheo-stats (6 ohm), each 6d.Dundas Loudspeaker, fullRise, 30:-.0005 Var. Condensers, each.5/-. 60-v. H.T. Batteries,M.A.L. 4111. postage 9d.Flash Lamp Batteries, 41-v.,per don., 3/6, postage 9d.

FREE

Banana Place and Sockets,each 2d.2-v.Triot roe Valves,each 316. 2-v. -06 NowakValves, each 4/.. InductionCoils, 35, 1'2; 50, 1/4;75, 1;6; 100, 1;9: 200,2'6; 250, 2;9 (centretapped 6d. extra).9-v. Grid Bias Batteries,each 1/-.B.F. Chokes,each 4;6. 2 mftl. Condensera, each 2;3. 16 -gaugeTinned Wire, 20 ft., 1;6.Aerian Wire, Copper, per

lb. 1;-. Red and BlackFlex, per yd. 11d. 2-v.Triotron Power Valves, each716. Basket Coil Holders,each 9d. Micro -Radio Rhe fatats, each 1;9. Transfers,per packet, 5d. On -and -OffSwitches, each 1/s. Loud-speaker Plugs and Sockets,for room wiring, each 1;6.Flusolda, Per tin, 1)3. Loud-speaker Cords, 1/-. Ultra'Phones, tisnally 1716, now8/6. Six -Pin Coil Bases.each 1/3. Six -Pin CoilFormers, each 4/-. D.C.C.Wire, 16, 18, 20 SWC,1 lb., 8d.; 22. 24, 26, 28,1/-; 30, 32, 34, 1;3.

To all buyers of complete partsfor any set, the Ebonite Panelis- given Free. Write for NewSeason's Catalogue, post free.

CECIL RIDLEY"RADIO HOUSE," MIDDLESBROUGH

MAKE YOUR OWNCONE SPEAKERTWO WONDERFUL 1UNITS AT is 1UPONLY

YOU'LL BEThe New Wonder " Nightingale"

CONE UNITwith Balanced Armature.

AS FITTED TO OUR CABINET CONE

r

jEACH

SURPRISED !GRAMOPHONEATTACHMENT

fiom a3ply'boanj.3t xparetut Cut, a OV'crcle. lion cuta atrip at wood sod

make a hole 2,i,aa a, Egan,fir na. . fix

t sea,' tnov.n.

BULLPHONEDOUBLE 9/.,PAPER 1"CONE -PdtatgExactly as fitted toour own Speakers,

with4 -inchdio-

uhroson.

Reduced from 32 6 to 15Csolely as an advertisementfor the famous BullphoneNightingale Loud Speakers.Cobalt Magnet guaranteedfor ali time.Astonishing Results,equal to the most expen-sive Loud Speakers yetmade, are guaranteedwith either of these Units.

BUY ON

sir TER21 its. !ugh, multi.14 -inch BellMahogany fin.ished, with platedarm and stand.

CABINET CONE

Size 17 ins. high by 1.5 ins. in Mahogany,Walnut or Rosewood li nish.

stDEPOSIT

DE LUXE77ig cash,orEASy TERMS 57/6 cash, or 5.'- deposit

/10;- deposit and 12 and 12 monthly pay -monthly payments of 6:- ments of 5' -

SEND DEPOSIT NOW ---NO REFERENCES -SPEAKER BY RETURN.

SATISFACTION GUARANTEEDOR MONEY REFUNDED.

Obtainable from your Local Deafer or direct from


THE LAMPLUGHPANEL PLATE TUNER UNIT

l'rois. Pat. Regd. Design.Enables amateurs to construct a highlyefficient Receiver equal in appearance to thebest factory products. Practically half a set,this Unit consists of a richly -engraved metalpanel in black and gold or silver, on whichare mounted coils and -specially calibrateddial, covering broadcast wavelengths, S.L.T.Slow Motion Condenser and Switch for chang-ing from low to high wavelengths. No ebonitepanel required, and the Unit can be mountedto any form of Cabinet. Pull diwiramssupplied for building two- or three -valve" set,We are receiving by every post eulogistictestimonials,and there is no doubt that thisremarkable Unit has come as a boon to thehome constructor and fills a long -felt want.

NEW "POPULAR" RECEIVERSThese new models were the sensation of therecent London Radio Exhibition, representingthe last word in Value. Constructed through-out of the very finest material -and housedin handsome oak cabinets enclosing all bat-teries, valves, etc. No loose wires nor coilsto change. Extraordinary range and excep-tional volume. Prices (set only) :

£5 0 0 (2 -valve set)

£6 14 0 (3 -valve set)Excluding Royalty.

"VARO-FIX "RHEOSTAT

This new model is built on aluminium basecarrying special spring slider. Very compact,and can bo placed near valve -holders, therebyreducing wiring. 6, 15, or 30 ohms.

112 each

LAtVir-LhVS. A, LAMPLUGH LTD.

King's Read.TYSELEY, BIRMINGHAMRepresentative for London and

Southern Counties: G. O. Shore & Co.,28, Newman Street, Oxf crd Street, W.I.

Send For Lists


(Continued from page 721)

short waves than an ordinary straight one -valveset; but it suffers from the disadvantage that itcannot work equally well upon the longer waves,such as 5 X X uses. -

Many other interesting circuits. might be named.as being specially suitable to particular Conditions,but undoubtedly the most popular one-valVe circuitis the good old straight circuit, in which the imlVeacts as a detector with reaction: In average _condi-tions. this is sure to give satisfaction, but where theconditions are in any way abnormal, or the require-ments are in some way out of the ordinary, 'expertadvice may be obtained from the Technical QueryDepartment, as to the receiver which is most- likelyto, give maximum satisfaction in the special -circum-stances. (The charge is quite a nominal one, andfull' particulars are obtainable upon application.)

" TERRIBLE TROUBLE " WITH ANAMPLIFIER.

" TROT!BLED " (Abingdon, Berks).-" I amin terrible trouble with my set, and I hope youcan help me out, for I don't know what myfather will say. We started wireless with acrystal set, and then last year we had a one -valve amplifier in order to get better signals.

A DETECTOR AND LOW - FREQUENCYAMPLIFIER.

a' SO TURNS

11FCreoralt 11

5 1917:

FtTRAN,S5

4003 Y

0,-3070.C.IS

11'

-0002

Dar.'.freefree-,

'

-N T.

L

Y.363.9.

The correct connections for a Detector anL.F. receiver with condenser -controlled reaction are shown above.

In the " What -is Wrong " diagram last weekthe H.T. negative terminal, 'phones; and chokewere omitted. The grid - bias - battery -wasreversed, and there was no H.T. to the plate ofthe let valve. and no L.T across the filamentof the 2nd valve.

This was satisfactory in a way but we couldnot " reach out," so last month I saved upenough to get the parts to build the Reinartzone -valve set which was given away with" P.W." on October 15th (Blue Print No. 3O).With this, I thought, we shall be able to addthe amplifier and possibly get Daventry on ,aloud speaker, as well as reaching out forforeign stations. But I have been bitterlydisappointed. When I try to connect up theamplifier to the one -valve set, the L.T.- bat-tery wires "spark"when I join up, and if Ikeep them together more than a minute theystart to get quite hot. Evidently somethingis seriously wrong. What can I do ? I amafraid to tell my father about it."

There is no need Tor you to get into a panic," Troubled," because you are experiencing quite acommon fault, which, fortunately, is very easilyremedied. What has happened is this. In theamplifier that you have, the 11.T, negative is joined toL.T. positive wire, whilst in the Blue -Print (No: 30)set the H.T. negative is joined to L.T. negative.

means that if you connect up all the terminalsin the way shown, the L.T. battery is shorting, andconsequently will be damaged ; . but you willfind'that there is no earthly need to connect up all theterminals. Try connecting up again to the terminalsas marked on the instruments, but be sure not toconnect a wire to the H.T. negative terminal onthe amplifier. Ignore that terminal altogether,and leave it without any connection externallywhatever. In all probability you will find that the

(Continued on page 724.) -

BRETWOOD GuaranteedComponent!

In all the finest circuits known " Bretwoodcomponents give highest efficiency.Here are three of the most popular and essential antsGRID LEAK DE LUXE.The most reliable variable grid leak obtainable.Known and fitinous the world over. Gives aminute.variation from 50,000 ohms to 10 megohms.

Panel type, 3 6. Baseboard type, 3 9.AMPLIFIER. Auto Audio Frequency (functions

as a super -choke).Perfect amplification at all frequencies. Mush andatmospherics piactic.ally eliminated. Can beobtained on a 19eday trial,

Price 21:1/".VALVE. HOLDERS (anti-capacity).Absolutely no capacity effects - always perfectcontact. Three types-Panel mounting, 16 ; Base-board, 1,11; Anti -Phonic Baseboard' mounting, 2,

. .

Obtainable from all dealers or from

BRETWOOD LIMITED,12-14, Ansdell St., Kensington, LONDON, W.8.

(Note our new addres,)

HEADPHONES REPAIREDRewound and re -magnetised 44- per oait LoudSpeakers repaired .9,- Transformers rewound 5 each. All work guaranteed and tested before delivery.Write for Trade Prices. 'Phone: Pier?: 1795MASON & CO., 44, East Rd., City Ed., NA.

THE PERFECT WET 11.1.Assured with our new Insulating Liner, Jars, 1/3doz, plain ; 1-6 doz. waxed ; Special Zincs, 1/- doz. ;High -Capacity Sacs, 1/6 doz.; Perforated Liners, V.doz. Post Free on three dozen Units and over, in-cluding special divided carton suitable as a container.S end5d. forsample complete unit,particulars and instruc-tions We stock Seamless Moulded Cone Farts.

Telephones and Loud Speakers re -woundSPENCERS STORES LTD.,

4-5. MASON'S AVENUE, COLEMAN ST., LONDON, E.C.2-'Phone London Wall 2592 (Nr. Bank.)

DAREX A eSAVEVALVE:andBatteries

Acci den :a Damage a voidci.

TERMINALS fisriZ","DAREX RADIO CO.

request.

Waldram Rd., Forest Hill, London, S.E.2,TRADE SUPPLIED

FREEA BOOKLET (G.F.I3/A),describing the high effi-ciency radio componentsx-hich are used in everycircuit.. of merit, will besent on receipt of request to

G.F,I3/A, GAMBRELL BROS., Ltd.76, Victoria Street, LONDON, S.W. 1.

I have No Aerial Troublenow I have fitted the

H OVEV 26Trice

Indoor or Outdoor.' Portable. OM ainabloat all dealers or from the nO VEY Aerial

Co 10, Red Lion Passage, W.0.1.

COMPLETE SETS, LOUD SPEAKERS,COMPONENTS, Etc.Send list of requirements, ant)Lest monthly terms willbe quoted byreturn. Best

British Batteries60-v. 8.'-,108-v. 15 -, 1.;c7et

THE P.D.P. COMPANY.91, GREAT TOWER STREET LONDON E C 3

PLEASE MENTION "POPULAR WIRELESS"WHEN REPLYING " TO ADVERTISEMENTS

Popular Wireless, December 3rd, 1.321 123

Have you tried thisnew Lewcos Coil ?The range of LEWCOS Centre Tapped Coils-already popu-lar among experienced constructors for their high efficiency-has now been completed. Wound with Litz wire, theygive greatest selectivity at a moderate price. All coils areidentical in external measurement. Obtainable from radiodealers everywhere.

LEWCOSLEWCOS CENTRE TAPPED COILS (Protected TYPO 1;),LIF

Coil No... .. 25

73

160

223

35

90

225

300

40 50 60 75 100 125 150 201 300

942

X60

188

X200

.00003 mid. .. 126

283

151 188 231 297 498 565 59! .7,95

141000025 arid. .. 316 391 500 652 995 1180 1414 2005 391

'0005 mid. 386 432 555 080 885 1330 1621 1960 2755 555 1960

Price 3/6 5/3 14/9 7/.

The LONDON ELECTRIC WIRE Co.& SMITHS Ltd.Play house Yard, Golden Lane, London, E.C.1.

ENTRE TAPPED(Protected Tkpe) COMPatent No. 27/384

ou must "wee aprecision instrument

shall) tunnyModern radio circuits call for critical tuning-criticaltuning demands precision condensers-precision con-densers means Pye condensers for accuracy and reliability.Pye Precision condensers are scientific instruments madeone at a time with great care. You need them to getthe best from your set.

FRICES-eoos, .0002, '0003 Mid. 17/6 each.'0005 Mfd. 18/6'00075 Mid. 22/6

Write for illustrated leaflets of P YE Receiversand Components (post free).

W. G. 1:01FE eat C . ,"Granta Works," Montague Rd.,

Announcement!The famous

LOEWE High Vacuum Resistancesand

LOEWE High Vacuum Block Condensers

LOEWE MIDI°

IOU/WADI° ii

are now available inGreat Britain. Theyhave been a full successon the Continent, andwill, no doubt, beequally favoured bythe British public.

Please mail the Couponbelow for free literature.

LOEWE RADIO COMPANY, LTD.4, Fountayne Rd., Tottenham, LONDON, N.15

Telephone :-Tottenham 2076

---tea, .,POST THIS COUPON TO-DAYrm...,"I To THE LOEWE RADIO COMPANY, LTD.,I 4, Fountayne Road, Tottenham, LONDON, N.15.

II

Please send me your literature concerning LOEWE HighIIVacuum Resistances and LOEWE High Vacuum Blockit

I Condensers. II

Name iI 11 Address . .

01 MO MI MI =I S 10 MY in Mb AO MU OM I. Sa hag



THE (Continued from page. 722.)

LEADING COMPONENT HOUSE amplifier then works in 'a perfectly satisfactorywemanner,and hope ,tilgt.t. both you and your

IN THE NORTH OF ENGLAND fan vt e p ease tt

" LONDON CALLING ! "" ONLY A NEWCOMER " (Sheffield).-" What

seems strange to me- is that when Sheffield'switches over' I can hear London calling asplain as Sheffield was. Does it come to my'aerial from London or Sheffield ? "

When Sheffield " switches over " they connectthe Sheffield aerial to the London studio (by landlinc).So when the announcer says, " London Calling," hisvoice comes down to Sheffield by landline, andoperates your local station. Actually he is speakin

, in London, but is working the Sheffield station bytelephone.

The most wonderful stock ofup-to-date Components andSets is held. Speakers andSets demonstrated in ourDemonstration Salon inDeansgate (bottom of MarketStreet) in quiet surroundings.

Parts for all the latest sets.including, the Cossor MelodyMaker, actually in stock. Cabi-nets made in our own Factoryat reasonable prices. Solid OakBureau (18 x 12 9 6panel)

Trade enquiries for cabinetsare invited.

A complete 3 -valve 1812 6Set in same ..

Will obtain Foreign Stations onthe Speaker.

If pop get it from Hash House it's the best

BUSH HOUSE40, Deansgate Manchester

And also at Shudehill, Manchester

EB ONITEBUSHES

FOR MOUNTING ONMETAL OR WOOD

PERFECTINSULATION

Orders under 1/- Two requiredsend Ild. post age 1 ' for each holeNUMBER 0 1 2 3 4 5 6Hole in Bush 6BA, 413A, 2BA, l", 5/16". 4". 7116°Price each: ld. ld. 16. ltd. 2d. 2d. 2d.

(Complete List of sizes free on application)DAREX RADIO CO

Waldram Rd., Forest Hill, London. S.E.112.6.' TRADE SUPPLIED.

"WET H.T. 13.11.7CTEEtImsBUT BRITISH. Complete Unite 3'6 per don Allgoods BRITISH MADE by BRITISH LABOUR.Jars 1/3, Since 1L, Sees 1/6 per don Carriageend Packing extra. Trade inquiries incited -DemonBattery Co..59,B ad Hand Wu Itha m a tow .H.17

EASY PAYMENTSLOUD - SPEAKERS, HEADPHONES,H.T.ACCUMULATORS. Anyttling WirelessSend a list of the parts you are requiring, and wewilt send you a quotation on monthly payments.H. W. HOLMES. 29 FOLEY .STREET,[hone infuse= 11. Gt. Portland St., W.I.

" P.W." TECHNICAL QUERY DEPARTMENT

Is Your Set "Going Good"?Perhaps some mysterious noise has =-= appeared and iS spoiling your radio

- reception 7-Or one of the batteries 7.4.:

F.- seems to run down. much faster than R-

E; formerly 7-Or you want a Blue Print ?-E.

Whetever your radio problem may be, remember that the Technical Query =T.- Department is thoroughly equipped to == assist our readers, and offer an unrivalled 1:= service. Full details, including a revised scale of E charges, can be obtained direct from the Technical Query Dept., " Popular

Wireless,'-' Fleetway house. Farringdon = Street, London, E.C.4.E. A postcard will do: On receipt of this an =E Application Form will be sent to yon == free and post free, immediately. Thisg. application will place you under noE., obligation whatever, but having the E7.-1, form you will know exactly what in- =E formation wo require to have bofore us E2.1 in order to solve your problems.

COILS FOR THE "REGIONAL TWO."R.J.S. (Wembley, Middlesex). - " What

number of turns will be required on the coilsto receive Daventry (5 X X), on the "RegionalTwo '1

Using the standard "Becol " ribbed former, andnumber 34 D.S.C. wire, 99 turns will be required forreaction. The grid winding should consist of 259turns, tapped at 70, 90, and 110 turns.

DIGBY'S CABINETSWrite for New 16 -page Catalogue

F. DICBY, 9 Banbury Rd.,8outh Hackney, E.9'Phone: Clissold 5458

From every anglePerformanceAppearancePrice

this High Capacity H.T. Batteryis the best you can choose.It will cost you a little more, but itwill last a lot longer-as,long, in fact,.as half -a -dozen small, cheap batteries. .Think of the money arid trouble thiswill save-and insist on

ColumbiaHigh Capacity

Radio BatteriesDrop a card jar literature.

J. R. MORRIS15 Kingsway, London, W.C.2

SCOTLAND:J. T. Cattlyright, 3, Cadogan Street, Glasgow

-"MELODY MAKER" COILS--New improved model. complete with stare and Wuxiscrews , lioaranteed wound to Messrs Cossorli.

. specification._:Pont 7/. 6 Free

KNIGHT & CO., 6, Chapel Street, London, E.C.Z.'Phone: Clerkenwell 4715 .

ADVERTISEMENTS

As far as possible all advertisementsappearing in " P.W." are subjectedto careful scrutiny benne publication,but should any reader experiencedelay o difficulty in getting ordersfulfilled or should the goods suppllenot be as advertised, informationshould be sent to the Advertise-ment Manager, "Popular Wireless,"4, Ludgate Circus, London, E.C.4.

FREEIt To advertise the Eagle ElectricI Irons we are giving away onefree with each of the first

ten orders we receive each week for a

CHAKOPHONE WIRELESS SETwhich is complete in every detail and includes a freeinsurance policy.

ro/- per month for valve sets, no deposit.Radio Dealers -Can stiSply on our H.R. - terms.

For free Booklet write your name and address on the back ofthis advertisement and seal in id. stamped open envelope to:-

EAGLE NM RAD/0 (P.W.),45, Pall Mall, London, S.W.1.

Tr

TLPIRTOID TUBING

The Ideal FormerTubes of any diameter, wall, and length supplied forformers to make your aerial coils and specialtransformers.: Pirtoid is recommended .by the TechnicalPress and by the leading wireless journals. ,An expertwrites: " Pirloid.is admirable for all wireless purposes,being easy to drill-and is unbreakdble."Clarke's have been well known for many years as Tiir.insulating material manufacturers, and Pirtoid iu-corporates the results' of their experience.

Pirtoid snitableJor the formers for use in theCossOr " Melody Maker."

Sole Manufacturers :H. CLARKE & CO. (M/er). LTD., Atlas Works, Old Trafford, Manchester,.

1111111iiiifluffs

I II1111

411=1111

Wr to forpr.ce I st,


ti.W."a.011:141114.N.MVAPINS.4%0:fig4f,9417416640fairttcltigitiat__

NEXT WEEK !

Price 3d. asUsual !

vraxvimr.aswziv.cntimiqoacfstr.owsuilr

The Finest ChristmasNumber Ever Published

Many famous people havecontributed to this SpecialIssue, including :-

The Rt. Hon.J. RAMSAY MACDONALD,

P.C., M.P.Sir OLIVER LODGE, F.R.S.

EDGAR WALLACE.

Sir GRANVILLE RYRIE(High Commissioner for Australia).

Sir JOHN REITHetc., etc., etc.

THIS year's Christmas Number of " POPULAR WIRELESS " willsurprise you. Greatly enlarged in size, its cover specially paintedby a well-known artist, " P.W." on sale December 8th will be

too good to miss.

The first constructional details of .a NEW CONSTANT REACTION RECEIVERby Mr. Percy W. Harris, M.I.R.E., and articles by Captain Eckersley,W. James, G. V. Dowding, G. P. Kendall, and many others willprove of wide interest to amateurs ; and besides these technical featuresother famous people-a few of whom are mentioned above-contribute to" P.W.'s " SPECIAL CHRISTMAS NUMBER.

Edgar Wallace, for example; the author and playwright of world-widefame, writes a special article, " WHAT WIRELESS MEANS TO ME," andthere are many other features which will surprise you when you open yourcopy of " P.W."

.-

sisagesr_wavecozoAbimAncaamwitenceDmirmetestaitamitmantidievisgansaivaitmatanietwarforwaamit)00'


I", ..,,,,,,

WIRELESS A

0

COMPONENTS ,,pGIVE UNEQUALLED SERVICE

Order from this List and save money.Orders 5'6 value carriage paid.

Under 5,6, 26. per 1:- for packing, - &c.(5)S.L.F.CONDENSER

EboniteTroliteVOWextra

Ends and 4-dial '0005 519

518. Vernier dial1/6.

ACCUMULATORS. - Ex ideD.T.G. 416,'D.F.G. ate, W.J.10-v. H.T. type 5/-, 20-v. 12/6.OLDHAM 20.v. H.T. unit, 12)6.AERIALS. -100 ft. 4" coppertape 1/9, 7/22's Bright 213,Ehamelled 3/3; Elebtron '118,Superial 2/6. O.V. complete216, Ashton Spreaders 12)- pr.INSULATORS.-Large Shell3d., Reel or Egg 16., Climax1/- pr., ditto -with shock_ ab-feathers 31- pr., Gal. Pulleys4d., 100 ft. Gal. Straining Wire116, Straining Bolts 6d.

CONDENSERS. - DubilierK.C. slow motion. 0005 12/-;Reliability S.L.F.. 0003 5/6.ditto -0005 5)9; Igranie B.B.Noel. 4/-; Pormo mid -log 10/6;Jackson -0005 11/6, Neut.3/6; McMichael- Balancing4/9; Peto-Scott Midget 5/6,Neut. 51. & 6/3; Ormond No.3 S.L.F., 0005 mfd. 43)-,L.P. TRANSFORMERS.-R.I. Straight Line and MultiRatio 251.; Genera Purposetype 151.; Ferra nti A . F.3 25/,

VERNIER (23)2 -COIL HOLDER

Slide Action , ....isi..

Nr.!.A.fil5,"'

..,4e, 4',NN,AN.2000ly For Base-

. board 2 /6or Panel.. .../

VERNIER

COIL

HOLDER

r,2-way gearedCoil Holderwith metalwork nickel

Slong

control 2,handle `

VALVE -HOLDERS.-Benia-min Antiphonic 2/-; Lotus 1/9i/.1.-13;iirWndept-214 ;149ajlieC1/o4n;Reliability, unequalled, 119;N.E. . Valve Sockets, flush tit -tin. 16.; Superior 6d. Red-fern's Rubber Holder, 2/6.H.F. CHOICE - COILS. -RI & PARLEY 9/6; Wright& Weaire 616 Watmer 51:

'McMichael 9/-; Lissen 518.1HEADPHONES. - Lissen8/6; Reliability 5/6; Adjust -able 816; Dr. Nesper 1216 A.8/11 ;B.7.H.15/-;Brandes13 /6.

.ti 'TAYLOR&4. RADIO HOUSE.

MACAULAY ST., 111.10DERSFIKt)'

EC:. 1)...' .1 7.,/ 341 Gnirns:71.401201101- HU001115F 1 1'0. Zti:bnie

REPAIRS -THREE MONTHS' GUARANTEEaccompanies all our repairs. Any

make of L,F. Transformer, Headphone, or LcudSpeaker, re-paired to maximum efficiency. II- Post Free. Terms to Trade.

214, HIGH ST.. COLLIERS WOOD,LONDON, S.W.19. (New Address).REPAIRS

/AO

7x 6. 1/38 x 6, 1/4Ox 8, 2/10 x 9, 2/42 x 10, 3!-4x12, 4/-4x 7 2/76x 8, 3/28x 5, 1/2

IvELs9x 6 I/

I I X 8, 2 312x 8, 2612x 9, 2 1014..(10 3:'516 x 9 3'621 x 7, 3324 X 7, 4/.

in. thickPost Free.

Money back guarantee that each and all Panels arefree from surface leakage Meager test Infinity.CROXSONIA CO., 10, South St., Moorgate,E.C.2.

'Phone: Clerkenwell 7853Agents: John Henry Smith 139, Anlaby Rd., Hull.

L. H. Helyar, 82. thamberlin Rd., Norwich.A. Stredwick & Co., 27 The Market, Chatham.Boynton &Co..Ltd , 34,Braciford St.. Birmingham

SOLID MAHOGANY CABINETSMoulded top and bottom; one or two-piece hinged lid;9" baseboard; 5' poi. ebonite panel and bark strips.Well made and nicely polished. Drilled, 1/6 extra.16 x 8 28/, 21 x 7, 32/6. 20 x 8, 33/6. 26 x 8,42,6.Any size pro rata. -Carr. paid.State requirements forestimates.-J. H. TOOMEY,137, River/Wale Rd., Hlghbury,

'he

*

PLEASE be sure to mention"POPULAR WIRELESS"when communicating withAdvertisers. THANKS !

11,1

EVERYTHINGSyRADIO

1111Rivisomi

WOOLLDRIDGE RADIO CO. LTD.2t' LISLE ST. LEICESTER SQVARE

LONDON. W. C.1.

* 4--4- *

SHORT-WAVENOTES.By W. L. S. +

*ONE of the strangest features of -short-

wave work is the extraordinary wayin which conditions will change in a

comparatively short space of time' withabsolutely no apparent reason, To take arase in point, Wednesday, November 18th,was one of the best nights for the receptionof the.. United States amateurs that thewriter can ever remember. Fourth districtstations were coming in well on a two -valvereceiver as early as 8 p.m. At 11.30 alldistricts were audible.

No watch was kept on the Thursday andFriday, but on the Saturday and Sundayit was practically impossible to log an " N U"of any description. It is also interestingto note that last year's " rule " still holdsgood-namely, that when the N U stationsare weak or inaudible, the Brazilians comein very well indeed.

R. C. Coupling Best.At the time of writing conditions for

transatlantic work generally seem verypoor, yet 2 X A D on 22 metres, relaying abaseball match. is being received' at goodloud -six a'mr strength with three valves.

It is well worth while experimenting withresistance -coupled note magnifiers for short-wave work, as it appears in quite a numberof cases that annoying noises resemblingartificial atmospherics are extraneous noisespicked up direct on the primary of thefrequency transformer. Suffice it to saythat the writer is now using two resistance -coupled stages, giving an amplification verylittle in excess of that previously obtainedwith one. transformer stage (with a step-upof 4.1: 1), and although the signals are veryslightly stronger than before, a good per-centage of the mush has disappeared. Acertain type of mush, if one may use theexpression, seems to have remained, butthere is no doubting the improvement ()Vol.the old set.

An anode rectifier also improves matters,for a fair percentage of the " mush " isin some cases due simply to a faulty gridcondenser or leak on the detector, andaccordingly disappears when they areremoved.

New French Station ?From the results of the Washington

Conference it seems probable that amateurswill in future take rather more interest inthe 80- or 90metre band of wave -lengths.It was only a few nights ago that a real" old stager " remarked to the writer thathe had never heard the New Zealand andAustralian stations at such a strength as heused to receive them on 90 Metres or so. andthis is certainly true. Meanwhile a perfectlygood band. of kilocycles is going begging !

Ii D K A. on apt,troximately. 00 metres isanother station that has been " comingacross " remarkably well during the pastfew .weeks. By 11 p.m. his strength hasoccasionally. been comparable- with -that of2 L 0 I There is also a very powerfulFrench station working on the same wave-length, and the writer would be very gladto hear from readers_ who -have heard thisstation.

?,1to

rear.'ton Atnata 100

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of ilta-et_DCS the cam

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THE " PROGRESSIVE" TWO.(Continued from page 695.)

The flexible from the 0002 mfd. fixedcondenser should first of all be taken tothe second tapping from the bottom ofthe coil, and when the handling of the sethas been thoroughly mastered it can betaken to the,Iowmr tapping. This increasesthe selectivity of the receiver and makesthe tuning somewhat keener.

You will find that the original 0005mfd. variable condenser-which, for clarity,I will in future refer to as the centre variable--is much the closer in tuning, and thatthe aerial tuning variable is somewhatbroad in its control; These- two variablesshould be rotated -"more or less togetherin the first instance, but as the desiredstation is heard the reaction condenserand the centre variable can be " balanced,"and subsequently the aerial variable ad-justed until loudest signals result.

An incidental advantage which resultsfrom the use of the H.F. circuit adoptedis that the H.F. stage can very easilybe cut out in the Progressive set. To do this,all that is necessary is to withdraw theH.F. valve from its socket, disconnectthe flexible lead from the grid coil, and takethe aerial flexible lead to a tapping on thegrid coil instead (as in the case of the

Progressive" One).

The Third Valve.Very simple, isn't it ? And it is also

much more efficient than switching.Now I am going to leave you for a while

to get the two valves going properly.You must not even think about the

third valve until ytii are satisfied thatthese two valves are giving two -valveresults, and that you can handle thereceiver with the aplomb of an expert.I want you to be so closely acquaintedwith the controls of the set that whenyou do add the third valve, you will beable to tune stations in direct on to theloud speaker. And then, when I havecompleted the programme and you havehooked up the fourth valve, you will beable to challenge with confidence anyaverage five -valve man to a " stationgrabbing " contest.

Next time we come to the first L.F.valve which is to be transformer -coupled.You can, if you like, leave this week'swork over and connect up the first L.F.before bringing in the H.F. But I do notadvise this procedure because it is muchmore difficult to tell whether an H,P.stage is working really properly when itis tacked on to a two -valuer than when itis added to a one -valve set.

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THE BENJAMIN RHEOSTAThas its windings protected inside the dial. Threewindings -6, 15 and 30 ohms. Price 2/9.

THE BENJAMIN IMPROVEDEARTHING DEVICE.

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THE BENJAMINBATTERY ELIMINATOR

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Electradix BargainsTABLE ELECTRIC PROJECTORS for Photo Slide

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THE DIX-ONEMETER. The 55 Range " Rdlls Royce 'of Radio. An instrument of exact precision reading,40 micro -amps to 20 amps., 2 milli -volts to 2,000 volts.Measures Crystal Signals or Resistances from 50 ohmsto 50 megohms. Instrument De Luxe, 55/. Multi-pliers, each 6/6. D.C. Eliminators, 30/. complete.

VALVE BARGAINS. AC to DC 50 m fa Cossor, B.T.H.,M.O., &c., with Holder, 8/6. List 25/-. Neons, 2!6.8 v. Grid Bias Battery, 1',

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ETON Primary H.T. Battery. P.I Porous Pot Cells,SI and S2 Sac Cells. All complete for assembly.

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,"

TECHNICAL NOTES.(Continued from page 698.)

or in total darkness. The system alsomakes .use of what are called markerbeams " placed at intervals of about25 miles along the air route, these actingas radio " milestones." In addition to this, -radio telephony is used to keep the pilotinformed of lauding conditions and weatherprospects. The control centre is alsoequipped with receiving apparatus so thatmessages may be received from aeroplaneswhich are provided with transmitters. -

Microphone versus Ear.-The human ear is remarkably sensitive

as an acoustical pick-up device, and untilthe 'advent of broadcasting, in fact, untilvery recently, electrical and suchlike de-vices for picking up sound were very muchinferior to the ear in sensitiveness.

With the increasing demands upon themicrophone, however, great improvementshave been made in pick-up devices, and nowthe broadcast microphone may even sur-pass the ear considerably in sensitivity.

A curious . example of this was noticedsome little time ago, daring one of the well-known attempts to broadcast' the song ofthe nightingale. Listeners heard the soundof a bird which was presumed to be somelittle distance from 'the microphone, whilstthe engineers in charge of operations failedentirely to hear the sound., It is presum-able that the - microphone picked lip thesound, whereas the engineers were unableto do so. The sound picked up by themicrophone was, of course, amplified in theusual way and reached the broadcastlisteners, although those in charge of opera-tions were even unaware that any song wasbeing received at all,

Socket Power.With the considerable- advances in the

design of power -supply devices, for takingthe radio power from the electric light,improved components and subsidiary de-vices have -become more and more neces-sary. One of the essential components,of course, is the smoothing condenser, or setof - condensers, and in cases where fairlyhigh output voltages are required, the con-densers must be properly designed andconstructed if they are not to prove thecause of breakdown trouble.

I notice that one firm is now producingspecial condensers contained in a metalhousing about 4 in. square by 5 in. high,the condenser having a capacity. up to0 mfd., and being provided with stoutprojecting terminals at the base of themetal container. These condensers aredesigned for continuous use with direct -current voltages up to 1,000 volts, whichmakes them particularly useful in high -voltage power units giving output voltagesof as much as 300 to 500 volts. It is im-portant that the filter condensers shouldbe capable of withstanding voltages con-siderably in excess of the rated output,for various reasons, which you will see atonce. These condensers are claimed to;save a capacity within about 10 per centof the rated value. They are extremelycompact and very small for their electro-static capacity. The metal container of thecondenser is completely filled up with in-sulating compound so as to seal in the con-densers and provide protection from.atmospheric and other causes.

Loud$peaker Improvements.I suppose most loud -speaker reproducer

units are fitted with an adjusting screw forvarying the sensitivity. This adjuster is not,

--however, always an unmixed blessing, fornot only. is its use, or misuse, frequentlyresponsible for' .much distortion-whichis often blamed upon other parts of thecircuit-but also the careless or unskilled

. use of the adjusting screw may result inpermanent damage to the electro-magneticunit.

An enterprising American manufacturerhas placed on the market a very handy andcompact loud -speaker unit in which thesedraWbaeks are entirely avoided by thesimple process: Of adjusting the unit once-and for all before it is sent :out -from thefactory. As no adjuster screw is pio-Vided,it is impossible for the user in ordinarycircumstances to interfere with the repro-ducer in any way.

' In addition to being inexpensive, it is.provided with an adapter for the outlet tubeso that it may be fitted to most existingtypes of horn.

-Personally, I think there is a good dealto be said for this permanently -adjusted,type of reproducer, not only because itprevents trouble of all kinds, but becausethe simplification which results in themanufacture or assembly-by the omissionof the adjusting system --permits of it beingproduced at a distinctly lower price.

A Trouble Saver.A very simple battery -testing device

pow being made by the Beede InstrumentCompany, and known as the " Test -A -Bat,' consists of a small " watch " meterwithits dial marked into three sections,instead of being calibrated in the usualway. These three sections are respectivelylabelled "start charge," 4' O.K." and "stopcharge." The meter is provided with twometal brackets by means of which it maybe permanently attached to, the terminalsof a storage battery. There is a smallbutton on the edge of the meter .which,when depressed, closes the circuit and; givesa reading. The meter is, therefore,always ready for use, but current onlyflows when the button -switch is depressed.In this way the condition of the batterycan always, be determined instantly andwith a minimum of trouble.

DID YOU KNOW THAT

WHEN a set slowly builds itself up intoa tremendOus howl the trouble isgenerally due to the fact that the

loud speaker is too close to the set or ispointing directly towards it ?

If you are running long leads round thehouse so that the loud speaker can be usedin different -rooms, it is a real economy touse a choke coupled or a transformer -coupled output, to prevent H.T. leakage ?

* * *

The long -contact on a flashlamp cellis the negative, arid the short one is thepositive ? * _ . *

Distortion due to high -frequency current -getting in on the low -frequency side of areceiver may be presented by the insertionof a high resistance, in series with the gridsof -low -frequency valves

RIR

December 3rd, 1927. POPULAR WIRELESS

g

*.

NTIVSPROM/0016Svivrtit cs AI

Simplymove

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say , Stucl

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gives place

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wlaichis hardly

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ait

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Weil bea universal

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neuralizing,

capacity and magneticreaction.

Reinartzand capacity

controlledreaction,

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acWatitages

equallyapplicable

in the caseof both

loltg and

?RICECONIPLETE

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'The popularityof the Standard.

RetroactiveTaller has steadily

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and published every Thursday by the Proprietors, The Amalgamated Press, Ltd., The Fleetway Rouse, Farringdon Street, London, L.C.1. Ad rtiserrientii s : Messrs. T. H. Lile, Ltd., 4. Ludgate Circus, London,,E.C.4. Registered as a newspaper and for transmission by Canadian Magazine Post. Subscription rates'

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