t
t
GEOR(:E H. COLLINS, Dcputvditor-in-Chief
llRIr~ONC HA NcE,S.. $ . GO(L, s~tIT, R. (i. HERB, HIEEwr}.J A}Es ,J IL1 .*N ~.~N1 l>r ’,
.J .\ MEs L. LAWSON, LEON B. LINFORD, CAROL G. MONTGOMERY, C. NEWTON, ALBERT
11 , STONE, LOITS A. TrRNER, GEORGE IZ. VALLEY, J R,, HERFIERT H. WHEATON
1.
.2 ,
3 ,
4 .
5.
6.
7.
8.
9.
RADAR BEA{ONS --Rok/ .x
LORAN--PiWW, .l[cli’eu zie, CMI W“rrodw ard
PC,LSE GEN EEATO RS -Glaww arLd I.ehmqz
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~LYS ~RONS ANI) 31 1(;r L0 wAvk ; TRIODEh
Hut, li lLorL, l irLipp, (LtLdKMper
PRINCIPLES OF MICROWAVE (.’IRc(IIT+ – i
lfOJLtqOl)Lerf;, f)ic!w, and Purcell
WAVE~UIDE H.A.NT)BOOK J la , cwitz
‘rEcHNIQUE OF .M1CROWAVE }IEAsLREMENT+ .Ilon l!lon wrv
MICROWAVE ANTENNA THEORY AND I)ESI,;X -S,lw,
PROPAGATION OF SHORT R.ADICI WAVES—Kf’r’f
MICROWAVE ~LTPLExERs—s?n7( ~~in and ~ontgfrmlerg
CRYSTAL Rec t ifie r s—Ter re.y an d J V hifm er
MICROWAVE M1 xERs—Pou n d
COMPONENTS HANDBoOK—Bkzckhu rF{
nd J Vdm an
WAVEFORMS—chanGt?, Huqh es, h fa c.V ich ol, S a !lre, an d li’z lliam s
ELECTRONIC TIME MEASURE~ENT:—(’h aNCP , Huk izcr , .l Jac.V i.hoi ,
a )~d JVzllia n ls
E LE CTRONIC I NS TRV MENTh —Gwen u wwi, Ho/ d u II I, u nd M u clr!a e
(’ATHODE RAY T[BE I) KrLAYs-SOW,, S/ fir r , an d I-a lle?/
31 1 CROWAVE RECEIVERS— l“a 71 VoorhLs
‘r HRES HOL1 ) SIG NALS—La UMOn on ff Uhknki
‘~NEoriY OF SERVOMECHANIS~S-J a~GS, .Yich ok , WLd PhilLip.*
RAi, IN SCANNERS INLI RAr)oM ~s-Cad ~, h -arelitz, an d T urn er
~OMPUTING h~ECH.ANISMSNDhNK.4GE s—&ohada
INrrEx-Henney
OFF ICE OF SCIENTIF IC RESEARCH AND DEVELOPMENT
NATIONAL DEFENSE RESEARCH COMMITTEE
.411 righ ts rescrvd . Th is book, or
purtsthereoj, m aynotbc R eprodu ced
in any-form without perm ission of
the p?[blishers,
 
J OHN F . BLACKBURN
P. F . BROWN
Foreword
T
HE tremendous research and development effor t that went into the
development of radar and rela ted techniques dur ing World War II
resulted not only in hundreds of radar sets for military (and some for
possible peacet ime) use but a lso in a grea t body of informat ion and new
techn ques in the elect ron ics and high-frequency fields. Because this
basic mater ia l may be of gr eat value t o scien ce and en gineer in g, it seemed
most important to publish it as soon as secur ity permit ted.
The Radiat ion Laboratory of MIT, which opera ted under the super -
vision of t he Nat ional Defen se Resear ch Comm it t ee, u nder took t he gr ea t
t a sk of pr epa r ing t h ese volumes.
Th e wor k descr ibed h er ein , h owever , is
the collect ive result of work done at many laborator ies, Army, Navy,
university, and indust r ia l, both in this co n t ry and in England, Canada,
a nd ot h er Domin ion s.
The Radiat ion Laboratory, once its proposals were approved and
fin an ces pr ovided by t he Office of scien tific Resea rch a nd Developmen t.
ch ose Louis Pi’. Ridenou r as Editor -in-Chief t o lead and dir ect t he en tir e
project . An editor ia l staff was then selected of those best qualified for
this type of task. Finally the authors for the var ious volumes or chapters
or sect ions wer e chosen from among those exper ts who were int imately
familiar with the var io s fields, and who were able and willing to wr ite
the summaries of them. This en t ire staff agreed to remain at work at
MIT for six months or more after the work of the Radiat ion Laboratory
was complete. These volumes stand as a monument to this group. “
These volumes serve as a memoria l to the unnamed hundreds and
t hou sa nds of ot her scien tist s, en gin eer s, a nd ot her s wh o a ct ua lly ca rr ied
on th e re ea rch , developmen t, and en gin eer in g wor k t he r esu lts of which
are herein descr ibed. There wer e so many involved in this work and they
wor ked so closely t oget her even t hou gh oft en in widely sepa ra ted la bor a-
t or ies that it is impossible t o name or even t o kn ow th ose wh o cont ribu ted
t o a pa rt icu la r idea or developmen t .
On ly cer ta in on es who wrot e r epor ts
or a rt i les h ave even been men tion ed.
Bu t t o all th ose wh o con tr ibut ed
in any way to this grea t coopera t ive development en terpr ise, both in this
cou ntr y and in England, t hese volumes ar e dedicat ed.
L. A. DUBRIDGE.
I
Preface
T
HIS volume is in tended pr imar ily as a compan ion and reference
work for Vols. 18 th rough 23 of the Radia t ion Labora tory Ser ies. It
con ta ins data on a number of cla sses of elect r ica l r ind elect ron ic com-
ponen ts whic a re of pr incipa l in terest to the designer of receiving and
test equ ipment . In so fa r as poss ble it emphasizes the componen ts
which wer e developed by or under the sponsorship of th e Radia t ion Lab-
ora tory, or were of pr imary impor tance in it s work . In order to avoid
a on e-sided pr esen ta tion , h owever , t his m at er ia l h as been su pplem en ted
with ot her data so th at in m ost cases an individual ch apter a pproxim ates
a su rvey of cu rr en t pra ct ice in it s pa rt icu la r field.
The t it le “ Componen ts Handbook” is undoubtedly too inclusive for
the volume as published, since the circumstances under which it was
wr it t en have unfor tuna tely preven ted the inclusion of chapter s on
severa l impor tan t classes of compon en ts and have a lso had some effect
on the con ten t s of those tha t were included. The most ser ious omission
is proba bly th at of fixed con den ser s.
Chapter s were a lso projected on
a ir -cor e in du ct or s, on m ech an ica l compon en ts, a nd on sever al ot her su b-
jects. Credit is due the au thors who con tr ibu ted to these chapter s; the
omission of their work was due neither to any fau lt s of the work it self
nor to a lack of in terest in the subject ma t ter , but solely t o the fact tha t
t he term in at ion of th e Office of Publica tion s ca used th ese ch apters t o be
left ou t. Their omission is a ser iou s if u na voida ble defect .
The completeness of coverage of a pa r t icu la r field depends in la rge
measure upon the amount of t ime which the individual au thor was able
to devote t o it . The nece sity for the immedia te acceptance of postwar
jobs, usua lly fa r from Cambr idge, made it impossible for most of th e
a uth ors t o ch eck th eir wor k in fina l man uscr ipt form.
In such cases the
editor hopes tha t the colla t ion and cond nsa t ion of the or igina l dra ft s
have not resu lted in ser ious er ror s of fact or in undue distor t ion of the
presentation.
In order to make the volume usefu l both to the academic resea rch
worker and to the engineer in the indust r ia l labora tory the editor has
 
PHEFA Ch’
with a reasonable amount of specific da ta , la rgely in tabular form. For
discu sions of t he a ccura cy and balance of sever al of t he ch apt ers indebt -
edness is expressed to their authors or t o o hers equally familiar with t he
subject s. These discussions have considerably improved t he book.
It is a plea ant ta sk to record apprecia t ion of the help of the many
people, bot h in t he Office o Publica t ions of t he Radia tion La bora tor y and
outside, who have had a hand in the prepara t ion of this volume. The
lack of space prevent s the list ing of names, but th is omission has been
rect ified as fa r as possible by the inclusion of credit lines t o sources out -
side t he Labora tory and by the following list of sources of t he individua l
sections.
In a book such as this one it is difficult t o appor t ion credit fa ir ly
because many of the chapter s a re the result of a process of synthesis and
rea rrangement that left lit t le of the or iginal reactant s. The names list ed
at t he heads of the chapters a re those of authors who are responsible for
m ajor por t ions of t hose cha pt ers; a somewha t m or e deta iled list of credit s
follows: O. Abbia t i, Sees. 12.9 through 12.11; F. N. Bar ry, Chap. 14;
P. F. Brown, Sees. 5.1 and 5“2; F. E . Dole, Chap. 8; G. Ehrenfr ied, Chap.
2 and Sees. 3.14, 3.15 and par t s of Sees 3.9 and 3.10; M. D. Fagen, Sees.
1.1 through 1.11, 3.1 through 3.8, and par t of Sec. 3.11; S. Frankel,
Sees. 5.3 through 5.5; S. N. Golembe, pa r t s of a ll sect ions of Chap. 4;
W. F. Goodell, J r., Sees. 101 through 10”16; E. A. Holmes, III, Chap. 9;
M. M. Hubbard, Sees. 12.5, 12.6, 12.8, and 12.12; M. M. Hubbard and
P. C. J acobs, J r. Sees. 12.3, 12.4, and 12.7; H. B. Hunt ington, Chap. 7;
H. E. Kallman, Sec. 1.12 and Chap. 6; T. B. Morse, Chap. 11.
The volume editor is responsible for the remainder of the book and
for numerous interpola t ions in the t ext s of some of the authors above.
F or a dvice and for miscellan ous dat a in conn ect ion wit h t hese in t er pola -
t ions, credit is due t o a number of members of the Radia t io Labora tory,
including the following: H. F. Brockschmidt a d D. N. Summerfield, fo
data on engine-dr iven genera tor set s in Sees. 12.3, 12.4, and 125; C. E.
Fost er , for reviewing Chaps. 10 and 13 and for addit iona l data fo these
chapters; C. E. Fost er and E R. Perkins, for or iginal rough dra ft of
Chap. 10; M. M. Hubbard, for reviewing Chaps. 4, 11, and 12; J . M.
McBean, for data on the elect ronic line-volt age stabilizer of Sec. 12”13;
R. J . Sullivan, for reviewing Chap. 8, and for addit ional da ta ; C. A.
Wmhburn, for da ta on high-v~ltage power-supply t ransformers of
Sec. 4“3, a nd for da ta on M-106O r egu la tor t ube in Sec. 14.2.
It may seem invidious to single out an individual for credit when so
many have helped, but the editor cannot refra in from expressing gra t i-
t ude to Mr. F. N. Bar ry, who per formed the labor ious task of compil ng
the tables of receiving tubes and who wrote the accompanying text for
Chap. 14.
 
!
Labora tory and his acceptance of another job, and at considerable per -
sonal sacrifice.
The editor is a lso deeply indebted to Mrs. Barbara D. Cot6 for her
fa it hfu l a nd efficien t ser vices a s edit or ia l a nd pr odu ct ion a ssist an t, a nd t o
his wife, H ar riet , for aid in t ypin g and pr oofr ea din g.
I
HooK-uPWIEE. . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Physica l Proper t iesof the FinishedWire. 9
Elect r ica lProper t iesof the FinishedWire 12
. . . . . . . . .
The Meta l Braid. . . . . . . . . . . . . . . . . . ...22
The Outer Cover ing. . . . . . . . . . . . . . . . . . ...22
1 . 10 Physica l Proper t ies-ofthe FinishedCable 23
1.11 E lect r ica lProper t iesof the FinishedCable. 24
1.12 H]gh-impedanceCable.. 27
2 .1 The Choice ofa Resistor . . . . . . . . . 33
2 .2
2 .3
2 .4
2 .5
2 .6
2 .7
2 .8
2 .9
StandardResistanceValues
3.1 StandardTypes . . . . . . . . . . . . . . . . . . . ...65
 
3,4 Rat ings. . . . . . . . .
37 Con st ru ct ion .
38 Elect r ica lCharacter is t ics
SpECrAEPURpOSENDMISCELLANEOUSESISTORS.
CHAP ,4. IRON-CORE INDUCTORS .‘
42Reactors . . . . . .
4.4 BroadbandTransformers
CHAP. 5. PIEZOELECTRIC DEVICES
5.1 Useof Qua rt zCryst a ls in Rada r
5.2 Specia lQua rt zCu ts.
SUPERSONICRYSTALRANSDUCERS.
5.5 The Reflector . . . . . . .
6.3 Lumped-parameterDelay Lines
77
80
82
87
87
90
91
95
95
97
99
Crystal Design Problems
CHAP.8. POTENTIOMETERS ,
82 Moun tingsand Enclosur es.
8.3 Leads and At t a chmen t s.
8.4 Co tact s . . . . . . . .
8.7 Other Character is t ics
8.8 Test Met hods and Equ ipmen t
8.9 Commercia lPotent iometers
9.1 Phase-shift ing Condensers
10,5 Common Synchro Systems.
107Torque . . . . . . .
10.9 Er rors . . . . . . . . . .
10.11 Mis cella n eou s Specifica t ion s
RESOLVERS. . . . . . . . . .
10.13 S in gle-fr equ en cy Syst em s
10.14 Use of Synchros with Nonsinusoida l Voltages
MISCELLANEOUS ROTARY INDUCTORS.
THE CHOICE OF AMOTOR
11.2 Miscellaneous Features
TYFES OF MOTORS, . . . . . .
11 . 3 Dir ect -cu rr en t Mot or s
11.4 Alterna t ing-cu rrent Motors
11.5 Special Types of Motors.
11.6 Motor Attachments and Auxilia ries.
CHAF. 12. POWER SUI’PLIES
12 . 1 Choice of a Power Supply.
PRLME POWER SUPPLIES . . . .
12,4 Select ion of an Engine-dr iven Genera tor Set .
GENERATORS
12 .6 Aircra ft -engin e Gen era tors .
CONVERTERS ,. ...,,..
12 . 7 Mot or -gen er at or s a nd Dyn amot or s
12.8 Inver ters
12.10 Vibr at or Con st ru ct ion
12,11 Vibr at or Cir cu it s.
REGULATORS .,... .. ..
12 . 1 2 Gener a tor -volt a ge Regu la t or s
12.13 Lin e-volt age Regu la tor s.
CHAP. 13. RELAYS AND RELATED DEVICES
13.1 Contacts . . . . . .
13.3 Opera te and Release Time
13.4 Other Aspects of Relay Design
.,
13.6 Devices Rela ted to Relays
13.7 Relay Tests at the Radia t ion Labora tory
CHAP. 14. RECEIVING TUBES
14.2 Diodes . . . . . . . . . .
14.3 Triodes . . . . . . .
599
BY M. D. FAGEN AND H. E. KALLMANN
This chapt erwill be concern edonly with two main classesof conductorsfor which
joint Army-Navy (JAN) Specificat ionshave been issued. These includethe types of
insu la ted wire ordinar ily used in in terna l chass is ir ing and in in terconnect ions
betweenchassis where the frequency, voltage , and power levels permit , hereafter
referredto as wires, and the recentlydevelopedlow-loss flexiblecoaxial cables gener-
ally used for th e tra nsmissionof tr iggers,gates,i-f an dvideo signals,an dhigh-voltage
modula torpu lses . Da t a on magnet wir e will be found in Chap. 4and on res is tance
wire in Chap, 8 of th is volume.
HOOK-UP WIRE
The class of wires used for hook-up and cabling purposes normally
consists of a solid or st randed t inned copper conductor , in sizes AWG
No. 24 to AWG No. 6, covered by a pr imary insula t ion of a na tura l
rubber compound, a synthet ic rubber like But yl or Buna S, or one of
th e pla st ic ela stomers like Vinylite or Polyethylene. Over this insula tor
is an outer cover ing of a text ile bra id made of cot ton, fiber glass, nylon,
or rayon. The pr imary insula t ion may be applied by extrusion, by
dipping or spraying, or in th e form of sever al la yer s of tape, subsequent ly
amalgamated or cured to form a cont inuous tube adher ing to the con-
ductor . The outer cover ing is a closely woven braid, colored and often
ca rr yin g a con tr ast in g t ra cer for iden tifica ti n , a nd t rea ted with mult ple
coa t ings of t ransparent flexible lacquer to impar t a smooth finish. Each
of the many possible combina tions of pr imary insula t ions and outer
cover ings has character ist ics and proper t ies that suit it par t icula r ly for
some specia l condit ions of opera t ion but there is no single type tha t
meets every requirement . The proper t ies of the var ious insula t ions
commonly used and of the fin ished wires commercia lly obta inable will
be discussed drawing freely from the limited amount o published infor-
m ation a va ila ble, 1 a nd fr om per tin en t join t Army-Na vy Specifica tion sz
a nd Compon en ts Lists. 3
‘J . M. Caller,“ Chara cteristicsof Radio Wire and Cable,” Radio,28, hTo.5, 25-28,
58 (May 1944),a nd No. 6, 28–31,64,66 (J une1944); E. D. Youmans,“ Plast icInsula-
tionfor Condu ctors,” Elec.World,CXX,457–459(August 1943)an d 812–815(Sept em-
ber 1943); Tablesof Dielectr icMaterials, I and II, Laboratoryfor Insulat ion Research,
MassachusettsInstitu te of Technology.
2Joint Army-Navy Specifica t ion JAN-C-76, Cable (Hook-up Wire), Elect r ic,
Insulated,Radio and Instrument,Aug. 191945.
Standards.@ency, Red Bank, N. J .
1
[SEC. 11
A lis of hook-up wires may be found in the Army-Navy Elect ronics
Standards Agency Standard Components List as issued May 5, 1945 and
J uly 20, 1945. These have been approved either by the Signal Corps
u nder Specifica tion 71-4943 or by t he Army-Navy E lect ron ics St an da rds
Agen cy u nder J oin t Specifica tion JAN-C-76, wir e t ype WL (gen er al pu r-
pose applica t ions, thermoplast ic insula t ion for use at 600 volt s rms or
less.)
For convenience of reference, the J AN type designa t ion is built IIp
as follows:
1.
2.
3.
4.
5.
let ter s r epr esent ing the t ype of wire, as WI.;
numbers giving t he approximate cr oss sect ion of the conductor in
t hou sa nds of cir cu la r r oils, a s WL-1~ for 1500 cir cu la r r oils;
a number in parentheses designat ing the minimum number of
st rands, as WL-1+ (1) for solid wire, or WL-lij (7) for st r anded
wire made up of 7 st rands
numbers represent ing the AWC wire size, as W’L-l+ (7) 18 for
No. 18 st randed wire;
numbers represent ing the color code, as WL- 1* (7) 18-96 for
white wire with a blue t racer .
1.1. The Conductor .—The conductor used in hook-up wire is soft
annealed round copper , st r anded or solid, and almost a lways t inned.
The reasons for the choice of copper are well r ecognized: low cost , good
conduct ivit y, low t emper a tu r e coefficien t, h igh duct ilit y, a nd good r esist -
ance to corrosion and fa t igue. St randed wire is a lmost invar iably used
for hook -up and in ter connect ion pu rposes because of it s gr ea t er flexibilit y
u nder t he sh ock a nd vibr at ion con dit ions pr esen t in mobile inst alla tions
of elect ronic equipment . There is a st rong feeling, ba ed on some evi-
dence, tha t solid conductor s used for hook-up purposes in sizes smaller
than AWG No. 22 may “crysta llize”
under susta ined vibra tion such as
is encountered, for example, in a ircraft service. Recommendat ions for
such applica t ions a re tha t st randed wire be used wherever pract icable,
and solid wire be limited to jumper connect ions or to r -f cir cuit s where
the conductor may be r igidly held in place to limit its mot ion. Other
r ea sons for t he ch oice of st ra nded wir e a re t he followin g:
1.
2.
3
.
A slight nick on the surface of a solid conductor , such as might
occur dur ing the remova l of insula t ion , can easily become a point
a t which , upon subsequent flexing of the wire, breakage will
occur.
St randed wire can easily be bent and formed into a neat wir in
ha rnes s for cha ssis a ssembly.
Unsolder in g a nd r esolder in g of a st ra nded-wir e con nect ion a re less
9
3
,
in g u su ally imposed in t he oper at ion .
Mechanical and Electrical Proper t ies.-After it has been drawn,
annea led, and t in coa ted, the copper wire should have tensile st r ength
and elongat ion limits as given in Table 1.1.
TABLE1,1.—TENSILETRENGTHNDELONGATIONIMITSOFTINNEDCOPPERWIRE
o.o12t00.020 39,000 15
o.021too.lo2 38,500 20
Splices a re permit t ed in the individual st r ands of a st randed con-
uctor if they ar e of the bu t t -type, brazed with a silver -a lIoy solder .
For wires in sizes No. 28 AWG and smaller , th e splice may be twisted.
TABLE1.2.-STRANDEDHoox-rm WIREDATA
AWG
size
Nominal
diameter,in.
0.0031
39
0.0035
38
0.0040
37
0.0045
36
0.0050
34
0,0063
33
0.0071
32
0.0080
r
31
0.0089
30
0.0100
29
0.0113
28
0.0126
27
0.0142
26
0.0159
25
0.0179
24
0.0201
[SEC. 1.1
Data on tinned copper wire as used in the manufacture of st randed
hook-up wire are given in Table 1.2.
A stran ded conductor is formed by twist ing individual wires in on e of
t h e t h ree following pa tt er ns.
1. Concen t r ic st randing; one wire forms the cent ra l core and is sur-
rounded by one or more layers of helica lly laid wires. The pitch
of the ou ter layer of conductors is r efer red to as the lay of the
stranding.
2.’ Bu nch st ra ndin g; t he r equ ir ed n umber of in dividu al on du ct or s a re
simply twis ted t oget her wit hou t r ega rd t o geomet r ica l a r rangemen t .
3. Rope stranding; groups of concent r ic st randed or bunched con-
ductors are assembled in the same fashion as the individual con-
du ct or s descr ibed u nder (1) a bove.
The concent r ic pa t tern is preferable because it yields a conductor
essent ia lly circular in cross sect ion so tha t uniform wall th icknees is
obta ined with ext ru ded types of insula t ion. In addit ion, the individual
wir es do n ot sepa ra te wh en t he ir kwla tion is st ripped for solder in g.
Som e ph ysica l ch ara ct er ist ics for t in ned copper con du ct or s as u sed in
the manu factu re of AN specifica t i n h ook-u p wire, solid and st ra nded,
are given in Table 1.3.
TARLE1.3.—PHYSKCAL~ARACTEEISTICSF TINNEDCOPPER CONDUCTORS
Army-
THE PRIMARY INSULATION 5
1.2. The Pr imary Insula t ion .-There is a wide var iety of insulat ing
mater ia ls tha t may be used for coat ing solid and st anded t inned copper
wire. The suitability of any par t icular type must be determined by
careful examinat ion of the elect r ica l condit ions of opera t ion and the
physica l environment in which each opera t ion is to take place. The
elect rica l pr oper t ies of t h e in su la tion will est ablish t h e dielect r ic st rengt h,
insula tion r esist an ce, loss fa ct or , a nd dielect ric const ant . Th e physica l
proper t ies will determine the upper and lower limits of opera t ing tem-
pera ture; resistance t o moisture, flame, sunlight , oils, acids, a lka lies,
fungus, oxida t ion ; effect s of aging, abr a sion , vibr a tion , shock ; flexibilit y,
t ou ghn ess, a nd mecha nica l st rengt h.
To some extent , these qualit ies
will be cont rolled by the nature of the ou ter cover ing used over the
pr ima ry in ula t ion, a discussion of which will be given in Sec. 1.3.
Th e pr ima ry insula tions most gen er ally used a re:
1. Thermopla st ic Polymer s.
A. Vinyl Res ins.
a . Plast icized copolymers of vinyl chlor ide and vinyl aceta te
(Vinylite , Geon).
b. P la st icized vinyl ch lor ide polymer s (Korosea l).
B. Cellulose Derivat ives.
a . Cellulose aceta te butyra te compound, used in the form of
t ape a pplied over . t he con du ct or (Ten it e II).
b. E thyl cellu lose.
C. Polyethylene (Polythene).
2. Syn th et ic Rubber s.
A. Butyl rubber , a copolymer of isobutylene and a small amount
of bu ta dien e or isopr en e.
B. Buna S, somet imes refer red to as GR-S, a copolymer of buta-
dien e a nd st yr en e.
3. Natura l Rubber Compounds.
A genera l qualita t ive summary of some of the character ist ics of these
mater ia ls is given in Table 1.4. Mor e deta iled quantita t ive informat ion
on t he elect rica l ch ar act er ist ics of t he t ypes of dielect rics common ly u sed
may be obta ined from the
“Tables of Dielect r ic Mater ia ls” of the
La bora to~ for Insula t ion Resear ch of M. I.T.l
An examinat ion of these data indica tes tha t the vinyl resins and
cellu lose der iva tives h ave gr ea t u tilit y for gen er a l-pu rpose hook -up wir e.
They have good dielect r ic st rength and excellent moisture resistance,
stability, and aging character ist ics. They are noninflammable and
1Tables of Die lect r icMater ia ls , I and II. Labora toryfor Insula t ion ReBearch,
M.I.T.
resistan t t oils and most acids and alka lies.
Alimit ing factor in their
use is tha t like many other thermoplast ics they soft en at h igh tempera -
tu res and st iffen at very low tempera tures, a lthough the ow liiit has
been extended to – 50”C by recen t improvem nts. Their rela t ively high
dielect r ic constan t and power factor make them undesirable for use a t
r a dio fr equ en cies, wher e polyet h ylen e is a lmost exclu sively employed .
The syn thet ic rubbers, Butyl and Buna S, have dielect r ic proper t ies
somewha t bet t er than the vinyl and cellu lose mater ia ls but their resist -
ance to solvents, par t icu la r ly oils, is not as good. The natura l-rubber
compounds a re lit t le used at presen t for wire insula t ion .
Technical
developm en ts du rin g t he yea rs 1938 t o 1945, in ten sified by wa r sh or ta ges
of na tura l ru bber , ha ve resulted in la rge quant ity produ ct ion of th ermo-
plast ic polymers which a re grea t ly super ior to the rubber compounds
which previously wer e standard, par t icu lar ly with respect t o th e effects
of h ea t, su nligh t, wea th er , a nd oils.
1.3. The Outer Cover ing.-An ou ter cover ing is applied to act as a
su ppor t for th e pr imary insula t ion .
It permits Klgher tempera ture of
opera t ion than would otherwise be possible, and also improves the
abrasion resistance of the wire. The cover ing is one of two types: a
closely woven bra id of cot ton , F ibergla s, nylon , or r ayon ; or an ext r uded
jacket of nylon . The bra id is colored for iden tifica t ion and coding,
frequent ly ca rrying a t racer of con t rast ing color . If F ibergla s is
used,
a colored text ile t r acer provides the marking. The bra id is t r ea t ed with
mult iple coat ings of t ranspa rent , flexible lacquer to make a smooth
fin ish . It is necessa ry tha t the bra id thus t rea ted be noncor rosive,
n on toxic, flexible, a nd r esist an t t o moist ur e, flame, a nd fu ngu s.
Lacquered cot ton bra id is super ior to glass with respect to abrasion
resistance, ease of color coding, and corona proper t ies. Glass bra id has
the advan tages of being inheren t ly noninflammable and resistan t to
fungus, but some difficu lty has been exper ienced with its t endency to
fray at the po n t where insu at ion is st r ipped from the wire. This fray-
ing, in addit ion t o a ffect ing th e appeara nce of th e wir e, ten ds t o t ransmit
moist re by t icking act ion . For some purposes, it is of in terest to
examine the effect of the var ious cover ings on the ove~ll diameter of
the wire. Table 1.5 is a compar ison of glass and cot ton bra id over
aceta t e-butyra te tape and vinylite for st randed No. 22 and No. 14 wire.
More complete data is given in Fig. 1.1. It is seen from Table 1.5 and
Fig. 1.1 tha t cot ton bra id adds to the over -a ll dkneter by an amount
tha t might be significant in a wir ing harness of 10 or 12 wires which is
to be used in a crowded chassis.
Nylon and rayon are other possible choices for ou ter cover ings.
 
The maximum over-a ll diameter permit ted for solid and st randed
. .
a pph ca t lon s, t hermopla st ic ms~lla tion , 600 volt s rms or less) is ~iven i])
Table 1.6.
[SEC. 13
have been made with it which pass all the J AN specifica t ions for flame
and solvent resistance, cold bend, and insula t ion resistance. Rayon
bra ids, in genera l, do not have abrasion resistance equal to cot ton or
nylon a nd a re less widely used.
0.250
FIG, 1.l.—Outsidediametersof radio hook-up wire: (a) bare stra ndedconductor;
(b) butyra te-tapensulat ed,glass braided;(c) vinyliteinsulated;(d) vinylite insulated,
glassbra ided;(e) Yinyliteinsu lat ed,cot tonbr aided .
(y,). :30.A}YGst ra ndingof all wires
for 750 \ .oltsront ]nuolwsem ice,!
Over-alldiameter,in
Iusulation
I
o 068 0 110
0079 I 0.128
0.090
I
0.141
 
sk;,. 1.4] PH k’S ICAL PtiOPh’it T IES OF THE FIN ISHED WIitE 9
‘rABLE 1.6.—hfAxmmr&1VER-ALL DIAMETER PERMIT-TEDFOR TYPE Ml WIRE
Type (J N-C-76)
0.170
0.200
0.255
0.310
Color s a va ila ble for hook -up wir e cover in g a r e lim it ed t o t h e following:
O Black 5 Green
4 Yellow 9 White
Two colors may be used: the first as the base color , the second as a
contrast ing racer . The digit accompanying the color is used as pa r t of
the wire specifica t ion . For ex mple, a white wire with a blue t racer has
t he n umber 96 as t he fina l t wo number s of it s t ype design at ion .
1.4. P hysica l P roper ties of t he Finish ed Wu e. High Temperature.r
To a large extent , the thermal proper t ies of the finished wire determine
its usefulness. At high tempera tures, some in ula t ions deter iora te
rapidly, others soften and deform. At very low tempera tures, they
become br it t le and may easily be damaged by flexing or vibra t ion. The
pr in ciples of maximum t emper at ur e r at in g for in su la tion s a re well formu -
la ted in one of the AIEE Standards.’ They are br iefly given her .
1.
2.
3.
Insula t ion does not fa il by immedia te breakdown at a cr it ica l
temper ature, but by gradual mechanica l det er iora tion \ vith t ime.
The quest ion of what maximum tempe a ture is sa fe can be
answered only on the basis of how long the insula t ion is expected
t o la st .
How long an insula t ion will last elect r ica lly depends not only on
t he class of insula t ion but a lso on the effect iveness of t he physica l
suppor t for t he in su la tion .
Insula t ion life is dep ndent t o a considera ble ext en t on t he a ccess
of oxygen , moist ur e, dir t, or ch em ica ls.
1AIEE StandardsNo. 1,
tireBasedin Tho Rating of k;lectricalMachineryand Apparatu s,”
 
[SEC. 14
4. Physica l deter iora t ion of insula t ion , under the influence of t ime
a nd t emper at ur e, in cr ea ses r apidly wit h t emper at ur e.
Maximum temper at ur e limits have been assigned in accor da nce with
the above pr inciples. For thetypes ofinsula t ion used inmost hook-up
wires, this is th Class A “hot test -s ot” maximum of 105”C. Class A
in su la tion con sist s of
1. Cot ton , silk, paper , and similar organ ic mater ia ls when either
impr egn at ed or immer sed in a liqu id dielect ric.
2. Molddor lmka dmatet ia ls with cellu low filler , phenolic resins,
a nd ot her r esin s of sim ila r pr oper ties.
3. F ilr nsa nd sh eet s of cellu lose a cet at e a ndot her cellu lose der iva tives
of s imila r p roper t ies .
4. Va rn ish es (en amel) asa pplied t o con du ct or s.
In elect ron ic appara tus, the lhnit ing tempera tu re may be reached
not by temperatu re r ise in the wire due to its own 12R loss bu t solely
by increase in temperatu re of the chassis in ter ior due to vacuum-tube
and resistor dissipat ion. It is not a t all unusual t o find a tempera tu re
r ise of 40”C over ambient in a compact piece of equ ipment designed for
a irborne use. If the ambient t empera tu re is 55”C, as is genera lly estab-
lished in Army-Navy service specifica t ions, a t emperatu re of 95°C is
a t t a ined apar t from any r ise con t r ibuted by the wire it self. If, in
a ddit ion t o t his, filamen t or power con du ct or s a re con sider ed it is eviden t
that some thought must be given to the cur rer+car rying capacity of
insu la ted wires .
The AN high-tempera tu re test ca lls for 24 hr of heat ing to 120°C,
coolin g t o r oom t emper at ur e, t igh tly coilin g t he wir e for five t ur ns a rou nd
a mandrel th r ee t imes the ou ter diameter of the wire, immersing the coil
in water for 1 hr , and finally applying a 60 cps test volt age. The genera l
purpose wir e (WL) must withstand 2000 olts rms for 1 min. High-
volt age wire (SRHV) must withstand 6000 volts rms.
Low Temperature.-At ver low temperatu res the br it t leness of the
wire may impose ser ious li ita t ions on its use, par t icular ly in in ter -
con nect in g ca bles wh er e some flexin g may be r equ ir ed or wh er e vibr at ion
condit ions a re to be met . P resent -day thermoplast ic polymers as com-
pounded for wire insulat ion should pass the following cold-bend test .
The wire is cooled to – 40”C, then t ight ly wrapped around a l-in .
m an dr el (for wir e sizes No. 24 t o No. 16) for a t lea st five t ur ns, u nwr apped
and r ewrapped in the opposite direct ion , immersed in tap wate at room
t emper at ur e a nd iven a 60 cps volt age t est a s in t he pr ecedin g pa ra gr aph .
Abrasion.-The abrasion resist ance of insulated wire is impor tan t in
 
,
bound wir ing harnesses or in flexible conduit to form interconnect ing
cables. The AN test descr ibes a machine for st roking the wire with
No. 3/0 120 sandpaper under specified condit ions of length of t r avel,
ta utness of wire, ra te, etc. Genera l-pur pose hook-up wir e t ype WL must
wit hst an d a minimum of 200 st rokes wit hou t exposin g t he con du ct or .
Solven ts.—In mobile a nd in du st ria l a pplica tion s of elect ron ic equ ip-
ment there is a lways the possibility of contact with wa ter , gasoline,
mot or oil, a nt ifr eeze solu t ions, a lcohol, and in t he case of mar ine equip-
ment , salt wa ter .
Test s a re pr escr ibed for solven t r esist an ce specifyin g
immersion for 24 hr a t room tempera ture, one sample in each of the
liquids ment ioned. At the end of this t ime the wire is wiped clean
immersed in water for 1 hr , and given the dielect r ic t est descr ibed in the
preceding paragraphs.
Flumm.ability.-1t is to be expected that a t some t ime dur ing the life
of equipm ent , t her e ivill be fa ilur e of va cu um t ubes or ot her compon en ts
which may result in excessive cur rent in some of the equipment wir ing
or in the components tha t may be close t o a wir ing ha rness. Inflammable
in su la tion or pr ot ect ive la cqu er may t hen become a da nger ou s fir e h aza rd.
The AN test specifies tha t the ra te of burning be not more than 1 in./min
after a Bunsen bur ner flame is applied for 30 sec t o on e end of a hor izonta l
length of wire in a dra ft -fr ee chamber and tha t burning par t icles shall
not fall from the wire.
FuWus.—Under t ropica l condit ions of high tempera ture and high
humidity t her e is likely t o be extensive fa ilure of insula t ions beca use of
moisture and fungus growth. The Signal Corps Ground Signal Agency
has been energet ica lly pursuing a pr ogr am t o impr ove the performance
and reliability of equipment in tended for t ropica l service by invest iga -
t ions of inherent ly resistant mater ia ls, and of fungicides suitabl for
surface t rea tment of components for incorpora t ion in to lacquer and
varnishes.
With r ega rd t o r adio h ook-u p wir es, t hr ee t ypes of fu ngjcide
h ave been fou nd su it able for in cor por at ion in to t he sa tu ra nt s a nd la cqu er s
used to impregna te the woven outer cover in . These a re 5 per cent
sa licylanilide, 1 10 per cent penta chlorophenol, 2 and 1 per cent phenyl
mercuric salicylate .
The AN specifica t ion requires a test in which the wire is exposed to a
composit e of four types of fungus organisms in a spore suspension for
t en days a t 95 per cent rela t ive humidity and room tempera ture. At
the end of th is t ime there is to be no fungus growth on the wire cover ing.
.
a tmosphere is pa rt icular ly insidious in elect ronic equipment where,
fundamenta lly, input impedances a re high and elect rica l lea kage must
I Du Pent Company “Shir lanExtra ,”
 
[SEC. 1.5
be kept to a minimum. This is par t icular ly t r ue when equipment is
nonopera t ive for par t of the t ime and where day-night air tempera ture
cycles may r esult in con den sat ion of vapor on th e insulat ion .
Hook-up
days, with t emper atu re cycling t o r oom t emper atu re; 95 per cen t r ela t ive
humidity and – 10”C for severa l hours of each 24-hr per iod. More
complete informat ion on a recommended humidity-temperature cycle
for moisture resist ance test s is con ta ined in specifica t ion J AN-C-76.
For ge era l-purpose hook-up wire it is requ ired that a ft er exposure to
t he moist ur e t est t he insu lat ion r esist an ce between a dja cen t ca bled wir es
should be at least 100 m gohms, t he dielect ric st rengt h should be at least
4000 volt s rms (60 cps) an d t ha t between wr apped elect rodes 1 in. a pa rt on
the sur face of the wire, 2500 volts rms can be applied without flashover .
1.6. Elect r ica l Proper t ies of the Finished Wire.-The elect r ica l
proper t ies of wire cannot be completely separa ted from its physica l
Cur ren tnamperes
FIG. 1 .2 .—Tempera ture r ise VS.current .
pr oper t ies sin ce, a s can be seen fr om
t he pr eceding sect ions, elect rica l
t ests must be applied to determine
the e ffect s of t empera tu re, humid ity,
and solvent s. Moreover , an elec-
t r ica l p roper ty like cur ren t -ca r rying
capacity is a lmost en t ir ely deter -
mined by the tempera tu re limita-
t ion s of t he in su la tion .
Current-carrying Capacity and
mat ion availabld on the cur rent -
carryin~ capacity of the wire sizes
genera lly used for radio hook-up
applica t ions, sizes AWG No. 14 t o
AWG No. 24. A considerable
amount of st an da rdiza tion h as been
done by t he AIEE on wir e sizes used
for commer cia l and hou se wir ing, but th e available tables ar e not ca rr ied
to sizes smaller than AWG No. 14. This data is of some use, however ,
for calculat ions of conductor s for filamemt or pr imary power if la rge
numbers of tubes are ut ilized. Table 1.7 gives safe curren t icar rying
capacit ies based on 30°C ambient tempera ture for w res insula ted with
polyvinyl chlor ide (Nat ional Elect rica l Code t ype SN, or J AN types WL,
SRIR, SRHV). Some informat ion has been obta ined on smaller -size
wir es, 1 b ut on ly for a sin gle con du ct or u nder con dit ion s of sem ir est rict ed
1J M, caller ) (ICharacter is ticsof Rad io Wire and Cable,” WW, 98, No 5) PP .
 
,
13
ventilation.
The data is shown in Table 1.8 and applies t o wire in-
sulated with 0.025-in. wall ext ruded polyvinyl chlor ide. The data does
not cover ot her insulat ing mater ials and liberal safety factors should be
applied where condit ions of reduced heat radiat ion are to be met , s in
ca blin g, r du e t o en closu re in condu it s.
Th ese fa ct or s ca n be est im at ed
from Table 17.
Size,
AWG
14
12
10
8
6
Dielectric
thickness,in.
0.031
0.031
0.031
0.047
0.063
Freeair
Current,Amp
Tempera-
AWG
AWG
AWG
AWG
NO.28
1.8
2.6
3,4
Volt age-dr op ca lcu la tion s may be n ecessa ry for filamen t a nd pr im ar y
power conductors. The values in Table 1.3 are maximum resistances
st randed wires from No. 14 to No. 6. It is to be noted that these values
hold at 25°C and that for temperatures differ ing from this value over
t he range normally encounter ed a cor rect ion factor [1 + a(t – 250)] must
be pplied. For soft annealed copper of 98 per cent conduct ivity, a at
25°C is 0.00378. Some uncer taint ies ar ise in determining the value of t
for n insulated conductor since t he thermal charact er ist ics of t he insu-
lat io affect the t emperature of the wire it self. The refinement of such
ca lcu la tion s for t un at ely is n ot oft en r equ ir ed.
Voltuge Ra ling.-Thr ee classificat ions of gen er al-pur pose h ook-up
wire based on maximum rms oper at in g volt age a re given in t he JAN C-76
specification:
SRHV. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..2500 or less
In Ta ble 1.9 compa ra tive diamet er s, dielect ric-st ren gt h t est volt ages a nd
spark test voltages a re given for the standard range of wire sizes.
TABLE 1.9 .—COMPARATIVE DIAMETERS, SPARK AND DIELECTRIC-STRENGTH TEST
Wire
size
AWC
24
22
20
18
16
14
12
10
8
6
SRIR
3000
3000
3000
3000
3000
3000
3000
3000
3000
3000
SRHV
6000
6000
6000
6000
moo
6000
6000
6000
6000
6000
q For t ype WL, t he OD k mea su red over t he br aided or extmded wt er c.ver imz. Th e ot her LVIES
have only p~imary ins”lstion,
. .
t The spa rk tes t s run in a cha in -e iect rodedevice tha t s“b ject~ the irmula t icmo irnp”lms of “ot lEZW
than 0.2 see dura t iom
$ The d ielect r ic-~t r engt h t it is r un wit h 60 .q.s n in e-wavevolt a ge brough t “p t o fu ll t es t va lw? in
len s th an 1 m in a nd main ta in ed for 1 m im
Indution
Resistance.—Insula t ion r esistan ce of hook-u p wir e is an
impor tant factor since in some cases it may be the liiit ing factor in
high-impedance input circuit s or it may give r ise to leakage cur ren ts
between circuits tha t are in tended to be isola ted. This is par t icular ly
t rue at the high temperatures, oft en more than 70”C, which elect ron ic
equipment freq ent ly reaches. Minimu insula t ion resistance values
at 15.5°C for the th ree types of wir e descr ibed in the previous paragraph
are:
Minimum
WE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
SIR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
SRHV. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 750
Measurements are made with a me ohm bridge, or with a galva-
 
15
immersed in wa ter and the conductor made nega t ive with respect to
t h e gr ounded con t ain er .
Some idea of the magnitude of the tempera tu re effect on insula t ion
resistance is given by the cor r ect ion factors of Table 1.10, which a re
specified t o n orma lize t he mea su rem en ts t o 15.5”C.
TASLE1.1O.—TEMPERATURE CORRECTION FACTORE
o 0.032
10 0.29
’20 2.5
17 5
35 48.0
Dielectric Constant a nd P owm F actor .-F or gen era l-pur pose h ook-u p
wir e, n o power -fa ct or or dielect ric-con st an t mea su remen ts a r e specified.
There is one type of wire classified in JAN-C-76 as SRRF for which
t h ese cha ra ct er ist ics a r e given .
It is in ten ded for r adio-fr equ en cy a ppli-
ca t ionsa t 1000 voltsrms or less.. The dielect r ic constan t measured a t
1 Me/see and over a tempera tu re range of 20° to 60”C is limited to a
maximum of 3.5. The power factor under the same condit ions is li ited
to a maximum of 0.05. These va lues a re easily met by the use of poly-
e thylene insula t ion.
CABLES
The ollowin g sect ion s will dea l wit h t he flexible coa xia l t ra nsm ission
lines us d for ca r rying video and i-f signa ls, CRT sweep curren t s and
voltages, t r iggers, range marks, blanking pulses, and other signa ls tha t
a re associa ted with receiver and indica tor circu its. The frequencies
normally considered do not exceed 100 Me/see, and the voltages ra rely
exceed 1000 volt s, peak. Although the frequencies a re considerably
lower than those required for r -f t ransmission and the voltages much
less than used in modula tor pulse cables, specia l considera t ions of
impedance, capacitance, and sh ielding have led to the development of
cables tha t form a group apar t from either of these types. For example,
pres n t pract ice in r -f applica t ions is limited to cables of 50 to 55 ohms
impedance. For i-f and video transmission it is highly desirable for
rea sons of ga in and bandwidth to use cables of a t least 70 ohms imped-
ance, and preferably h igher , and with capacitances lower than tha t
obta ined in the W-ohm lines. Cable capacitance is a lso importan t for
sweep cur ren ts and voltages, t r iggers, and other signals, and specia l
types of cable have been developed with capa citances of 10 to 14 ppf/ft .
The problem of shielding between a mixer and i-f amplifier becomes
 
consequ nt danger of pickup. Specia l cables with two
woven met al br aids a re oft en r equir ed.
Under the war t ime guidance of the Army-Navy R.F. Cable Coordi-
.,.
(f) b)
F IG. 1.3.—R-f ca ble: (a ) RG.58/U ; (b) RG-59/u ; (c) RG.5/U; (d ) RG-6/U ; (e) RG-13/U ;
(j) RG-12/u; (g) RG-9/u.
a t ta ined an excellence and simplicity to be found in ew, if any, other
radio components .
Much of the data in this sect ion has been obta ined
fr om publica tion s cr edit ed t o t ha t gr ou p, dir ect ly or in dir ect ly.1
The cables to be discussed consist of
1. A group of cables having character ist ic impedance of 70 to 80
ohms, ranging in size from 0.242 to 0.475 in. over-a ll diameter ,
wit h sin gle a nd dou ble sh ieldin g br aids.
2. A gr oup of low-ca pacita nce cables, ca pa cita nce 10 t o 13.5 ~pf/ft ,
impedance from 90 to 125 ohms, va rying in size from 0.242 to
0.405 in ., wit h sin gle a nd dou ble sh ieldin g br aids.
3. A high-impedance cable having a character ist ic impedance of
950 ohms, in tended for video applica tion s.
Th ese ca bles a re list ed a nd t heir ch ar act er ist ics summa rized in Ta ble
1.11. A number of standard cables a re illustra ted in Fig. 1.3.
1.6. The Con duct or . Stranded Copper . dt randed t inned copper
wire is used for cable types RG-1 l/U and its modifica t ions, RG-12/U
and RG-13/U. Seven strands of No. 26 AWG with a nominal st rand
I
1J oint &my-Navy SpecificationJAN-C-17A, J uly 25, 1946,Cables, Coaxial and
Twin-Conductor , for Radio Frequency. (Army No. 71-4920A; Navy No. 16C8C,)
See a lsa t he S hm dard Corn pon en Ls L int of the Army-Navy Elect ron ics S tandards
Agency, Red Bank ,N. J .
  .- --
I I I Nomi-1
mm
iveigbt,
o 195 0 025
0,4 05 0.1 06
dium-size flexible ca-
e xce pt a rmor ed for
Naval equipment
Naval equipment
00
Nomi-
Army-
Dielec.
pe r
in .
Vin yl ( non con tmm - 0.615 0. a 10 52.0
inatirw)andsrmor
mor
Vinyl(nOncOntam-
Vinyl
0 .285 Shgle; t i nnedcoP-
AWG copper
pe r
0.472 Single; t inned coP-
AWG coP-
pe r
perweld I
0 .420 0.126
Eexible power trsm-
Nsvsl equipment
.ideo and communi- 0
Naval eq”ipme”t
i-f cable
Vinyl
ductor cable
Juctor cab,.
27001pecinlt tenust int t i~” ‘r fi. ?
 
.
tion
ed copper , outer ,
copper
Pr
0 .308 Tinned coppe r
0 .455 Inner , t i nnedcop-
p er ; ou t+r , ga l-
vanimd steel
I
inating)
Vinyl
vinyl
vinyl
Polyethylene
C Synthet icrubber compound
D byer of e .ynthet icrubber dielectr icbetween thin Iayeraof conduct ingrubber .
t Tbia value i s the d iame te r over the ou te r l ayer of conduct ing rubber .
0 ,405 0.096
perat ure coefficient of
730 Smalbiz.e 10w-caPmi-
ble
psci tance air-spat-d
b le for i -f p“rpmm
E lm Med ium-t ixe puk e ca -
p es k) b le a rmor e dfor Nava l
equipment
equipment
pea k) ca ble
[SEC. 1.6
diameter of0.0159in. make up a No. 8 AWGconductor , fu r ther deta ils
of which are given in Table 1.11.
Copp rweZd.-In order to obta in cables of smaller size but with the
same or h igher impedance than the above, the size of the cen ter con-
du ct or must be r edu ced in a ccor da nce with t he followin g expr ession s for
impedance and capacitance per unit length of a coaxial line:
and
loglo ;
wh er e c = dielect ric con st an t o in su la tion ,
a = diameter of ou ter conductor ,
b = diamet er of inner conduct or .
This reduct ion is accomplished by the use of a cen ter conductor that is a
copper -cover ed steel wire fabr icated by a process that welds th e copper
con t inuou ly to the steel core.
This resu lts in a composite conductor
having the high tensile st rength of the steel core and the good con-
du ct ivit y of its copper sheath .
Data for 30 per cen t conduct ivity grade
solid copperweld wire of the sizes used in cable des gns are given in
Table 1.12. These data apply tothegrade spe ified in J AN-C-17 which
has the following cha ract er is tics :
Gr ade. . . . . . . . . . . . . . . h igh st r engt h ,30 per cen t conduct ivit y.
Tensilestrength...,.,. notless than 127,0001b/in’.
Elongat ion.,,.... not less than I percen t in 10 in .
Maximumresistivity. . 39.180hms percircularmiLft (20”C).
Diameter tolerance. . . . +0.5 milsfor diametersfrom 0.020 to0.035 in .
~1.Omil for diametersfrom 0.035 to 0.060 in.
TAZLE 1.12.—SOLID COPPERWELD WIRE (30 PER CENT CONDUCTIVITY) DATA
Size,
AWG
16
17
18
19
20
21
22
23
24
Diameter,
in .
0.0508
0.0453
0.0403
0.0359
0.0320
0.0285
0.0253
0.0226
0.0201
THE PRIMARY INSULATION 21
The small-size 75-ohm cables, RG- 9/U and RG-6/U, have a cen ter
conductor of No. 22 AWG and No. 1 .AWG, respect ively. The low-
capacitance cables, RG-63/U, RG-62/U, and RG-7 l/U have a cen ter
con du ct or of No. 22 AWG.
Wound-center Conductor .-In order to match the load impedance of
video amplifier s, a specia l h igh -impeda nce ca ble h as been design ed wit h
a ch ar act er ist ic ZOof 950 ohms. Su ch a cable offer s con sider able a dva n-
tage where the length of run is not so grea t tha t the a t tenuat ion , which
(a)
(b)
(c)
FIG.1.4.—Low-capa citance-f cable:(a) RG-62/U; (b) RG-71/U; (c) RG-63/U.
is con sidera bly h igh er th an for con ven tion al cables, does n ot ca ncel t he
ga ins t o be der ived fr om ma tch in g t o high loa d r esista nce. Th e RG-65/U
ca ble is fu rt her descr ibed in Sec. 1.12.
Resistance
Wire.—A few types of cables hav been designed to have
high losses, for use as a t tenuat ing or terminat ing devices. These losses
may be in t roduced by using a high-resistance metal for the center con-
du ct or , as in RG-21/U cable, wh ich has a cen ter con du ct or of No. 16AWG
Nichrome or similar a lloy. Three types of high-a t t nuat ion cable are
shown in Fig. 1“7. (The high losses of the RG-38/U are due to the use of
a los sy rubber d ielect r ic, not t o a h igh -r esist ance cen t er conductor .)
1.7. The Pr imary Insulat ion . Solid Dielectr ic.-The dielect r ic for
all the cables t rea ted in Sees. 1.6 through 1.11 is polyet ylene, ch arac-
ter ist ics for which are given in Sec. 1“2. Polyethylene is, t da te, by
 
[SEC.1.8
losses, flexibilit y, an d t em per at ur e st abilit y. Inca ble con st ru ct ion , it is
ext ruded around the cent er conductor and is substant ia lly fr ee from
voids or other imper fect ions. In genera l, it is r equir ed that the cen ter
conductor , a fter the ext rusion process, should not be off cen ter by more
than 10 per cen t of the core radius and that the diameter of the dielect r ic
should not vary from a sta ted nominal va lue by more than *3.5 per
cent or ~0.015 in ., whichever is smaller .
Conductor
Wrap
Polyethylene
extrusion
Copperbraid
RG-62/U ca ble.
cables RG-63/U, RG-62/U, and RG-7 l/U (see Fig.
1.4) the core is const ruct ed by wrapping the con-
ductor with a polyethylene thread widely spaced
between turns and cover ing this with a ext r uded
tube of solid polyethylene as shown in Fig. 1.5.
The effect of this wrap is t o include a substant ial
amount of air in the space close t o the conductor ,
t hu s lower in g t he effect ive ca pa cit an ce of t he ca ble.
The reduct ion in capacit ance can be seen by com-
pa rin g two ca bles h avin g iden tica l ph ysica l dim en -
sion s; t h e solid dielect r ic RG-59/U and t h e sem isolid
a ir -spa ced dielect ric RG-62/U. Th e figu res a re 21.0
~~f/ft a nd 13.5 ~~f/ft , r espect ively.
1.8. The Meta l Bra id. SiWZe Br-a id.-The
outer conductor is a woven metal bra id, usua lly of plain or t inned No.
33 or 34 AWG copper wire. The mechanica l requir ements a re tha t it
r ide t ight ly, even ly, and smooth ly without piling on the sur face of the
dielect ric mater ia l and wit hout imbedding it self with in t he dielect ric.
Types RG-1 l/U, RG-12/U, RG-59/U, RG-63/U, RG-62/U, and RG-
65/U a r e sin gle-br aid ca bles.
Double Br aid.—For i-f applica t ions, a single braid is insufficien t t o
preven t pickup at the frequencies and signal levels usually used. For
such use, double-sh ielded cables (such as RG-13/U, RG-6/U, and
RG-71/u,) a re requir ed. The bra id may be a double copper braid
(RG-13/U), a silver -coa t ed copper inner braid under a plain copper
ou ter braid (RG-6/U) or double t inned copper braid (RG-7 I/U). There
is some preference for a t inned-copper ou ter bra id ra ther than a plain
copper ou ter br aid beca use it is less su bject t o cor rosion an d less difficult
t o handle in solder ing. The argument for silver -coa ted inner braid is
that it seems t have grea t er stability for h igh-fr equency use. The data
bra ids and shielding is not yet omplet e enough for the ormulat ion
f conclus ive recommendat ions .
1.9. The O ter Cover ing.-For mechanical protect ion and sea ling
against t he ent rance of moist ure, t he ou ter br aid is cover ed wit h a t ough,
 
23
severe usage, the ja cket may then be covered with a meta l a rmor , aa in
t he RG-12/U ca ble.
The J acket .-P last icized polyvinyl chlor ide or plast icized vinyl
chlor ide-vinyl aceta te copol~ers have excellent cha racter ist ics for
ja cket in g pu rposes. Th eir r esist an ce t o a br asion, flexibility a t low t em -
pera tu re, resist ance to ozone, sunlight , and oil and other chemicals a re
a ll su5cient ly good to make such mater ia ls the most sa t isfactory avail-
able a t present . It has been found, however , tha t a specia l plast icizer
must be used o prevent contamina t ion of the polyethylene dielect r ic
with aging and use, pa r t icula r ly a t eleva ted tempera tures.
This con -
t amina tion or “poison in g” r esu lt s in in cr ea sed ca ble 10SSSSwhich m ay
ser iously a ffect the per formance of the over-a ll system at microwa ve
frequencies if long c bles a re pa r t of the in terconnect ions. The J AN
specifica tion s ca ll for such a non con tamin at ing ja cket on t ypes RG-O/U
and RG-12/U. It is in terest ing to note tha t the contaminat ion test
consists of hea t ing the cable for seven days a t 98 C, a ft er which the
a t tenuat ion a t 3000 Me/see is to be not grea ter than 2 db/100 ft more
than the in it ia l va lue. The standard vinyl jacket is refer r ed to i this
specifica tion as Type I, th e noncontaminat ing t ype as Type II.
Wher e”minimum size is a considera tion , it is somet imes desir able t o
use a th in ext ruded sheath of polyethylene as a protect ive jacket . Poly-
et hylen e h as ph ysica l pr oper ties a s good or bet ter t ha n t he vin yl polymer s
but it is not as good with respect to flammability or oil resistance. For
in ter na l wir in g or in ter con nect ion s between ch assis in a pr ot ect ed equ ip-
ment , polyet hylene ja cket s may be t he ma ter ia l of best cho ce.
Such a
ja ck et is u sed in RG-71/U .
Metal ATmT.—A meta l a rmor may be used over the plast ic jacket
where par t icular ly severe milita ry condit ions a re to be met . T e Navy
specifies such a rmor for ma ny of it s sh ipboa rd equ ipm en t in st alla tion s,
ca lling for a bra ided meta l a rmor of galvanized steel wire, pa in ted with
a luminum pain t .
1.10. Physica l P roper t ies of the Finished Cable. High Tempera-
lu re.—po]yet hylen e a nd vin yl polymer s h ave defin it e lim it at ion s a t h igh
t empera tur es, pa rt icula rly if a t th e same t ime th er e is hea vy mecha nica l
loachng due to flexing or to the weight of long lengths of cable. Dis-
pla cem en t of t he cen ter con du ct or ma y t ake pla ce u nder su ch con dit ion s
if t he con duct or t emper atu re is much a bove 85”C, th e norma l sa fe maxi-
mum oper at in g t emper at ur e for a con du ct or in a polyet hylen e dielect ric.
The flow character ist ic is specified for va r ious cables by g ving the
va lue of a weight t o be hung a t the ends of the center conductor of a
cable suspe ded over a mandrel 10 t imes the cable diameter . After
74 hr a t 98°C it is r equired that the cen ter conductor shall not be dis-
 
[SEC. 1.11
t emper at ur es a re su st ain ed, h ea t-a gin g ch an ges ma y t ake
place in both th e dielect r ic and th e jacket , render in g the plast ics br it t le
and subject to cracking when flexed. A heat-aging test is specified
which calls for subject ing the cable to seven days opera t ion at 98°C
after which the cable is wound and unwound ten t imes over a mandrel
ten t imes the cable diameter . After such a test the dielect r ic mater ia l
and the ou ter protect ive cover ing a re expected to be free from signs of
cr a ck ing or loss of pliabilit y.
Low Tempera tu re.-At very low tempera tu res the materia ls in the
dielect r ic and cover ing may become br it t le and subject t o crackin g wh en
flexed. There has been considerable pro ress in improving the low-
tempera ture pliability of these materia ls and, at present , t hey can be
used at —40”C with no specia l precau t ions.
A cold bending test is
specified which calls for cooling t o – 40”C and immedia tely bending t he
cable 180° a round a mandrel of a diameter ten t imes the cable diameter .
After this test , the dielect r ic and ou ter cover ing are expected to show
n o signs of cr acks or fr act ur es.
Moisture and Solven ts.-Polyethylene and vinyl compounds a re
pract ica lly immune to moisture if su itable plast icizers ar e u sed in th eir
formu at ion . The vinyl jacket has excellen t chemica l resistance to
gasoline or oil; the resistance of the polyethylene is only fa ir . A test is
specified which calls for immersion of the cable, except for th e exposed
en ds, in 100-oct an e a via tion -t ype ga solin e for 4 h r a t r oom t emper at ur e.
At the end of th is t ime, it is expected tha t there will be no evidence of
liqu id pen et ra tion t hr ou gh t he ja ck et .
1.11. Elect ica l Proper t ies of the Finished Cable. Impedance and
Capacitance.-The proper t ies of par t icu lar in terest in th e choice and u se
of cables for video and i-f applica t ions ar e impeda nce, capacitan ce, and
at tenuat ion . For example, in 30-M c/sec i-f links between t e crysta l
mixer and the i-f amplifier , low capacitance and high impedance are
desirable even though the line may be only 6 to 12 in. long. Idea lly,
the impedance should approach 300 ohms, the order of magnitude of the
ixer output impedance, but because no such cables are a t premnt
available it is customary to use 73-ohm or 93-ohm typ s.
Capacitance
of i-f cable is a major problem in broadband i-f circu it s where the input
circu it must have a bandwidth of 12 to 15 Me/see if the over-a ll band-
width s to be 6 to 8 Me/see. It has been found tha t even very shor t
lengths of i-f cable presen t complica t ions in t hese circuit s becau se th ey
cannot be t rea ted as lumped constants. Tr ia l-and-er ror adjustments of
t he input circu it a re requ ired for optimum performa nce.
The length of the cable was not cr it ica l for the older type of i-f cir -
cu it , in which the mixer was followed by a preamplifier and the i-f
 
25
amplifier , beca use an un tun ed input circu it was used. It was customary
sim ly to use a 73-ohm input terminat ing resistor . For thk type of
insta lla t ion , lines of h igher impedance which were not then available
wou ld h ave r esu lt ed in bet ter over -a ll ga in a nd ba ndwidt h by permit tin g
a la rger shu nt r esistor a t th e input circu it , thus increasing t he available
voltage. RG-71/U cable with an impedance of 93 ohms and a capaci-
t an ce of 13.5 ppf/ft , dou ble sh ielded, is on e of t he two ca ble%p ar ticu la rly
applicable to i-f uses. The other is RG-6/U with an impedance of 76
ohms and a capacitance of 20 ypf/ft , a lso double shielded.
In t he tr an sm ission of video signa ls, ca th od~r ay-t ube sweep cu rr en ts
a nd volt ages, t rigger s, bla nkin g pu lses, a nd ot her sign als a ssocia ted wit h
r eceiver a nd indica tion cir cu it s, ca ble ca pa cit an ce is a dvan ta geou sly k ept
to a minimum since lengths of cable up to severa l hundred feet a re fre-
quent ly requ ired. Air -spaced dielect r ic cables such as RG 63/U and
RG-62/U are most often use . The first has a capacitance of 10 wf
per foot , and an impedance of 125 ohms; the second, a capacitance of
13.5 ppf per foot , and an impedance of 93 ohms. A specia l type of
h igh -im peda nce ca ble for video u se u tilizes a wou nd cen ter con du ct or , a e
has been ment ioned in Sec. 1.6. Complete informa t ion on th is cable,
type RG-65/U, ie given in Sec. 1.12.
At ten ua tion .-Th e a tt en ua tion of polyet hylen e ca bles a t video a nd i-f
frequencies is fa ir ly low. None of the cables discussed here, with the
except ion of R -65/U, has an a t tenuat ion grea ter than 2 to 4 db/100 ft
TABLE 1.13.—ATTENUATIONNDVOLTAGEHARACTERISTICSFR-F CABLES
At 10 Me/see At 100Me/s ee Oper a tin g,max
Test
RG-12/u
RG-13/u
RG-59/u
RG-65/U
21.5
1.0
3
100.0
7
4
20
~ 10.0
87
c
g
4
E
71OOO 2 4 710,000
Frequencyin MC/eeC
Fm. 1.6.—Attenuat ion of standard r -f cables vs. fr equency, Cable RG-/U number :
(a)55and 58; (b)59; (c 62 and71; (d)5and 6;(e) 21; (f)8,9, and 10; (u) 11,12, and 13;
(h)22; (t )63and 79; (j)65; (k)14and 74; (l)57; (m)17and 18; (n)19and20: (o) 25,25A,
26,26A, 64, 64A, 77, 78; b) 27and 28; (g) 41.
(a)
(b) (c)
 
27
a t 100 Me/see. Compara t ive figures ar e given in Table 1013for a t tenua-
t ion in db per 100 ft at 10 and 100 Me/see. More extensive data for all
the standard r-f cables are given in Fig. 1.6. F igure 1.7 is a photograph
of t hr ee h igh -a tt en ua tion r -f ca bles.
Dielectric Strength .-The voltage ra t ings of the cables discussed pre-
viously are well above the maximum values genera lly required. CRT
deflect ion voltages are perhaps the on ly case where t e dielect r ic is
subjected to an appreciable fract ion of it s ra ted voltage. The medium
size 7$ohm cables are ra ted a t 4000 volt s, rms; the small size RG-59/U
an d RG-6/U at 2300 a nd 2700 volt s, rms; t he semisolid low-ca pa cita nce
cables a t 750 or 1000 volts, rms. A dielect r ic st rength test is specified
in which an a-c voltage (sine form, 15 t o 65 cps) is applied to the cable for
60 sec.
1.12. H igh -impeda nce Ca ble. ‘—H igh -impeda nce ca bles ma be u sed
for th e transmission of video signals over distances of approximately 1
t o 100 ft .
P resen t-t ype video amplifier s a re bu ilt wit h loa d impeda nces of a bou t
1000 ohms. Ordinary coaxia l cables have impedances of 50 t o 100 ohms
and capacitances of 10 to 30 ppf/ft . They may be matched to cor-
respon din gly low loa d r esist an ces, or t hey ma y be t rea ted as lumped loa d
capacit nces. In either case the cable load lowers the peak voltage
utput and gain available from a given tube.
To avoid th ese loss s cables with much higher su rge impedance have
been developed. Their design is der ived from that used for delay lines
f th e dist r ibuted-parameter type, but their dimensions ar e chosen so as
t o yield a h igh impeda nce wit h t he lea st possible sign al dela y a nd a tt en ua -
t ion per unit length . The less the signal delay in the cable, the more
accura te will be the isochronism of the separa te units and the less will
be the spacing of spurious echoes from improper termina ions.
Electrical Characteristics. -In
(1)
and
C is th e capacitance per unit length ,
2’ is the delay per unit length .
i Thematerialgiven in this sect ion has been publishedby the author;H. E. Kall-
mann ,“High-Impedance Cable,”
 
[SEC. 1.12
In order to make the impedance Z high and the delay T low, t he in du c-
tance L should be made large and the c pacitance C kept small. In
high-im peda nce cable, induct ance is incr ea sed by r eplacin g t he st raight
inner conductor of the ordinary
coaxia l cable by a close-wound con-
t in uou s coil of in su la ted wir e, a nd
capacitance is kept low by using
wide spacing between the inner
and outer conductor and by using
FIG. 1 .8.—Essen t ia l dim en sion s of h igh - a low-dielect ric con st an t m at er ia l
impedance cable.
The approximate computa t ion of the inductance, capacitance, imped-
ance, and delay of a high-impedance cable may be car r ied out as follows.
Refer r ing to Fi . 1.8, the inductance ~ of a cont inuously wound single-
Iayer coil will be
L = 10-’%r%2d2
(3)
The capacit ance C of a concent r ic cable will be
~ = 24 x lo-%k
:
From Eqs. (1), (3) and (4) Eq. (5) for the impedance Z follows:
.=J 5=@_J q. (5)
From Eqs. (2), (3), and (4), Eq. (6) for the t ime delay T follows:
T=lo6J 7=’Oj:o::y ‘sec. ‘6)
Wit h n egligible er r or , t he su rfa ce of t he coiled in ner con du ct or is a ssumed
t o be a cylinder of diamet er b. Then
b=d+w
c
(8)
The design of a cable sta r t s with the choice of the largest pract icable
outer diameter , for it follows from Eqs. (5) and (6) that the impedance
Z r ises and the delay T decreases as the outer diameter a is increased.
 
HIGH-IMPEDANCE CABLE 29
~-in. connector . Allowing for a protect ing jacket and the th ickness of
the outer conductor , t he following example is computed for a diameter
a = 0.78 cm (0.308 in. ) and for a solid dielect r ic spacer of polyethylene
with dielect r ic constant k = 2.25. Both the impedance and the delay
could be improved by l/~ if the effect ive dielect r ic const ant were
r edu ced, for example by inser tion of a h elica l spa cer .
The impedance and the delay, ascomputedfrom qs. (5) and (6)
for a =0.78 cm (0.308 in .) and k = 2.25, are plot t ed in Fig. 1.9 and
Fig. l.lOasfunct ions of t hecor ediam et er c. Th ree cu rves ar e pr esent ed
1300-
*32F
1200-
Corediamet erncm
FIG.1.9.—Cablempedancevs. cor ediam eter .
in ea ch ca se. Th ey a re compu ted for coiled in ner con du ct or s close-wou nd
wit h t h r ee differ en t wir e ga uges.
1. Formex copper wire AWG No. 30F, with w = 0.0108 in.
2. Formex copper wire AWG No. 31F, with w = 0.0099 in.
3. Formex copper wire AWG No. 32F, with w = 0.0089 in.
F igure 1.9 shows t a t in all cases the impedance Z goe through a
maximum, r ising at fir st linear ly with d = c + 2W in the numera tor of
Eq. (5), and then eventua lly falling with <log10 [a /(c + 2w)]. As can
be seen the maximum is reached in each case a t approximately the same
value of the cor e diameter c. If the th ickness of the wire w is negligible
in compar ison with the coil diameter d, so tha t d = b, t hen it can be
 
[SEC. 1.12
thus fora = 0.78 cm the highest impedance is obta ined with
d = 0.475 cm and c = 0.45 cm.
J udging from Fig. 19 a value of c a t or near 0.45 cm would be the
prefer red choice for th is yields maximum impedance and in addit ion
mainta ins the impedance u changed with la rge var ia t ions of the core
diameter . The ollowing factors, however , a re opposed to th is choice.
0.7-
0.6-
0.5-
B
Corediameterin cm
F IG. 1.lO,—Dela y vs. cor e diamet er .
1.
2.
As shown in Fig. 1.10 the delay per unit length of cable r ises
rapidly with the diameter of the core due both to the increased
coil diameter (increased inductance) and to the closer spacing of
th e conductor s increased ca pa cita nce). F ur th erm ore, t he la rger
the delay, the la rger will be the spacing of echoes due to improper
terminations.
and A r is es wit h
loss A due to the ohmic resistance R in th e coil
A = 4.35R
z’
(9)
the length of the wire which is propor t ional to
i
I
 
HIGH-IMPEDANCE CABLE 31
3. Par ts of the magnetic field around the coiled inner conductor will
t
cause eddy cur ren t losses in th e closed turn of th e ou ter con du ctor
unless the ou ter conductor is either far enough away or bra ided of
s epar a tely in su la t ed wir es .
A suitable compromise value for the core diameter is c = 0.28 cm
(0.110 in .), (indica ted in Figs. 19 and 110). This choice of c yields an
impedance tha t is only 89 per cen t of the maximum value, but it reduces
the cor responding delay o 49 per cent of the value tha t is obta ined for
c = 0.45 cm and it reduces the coil resistance to 65 per cen t . The ou ter
conductor has a diameter 2.8 t imes tha t of the coil which is sufficient ly
la rge so tha t eddy cu rrent losses ar e small.
It may be noted tha t the core diameter c so determined depends only
on the ou ter diameter a and its choice is not a ffect ed, for example, if
another impedance is specified. F igure 1.9 shows tha t in such cases
choice of a differen t wire gauge, wound on the same core diameter is the
only change required. The impedance Z rises by over 10 per cent each
t ime the wire gauge is made one AWG number finer; the delay rises in the
same propor t ion but the transmission loss A rises by about 20 per cen t .
A cable based on th is design is manufactured’ as the type RG-65/U,
(see Fig. 1.11). Its specifica t ions are:
Core; polyethylene 0.110 ~ 0 010 in . in diameter .
Inner conductor ; close-wound helix of AWG No. 32 copper wire.
Spacer ; solid polyethylen e ext ru ded t o 0.285 ~ .010 in . in diameter .
t
Fm . 1.11.—RG-65/Uhigh -impedan ceable.
Ou ter con du ct or ; single-bra id, pla in copper wir e No. 33 AWG, max.
diamet er 0.340 in .
J acket ; polyvinyl t o overa ll diameter 0.405 + 0.010 in.
Surge impedance; Z = 950 + 50 ohms.
D-c r es is tance; 7.o ohms/ft .
Capa cit an c~ 42 ppflft .
Delay; 0.042 psec/ft at 5 Me/see.
Maximum oper at in g volt age; 3000 volt s rms.
At tenua t ion; 5.5 db/100 ft a t 1 Me/see.
10.2 d /100 ft a t 3 Me/see.
14 db/100 ft a t 5 Me/see.
21.5 d /100 ft a t 10 Me/see.
40 db/100 ft a t 30 Me/see.
 
112
The ecrease in t ime delay with increasing freq ency is small. The
dela y m ea su red on a pr epr odu ct ion sample of a bou t 1200 ohms impeda nce
was found to drop steadily about 0.032 per cen t per Me/see so tha t a t
20 Me/see it h ad fa llen t o 99.35 per cen t of t ha t for t he lowest r equ en cies.
Through choice of
the cable RG-65/U is delibera tely
designed for low signal delay per unit length . It is not meant to be used
as a delay line.
However , cables of similar const ruct ion but with
a/b > V have been design ed for u se a s dela y lin es in specia l a pplica tion s
(Chap. 6).
Terminating the Inner Conductor . -In order to a t tach connector s
r elia bly t o t he in ner con du ct or of h igh -im peda nce ca bles, t he followin g
p rocedu re is sugges ted :
1.
2.
3.
4.
5.
6.
7.
Cu t back the jacket and push back bra id, then remove dielect r ic
spacer to clear # in . of th e coiled in ner con ductor .
Unwind & in. of the coil, cu t fr ee wire down to 1 in ., r emove For-
mex insula t ion with emery cloth , and tin wire.
With a pair of pliers squ eeze th e exposed stub of th e polyeth ylen e
cor e t o a bou t on e-h alf of its or igin al t hickn ess.
Punch a hole a t least & in . wide with a needle (scr iber ) th rough
t he m iddle of t he fla tt en ed por tion .
Bend one end of 2-in . t inned copper wire (No. 20 to No. 22 AWG)
to U shape around ~ in . diameter and hook th rough the hole.
Wrap the t imed end of inner conductor two or th ree t imes around
the shor t end of the hook, and solder .
With the hea t of solder ing the fla t tened end of the polyethylene
core will melt and form a drop a round the U-shaped wire hook.
Hold the la t ter in place until the drop has hardened.
This procedure has proved both simple and reliable. The free end of
the wire hook can b inser ted in to any of the usual connectors and
soldered t them. The tensile st rength of the hook-and-polyethylene
weld is considerable and stra in on the coiled conductor is taken up by a
,’
,
 
f
The var ious types of fixed resistors form the subject mat ter of the
next two chapters. Chapter 2 is devoted en t irely to genera l-purpose
fixed composit ion r esist or s wh ich con form or n ea rly con form t o t h e specifi-
1
ca t ions of J AN-R-11. Chapter 3 discusses var ious types of standard or
near -standard fixed wire-wound resistors and also a number of specia l
types of resistors, both wire-wound and otherwise. A in most of the
ch apters of th is volume, specia l emphasis is given t o types con forming
t o ANESA specifica tion s beca use of t he con cer n of t he Ra dia tion La bor a-
t or y wit h m ilit ar y equ ipmen t.
2.1. Th e Ch oice of a Resist or .—Resistor s a re amon g t he compon en ts
most widely used in elect ronic circuit s and may be classified in to two
main ca t egor ies: composit ion r esist or s a nd wir e-wound r esist or s.
If the
requ iremen ts a re not such as to demand one or the other type, composi-
t ion resistors a re usually employed becau se of th eir cheapness and com-
pactness. For more st r ingent requirements the choice is usually based
u pon on e or mor e of t he followin g fa ct or s.
Size.-A composit ion resistor for a cer ta in job is often much smaller
than a wire-wound resistor for the same job. This difference is most
ma rked in high resistan ce values and in low dissipat ion ra t ings because
the th innest wire tha t can be used to make a reasonably mgged wire-
wou nd resistor st ill has such low resistance per foot tha t a la rge amount
of it must be used.
High-frequency Proper t ies.—Composit ion resistors of low wat t age
ra t ings and medium resistance values can be considered as having
pract ica lly pure resistances well up in to the megacycle region . At high
frequencies a small wire-wound resistor has a reactance tha t is of the
same or der of ma gn itu de a s t he r esist an ce itself.
Stability .—The
chief disadvan tage of composi ion resistors is th eir
t en den cy t o ch an ge in r esist an ce wh en su bject ed t o ch an gin g con dit ion s.
They do not , in genera l, r eturn to their init ia l va lues after cycles of
change. Thk lack of stability is a fa ta l disadvantage in many applica-
t ion s in wh ich r esist or s a re u sed in a ccu ra te m ea su rin g cir cu its.
Iioise.-A composit ion r esist or gen er at es a con sider able n oise wh en a
 
FIXED COMPOS1 TION RES ISTORS [SEC. 2.2
differ en ce makes in advisa ble t he u se of composit ion r esis tor s in low-level
circui t applicat ions.
Power4ist ipa tiW Ability.—Composit ion resistor s a re seldom used
for dissipa t ions of more than 2 wat ts, and are pract ica lly never used for
dissipa t ons of over 5 wat ts.
Wir e-woun d r esist or s a re a va ila ble wit h
dissipa t ion ra t ings up to 200 wat ts per unit . Wire-wound resistors a re
usually capable of oper at ing a t h igher tempera tur es than composit ion
resistors—up t o sever al hundr ed degr ees cent igr ade in many ca ses.
Accu ra cy .-Be a use of t heir inst abilit y few composit ion r esi t or s a re
furnished in tolera nces loser than 5 per cen t. Wire-wound resist ors a re
regular ly st ocked in tolera nces down to% per cent , and may be obta ined
down to 0.05 per cent on specia l order . Wire-wound resistors, unlike
composit ion resistors, may also be obta ined in const ruct ions tha t have
lit tle ch ange of r esist an ce wit h ch anging t emper a tu re or ot h er condit ion s.
To sum up, wire-wound resistor s a re usually demanded by applica-
t ions wit h r igid sta bilit y or a ccu ra cy r equ ir emen ts, or if powers of over
a few wat ts must be dissipa ted. Composit ion resistors a re usually used
for less cr it ica l a pplica tion s; if h igh fr equ en cies, h igh r esist an ce va lu es,
or a crowded chassis a re involved, their advantages a re marked.
2.2. Standards and Specifica t ions; Coding and Labeling .-Unt il
r ecen t ly, t h e choice of r es is tor s for specific applica t ion s was made difficu lt
by differ en ces between t he wa ys in which ma nu fa ct ur er s descr ibed t heir
products and differences between the types of tests they used on them.
Th e pr oblem is con sider ably simplified n ow by t he exist en ce of st an da rds
that have been agreed upon by represe ta t ives of most resistor manu-
facturers and many users.
Two closely r ela ted sets of standards on fixed composit ion r esist ors
ha ve been in r ecent use by the elect ronic indust ry. The first is America n
War Standard C75.7-1943, approved Oct . 8, 1943, and issued by the
American Standards Associa t ion , 70 E. 45th Street , New York City.
Copies can be obta ined from this organiza t ion for 60 cent s apiece. The
other is specifica t ion J AN-R-11, issued on May 31, 1944, by the Army-
Navy Elect ronics Standards Agency, 12 Broad St reet , Red Bank, N. J .
Thh specifica t ion was issued ainly for us by those who make equip-
ment for the a rmed services. It is der ive from the American War
Standard and is similar to it in most respects.
The differences between J AN-R-1 1 and AWS C75.7-194 will be
not ed in a ppropr ia te places in this cha pter .
At ten tion sh ou ld be ca lled
t o t wo ot her documents connected with these standards. America n War
Sta ndard C75.17-1944 ent it led “Met hod of Noise-Test ing Fixed Com-
posit ion Resistors” is a descr ipt ion of the method of ca rrying out one of
t he tests prescr ibed in the AWS C75.7-1943 standard. This descr ipt ion
was separa ted fr om t he gener al r esist or standa rd beca u e it is fa ir ly long
t
S TANDARDS AND CODING 35
and i of in terest mainly to those who make the test and not t o those
who use the resistor s. Another document of in terest is the proposed
Amendment h’o. 1 to .J AAT-R-l1. This amendment , if approved, will
make two major changes in the specifica t ion and a number of minor
changes. 1
The major changes are: addit ion of a ne~v-sty]e insula ted
resistor , RC-42, a two-wat t style much smaller than those previously
list ed; a nd a ddit ion of a n elv ch ar act er ist ic symbo , G, cover in g in su la ted
resistor s that can be used at higher ambient t empera tu res than those of
character ist ics A, B, C, and D. Deta ils on these changes will be given
in appr opr ia t e pla ces.
The AWS and JAN standards descr ibed her e a re not in tended to
cover a ll va r iet ies of fixed composit ion r esist or s.
h lany specia l-purpose
r esist or s a re n ot in clu ded in t heir scope—for example, h igh -r esist an ce
power r esist or s con sist in g of a spir al band of ca r bon composit ion deposit ed
on the ou t side of a ceramic tube. Even in cases like th is \ vher e dimen-
sions and st ructu re depar t from those of the standards, it is the custom
t o us the test pr ocedures given in the standards wher ever applicable as
cr it er ia by which to judge the quality of a resistor .
For fu r ther deta ils the reader is r efer red to JAN-R-11 and to the
ot h er st an da rds a nd specifica tion s cit ed a bove.
It shou ld be noted tha t
t hese wor ks do n ot speci y t he h igh-fr equ en cy pr oper ties of r esist or s.
Standards Descriptiw Code.—By specifyin g r esist or s a ccor din g t o t he
descr ipt ive code included in the J AN standards a user can obta in from
differ en t m an ufa ct ur er s r esist or s t ha t a re for most pu rpose in ter ch an ge-
able with each other . This code consist s of symbols using five let t er s
a nd five n umber s, Ir hich complet ely iden tit ’y a r esist or a s t o t he followin g
pr oper ties: dimen sion s, wa tt age r at in g a t r oom t emper at ur e, pr esen ce or
a bsen ce of in su la tin g ca se, h um idit y a nd sa lt -wa ter r esist an ce, va ria tion
of resist an ce \ vith t emper at ur e, r esist an ce value, r esista nce t oler an ce.
The type designat ion of a par t icular r esistor breaks down as follows:
RC 10 AE 153 hI
—————
Value
Compon en t: F ixed composit ion r esist or s a re iden tified by t he symbol
l, RC. J I
Style: The first two numbers ident ify the power ra t ing, shape, and
size as given in Table 2.1 and Fig. 2.1.
Character ist ic: The next two let t er s ident ify the resistor as to it s
in su la tion , a s t o it s r esist a nce t o humidit y and sa lt -wa t er -immer sion
1At the timeof writ ingit seemslikelythat thisamendmentwifl be changedsome-
whatbefore it is approvedand iszued.
 
TABLE2.1.—JAN COMPOSITIO~-nESISTORIMENSIONS
Exceptas noted,all types have1+ i ~in. leadsand aremade in resis tancevaluesfrom
10 ohms to 20 megohms
Typ(?
. .
q Rcwh t . r wer an ge 150ohm, t o 4.7 me~ohms, lea d len ~t h 1~ in . + i i,).
t Special unirwulate, lh,gh-voltsge ty])e, resiatarwxrange0.27 to 20 megohms.
i Rmlis l-lugtype.
STANDAltDS AND CODING 37
cycling, and as t o its change of resistance va lue with tempera ture,
a ccor din g t o Ta ble 2.2.
TABLE2.2.—JAN COMPOSITION-RESISTORHARACTERISTICS
L&ter
A Insula ted
c
Uninsulated
Humidity
D
Uninsulated
axlmumallowableper cent cha ngein resist an cefrom 25°Cvalu e;
Nominal
resistance
10-1000ohms
1100-10k
*22
Resistance Value: The next th r ee numbers ident ify the nominal
resistance value. The first two digits a re the first two figures of
the resistance value in ohms and the third specifies the number of
zer os that follow t he fir st t wo figu res.
Resistance Tolerance: The last let t er of the symbol designates the
symmetr ical resist an ce t oler an ce; “J ” signifies a toler an ce of plus
or minus 5 per cen maximum; “K,” 10 per cent ; and ‘r M,” 20
per cen t.
Color Code.—Since i is hardly pract ica l to pu t much informat ion on
a resistor , and since the component and style a re self-eviden t upon
inspect ion , the resistance value and tolerance are designated by a color
code. This code employs bands or dots of color as shown in Fig. 2.2.
The use of colored bands around the resi tor is genera l for the insula ted
types, and the “body end, and dot” system is usual on the radia l-lead
uninsula ted types. Many char ts and other devices are available to help
the occasional user to in terpret the code, so an explanat i n is not neces-
sary here. It must be noted, however , that the char t of Fig. 2.2 is
 
[SEC. 2.3
gold st r ipe in the th ird posit ion means tha t the’ va lue
given by the fir a t two st r ipes must be divided by 10; a silver st r ipe means
tha t the va lue must be divided by 100. This means that there is a choice
of two codes possible for cer ta in va lues; for instance, a 3-ohm resistor
ca n be coded eit her or ange-bla ck-gold or bla ck-ora nge-bla ck. Fr om th e
u ser’s point of view it is decidedly pr efer able t ha t a ll r esist or s between 1
and 10 ohms should use gold in the th ird posit ion and tha t all between
0.1 and 1 ohm should use silver , so that the decade into which a resistor
va lu e fit s ca n be qu ickly iden tified.
I
n
I
FIG. 2.2.—Standard color code for fixedcompositionresist ors.
It should be noted that in spite of wha t has been said above about
the difficulty of pr in t ing numbers on small resistor s, In terna t iona l
Resistance Company, IRC, uses both the color ed st r ipes and a wr it t en
iden tifica tion on ma ny of its u nit s.
This is pa rt icula rly h elpfu l t o color -
blind individua s, and also in cases wher e dir t or overhea t ing have made
the colors of the bands hard to ident ify.
2.3. Standard Resist ance Values.-Specifica t ion J AN-R-11 gives 10
ohms to 20 megohms as the standard range of va lues of most types of
composit ion resistor s. Resist an