ARMED SERVICES TECHNICAL INFORMATION AGENCY ARLINGTON HALL STATION ARLINGTON 12 VIRGINIA

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP81-01043R003100230009-9
• Release Decision: RIPPUB
• Original Classification: U
• Document Page Count: 200
• Document Creation Date: December 23, 2016
• Document Release Date: March 27, 2014
• Sequence Number: 9
• Publication Date: January 9, 1959
• Content Type: REPORT

Declassified in Part - Sanitized Copy Approved for Release @ 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
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Declassified in Part - Sanitized Copy Approved for Release @ 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
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OBJECT
DEVELOPMENT OF SIMPLIFIED PRINCIPLES
OF DESIGN AND STUDY OF MATERIALS Of
CONSTRUCTION FOR HIGH FREQUENCY TRANSFORMERS
0
SIGNAL CORPS ENGINEERING LABORATORIES
FORT MONMOUTH, N.J.
CO-SPONSORED BY
THE ELECTRONIC COMPONENTS LABORATORY
OF THR WRIGHT AIR DEVELOPMENT CENTER
WRIGHT?PATTERSON AIR FORCE BASE, OHIO
0
Final Report
July 1953 to 30 November 1955
Contract No. DA-36-039 SC-52679
Dept. of the Army Pro!. No. 3-26-00402
Signal Corps Nei. No. 2006C
In Accordance with
SqUi Of Signal Laboratory
Technical Requirements
Dated 8 January 1953, For
PR&C 53-ELS/D-3438
0
Report Prepared By
Allan M. Hadley
John P. Tucker
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DF:SIGN MANUAL FORI. F. TRANSFORMERS
The tenttector agrees to end does tierte,v ,P *?' 00 "," '41*grire,"Pant a reyelty.ftedl?
nen exclusive and irrevoca", Vcortse to ...Q. .1 finest,. publish, use sod
di*P014 of, end to authorize *theta so to do. all copyrighted and copytiohlabli
oriefetial contained herein.
PRINTED IN Tiff: UNITED STATES OF AMERICA
The conttoctot slimes ta ar.:1146.-? "-c f gram to the government a eayalty4rateg
non 4111C1141141 end istravocs' transiate, publish, ases gni
dispose of, and to (Putties's' whets sot. do, all copyriuhted and copyrigiatotaif
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Inatoriot contained heroin.
PRINTED BY GORDON ASSOCIATES, INC.
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Preface
I NIA1'E111A15 OF CONSTRUCTION
Introduction to Part 1
UI
ii
Section 1
Conductors
14
Section 2
Shields
24
Section 3
Nlagnetic Materials
34
Section 4
Electronic Hardware
4-1
Section 5
Ceramics
5-1
Section 6
Plastics
6-1
Section 7
Waxes, Varnishes. Cements.
and Lacquers
7-1
Section 8
Tapes and rilm Insulations
Section 9
Finishes and Marking
9-1
I ntroduct ion
Section 10
Section n
Section 12
Section 13
Section It
P 111T 11 DESIGN wrii(ms
to Part 11
indings - Equipment and Tel. liniques
Types of Construction
Measurements, Theory and Practice
Techniques of Fabrication
Theory and Design
introduction to Appendix
Appendix
Subject Index
7.alr
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; .-1- ? 4: ;
V
A-1
ii
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1-*,eit..h year, of many new engineers and tech-
nical assistants entering the electronics field,
some will be involved with the opplication and de-
sign of 14 transformers and coils. This rn,fanual on
"llemiKa Methods for High Vreqoeticy Transformers"
is directed IT particular to these newcomers and to
those eilready engaged in electronics who are con.
fronted with the many complex pre?blems relating to
r-f ;;ailictors. It comprises in attempt to bring under
one. cover, to as great a degree as possible, some
ilittlide explanations of the basic fundamentals of
coil design and construction.
Inductive components ate un;que among the
many Ieemilies of electronic parts. Vthereas resistors,
Ctilbstl hors, switches. etc., are .available as st andard
stock parts having established characteristics.
the audio, power, pulse. r-f and i-f transformers and
other specialized coils used in electronic equip-
ment invariably must be designed for a specific ap-
plication.
Since %odd Aar 11 considerable attention has
been given to the devslopment and refinement of the
techniques of design of audio, power and pulse
transformers. As a result, a wealth of straight-for-
ward, practical design information is av.iilable. In
contrast, the r-f coil iletsign field hashad no con-
contrated effort aimed specifically at relating the
highly analytical text-book approaches to the prac-
tical problem of building a toil or transformer.Ais *
result, the design of radio frequency coils is still
practiced more as an art than as a science. shiny
formal text books are excellent in their scientific
treatment of the subject but the designer needs, ia
addition, the experience of those long established
In the art in order to translate into a practical de.
sign the scientific principles presented.
r.'
Literetaro rantei;nei many analytical articles on
various specialized phases of this art but these
imt us unrelated efforta and are difficult to quickly
locate and utilize when a problem is presented. It is
time cons.ming and vonfu?iing tor each engineer to
individually conduct the literary research necessary
In establish the threshold to this specialized branch
of electronics design. N' earn of apprenticeship are
often required to establish a mature level of prac-
ticed and academic "know-how".
Realizing this, the Wright Air Development
Center, %right Patterson Air Force Base, propoaed
the preparation of a treatise on high frequency trans.
formers. This was implemented through the Signal
Curtis Engineering Laboratories on Contract No.
DA-36-0:19-SC-52f)79 whi:h has resulted in this
manual.
The experience and "know-how" previously
only available through association or years of ex-
perience are presented herein by chart and ex..
ample in condensed loin.. A complete discuanion of
each element of a coil or transformer such no wire,
shield, magnetic tnuterials, etc., is included along
a section devoted to Theory and Design. This
section outlines new approaches which are return?
mended to the engineer who has had little, if any,
experience in the design of r-f
Certain in )duct* ilit2 more commonly known
in :adustry by "trade names" rather than by their
technical or chemical designation. These terms
have, in some instances, been used in this manual.
Many vendors and their products are mentioned
directly for purposes of illustration.Tbere has been
no attempt to completely survey the field. This (toes
not imply an endotaeneent or preference of a podia,
cular product by either the government ot the cos.
tractor.
iv
.,:'i'S.Ver4/444:r?NNStcreli??444?.3r?A'.? :;4.1104V....144.1:44,14;04.:4?100404"..V ?4;..$1" '4" '??46'?'',Ait?rs 4t1.wS4.!..4***1; \144.4?4.404,44?V0446.4444:*****, ?-??????????'"
; 4
1
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Declassified in Part - Sanitized Copy Approved for Release
50-Yr 2014/03/27: CIA-RDP81-nin4nPnnqinn-rznrmn
4
Declassified in Part - Sanitized Copy Approved for Release @ 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
POOR
?3/4?????rn Kt (??????????ma s
ORIGINAL
?????????????????....? .....114111110?0??????????????*????????....11.
?lany people have contributed in rte way or ?
another to this manual. It -would be impossible to
acknowledge each of these contributions. Acknow.
ledgme.ats to specialists who have coutributed to
specific chapters have been included at the end of
those chapters. Special recognition is given to Mr.
Czorge C. Seikliti of the R.C.A. Laboratories,
Princeton, New Jersey, for his advice awl comments
relating to the section on Theory and Design. Re-
cognition is also given to Messrs. S. Danko and
D. Elders of the Signal Corps Engineering Labora-
tories and Messrs. G. Tarrtmts anti D. Crockett
of the Wright Air Development Center. A knowledg-
meat is also made particularly to Philip J. Reich
for his valuable editorial comment and to other
.members of the Automatic Manufacturing Corporation
and F. IN. Sickles Division of General Instrument
Corporation Engineering Departments for their tech.
???????????????????????????????111?111M, /111.01/1"
ideal suggestions. Thauks are also due to the
Boonton Molding Company, the Institute of Radio
Engineers, Inc., and the McGraw-Ifill Book Company,
Inc., for pt.:mission to reproduce variouscharts and
other in format 'noted throughout the manual.
Even though the manuscript has been reviewed
iiith painstaking care it is recognized that some
errors may appear. If any should be found the authors
sincerely hope you will cull them to their attention
so that subsequent printings may be corrected.
AUTOMATIC MANUFACTURING CORPORATION
????,..,4.- 01.
?
?
?
?
?
41???? 04.?
,???? 40st ..???? ?
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Part I ?
MATERIALS OF CONSTRUCTION
vi
? ??'?Xj, ? .44 1,'1,??? ;4??,:4.1r' ",
?
*
3- .1. ? ? ? ??,;?
Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2014/03/27 ? CIA-RDP81-01043R003100230009-9
Declassified in Part - Sanitized Copy Approved for Release @ 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
POOR
ORIGINAL
"N.
0
?
?
4
i'wo?w?csw???????w?????ww. ??? ? w....weiwe ?01?????. ???????????????????rocoweilmtiOw
? The engineer confronte41 with the design of mil,
itoryr-f inductive componento must he familiar with
the rigorous environmental conditions imposoll
military service awl with the very practical and
unique designs often employed in civil inn compo-
nent," which are responsible for economical most,
production. With this knowledge of military require-
memo and commercial practices, he can develop
proictical, economical erwasatisfactory deeignn
salt-
nt)lr for military service.
The various sections of Part I contain 4ties-
cuss ions on the materials of construction peculiar
to r-f inductive components. Subjects covered In.
elude conductors, shields, magnetic core materials,
electronic hardware, ceramics, plastics, impreg-
nating materials(waxea, varnishes, etc.), tapes and
film insulations, and finishes. It is the purpose of
Part I to fully acquoint the user with all of the
critical elements that Ara used in r-f trannfornire
construction.
Supporting ,lata, which. is graphical in many
cases, in incliabol to onsist in the selection of the
proper Inaterieln for a given application. The prac-
tical aspects, int lading suggestions for preparing
parts specificotions for procurement along with
established commercial tolerances, are fully coy-
ered.lt in rerommeialeil that Part I of this manualbe
carefully studieil to provide a working background
for the Design Theory presented in Part H.
It must be remembered that the r-f coil design
art is a fast changing one and that design practices
dna material,' used to-any may be superseded by
newer developments tomorrow. It is supgested that
the coil arnigner keep abreast of all new aevel-
opments through the medium of literature such as
technical articles, vendors' catalogues and data
books. This slocomented source of information
should be *supplementer, by frequent contort with
suppliers awl manufacturers and with other 41evel-
opment groups where exchanges of tecOnical in-
formation will provide an up-to-date design back-
ground.
LOAN DOCUMENT
This document is being forwarded on a loan
basis. Please return to ASTIA as soon as
the need for it has expired.
ra,
? ?
I
11
4
ATTACHMENT NO. 7
044
6?4:?iti:aitkC 1%.
?wwww.www????? w
viii
st. .....?????????
tiENERAL
Section 1
CONDUCTORS
As a general rule, coils are wound of insulated
copper conductors commonly known as magnet
wire. Because of its ductility, copper may be drawn
through dies into the form of rods and 'or filaments
of a size in conformance with specificationJAN-R-
583 (similar to that provided by the National Elec-
trical Manufacturers' Association (\FM:1). After
being drawn, the wire is annealed to give it elon-
gation properties suituble for winding into coi)s.
She is most often expressed in American Rice
Gauge (AAGl, numbers. These numbers are so ar-
ranged that 44 larger number denotes a snuffler wire
with each gauge number approximating the suc-
cessive steps in the wire drawing and every sixth
smaller number representing a wire with a doubled
diameter. In the electronics industry, the range of
sizes usually falls between No. 1-1 with a diameter
of 0.0611 inch and No. 41, with o diameter of
0.0020 inch. Special applications may involve wire
as small as No. 50 with a diameter of only 0.0010.
inch. (A complete cob, er wire tohle appetite in the
Appendix of this manual.)
In a few highly specialized came*, conductors
of aluminum, silver, or resistance metals are em-
ployed. Limited use, particularly in the higher
frequencies, is found for conductors which are in
the form of ribbon. Silver plated copper is also
used in many high frequency applications because
of its lower resistance. Electro-deposited metals
?commonly copper or silver?are also becor...;.ng im-
portant as coil conductors, particularly in printed
circuit applicatiotai.
Bare copper wire is rarely used in electronics
bece.ase of the danger of shorted turns and also be-
conee of the fact that unprotected copper very
(Nickly acquires an oxide coating which makes it
difficult to solder. Where an uninsulated wire is
specified, the choice is invariably copper which
has been run through a hot tin bath, thereby pro-
ducing what is called tinned copper wire.
.? 7' -???,?.?r,?), 94%., 41.4. . ? ,,??? 4?400,C.644111.4A
???????? ?
''',V,`,;S:t ? ? 79 41" ?
- ? ?,-; .???
?
????11.1
CONDUCTORS
FILM INSULATED WIRES
Insulations applied to bare copper wire are of
two basic types. The most common arc insulations
of the "film" type such as Formexl
vinelformal), nylon, and other specialized insulii.
lions. insulations of this general type are eh:tract-
rrited by high dielew.eic Ntryngth and %%ill be found
to possess ?arious degrees of abrasion and solvent
resist anCe.
ENAMEL
The most common film insulation is plain
enamel which consists of an oleoresinous varnish.
The film is applied in multiple coats by running
the wire at controlled speeds through a varnish of
low viscosity followed by baking in a continuous
oven. Enamel is commonly applied in vertical
coating machines without the use of dies, although
some manufacturers do use dies when enameling
the larger sizes. Electrically, this is one of the
better film insulations, .possessing good dielectric
strength, hardness, adhesion to the copper, and
film flexibility. In addition, enamel films are re-
sistant to most acids and alkalies and have re-
markuble.' moisture resistance. Abell thoroughly
cured, they are but slightly affected by varnish
solvents of the petroleum types or by neutral min-
eral oil. Lack of abrasion reaiatance is the most
serious defect since it greatly limits the applied.
tions in which enameled wire may be used with-
out an additional protective coating?usually a tex-
tile then served wires are used, it is the
enamel which vrovides the moisture resistance and
the dielectric strength, while the textile serving
protects the enamel film and spaces adjacent turns
of the winding.
VINYL ACETAL
One of the most popular film insulations in cur-
rent ass la the polyvinylforsail film sold under the
Illenulactured by General Electric Company.
? s.wW. w?*." ww....*.4?1101,????',4?4,???4?40,40,????????P,????????????????
?
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Declassified in Part - Sanitized Copy Approved for Release @ 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
POOR
ORIGINAL
i;
0
I4 ?
Part I MATERIALS OF CONSTRUCTION
trade oilmen of "Formex" or "Forrnvisrm ? terms
which will be used interchangeably throughout the
balance of this discussion. The viustish? which
forms this film is based on the synthetic organic
reain, vinyl acetate,, and also contains a phenolic
renin which serves as a heat Ntabilizing and hard-
ening agent. This varnish is applied directly to
the copper from a solvent solution, usually in hots
izontul coating muchinem. ccial diem limit the
amount of varnish which remains on the wire, and
the addition of multiple coats insures an extreme))
uniform bniliiatp of the insulatiog film..
Forme* wire is made in four grades?single,
heavy, triple, and quadruple. Compared to enamel
wire of the oleoresinous type, !Airmen littS mach
greuter resistance to abrasion, exceptional film
flexibility, and far better nolvent resistance. In
the opinion ol many engineers, its electrical char-
atertiestics are not quite so good, particularly at
temperatures in the vicinity of 75 C, but the slight
loss in Q when coils are wound with Fornicx coat-
ed wire* in more than offset by the improvement in
abrasion and solvent resistance and by the lowered
tendency to crack when bent around small diame-
ters.
One property of polyvinyl acetid films is com-
monly known as solvent crazing and is of special
significance In the case of coils which are to be
varnish impregnated. Solvent crazing takes place
when Formex coated wires in which the insulating
film is under strain?usually as the result of bend-
ing?are placed in a solvent which wets the sur-
face of the film. Under these conditions, what
seem to be minute cracks appear in the Formex
film. Actually, there is sonic question as to
whether these marks are crunks in the convention-
al sense, since they do not penetrate through the
film to the copper conductor. Tests, however, do
indicate thot the dielectric strength of salvent-
crazed .Formex Is substantially lowered, and it is
therefore recommend that coils wound with For-
mex be annealed prior to the upplication of any
varnish or similar treatment material.
Annealing consists simply of heating the coils
before applicat!on of any treatment material for *
period of time varying from five minutes at 105 C
to one hour at 80 C. Once cracks due to crazing
have occurred, it is somewhat more difficult to
heal them, and a cycle of one half hour at 150 C is
?Suppliod by ',olden Manufacturing Company. Chicago. Illinois;
Hodson Wire Company. Winat?d Divisicwt, Winet?d, Connecticut:
Phelpe.Dodes Copper Ploducts C orpfeat Ion, Fart Wayne,
Indiana; Warren Wire Company, Poernal, Vermont; Wheeler
Insulated Wise Company, Wats:bury. Cor,necticuti and many
others.
1-2
. tromorromermormor............ ? ? rr -- 0 .................
0
generally accepted as being required. Exhaustive
tests nem to indicate that no attention need be
given to solvent crazing in those instances where
the varnish treatment receives a baking cycle of it
least two hours at 125 C.
In tuoihture resistance, acI41 and alkali resin.
tnnce, and in dielectric . strength, Foffnvar com-
pare?* invorably with enamel, but its improved a-
brasion resistance accounts for .its great popularity
throughout the electrical industry.
It is this same high abrosion resistance, coupl-
ed with :tit good adherence to copper, that has
.brought about one of the major problems facing the
electronics industry today?the removal of Formex
film from fine wire. In the huger sizes?which in
the electronics industry means No. 30 or larger?
this is less of u problem, mince, if the wire is
panned quickly through it small guts or alcohol
flame, the insulation may then be easily removed
by rotating wire or glass filament brushes, emery
paper, or others means. The larger sizes, poetic-
ulnrly No. 25 and larger, may he cleaned by dip-
ping the wires in a solder pot filled with 50/50
solder anti operating at t! tentp,-ritture of not less
than 5(X) C. This method hits the added advantage
of providing a freshly tinned surface on the clean-
ed copper, milking subsequent soldering operations
much easier. The real difficulty in removing Form-
vur conies in the smaller size* /such as No. 38,
No. 39, and No. 10, all of which arc commonly
used in high frequency transformers. Many methods
have been evolved, ranging from actual chemical
attack to the use of glass filament and wire brush-
es, Opposition to the use of chemicals is great be-
cause of the fear that some ionizable material will
be left on the wire surface following the cleaning
process. Should this occur, it would constitute an
invitation to corrosion and electrolysis. (See Sec-
tion 8 for more detailed discussion of electrolytic
'..,i-rosion.) Of those methods of removing Forman
sancii are currently in effect, the one which seems
safest and best but is L)y no means foolproof, in-
volves the use of rotating brushes, preferably of
the glass filament type. The wide acceptance of
Formex tind Formvar by the electronics industry is
largely due to their toughness, resistance to mois-
ture and solvents, and the fact that, properly ins
pregnated, they can be used continuously at temp.
endure? as high as 125 C. These and other meow.
nixed properties of vinyl acetal insulated wire QC.
count for its choice as the standard of comparison
for the temperature coefficient studies performed
in support of this manual.
.4
"IP ?
?
?
00????? .1.1.00/00114.**????????0.0.0 00010
c
"SOLDEKAULF." INSULATIONS
Because of the serious difficulties encountered
in removing rooliex from the copper ond also be-
cause plain enamel itself is somewhat difficult to
remove, a need developed within the iniksity for a
so-called "eolderoble" wire. In answer, a number
of formulations have appeared OA the marliet, rang-
ing from applications of cellulose acetate lacquer
to extruded nylon coatings and nylon vominh films.
Unfortunately, soluierable wire insulations site gen-
erally lacking in abrasion resistance and in tem-
perature stability, and their use is recommended
only for single layer windings or for eipplications
where performance in secondary to cont. As may
be expected, those contingt; made up ot cellulose
lacquer formulations are low in solvent $Pthint,Ince,
and particular core must be taken in treating these
wires to avoid dissolving the film inrialuition. A
vast amount of research is under way on solderable
film insulation, and the design engineer will do
well to keep in close contact with the ()inane' wire
manufacturers as indications are thist sotiefoctory,
easily solderable insulations will soon appear on
the market. A list of some of the currently avail-
able solderable magnet wires and their tunnufactur-
ers appears ir Fie. H.
Fig. 1-1
...0010.000.0000 0.r
CONDUCTORS
the use of inorganic ceramic coatings and by the
use of organic materials such as Teflon and Sili-
cone.
Ceramic coatings by Nenoselvos hove not been
entirely satisfactory, ewe :tally fine wire. 'Ahem
combined with materials such as Teflon,- magnet
wires capable of continuous operation at tempera-
tures in excese of 200 C have been successfully
produced. Teflon (known chemically as polytetrn-
fluoroethylene) is characterized by exceptionally
high chemical resistance and by an ability to opera
ate over wide temperature ranges. Its electrical
characteristics arc good, part i tit 01) lit higher
frequencies, and it, moisture renh.totice is excep-
tioenlly high. ,hen Teflon is ascii by itself in
coating muignet wire, the resulting wire I. so smooth
and slippery that its use in winding coils of the
universal type often presents rather serious prob-
lems. Ven applied directly over ceramic insula-
tions, the surface is less smooth. making winding
somewhat easier.
Enamel noatings based on allicones are pro?-?
ently becoming available. Recommended by their
manufacturers' for use at temperatures up to 180 C,
these wires are so new that it is difficult at this
time to astiess their true value to the industry. In-
TYPICAL. ',Ol.1)).R ABLE MAGMA SIRES
Trade Name
(Film Insulated Type)
???0?00000000000.0,11,1090010100,
Celennniel
Dipen1
E./. Sol
Nylon Enamel
Nylonel
Soden. Ite
Nylon ?' %rniob
??????????0000?0??????000?01000000.0.
Manufacturer?
0?00.0?0020000000 000000?000?000- 000?000?000.0100110010011000100o 00.0000000.
Belden ?lanufa%-tsiring Company
'A heeler Insulated Wire Company
Hudson Wire Company, Winsted Division
Hen Magiv4 VI ire Company
Warren Wire Compik..y
Phelps-Dodge Copper Products Corporation
Fssex %ire Corporation
*Addressee may lie found at the end cif this section.
TEMPLItA rt. ItE: INSULAT:UNS
The growing domand among users of electronic
equipment for coils capable of wit/104101ns muckt
higher operating temperatures 'nes resulted in the
appearance of is number of new film Insulations.
This problem has been nttnnkeel in two wayet by
? - .1r
rorrom
'
4-000 it.' 0.1.000,r1;40-0 tkl?
formation available at this writing would seem to
indicate that ? very satisfactory high temperature
film insulation will sbo.-tly be on do market in the
form of silicone enamel..
11Hiternp Wires. tnt., 21 Windsor Avows*, 'Wools, Now Yorks
Hudson Wirt Conyany. Winotorl Divi. Wok
;0:449004i.
4,4404444i?* ? rtr5t*.rwrif-Trodn*,Atr", ?
1-3
, Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
Declassified in Part - Sanitized Copy Approved for Release @ 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
POOR. 0R-1-GINA!.
notormworwavoille
\
Part I MATERIALS OF CONSTRUCTION
1PLCIAL PURPOSE INSULATIONS
Numerous other film insulations are available
and are included in the temperature coefficient re-
sults shown in Fig. I-2. Many of these insulations
100
80
60
4
o:o
a. 20
0
Fig. 1-2 Effect of wire insulations upon temperature coefficient of universal coils.
4w?
???????????..........????????winv
heat or solvent action, softens sufficiently to per-
mit the turns of a winding to bond one to another.
Aires insulated with alternate films of vinyl acetal
and nylon' also typify attempts of the wire induf.ay
EFFECT OF WIRE INSULATIONS UPON TEMPERATURE
COEFFICIENT OF UNIVERSAL COILS
39 WIRES I II 3 a
CERAMIC FORM /2 0.D. X /8 I D.X 2" LONG
CAM VI6
INDUCTANCE 1.275 MH t 3%
NO IMPREGNATION
NOTE: PRIOR TO TEST ALL WINDINGS GIVEN 20
ALTERNATE 15 MINUTE EXPOSURES TO
-12 AND +85C.
ALL VALUES ARE POSITIVE AND REPRESENT
AVERAGES OF 6 COILS.
f?-
7
0
In
7
were developed to fill a particular need 1:s, for ex-
ample, those wires which are actually Formvar cov-
ered with thermoplastic material' which, under
sr offribnad ^am* WW1 Company. Nees Howse. Conne.tteut
Donde* -- It?osa Vitt* Co/eve/sr, Port Warne, lodisirs.
I:lenders -- Phelps-Dodge Copper Product* CarperMloa
1-4
,
to combine the good points of two of their insula-
tions and, at the same time, supply their customers
with a more satisfactory product.
INyteled -? Holden Mentafacturing Crayon,
Phrterre Werree Wire Ceetreop
?
LITZ WIRE STUDY
AND. 0.0.
CAM 3/ FORM 1/2 10.0. X 3/811 I, D. X 2" LONG
INDUCTANCE I.725MH t 3 0/0 TEST FREQ. 455 KC
NO IMPREGNATION
NOTE.ALL WIRE SINGLE SILK ENAMEL EXCEPT
544 EVIG (APPROXIMATELY EQUAL TO 5/40AWG.)
WHICH WAS SERVED WITH SINGLE RAYON.
*37 EQUIVALENT IN CIRCULAR MILS TO 5/44 AVG.
ALL VALUES ARE AVERAGES OF 5 COILS.
1.50
300
1.25
250
o EFFECTIVE
v
cA
1.00
200
0.0.
Ui2
0.75
150
?
Ic
Ui2
?
0.50
C: 100
0
U
U.
Lu
CY
0.25
50
??...--?..sies 4 411.44'11 f1,44441,
RT
r%cr rricr? iti4? pc
e) r cf
WIRE S#ZE
1-1 Effect f vire upon OD and Q of universal coils.
/??
Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
r??????? ?wok?
Declassified in Part - Sanitized Copy Approved for Release @ 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
POOR ORIGINAL
?
0 AND RESISTANCE
VS
BROKEN STRANDS
12#
WIRE 143 S.S.E
CAM 1/4
GEARS CAM 66
SPINDLE 68
TURNS AE100
F01-1M 0,0, BAKELITE XXX
250 200 150 100 50
0 EFFECTIVE LC2100 AA, fdi Fs 135 KC j
12
10
6 BROKEN
STRANDS
2
590 " 400 300 2C0 100
D.C. RESISTANCE IN OHMS
Fig. 1.4 Effect of broken strands spon Q and resistance of universal coils
11*
a.
?
........?1 ? ?el? ? Iiihno?? ow ?????..
LITZ WIRES
At frequencies up to 2000 kc, Litz wire is wide.
1y used in coils where high Q is of primary import-
ance. Litz wire consists of u number of strands of
very small wire, each Arend insulated from the
other. The insulation most commonly used is einem-
el, but Forrnex Litz is available on special order.
Most commonly, the strands of insulated wire are
enclosed within a textile wrap, but Utz wire with-
out a textile serving and even without a means of
bonding between strand,' has been used. In general,
better results are obtained with the use of textile
served Litz. However, its use greatly increases the
size of the winding and is, therefore, npractical
for atini.ttire and subminiature applications. (See
Fig. 1.3)
Fig. 1-5
CONDUCTORS
exe simply bunched, and any twist that they may
assume is the result of having the textile Wrap
placed 'about them. Other manufacturers make their
Litz wire with a definite number of twists per soot,
usually somewhere between 8 and 36.
Tables appearing throughout this discussion
show the results of tests coniuctd on ?arious I% pen
and sizes of 1.11/ .111,1 solid wires and are intended to
give an idea of the effect of these various wires
upon the electrical chitracteristics of universal
coils.
TEXTILE LUVI.ItED WIRES
General: The thickness of film insulation which
can be placed on a wire is definitely limited, anti
cause many applications require an appreciable
EFFECT ON Q OF NUMBER OF rusrs
PER FOOT IN LITZ WIRE
....?????????? ????
Twists/ft.
54/106 Gears
67/41 Gears
51/48 Gears
Cam 1/4" .
Cam 3:32"
C.am 1/16"
(5/44 SSE)
Form 00 .1/2"
Form 00 -,,, 1/2"
Form 01)
1100 turns
300 turns
2.50 turns
?
Q
L in mh
Q
1, in nth
-Q
I. in mit
Commercial
89
19.75
113
1.72
76
Grade ?
?
Parallel
8-1
19.75
108
1.74
75
. 0,48
. IR twist/ft
87
19.70
109
1.72
74
0,47
67; twist/ft
115
19..15
110
1.71
76
0,16
A.M*0...?
?Or?
..?7?..?.?....?
Noll:: owl% of separate strands measured over the enamel
(Limits 0.00200. 0.00230)
VIIIIN?????
Conuncrcial Grade
0.0022
0.0021
0.002?
0.00'1/
0.0021
Parallel
18 'rift
65 T/ft
OWN.
...????????????????????????0?
?I?
0.0021
0.0020
0.0020
0.0021
0.0021
0.0)20
0.0021
0.0020
0.0021
0.0020
0.0020
0.0021
0.0020
o.on2o
Throughout the years that Litz has been used,
conriderable disagreement ham been noted among
use's as to the relationship the various strands
should bear with respect to one another. It is pos.
sible to buy so-called Litz wire in which the strands
????. o.
ow"
.".
Declassified in Part - Sanitized Copy A ?proved for Release ? 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
spacing between adjacent turns, a textile eery'sg
is frequently placed on the wire as a mean* of ob-
taining this spacing. The textile may be applied to
bare copper wire or to film insulated wire with the
latter being far more common since the textile my-
. 9
c.:J 10* ? w ?A-4.1.."7t-:*1".:1;
2,
Declassified in Part - Sanitized Copy Approved for Release @ 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
POOR
***********00W*0****????01140?10.440reeeosearo010*Nareaufthre*Va*.seenmere
ORIGINAL
?
ekee
Port I MATERIALS OF CONSTRUCTION
log itself is of little ectnal insulation value. Of the
Various textile servings which are applied to wire,
eilk is probably the best known and enjoys the wid-
est tine in the electronics field. Other textiles used
for wire serving are nylon, orlon, and celaneee.
In each case, the textile is applied to the wire
by it wrapping action. The effect is to enclose the
conductor within a continuous spiral of textile eib-
bon.These ribbons are made up of a certain number
of "ends" or strands, each of a given "denier" or
size. (The term denier is borrowed from the silk In-
dustry and is a meaeere Of finences of textile fibers
with a smaller number indicating a iimeller fiber).
Silk.im available in much finer denier is than are the
? synthetic Manna, 20 denier silk is relatively com-
mon, while 80 denier is the finest orlon available
at this writing. The use of more ends of fine denier
fibers results in better coverage and a mere flexible
wrapping, therefore automatically giving silk an ad-
vantage over synthetic fibers in difficult winding
applications. In the case of double wrapped wires,
the second layer is applied in a direction opposite
to the first?the idea being to eliminate us com-
pletely as possible open spaces in the wrap.
Many problems are connected with textile served
wires, not the least of which is a satisfactory method
of measuring the outside diameter (01)) of the Nerv-
ed wire. Many methods have been suggested, but
the one most commonly Used is dependent upon
band micrometer", closed to a point where the wire
can be dragged through the opening with a recog-
nizable amount of resistance. The very means of
stating this method of measurement indicate? the
amount of inersonul touch involved. Surprisingly
eneagh, there is exeellent correlation among the
readily? of experienced operators once the necess-
ary skill has been acquired.
Another serious problem connected with the use
of textile?served wire concerns the variations in
a particular wire as supplied by different musufac-
livers. These differences are largely the result of
employing different angles of lead and different se
mounts of tension in introducing the textile ribbon
onto the surface of the conductor. A long angle of
?: ?i'1?that is with the textile more parallel to .the
conductor?results in a "soft" wire, often showing
a tendency for the textile to open up when the wire
Is bent. Because this type of wire is soft, it is dif-
ficult to use on a narrow winding of large diameter
since the resulting mechanical structure ia springy
and subject to collapse.
Allen the textile serving is applied at nearly
right angles to the conductor, the resulting wire is
LJt
r4*4?11#141?114kront01?,..
4
4.
????
I, 01?11/1?W10011010.????? ? re, -???*??????? oe.?????????????? ...ye.. ?? Imo?????,,,. ................. ..............,,. ,,,?......, ' "....''.
? ' '
. -
much less flexible und,in general, prenents a hard-
er surface when compared to the more loosely wrap-
ped wire. Carried to an extreme, this type of wrap
can work-harden the copper to a point where the
wire beeomem too stiff and too erittle to wind with-
out breaking. Unfortunately, no standards?military
or civilian?include any reference te the way textile
servings shall be applied to the wire other than to
give minimum and maximum builds and to include
referencca to skips and barberpoling. It follows,
therefore, that the product of one manufacturer may
be definitely superior to that of another when used
in a opecific application. So greet may this diffele
ence be that it lictually may he neceetiary to change
the 14 rt-up of a winding machine. whenclianging from
the wire of one supplier to that of another.
NYLON SERVING
The use of nylon-served wire may occasionally
introduce some unusual situations in winding.Nylon
tends to be slippery and in addition is elastic to
the point where tension applied It', the winding
causes nylon to stretch in a Nubian similar to a
rubber band. Ahtle this is taking place, the copper
is being elongated (Specification JANA-583 re-
quires ii minimum elongation of 7.5 to 35 per cent
depending upon insulation and sine), and when the
winding is completed and the tension released, the
uylou tends to tiring back, whereas the copper has
taken a permanent set. The result is a winding
which tends to "explode"?a term more descriptive
of the result than of the act?particularly when the
winding is of a high and narrow type. ?.ben this
action occurs, the wire will stick out through the
textile wrap in a series of loops. This phenomenon
does not occur in the case of milk?served wires,
since the silk fibers lack the elasticity of the
nylon.
ORLON SERVING
Orion, one of the newer synthetic fibers, is
slowly coming into use as f. substitute for nylon.
In winding characteristics, orlon-served wire close-
ly resembles milk except as noted below and is
slightly better than nylon in its electrical charac-
teristics. A major trouble with orlon at this time is
a lack of tensile strength in the fiber which often
3110*? the textile to break when going through the
tension devices and other guides leading the wire
onto the winding form. Once a method Is developed
for overcontieg this weekness, it is,likely that in-
terest will develop rapidly in erion-served wires.
"
0
ikaworos441404411047,44 :44 t,Voi:?;?
4
?
?
' 11..4 111. '4> '';?4 Web, "Ay 4,
?????????. ........".????14?411.4?111
?
CELANESE SERVING
Celanese like orlon, is low in cost compared to
other served wires, Also like orlon, celaneme yarn
is low in tensile strength and is therefore difCcult
to wind on eonventtonal winding equipment, In many
instances, the high percentage of rejects at wind-
ing traceable to breaks in the celaneme yarn will
far More than offset the lower 'nick) cost of the
wire. An .added (emery of this type of wire is that
the nature of the serving makes it possible to solo-
er, without removing the textile, provided, of coarse,
that the serving was applied over bare or solder-
able type wire.
Another point to be considered in the Case of
ceiunese served wire is ita low resistance to sol-
VLat attack. The yarn used in wrapping this type
of magnet wire is ti form of cellulose acetate rayon
which, therefore, is readily attacked by nearly all
common solvents. This property of celtinese?cover-
ed wire requires pa:Ocular care in the selection of
impregnations and other treatments subsequent to
winding as well es in the selection of the cements
used to start and trratinate the coils. The presence
of acetone in either instance is an immediate invi-
tation to the dieintegration of the textile?ti con-
dition sometimes drliberetely introduced and means
of producing a self-supporting winding.
One feature ef wire. covered with celanese yarn
Is emphasized in lig. 1.2 where it is shown that no
other served wire will produce universal coils with
so high a degree of temperature stability as will
celanese-served wire. The reason for this greater
stability is not immediately apparent, but repeated
tests in every instance have shown similar results.
In view of the obvious disadvantages as well
advantages to be found in the use of vela/nese-
nerved wire, it Is recommended that specification
of this type of serving should come only after care-
ful weighing of the relative merits of celsneme and
and other available textile servings.
UNIFORMITY 01' COVERAGE
The textile serving should be continuous over
the surface of the conductor. The upplicisble NEMA
standard (M21-1053 Section 3.2.2 "Coverage of
Silk") states that "the silk-covered wire shall be
wound around the niendrel having a diameter equal
to ten times the diameter of the bare wire under
sufficient tension to insure an even compact layer.
After being so wound, the silk covering NW! not
open sufficiently to expose the bare wire on the
film or the film-coated wire when examined with
awned vision." Normal vision is defined in a foot-
?
.+1
??????????????........ ...1111*
???? - ,
CONDUCTORS
note as "20-X vision after correction with eye-
glasses if necessary". In actual practice it is
difficult to purchase wires completely free from
"skips" or "berberpoling"?ekipts being occesiona1
open spots in the wrap, while barberpoling indi-
cates ti serving applied in an open spiral with the
conductor clearly viaible betweeu the turns. In gen-
era', barbernoling is recognized as a basis for re-
jection of served wires, although instances are on
record where thin type of wire has been specified
for reasons of space and :or cost.
MORISETsURE RESISTANCE OF TEXIILE COVERED
c
The teme of textile-served wire complicates the
procedures neccosary to protect a winding against
moisture, since regardless of the type of treatment
Used, the textile fibers serve ei ii wick through
which moisture may travel to the interior of the
coil. Reference to rig. 1-4) will show that ie all in-
istaticea, lettileoserveti wires exhibited less resist-
ance to humidity than did wires insulated only with
film coatings.
cosr
Coat?witie, textile serving is an expensive pro-
cedure. In Fig. I?7 are shown comparative costa of
the varioua types of wires based on prices in ef-
fect during Ottober 1953. At first glance, it may
appear that the difference in cost between plain
enameled wire and ?ingle silk enameled wire is ex-
ceseive, but it must be considered that un average
sTrving mit hint, required 23.9 hours' to serve one
pound of No. :19 single silk enameled wire.
The period since Woehl Ler H has seen a
nificant decline in the demand for textile-served
wires. Thin atetement is not meant to imply that
textile.served wire no longer occupies a prominent
place in electronics, but rather that increased em-
',heels on Cost, a definite swing toward thiniatiar.
ized coil components, improvements In winding
techniques and equipment, and in film Insulation
have, during these years, added to the attractive-
ness of the non-textile served wires.
SELECTION 01" IVIRE
Selection of the proper wire fors particular coil
wee: be based on several factors, including size of
the end produit, Its operating frequency, Q, type
of winding, operating temperature, humidity re-
quirements, tensperettare stability requirements, im-
pregnation, anti cost. In nearly every case, some
'Thu
Claw. ....wive, The ?Whe?let leauleteil Cara Ceemaisear.
YAW a..1k, 4144.4.440110.04"0".."4".""'-
1.9
??,....??????????????? Ie.,. ?
?
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POOR'.ORIGINAL
?
Part I MATERIALS OF CONSTRUCTION
compromise Is necessary. This is especially true
in the design of minimum and subminiature coils
where space limitations may demand the use of a
film-insulated wire regardless of all other factors.
An idea of the comparative size of equal induct-
ance windings made from various served and un-
act ved wires may be gained from Figs. 1-3 and 1-
12.
Fig. 1-6
upon the insulation. Unis.lreal windings, on the
other hdnil, require a wire possessing good abras-
ion resistence together with the ail;Ility to stand up
under the pressures resulting from the winding
process anil the coil structure. These pressures
are of considerable mugnitude at the points of
crossover since the nature of a tiniversol winding
requires the wire to cross at regular Intervals while
COMPARATIVE MOISTURE RESISTANCE OF
TEXTILE-SERVED AND FILM-INSULATED WIRES
110??????????????????????101.
T'ire Initial Q
Q \lessurell 1/2 hour
after Humidity'
????????????? 10????....?
Per cent of Q
Remaining
4.41?????? 41%.*Tt
1.?????r
,??????
3/41 SSE
39
30
70
3/41 SSE
39
29
67
3/41 SSE
19
30
70
3/41 SSE
39
30
6/42 LW
35
31
119
6/42 1W
36
31
86
6/42 1IF
35
31
R9
6/42
34
31
91
411.4.4.414. ---
04441,4144.444.44/4/44114.414/41.4404?044
NOTES:
'Al) coils treated with one coat of synthetic baking varnish followed by one
varnish.
196 per cent relative humidity and 40 C for 200 hours.
-Where space is not particularly limited and
where emphasis is on Q or voltage breakdown, a
textile-served wire is indicated. If Q Is of the
greatest importance, silit is the logical choice with
orlon, celanese, and nylon following in respective
order. When voltage breakdown is the chief concern-
foe example, in bailer winclings-the order would
probably change to celanese, nylon, Orion, and silk
simply because of the relative thickness of the
servings.
Choice of a particular type of winding may di-
rectly influence the selection of wire because of
? proximity of turns and/or mechanical stresses re-
suiting from the winding process. In a space-wound
solenoid, any wire-even bare wire-may "safely be
used. Close-wound solenoids may use any insulat-
ed wire whose covering is electrically satisfactory,
since once in place, there if. no mechanical strain
1.10
cort of eilicone baking
under winding tension. To be satisfactory under
these conditions, the insulation Must afford maxi-
mum mechanical protection and exhibit a minimum
of cold tlow to prevent shorts at the crossover
points.
Best suited for universal windings are wires
with a textile serving applied over either enamel
or Formvar. If space does not permit the use of a
textile-served wire, the designer's next best choice
is heavy or triple Formvur or one of the nylon-
Formvur combinations. Wires of the solderable type
are, hoaever, generally undesirable because of
theirtendency to short at the crossover points with-
in the windings. Plain enamel wire Is also gener-
ally unsiitisfactoiry for universal windings because
of its Inability to withstand the scraping action in-
volved in the winding process.
If it is known that the transformer must operate
?
?
ko, .1.5ri42,0.0.44,1114....?ValerlOSSOWN01.4.10.PflP?111001?01161414.11.114W4 Algibli00010:010,0...004.140,104#449),1,011?lpike0~MiltititaltrWAll, et:04. 14 ??;.1000.f.k,a?.44Lii * %PO' .:,141),;40,4 44,;??? iS 4
lb
-
4 ?
?
? Ow ????????? ?????????????????????????.? ?????
?
50
O
Zi 40
03
wt2
01.
ff, 830
Wuj
a.
Lii
>
820
Zoi
>
SEto
?
COMPARATIVE COST OF 4139 WIRE
n FILM INSULATION NOT SOLDERABLE
BM FILM INSULATION -SOLDERABLE
(TA TLXTILE SERVING OVER BARE COPPER
TEXTILE SERVING OVER NON-SOLDe..ilADLE FILM ?I:3
DA TEXTILE SERVING OVER SOLDERABI E FILM Cc et
cr 4 N.
t)?SUITED FOR OPERATION ABOVE 125C >
ILI LU
Cr: N X r.4
Cr J 4 j W
J Z
W 0:'7.. tki 'Z. ? , cr) id 0
.c."c. ?-i (.1: ( ) 0-1 ?.,' ?J LI Ce 0
fr .4 >-? 0 0 1.0, \-' ?- -ONO ww ci.0022
CONDUCTCRS
0 id tiJ Lij ct W?j W-j
Z C)
u z > z > >> > > 0 C) C) u u
- 0 0 ct al 41 .1 4tL Z ?
t 1?
?-
??-?
-FILM INSULATION
TEXTILE: SERVED
Fig. 1.7 Comporotive cost of various Oisrs uf .1o. 19 magnet wire,
under conditions of high humidity, the use it a tex-
tile-served wire is not recommended, regard:ems of
its subsequent impregnation. Film insulotions in
general, partli %Addy those of Forme% or enamel,
are definitely superior to any textile?arrvrti wire
when subjected to either static or cycling humidity
exposure. No treatment has yet been found which
will effectively arid the fibers of thr sciveil wire
rand prevent the movement of moisture I slang these
fibers toward the interior of the coil.
Ahen 85 C is the maximum operating tempers-
lure of a transformer, the designer has complete
freedom of choice In selection of wire insullit!on.
lieising the operating temperature to 125 C begins
to limit the lhIlite Since all insulations that are
demo-1,1,1.1k in nature are unsatisfoctor) in this
timperature range, 1 he use of enamel is not recom-
mended since it is sit about this temperotur,. that
the film begins to disintt!gr.-At from the actic:s of
heat. rated by its manulacturera
: ??.?p: ? :iv e. 4:14
?
?
??????.......
FILM
1NSULAT
.44.441.1.0.110
as being satisfactory for use above 105 C, has
y f
'wen 1,und to operate SUCCCS*full it 125 C %hen
prOteCtril tq an adequate impregnation, such as tic
dual varnish treatment recommended for maximum
moisture protection and deecribe.I in Section 7 of
this manual. 1:or units intended la Olmtate aboWe
125 C, o designer is, for the most part, limited to
wires insul.ited with Teflon, cera11114 Materials. or
combinations of the two. It is politely possible
that the fir w silicone enamels ail) prove satis?
factor) in this range, but too little is knos.a of
them at this time to warrant a definite recommends.
lion.
Ileferrece to Fig. 1-2 will give sin indication
of the degree of temperature stability which may be
expected from coils wound with iiloUsts pea of in?
halides! sites', An indication of IheI
0%ent resist-
ance of VitfloUs insulations is presented in the
table appearing as Fig. 1-9 which ma) be Used as a,
guide in the selection of compatible impregnation.
I-I
?
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\k,
?
41.14`,44.1?44444141414400 4
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Part I MATERIALS or COliSTRUCTION
Fig. 1-8 ? RECOYMENDED MAGNET WIRE INSULATIONS FOR
TIIREE MAJOR TEMPERATURE CLAS.:1"ICATIONSs
44.41?4440.4444104
R5 C
I 25 ?C
F.narnel
Ail nolderahle films
All textile kervings
Vinyl weetal
Silicone enamel
Vinyl acetal'
??????????????????
POOR
ORIGINAL
ev,111K,10444?4?444114?441,44441414,4141?444.14?44.441.440444444. +444....404.444.44.?444.4444044.444.4.44441?441.44144?44441.44?4414,4?4114?1144044441?11.
200 C
..../././???*/10.1.????? ??//somma?/????????../...../????????????=11/0//?????????????????/?/0/.1/4
Ceramic
Tenon
Ceramic plus Teflon
Silicone enamel'
NOTES: 'Any wire listed in a higher group may, of course, be used safely in a lower group.
'Not recommended by their manufacturers for operation in this classification. however, tests con-
ducted daring the preparation of this manual indicate that with proper impregnation these wires
'may be used as shown above.
Fig. 1-9 SOLVENT RESISTANCE. OF COMMON FILM INSULATED WIRES?
SOLVENT
Naptha
Kerosene
Alcohol
Xylol
Acetone
5%
Gasoline
Benzene
Toluol
Ethyl Acetate
Ill
Ethanol/Toluol
Cresylic Acid
Antmonia
Carbon Tetrachloride
K011
ENAMEL ? FORMVAR
Poor
Poor
Fails
Fails
Fails
Very good
Fails
Poor
Fails
Fails
Fails
Fails
Poor
Fails
Very good
Very good
Very good
Good
Good
Good
Very good
Very good
Very good
Good
Fair
Poor
Good
Very good
Very good
NYLON
Very good
Very good
Very good
Very good
Very good
Fair
Very good
Very *rood
. -
Very good
Very good
Good
Fails (dissolves)
Very good
Very good
Very good
Thi, table compiled at Automatic Manufacturing Corporation from information supplied by Phelps-Dodge
Copper Producos Corporation and %heeler Insuleted lire Company.
?
?
?
?
....4?444111111101
?
materials. In this connection, it should be stress.
ed that under certain circtuustances it is perfectly
possible for a wire insulation to soften in the prem.
once of the aolvent and still be acceptable for use
II not subjected to stress while softened aail if
subsequent treatments insure complete removal of
the solvent. Because of the difficulties often en-
countered in identifying various wire insulations,
a series of simple ideritification tests have been
worked out and incorporated in the tables appear-
ind as Figs. 1-10 and I-II.
Fig. 1-10
CONDUCTORS
The importance of magnet wire in high fre-
quency transformer design is great. Fottunattly for
the design engineer, the Major wire manafoctuzers
have excellent product information available and
will be found willing to lend their "know-how" in
new and special cases. Close contakis with the
representatives of these various companies will be
most valuable.
11?: NTIFICATION I'S FOR FILM INSULATIONS*
TEST
....
FILM INSULATION .
....... .
?
ENAMEL
FORMVAlt I
MI ,ON
Dip in Acetone
Film softens in very
few minutes.
No effect
No effect
Dip in 600 to 700 I:
No effect
No effect
Wire tins
Solder Pot
I.
Dip 950 to 1050 F
Solder Pot
Enamel may crumble
but wire will not tin
'Aire tins
Wire tins
Apply small flame
liurns with black smoke
Borns wiih blac.k smoke
Melts anti burns
I.enves black surface
Leaves black surface
leaving clean copper
Dip in
Cresylic Acid
Film softens and is
easily removed
Film softens slightly
Disso:ves
Dip in boiling mixture
Film softens anti is
Film softens and is
No effect.
of 30% toluol and 70%
denatured alcohol
easily removed
easily removed
?
?Ihis table compiled at Automatic Manufacturing Corporation from information furnished by representatives
of Belden 'Aire C.':ompany, Phelps Dodge Copper Products Corporation, %heeler Insulated lire Company,
anti linste-i Division of Dodson lire Company.
Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2014/03/27 ? CIA-RDP81-01043R003100230009-9
_r
'a^
-
4
Declassified in Part - Sanitized Copy Approved for Release @ 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
OOR
ilaatiViteamiaaaaarkassmarawamaanakansuaaaNtraaars
?
ORIGINAL
ateMaaaft?Maaaitaa?VOMMI.???????InalaNalliaamaaaallnitahlaialaaa ?/..laaaaa?VaalNall
? 'a..., ? ???????????????????????? %????????????amar?a?laaa???????,?-? ????? Od.?????????? ??????????????????????????
?
Part I MATERIALS OF CONSTRUCTION
Fig. 1-11 SIMPLE IDENTIFICATION TESTS FOP TEXTILE SERVINGS'
???ftflafrilralIMIllai.Wiaimift.
TEST
TEXTILE
,I0MON?aaiaalakt
.....,........
-
S11.1.:
NYLON
0111.0N
(:1,,,i,..?Nrst,,,
Pa t?r 0..
?.??????????Wa?Aail,??.1,11N
?
...????????????,
.
Dip in Acetone
No effect
No effect
No effect
Diknolves
Dip in Cresylic
No effect
Dissolves
No **(foil
analoata.? atr?aaaavaaa
Acid
Strip from con-
Borns. Ash dark
\1e Rm. \lay burn.
1Idlea, \lay burn
doctor and
and easily crum-
Forma hard resin
in (lashes. Le ilV e8
.bring
near small flame.
bled. Odor re-
boll of greyish-
hard, mlightly gum-
aembles burning
tan color. Odor
my hall. %tort, in
feathers.
rementhles burn-
int flesh.
color,
'Dip in
an liaso. ,
Dissolves
No effect
airaati...,61,,Coallaisi ???
.......................-.?...
-arr-i.a...o.aaimiam??????????
?????????????????????????
???????????????.V.h,~0011
OM !Noma*
?This?table compiled at Automatic Manufacturin:., Corporation 1r,-.m informatit a furnished by rrtiresentatives
of Belden Wire Co., Phelps Dodge Copper Products Corp., Wheeler Insulated Wire Co. and Winkled
Division of Hudson Wire Co.
Flit. 1-12
COMPARATIVE SIZE OF COILS' WOUND Aim
FILM-INSULATED ANI) TEXTILE-SERVED LR ES
r
t
1. in nth
????????????0?????????????????????11.14,10 4,14
(.ibil 01) in inches
......
No. 39 HF
No. 39 SSE
war.
1
???????????? *Nana
55.0
20,4
0;0
11.0
10.0
4 .7
4,4
1.2
11
1.000
al?????? ...NW
..........
1.430
1.130
en???????????
0.790
?
0,722
????????, Ma
0.9110
....MOMS
0.1127
..........
0.672
.........
????????????
0.649
?????????????
0.577
ICoil data: Form ? 01); 1/2 inch, Wire also ? No. 39, Gears ? Formet 59/158, SSE 100/64
???????????????? 4.???????????fframmorlaie ???????????rma?
144
. 011??4?? 1??????aaaba?laatta10????????aaaaiparalailaa?????????,?????? ben 1?????????4114,.......raaaaa??????4461.........,a? 'Mai. ? 44. ?{$4.fa , agataal?????411.* ita . a ? ????.? ????????a ? ?hiata?
* ????? ?,..iira????*?,.4. ,II . 4?41111.... ? .? row ? ? ?
k
???
1. 4..4.... ..????????????????????? ,t ???.11?1,4?????? ??? .?
?
-.a.... ? "????
s,
1\1111.10GRAPHY
? 1 oung, James F.
Ilitterialx and ProrrAleN, Fit:11th Printing
John Wiley 8, Sons, Inc., Ne W York, 1919
fttieontla Wire and Cable Company
liroatlwav
New York, New York
I !ride n Manufacturing Company
Chicago RO, Illinois
The F.lectric Auto-1...ite Company
Point Huron, Alichigan
Coneral Electric Company
Construction Material Deparlment
Bridgeport, Connecticut
Ilitemp Aires, Inc.
Windsor Avenue
Minneola, Long Island. New York
JAN.11.11-0(3)
"Wire. Magnet"
1,1Q-A-31141(21
ire,(:opper, Soft oi Annealed'
CONDUCTORS
ANI) H.( 1INICAL INFORS1ATI0N 0E;
Hudson Wire Company
insted Division
Winsteti, Connecticut
Phelps-Dodge Copper Products Corporation
Fort Wayne, Indiana
Ilea Magnet Wire Company
Fort Wayne, Irdiana
Sprague Electric Company
North Adams, Nlivoinchumettor
Warren Wire Company
Powniti, Vermont
si?x;it ICATIoNS
-pry ificot ions or the .1merican Standards
Sal in sponsorell tu Nat ',mai 1:1eciric4tl Vlanu.
fai tigers Association if i hit. 11 examples are:
+. ? ?411 ?
?
C9.1.1955
"Enamel-Co4te,111oliml Copper Magnet Wire"
C9.3-1953
"Silk-Coverrd Hound Copper Magnet Wire"
C9. I-I951
"N),Ion-Fits-r-C9vereci Hound topper Mdsnet Aire"
? v ? .111,aa?a ? ,????????,.....,?4.? ??????lb??,,,,
- ? -0 ??.7.4 . ? ? ? ??
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Declassified in Part- Sanitized Copy Approved for Release @ 50-Yr 2014/03/27 : CIA-RDP81-01043R003100230009-9
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Port I MATERIALS OF CONSTRUCTION
ACKNOCVLEOGEMENT
For the assistance that they have rendered in connection with the preparation of this 'normal, we are
especially grateful to the following individuals who are associated with the magnet wire industry;
Mr. jamen Ititzer
Ainsteil Division of the
Hudson Aire Company
Whinier!, Connecticut
Mr. Ralph hail
Phelps-Dodge Copper Products Corporation
Fort Rayne, Indiana
Mr. Ceorge Horn
The Wheeler Insulated Wire Company
Waterbury, Connecticut
Mr. Arthur Mignot
The %heeler Insulated Wire Company
Waterbury, Connecticut
Mr. ILL. Heading
Belden Manufacturing Company
Chicago, Illinois
Mr. Walter Samoa
Radio Wire Manufacturing Corporation
New Augursta, Indiana
11r, Earl L. Smith
Phelps-Dodge Copper Products Corporation
Fort Wayne, Indians
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REASONS FOR SHIELDING
Section 2
SHIELDS
operate succemafully., modern eleczronic
equipment must he so cioistracted that coupling
between the various circuits is Ihnited to the
mount intruded by the desigerr of the equipment.
Essentially, this requirement can be met by con.
fining within a Ihnited spat r the electromagnetic
and electrostatic fields which surround any in-
ductaner through which is cnrient is flowing. He.
causs both of these fields tend to link (couple)
readily with other similar IitiIs, it follows thrit
coupling may be either inductive as a result of
the electromagnetic field, or erspacitive as a re.
sult of the electrostatic field. It is usually fleet*.
sary to prevent both types of coupling, and the
means moat often employed Is that of shielding
the inductive components.
Shielding, an practiced, in electronics, Hsu.
allyon ala of enclosing an inductive component
within IA metallic container called a shield can.
The t ontainers are usually made of a metal hay-
ing a relatively high eraninctivity. Aluminum is
the most common shield material with copper and
zinc bring used for those caaria where it is neces.
nary or desirable to aolder directly to the can.
Sometimes iron or steel is used although it is not
it common practice at radii) frequencies.
ELECTROMAGNETIC SHIELDING
Electromagnetic fields may be confined in two
ways: (1) by the use of conducting shields of non-
magnetic material or (2) by the use of high-permeri
ability, low-reluctance magnetic shields.
In the case oi conventiunnl shield cans made
from low resistance, non-magnetic metals, the
shielding (reduction in indlictive coupling) is
largely the result of eddy currents induced in the
metal can. The energy used to form th-zse currents
Is drawn from the field of the inductance to whieh
the shield bears somewhat the relationship of an
; ;,
SHIELDS
moaned secondary. thus.creating a loss in the eie.
closed intl which shows tip as ac increase in
thi effective resistance of the coil and it S114.
scquent lowering of its Q,
Since the 14164.1,16y, of a imigiwtic field is an
ellitY current phenonielom, it is apparent that one
kris these currents t. MI flow freely wherever they
'dense, the shielding will not be effective. Ibis
means that shield man' tolls t be made from low?
resistance materials, free from breaks or high.
resistance joints. In .alter words, if shielding is
to be effective, there +mint ? lie a continuo4, 11?Nvi.
renintance path through which eddy currents can
flow with complete freedom. Were it not for thin
fact, shield cans marls tip of metal foil interripnced
between layers of paler could provid mailerpotte,
low-L:ost shielding. Thot this is .not tie Case Can
lir easily demonstrated by using cop ier foil as
liner in steel shield cans - mu shield,rig procednre
which will be found completely ineffective at radio
fiequencies until the overlapping portion of the
Copper foil is soldered throughout its length.
Eddy currents which are set up in nhield cans
wIll be found to he in opposition to the fields of
the enclosed wholings and therefore will act to
reduce the effective coil inductance. It is for this
reanon that it is alwava necessary to specify the
conditioas under which inductance readings have
been taken. The effect to which "in shield" and
in air" rea4ingn may vary is illustrated by mro:s.
tiremente made on a e ow..e nt 'tonal .115 kis inter.
mediate frequency transiorn,er. Nleasured in air,
this transformer hall a primary inductance of 2,02f
teli, and .4 secondary inductance of 2.412 mh, hut
when enclosed within its shield I, became liql111
immim and I, became 2,00$1 mh ? an average loss of
approx imately 2 per ce nt in inductance. Nlutual
slut tance between the two windings was nisi, itfr.
levied and to an even greater extent since 3 MOMS*
ta ea 12 8 microbe aryls In air and only lo5 'pivot).
!levy* when encloard in the shield can. It prober.
2.1
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Declassified in Part - Sanitized Copy Approved for Release @ 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
POOR
ORIGINAL
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Part I MATERIALS OF CONSTRUCTION
Lily should be noted at this point that variations in
inductence and Q can be introduced not only by
shielding but also by placing a coil in close pros.
iniity to pinch metallic objects as mounting brackets,
a c'utrisiet, core screws, or other eimilar masses of
metal.
Nlagnetic shielding may alto) be acconiplished
through the use of cups or sleeves of powdered
iron, ferrite, or other $uititbly high-permeability,
loyeeeluctance material. In such cases, external
coupling is reduced because the magnetic flux is
concentrate(' in the low-reluctance path which is
pInceil about the coil. Unlike the shielding result-
ing from eddy currents, this type tends to raise
both the inductance and the Q of the enclosed
windings. In general, magnetic shielding is not
particularly effective in the reduction of extraneous
coupling, and it is customary in the design of trans-
formers utilizing this type of shielding to enclose
the complete assembly in a conventional shield
can despite the presence of magnetic cores or
sleeves. In such instances the outer shield can
serves primarily as an electrostatic shield since
an amount of? flux sufficient to generate eddy
currents rarely reaches the outer can but instead
stays within the low-reluctance path of the meg.
netic material.
The discussion up to this point has been pd.
manly concerned with electromagnetic shields.
Since, however, the basic requirement for electro.
'static shielding is to enc'oPie by a conducting
surface the space to be shielded, it will be Been
that the use of conventional shield cans provides
electrostatic shielding as well as electromagnetic
shielding. The electromagnetic shielding is, of
course, the result of the eddy currents which are
set up in the shield and which oppose the passage
of the flux lines. The -continuous conducting pails
provided by the shield can is nufficient to prevent
capacitive coupling through the electrostatic field.
In this connection, it should be noted that a
solid conductive screen is not necessary for e-
lectrostatic shielding and that a grid-like structure
of the general type shown in Fig. 2-1 will be satis-
factory for this purpose. Because only one end of
the conductors making up this device is connected
to the common bus, there is no opportunity for the
formation of circulating currents, and therefore
there is little or no effect upon inductive coupling.
Such an arrangement is known as a Faraday Screen.
and examples may be found in many modern cont.
nisrcial receivers where the screens are often made
by printed circuit techniques.
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Faraday Screens must, of course, be grounded
if they are to be effective. The principal purpose
of these devices is to furnish a means of
elimi-
nating capacitive coupling while at the same time
permitting inductive coupling ? a condition which
cun result from the inmertion of a properly grounded
screen in such a manner as to seperate and enclose
the windings of a transformer.
Fig. 2-1 EXAMPLE Of FARADAY SCREEN.
Note: Space between vertical conductors should
be approximately equal to the OD of the Con-
ductors.
FACTORS AFFECTING SHIELDING
Several factors may be said to influence the
overall effectiveness of shielding. If the shield
material and its thickness remain constant, fre-
quency will have a direct influence upon the ef-
ficiency of the shielding, since increased fre-
quency means increased eddy currents which in
turn mean better shielding. Shen the frequency
remains constant and the metal is not changed,
the effectiveness of shielding increases as the
thickness of the shield increases. Actually, this
letter condition is not a linear function, and ex-
perience has indicated that at common r-f frequen.
cies little is to he gained by increasing OW thick-
ness of an aluminum shield beyond the normal
0.018 to 0.020 inch. Heavier shields may, however,
be required at lower frequencies.
It must be remernhered that the efficiency of a
shield is directly related to the LonductivIty of
the metal used in the fabrication of the shield.
This means that copper cans are more effective
than those made of aluminum, although for average
applications aluminum is perfectly satisfactory WO
is evidenced by its almost universal acceptance
in all equipment except the most precise, as, to,
example, standard signal generators. Reference to
Fig. 2-2 will provide an indication of the cow
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partitive effectiveness of various materials when
!mole into shield cans of uniform size and checked
over a wide range of frequencies.
In the design of high-gain amplifiers, care
should be taken to avoid direct . contact between
shield cans since there may be considerable coup-
ling between stages if the shields are in contact
at any point. For those cases requiring maximum
inolation. it is desirable rather than to increase
the thickness of the shield cans to use two or 111.11re
srparete shields loceted one inside the other with
comets between the two limitea to one point, a
poeeilde. It is this type of double shielding which
has preved most successful in the manufacture of
mtarelard signal generatois wheie stray couplings
are of the utmost importance.
Among the effects of shielding which should be
me nt ioned is the increase in distributed capacitance
thnt is always noted in shielded windings. This
increume in Ca is essentially an electrostatic phe-
nomenon which occurs because a shield is at ground
potential while at least a part of the Winding is
always substantially above ground. Since dia.
tributed capacitance is a factor which influences
the self-resonance of a winding as well as the res.
lationtihip between its true and apparent inductance,
it therefore becomes clear that it is difficult to
predict accurately the effective inductance of a
ahiehled coil. It is, however, equally obvious that
the closer the shield approaches the coil, the
greater will be the difference between the true and
the apparent inductance of an enclosed winding.
Not only is the size of the shield important
when viewed from the standpoint of its electro-
static effects, but it must be remembered that when
metal of any sort is moved closer to an energized
winding, the .amount of magnetic. field that will
enter into that metal is increased. Vlost. engineers
consider it to be an accepted fact that this en-
trance of energy into the walls of the shield can
and the resulting eddy currents -formed therein will
show up as a circuit loss and that a shielded coil
will lose both in inductance and in Q.
EFFECT OF SIZE AND SHAPE OF SHIELD CANS
In the course of laboratory work performed as
background for this manual, a suhstantiol amount
study was devoted to the effect upon enclosed
windings of variations in the shape, size, and ma-
terial of shield cans. As can be seen from the
graphs and tables throughout this section, the ef-
fect of shielding is not one which is clear-cut but
rather is one which is dependent upon a number
? 4 ? yr ? riA? ? 4...4.?.11, ? ? ? N ,?ti ? , A ? .9.
Sill ELIA
of factors includieg freqeency of operation, core
material used in the inductance, and the Q an sir of
the e 'Closed winding. Reference to Fig. 1-3 will
show that at frequetwiem of 30 NIc or higher, it is
entirely possible for cod to gain as much as 30
per cent in Q ?Nhell enclomed within a relativelv
clone-Fining aluminiun shield. It is important to
note in this regard that .tir-core coils do not re.
!Tuna to shielding in this manner al env fretpiency
lictseen .151 kc dna 180 \he Only those coils ha% ing
iron cores show this property, and here 418ai1 it
of
shim Id be noted that the mere prese ncr an iron
core is insufficient Ihtsis for this behavior. (tidy
certain kinds of iron curem induce. a response of
this sort, thlw intik ming .something of. the general
difficulties involved in predicting the performance
of shielded coils.
As will be seen from the experimental
hit us at-
Compmtnvng this sectio., there is good reason to
accept the oft-quoted rule or design that "a shield
can should never come closer to a nonniegneticallv
shielded inductor than a distance equal to the
diameter of the coil itself", thus pointing out the
importance of cup cores or other magnetic shielding
in miniature and subminiature transformer armign.
Because the selection of the size and shape of
transformer shield cans is more often dictated by
the available space in the end equipment than by
those factors conmtittaing optimum coil design,
it follows that gieul transformer des:gn practice
should start with the shield since it is necessarily
ti limiting factor in the physical size of the cons-
pleted unit. A study of the sizes of shield eons
presently available .from established manufacturers
lends credence to the theory that all too often engi.
neers.design a tranmfortner and then as their last
move design a shield can to fit their new creation.
One major shield .111/111ufecturing company' reports
that it has on hand npproximately 150 setn of draw.
ing tools representing 'in investment is the order of
$30,0,000 ? a figure whith is easy to liteleretnntl
since a single set of tools may cost anywhere
between $1500 and $1000. This figure of $100,000
does not include piercing tools ? those tools which
punch the required holes and other openings in the
cans. No estimate ale to the nnruber of piercing
tools owned by this company was available other
than thet for one particular shield can (an item lamed
in large quantities on military equipment) twelve
different sets of piercing tools were in current op-
eration at the time this gurvev was made. Ad-
IPaul lk Beekman, Inc.. PhIle4olphio. P?nno)Iltania.
4.. ? 10.. Lik.4.
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Declassified in Part - Sanitized Copy Approved for Release @ 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
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? ,ro? ;,..???,.....111k1.....11101???????^1W010aaramisidlaitipaa.1... ?????, ? '?'?' .?i',......???????????????????????????????????????????????????1111?,,,,,a? 0111.41,4.?????????????????.????????????????????????.????.0?11111160a?MM?or 4...???????????????
Part I MATERIALS OF CONSTRUCTION
mittedly, piercing tools are far less expensive
than drawing tools, but the fact remains that had
more thought been given to the bustle design of
this series of coils, production costs could have
been aubstantially lowered through 14 reduction in
the cost oi tooling,
4 METHODS OF FABRICATION OF SHIELD CANS
cans inlay be made in Et number of ways
with the Most impnrtant and generally aniisfactety
method being known. ns drawing. This operation te
curried out in multiple stage presses utilizing
stiip atock which Is blanked in the first 'hinge and
then is progressively formed into nhaposi and sizes
more nearly approaching the final ratio as it passes
thrcugh each successive stage in the drawing oper-
ation. In some tools, provision is nattle in the
.final stage for piercing and cutting la length,
whereas in other instances these two operations
are performed on seepnrate equipment after the shield
has been drawn. It is worthy of note OW drawn
shields are very uniform in size and in wall thick-
ness, and that they have an end thickness equal
to that of the stock from which they were drawn.
A second manufacturing process which at one
time was of considerable importance in shield can
production is known as extrusion. In this method,
the can is formed from a predetermined mass of
metal which is placed in a cavity having the size
and shape of the can which is to be formed. A
ram having the dimensions of the inside of the can
then enters the cavity and by tremenilnua pressure
actually causes the metal to flow upward into the
space between the ram and the cavity. well, thus
forming the shield can. This method 1* used today
by some nuteufacturers for small sizes of round
cans but, in general, it has been reploced by draw-
ing. Extruded shields can easily be far neftlied by
the thick closed ends which are always present ? a
somewhat undesirable condition inasmuch as it
makes piercing that, much more difficult. Another
point in which extruded shields are inferior is
foetid in the nonuniformity of sidewoll thickness
which is a characteristic of the extrunion vocalic
Round shields are sometimes spun,' .but like
casting?a method once used in certain instances?
this method of melting shield cans offers no ad-
vantage great enough to warrant its additional cost.
In view of the trend toward miniaturleation, it is
?highly improbable that spun shields will again be-
come a factor of any importance In the electronics
Industry.
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DIMENSIONS AND TOLERANCES
The most critical dimensions in shield design
are the internal radii. For fairly obvious reasons,
It is not possible to prodace a drawn shield can
with perfectly square corners on either the inside
or the ontnide of the shield. It In, however, de-
sirable to keep these radii as small its possible in
order to utilize most fully the space within the
Since, however, tool cost nod tool main-
tenance ore both influenced by the nize of the radii
? specified, it in generally accepted that 1/16 inch
is the timeliest practical radius that should be
specified In shields of approximately 0.750 inch
inside dimension. Larger mhieltis, of course, de-
mand larger radii with 1.250 inch shields requiring
7/64 itt-h radii for economical and satisfactory
production. !loth inside and outside dimensions
have been used at one time or ()thee in specifying
shield *ilea, but the bc3t and most widely ac-
-cepted practice seems to be to work with inside
dimensions on cross sections and with outside
dimensions on length. Commonly accepted toter.
ances are i0.003 to 0.005 inch on the cross sec.
tioa; t0.003 inchon wall thickness; and either
to.00e or 128 inch on the length. Most Can
manufacturers will find these tolerances accept-
able without additional cost. To speciiy closet
tolerances will inevitably require special tools,
special handling, and additional expense.
Up to this time, very few serious attempts have
been mails to standardize on shield can sizes. At
various times designers have specified shields
which in cross section were round, rectangular,
oval, or square. Because of a desire to conserve
chaasis space, the recent trend has been away
from raund and oval shapes toward either rectanr
ular or square shields. Probably the nearest to a
"standard" size in use today is the so-called
"3/4 Inch" which actually merieures 0.735 inch
square on the inside. Other popular sizes have
inside dimensions of 1.125 inches and 1.375
inches, and It is upon those three sizes that the
majority of the enperimental work for this section
was hissed. As these words are written(toward the
end of 1954), there is good evidence that a new
subminiature size of square cross section having
inside dimensions of 0.500 ""(56 inch will be
come mulles
keIT11003 OF MOUNTING
When Installed in a piece of equipment, shield
cans must be firmly connected to the chassis both
electzleally and methanically since shielding be.
14 4
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2-7
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Declassified in Part - Sanitized Copy Approved for Release @ 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
POOR
ORIGINAL
Past I MATERIALS OF CONSTRUCTION
Fin, 2-5 Nescription of various coils used in shield can studies
SHIELD CAN STUDY
COIL DATA
C011, "11"
C011. "A"
??????????????????????????.....
ire
No, 39 11.1'.
Cam
3/32
tear.
56 '74
Tur
500
Elol Spacing
0..125"
01)
0,516"
Coil Width
? 0,115"
Coil Form OD
0,285"
Core
None
Impregnation
Wax
Frequency
455kc
Coil "Q"
(No Shield)
f;9
46.91 mil
COIL isErs
W ire Nu. 36 SSE
Winding Solenoid
Turns 10
End Spacing to
4:oil Center
End Spacing
to Coil
01)
Coil Width
Coil Form 00
Core
?
Imprepnation
Feequency
Coil "Q"
(No Shield)
C.
0,4i7"
.0.301"
0.44A17'
0.285"
None
Wan
10.7 Mr.
so???199,9???????????????????
No, 39 II.F.
3/32
56/74
500
0.425"
0.516"
0.115"
0,285"
I'laat-!ron
11-231
Wax
455 kc
74
27.93 nut
COIL
???????m????????????????????10
No. 36 SSE
Solenoid
10
Coll, "C" COIL "10"
???????????? .1.0=????????????????
??spls????1??????,411?81IIIIMINAVIIIII
No. 1/44 SSE No. 5/41 SSE
1/32 3/32
51/67 V 51/67
or r V ? 255
0.425" 0.425"
0.523" 0.523"
0.120" V 0.120"
0,285" 0.285"
None Carbonyl 1.1
Wax Wax
455 kc 455 kc
79 122
252.09 nor 155.91 our
COIL "G" COIL "II" ?C011. "1"
No. 30 SSE No. 30 SSE
Solenoid Solenoid
15 15
0.511" 0.528"
0.467"
0.301"
0.087"
0.285"
Cart.onyl
Wax
10.7 Mc
0.421"
0.310"
0.214"
0.285"
None
Wax
10.7 Mc
0.421"
0.110"
0.214"
0485"
Corbonyl E
%rx
10.7 Mc
No. 30 SSE
Solenoid
16
0.512"
0.523"
0.213"
0.500"
None
Wax
10.7 Me
64 92 95 116 114
184.42 nut 103.60 %nal 141.07 nut 68.58 nut 54.61 eta
1'9 ? .41.
..99.fs4c?
I94,..........?.........., ... .........?????.????*411./. ..........00?;04.40014.????????????????????.4111W
?
?
1 a.
SHIELD CAN STUDY
cou, "sr'
Wire No. 20
Wing Solenoid
'turns ? 71:
}nd,Spoe in g to .
Coi; Center 0.503"
rmi Spacing to
Coil Edge 0.358"
01) V 0.371"
Coil Width ? ? 0.290"
Cod Form OD ? 0.285"
Core None
Impregnation Wax
Frequency 30.11e
Coil "Q"
(No Shield) 143
67.05 out
4.011, "P"
lire No. 20 II.F.
Winding Solenoid
Turns 1)
End Spacing to
Coil Center 0,499"
End Spacing to
Coil Edge 0,427"
01) 0,362"
Coil Width 0.113"
Coil Form OD 0.285"
Cora None
Impregnation Wit%
Frequency 60 Mc
Coil "Q"
(No Shield)
31.49 wit
''11144-t4i'l444"140,41.1049141/411999.441199.349,019U,"9,4"9"" ..^?`..4"""'"'-'?","''''''''''"'""."'..9999"."99.9,990999-909.90.4-99.9.99199.99*???.......?????????99.0.9???????????????,......? 9.-9.-9-9.99 .99999-9 9-9?99-999,-
?
? ,
.9910/011119.9* or ... ,9,99???????????????????????. ......... ????11...?????;?? ?????? 99. ? a...yr 999
11..-
40 ' VV
' 0 .
44
?
? ? ? vovu,
?
COIL DATA
SHIELDS
COIL "N" 'COIL "0"
No. 20 11.1". No. 20 11.1".
Sole noid Solenoid
I '2
0.501"
0.158"
0.371"
0.290"
0.285"
Carbonyl E
VI ax
10 Mc
99
35.30 nut
C.0114"Q" (.011, "It"
No; 20 Hy. No. 20 11.F.
Solenoid Soleroid
0.503"
(058"
0371"
0.290"
0.285"
Carbonyl C
ikax
30 Mc
40.8
32.98 ;nil
COIL "S"
No. 20
Solenoid
31)
0.499'9
0.499"
0.499"
0.427"
0.427"
0.427"
0.362"
0.362"
0.362"
0.113"
0.113"
0.143"
0,285"
0.285"
0.285"
Cabonyl E
Carbonyl C
Wit%
Wax
60 Mc
? 60 Mc
60 Mc
76,0
. 27
158
22.85 uuf
21,25 uuf
28.62 nut
t11.'
......'-?????~1.9.19?99**10141.-910.,(01.19*.1.947.100,14.????????????9999.9 ?????? 91.?{4 ?nr ? .19.9,, 9 9 ???? ???.
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44000O03101010400?0041.00???????????????????ols
ORIGINAL
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Part I MATERIALS OF CONSTRUCTION
SHIELD CAN STUDY
COIL DATA
COIL "T" COIL "U"
??????????????????144 ?
roy
C011, "V" COH, "W"
11101~4.?????????????????
? Wire No. 20 ILF. No. 20 HY, No. 20 IV. No, 20 II.F.
Winding Solenoid Solenoid Solenoid Solenoid
Turna 14 1% Itt 1 S
End Spacing ta
Coil Center 0.501" 0.501" 0.501" 0,501"
End Spacing tas .
Coil Edge 0.465" 0.465" 0,465" 0,465"
OD 0.358" 0.358" wis8" 0,330
Coil Width 0.072" 0.072" 0,072" 0.072"
Coil Form OD 0.285" 0.285" 0,285" 0.M5"
Core None Carbonyl E Carbonyl C llIN8
Impregnation Wax Wax Wax W4111
Frequency 120 Mc 120 Mc 120 Mc 120 Mc
Coil "Q"
(No Shield) 171 76.5 30 150
C 12.79 uuf 10.52 uuf 10.41 uuf 11.90 uuf
?
?
COIL "X"
COIL "Y'
COIL "1"
COIL "1"
Wk.
No. 17 11.E.
No. 17 ILE.
No, 1" ILE.
No, 17 ILE.
Winding
Solenoid
Solenoid
Solenoid
Solenoid
T=--...7.
gad Spacing to
1%
Coil Center
0.496
0.496
0.496
0,496
4
End Spacing ta
Coil Edge
0.437
0.437
0.437
0.437
OD?
0.392"
0.392"
0.392"
0.342"
?
Coil Width
o.o95
0.095
0.095
0,045
Coil Form OD
0.285"
0.285"
0.285"
0.286"
Core
Nona
Carbonyl E
Cahonyl C
111N8
Impregnation
Wax
Wax
Wax
Wax
? ?
Frequency
180 Mc
180 *
180 Mc
100 Mc
I ?
so
/
Coil "9"
(No Shield)
238
50
17.5
1M
C
10.25 nut
7.91 uuf
7.53 oaf
8.76 uuf
?
2-10
q?
?1044100:00000,400????????????????jp. ?0P0-
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?
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SIIIELD SIZE
044
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1??????????????????
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7: CIA-RDP81-01043R0031on7mnma
14
Declassified in Part - Sanitized Copy Approved for Release @ 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
POOR
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coma less effective whenever resistance is intro.
diced between the shield can and the chamois,
If this resistance varies ender operating cone
ditions, noise may be intesoluved into the circuit.
For many years, the conventional method of mount.
ink shield cans wan by the use of spade bolts
which were riveted to the ahielii cans and attached
to the chassis through the use of nuts and lock
washers. Recent advonees reechonical design
have produced varioio. ;nap. of spring mounting
devices intended as repIncements for spade bolts
and purporting the selvnotages of being few lees
evpennive and' much fneter to install on the pro-
&akin line.
successful eXamplit of this type of trans..
(orator mounting is t! ehot.e,i, spring moUntinh
clip developed and patented by Automatic Menu-
Inctitrine Corporation, Newsck, New Jersey for use
with its K-Trans. The ileaige of this clip is such
as to assure a permanent, non-oxidizing contact
between the shield can and the chassis us well its
a means of mounting which satisfies even the
strenuous requirements of the Navy shock test.'
ssitics.??
elbattri
1110110111
SUOIAOSS
?":7811441.111"71/Pir
Fin, 240 &-TRAN mounting dip and mounting tool.
The cAvings that result from this method of
mounting are considerable as may be seen from the
fact that spade bolt mounting requires the use of
a total of 10 small parts' compared to the single
mounting clip described ahoy, and pictured. in
'esoiu.ssolaxa at Signal Corps 5tsgineetts4 Laboratortes Cuing
the tint se of work on Signal Corps N?sitetek sad Dtivaloptasal
Centro', Ho. DA...36-0304C?11133i,
4,4
04 2 ePodo belle, I fleets, twat I washers to ate
lath the spode bolts to the shiehis plus II owe an/ 3 lotto
washers Is iviount ths shield Is the sheathe.
41,1- ff-^ V.??????????????????V 'V,. ?
???????????,.... wt. ,???
SHIELDS
Fig. 2-10. A further advantage is to be found in the
ease with which ehield cons designed for use With
with this clip can be mounted and demounted, The
simple snap-artien of the clip responds readily to
the simplest .of tools, and wish proper care the
clips may be toted over and over again ? a point
which could be of considerable importance when
making reptiles under emergency field conditions.
A number of other types of spring-octemed
mounting devices have been made available from
commercial sources, ViIt ile offering certoin
vantages over spade bolts, especially in the ease
with whiCh. they may be attached to a chassis,
these devices all triptire riveting to' the .ehielibt
with the consequent handling of .a minimum of 6
small parts. This fact in itself reduce* the at-
tract;veness f thesr devices which, while soleisnete
for many civilian applications, are not believed to
be sufficiently steoly for the average militoty re?
quirement.
Since the shield can is an essential port of
a high-frequency transformer, and since such trans.
formers will operate successfully only when firmly
nttached to the chassis, it follows that for those
units requiring shield cans of a size other than
the "3/4 inch", the iniott.reliable mounting nietliod
is that involving the use of spade bolts. If mini..
mute components see being -used, it would seem
wise to give consideration to the obvious ad.
vantages,. attached to the U-shaped, spring mount.
ing clip.
DES1CN SUMMARY
From the foregoing dieenssion of shields, it
wculd seem that Kumi high freciency transformer
design pracLice calla for --
1. The use of etanditril sizes of drawn alsseinum
shield cans supplemented by magnetic shield.
lag in minimise'e and subminiature units or
where extremely high Q must be obtained
in small spaces.
2. :specification of normal commercial tiller.
ances on all dimensions including internal
radii.
3. The Lige of a substantial mounting method
consisting of spade bolts, nuts, and lock
washers for the larger sizes of shield cans
and either the same or the patented U?ohnped
spring mounting clip for "3/4 inch" cans.
.....???????????? ?C? ? ...font,. v ?
????. ?????? ? ?????????????
245
P.\
Declassified in Part - Sanitized Copy A ?proved for Release ? 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
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Declassified in Part - Sanitized Copy Approved for Release @ 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
POOR
ORIGINAL
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VV.
Port I MATERIALS OF CONSTRUCTION
4
TEMPERATURE CONVERSION TABLE
The numbers in itilica refer to the temperature in either centigrade or Fahrenheit which is to he convorted
I, the other scale. To convert Fahrenheit to centigrade, read the left hand !column. To convert centisrlide
to Fahrenheit, read the right hand column.
2.16
.100 -148.0
-72.8
? -72.2 - 98 -144.14
-71.7 - 97 -142.6
-71.1 96 -140.8
-70.6 - 93 -139.0
-70.0 - 94 .131.2-
.69.9 - 93 435.4
-68.9 - 92 -133.6
48.3 - 91 4 31.8
-67.8 . 90 430.0
471 - 89 428.2
-66.7 - as -126.4
46.1 ? sr 424.6
45.6 - 86 -122.8
-65.0 - 85 121.0
44.4 ? 84 4 19.2
-63.9 - 83 -117.4
-63.3 -? 82 416.8
-62.8 ? 8/ -113.8
-62.2 - so -112.0
41.1 - 79 -110.2
-61.1 - 78 -1C41.11
-60.6 ? 77 -106.6
-60.0 - 76 404.8
-59.4 - 73 403,0
48.9 ? 74 -101.2
48.3 ? 73 ? 99.4
-57.8 72 ? 97.6
-57.2 - 71 ? 95.1
-56.7 - 70 ? 94.0
-Et .1 - 69 ? 02.2
? 90.14
-65.0 .67 -88.6
-54.14 - 66 86.8
44.8 . ss - 85.0
-53.3 . 64 83.2
?S2.8 . 63 ? 81.4
-52.2 - 42 ? 79.6
41.7 ? 61 ? 77.8
-51.1 .60 ? 76.0
40.6 ? 30 ? 74.2
-50.0 - 38 72.4
-49.4 ? -70.6
Art .1-47;40044:#.0"" SO WI. ? WI o' ?
4 t
-48.0 56 -68.8
-48.3 0.35 -67.0
-47.8 34 65.2
-47.2 - 53 - 63.4
-46.7 ? 52 61.6
-46.1 . si - 59.8
45.6 - 30 -58.0
-145.0 ? 49 - 56.2
44.4 ? a - 54.4?
43.9-.4 52.6
-43.3 ? - 50.8
-?2.8 ? 43 - 49.0
-42.2 ? 44 - 47.2
...41.1 ? 43 - 45.4
.41.1 - 42 - 43.6
-40.6 ? 41 - 41.8
40.0 40 - 40.0
49.14 39 - 38.2
? as 36.4
-38.3 ? - 34.6
-37.8 36 ? 32.8
-37.2 ? 33 - 31.0
-35.7 34 -29.2
-36.1 - 33 - 27.4
-35.6 ? 32 - 25.6
45.0 . 31 - 23.8
.14.4 - 30 - 22.0
.. 29 - 20.2
-33.8 ? is ? 18.4
42.8 27 - 16.6
.32.2 26 - 114.8
?31.7 23 - 13.0
-31.1 ? 24 -11.2
-30.6 ? 23 9.4
-30.0 ? 22 - 7.6
49.4 . 21 - 5.8
-28.9 ? 20 ... 4.0
48.3 2.2
-27.8 . is - 0.4
47.2 ? ir 1.14
46.7 . 16 3.2
-26.1 . is 5.0
?25.6 . 14 6.8
.a.0 ? 13 ? 8.6
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11'. id, - ? '.-
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-24.4 - 12 10.4
-23.9 - 11 12.2
-23.3 - 10 14.0
-22.8 ? 0 15.8
-22.2 a 17.6
-21.7 r 19.14
-21.1 6 21.2
-20.6 - ? 23.0
-20.0 ? 4 24.8
-19.4 3 28.6
-18.9 ? 2 28.4
-18.3 - 1 30.2
-17.8 o 32.0
-11.2 33.8
-16.7 2 35.6
-16.1 3 37.4
-15.6 4 39.2
45.0 s 41.0
-14.14 6 42.8
43.9 7 44.6
.43.3 8 46.4
-12.8 9 48.2
-12.2 20 60,0
41.7 11 51.8
.41.1 12 63.6
40.6 13 56.4
-10.0 14 ? 67.2
? 9.4 is 69.0
? 8.9 16 60.8
? 8.3 it 62.6
? 7.8 48 64.4
?7.2 if 68.2
? 6.7 .10 68.0
? 6.1 21 69.11
? 5.6 22 71.11
^ 5.0 23 ? 7384
? 4.4 24 75.2
? 3.9 25 77.0
3.3 24 78.8
? 2.8 27 BOA
? 2.2 28 62.4
? 1.7 29 84.2
? 1.1 30 MO
.6 31 87.8
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SHIELDS
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0
32 89.6
29.14 .
8s
85.0
68.9
it
280.4-
0.6
33 91.14
30.0
86
86.8
59.4
139
282.2
.1,1
34 93.2
30.6
8?
88.6
t i 0.0
140 .
284.0
1,7
33 95.0
31.1
88
90.4
60.6
141
285.8
2.2
x 96.8
31.7
at
92.2
61.1
141
287.6
2,8
37 98,6
32.2
90
94.0
61.7
143
289.4
3.3
3.9
38
00.4
02.2
32.8
33.3
91
92
95.8
97.6
6j. I:
;4443
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11.4
.79
.7o
04.0
33.9
93
99.4
63.3
146
294.8
5.0
41
05.8
94 201.2
63.9
147
296.6
5.6
42
07.6
?34.4
35.0
95 203.0
64.4 .
i 0
298.4
6.1
43
09.14
35.6
96 204.8
65.0
149 .
'130
300.2
6.7
44
11.2
.1
97 ? 206.6
65.6
302.0
7.2
45
13.0
36.7
98 206.4
66.1
151
303.8
7.8
46
14.8
37.2
99 210.2
66.7
152
305.6
8.3
14.9
47
48
16.6
18.4
37.8
100 212.0
101 213.8
67.2
67.8
153
154
307.4
309.2 ?
9.14
49
20.2
?38.3
38.9
to 2 216.6 ?
68,3
155
311.0
0.0
50.
22.0
39.4
103 217.4
68.9
156
312.8
0.6
Si
23.8 ?
40.0
104 219.2
69.4
isr
314.6
1.1
32
25.6
40.6
105 221.0
70.0
i58
-316.14
1.7
33
27.14
41..1
/06 22.2.8
70.6
159
318.2
2.2
54
29.2
41.7
Mr 224.6
71.1
160
320.0
2.8
55
31.0
42.2
ion 226.4
71.7
161
321.8
3.3
36
32.8
42.8
zoo 223.2
72.2
162
323.6
3.9
57
34.6
43.3
MI 230.0
72.8
163
32504
14.4
se
36.4
143.9
lit 231.8
73.3
164
327.2
5.4
59
38.2
44.4
/ i 2 233.6
73.9
163
322.0
5.6
60
40.0
45.0
113 235.4
74.4
/66
330.8
6.1
61
41.8
45.6
114 237.2
75.0
167
332.6
6.7
7.2
62
63
43.6
145.4
45.1
46.7
iii 239.0
116 240.8
75.6
76.1
168
169
3314.4
336.2
7.8
8.3
64
6s
47.2
49.0
47.2
47.8
117 242.6
/18 244.4
76.7
77.2
zro
111
338.0
339.8
8.9
9.4
20.0
66
67
as
50.8
52.6
54.4
48.3
16.9
49.4
50.0
119 . 246.2
im 248.0
121 24to.8
251.6
77.8
78.3
78.9
79(4
112
173
174
341.6
343.4
3451
0.
20.6
21.1
69
ro
56.2
58.0
93.6
in
123 253.4-
8
1"763
%.80
21.7
7 1
59.8
51.1
124 255.2
iiii
22.2
22.8
7 2
73
61,6
63.4
51.7
52.2
123 257.0
126 258.8
ill
iii
--
23.3
7 4
65.2
52.8
127 260.6
82.2
180
356.0
23,9
73
67.0
53.3
121 262.4
82.8
181
357.8
24.11
76
68.8
53.9
In 264.2
83.3
182
359.6
25.0
77
70.6
54.4
130 266.0
83.9
zsa
361.4
25.6
78
72.14
55.0
in 267.8
84.4
184
363.2
26.1
26.7
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80
74.2
76.0
55.6
56.1
/32 269.6
133 271.4
85.0
86.6
181
va
365.0
366.8
274
81
77.8
56.7
/34 273.2
86.1
187
368.8
27.8
82
79.6
67.2
us 275.0
86.7
pis
370.4
28.3
83
81.4.
57.8
134 276.8
87.2
189
372.2
28.9
84
83.2
68.3
/37 278.6
81.8
190
374.0
4.?
2-I
Declassified in Part - Sanitized Copy Approved for Release ? 50 -Yr 2014/03/27 ? CIA RDP8
02
A
Declassified in Part - Sanitized Copy Approved for Release @ 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
Part I MATERIALS OF CONSTRUCTION
u.
0
.?
? QQ-A.3186
"Aluminum alloy 52S; plate and sheet"
QQ-A.359e
"Alumintun alloy 3S; plate and short"
90.0
90.0
91.1
194
193
196
391.2
383.0
3811.8
91.7
92.2
92.8
934
197
S98
no
200
386.6
388.4
390.2
392.0
SPECIFICATIONS
QQ-A.561b
"Aluminum alloy 2S; plate and sheet"
Ql,}4:-576(1)
"Capper plates, sawed bars, sheets, and strips"
BIBLIOGRAPHY
Bogle, A.G.
"The Effective Inductance and Resistance of
Screened Coils"
Journal institute Electrical Engineers, September,
1940
Howe, C.W.O.
"Q Factor 'of Single Layer Coils"
fireless kngineer, June, 1949
, Ponder and Mcllwaia
Electrical Engineers' Handbook Fourth Edition
John Wiley & Sons, Inc., New York, 1960
? 2.111
Sturley? K.R.
Radio Receiver Desipfri, Part I
Chapman & Hall Ltd., London, England, 1951
Terman, Frederick E.
Radio Engineering, Third Edition
McGraw-hill Book Company, Inc., New York, 1947
Welsby, V.G.
The Theory and Delign of inductance Coils.
Macdonald and Company, Londrat, England, 1950
? 46.:4;174;1.411.2,:..S1 A1;444 JCA,, 04011}J?Irdes..040.14.3.0.....4...mr.irwornouripop. *****0
***?" 0?1044110,,1/4
r
a
'th
4. ?
?
Sectitni 3
MAGNETIC MATERIALS
INTRODUCTION
The use of solid iron as a core for an electro-
magnet was utilized as far back as the time of
Michael Faraday. The inefficiency of a solid-iron
core for alternating-current applications was quickly
recogniAe,I because of the excepoive amount of heat
generated within the core. The electrical loss pro-
during this beat was found to lie due to eddy cur-
rent* induced within the iron. These losses were
reduced by substituting iron wire of flat laminations
which reduced the path of the circulating currents.
As usage developed in the higher-frequency
range, it was discovered that smaller and smaller
laminations were necessary. As far back as the
late eighteen hundreds, iron filings imbedded in wax
or shellac were used for high-frequency applications.
This aventually led to the realization that finely.
divided iron, treated to insulate each particle from
the other, could be bound together by the addition
of a binder, molded into the demired shape and heat
treatol to harden the binder, thereby producing a
low-loss high-frequency core.
It was not until about 1930 that high-frequency
powdered iron cores manufactured by mass pro-
auction methods appeared. IN.J.IlolytIoroff and Hans
Vogt were early pioneers in this work.
Prior to World War 11, iron cores were used in
many high-Q antenna coil*, especially in auto-
mobile radios and in permeability tuners in place
of gang capacitors. Permeability tuned i-f trans.
formers made their appearance but were expensive
and, therefore, not popular.
'Thread-grinding equipment for mass production,
developed during World War II, *a& possible the in-
expensive permeability-tuned 1-1 transformer as we
know it today. Relatively few capacitor-tuned units
are manufactured now.
Increasing demands for smaller coils for use
in miniaturised equipment. forretl tlessigners to look
fur other magnetic materials which would permit
size reduction without sacrifice in the quality of
performance. One such class of materials, ceramic
in nature and called ferrite'', was introduced as far
MAGNETIC MATERIALS
l%stsk as 1909, but (lid not receive, much attention
until a more extensiv.tinvestigntion of this maierisl
Vi at, made by Philippi Glorilempenfabrieken of Find.
hove a, Holland in PM. Owing World War II a Von*
iiiiierable amount of further retrearch was conAnt.teil
and in. 1947 J.S. Snoek publishe,1 his well knawn
book, "New Developments in Ferromagnetic Mate.
fiats" (Elsevier, N.1,1, covering the work of that
period.
After the War, a number of industrial concertos
In this country us well an the military departments
initinted ferrite ilevelopment programs aimed at
e?ploiting this very promising material. At this
writing almost every television receiver and many
radio receivers in dontratic and military usage ail.
lite this material in one way or another.
ELECTRICAL PROPER1'1LS OF MAGNETIC
MATERIALS
Let us first consider the justification -? other
than possible economic reasons ? for the use o a
magnetic core and what it can do for the coil
signer. Why not design all inductors wound alt
tore. which would have lower losses?
A magnetic core basically performs one of, all
of these function.:
(a) Miniaturization
(b) Inductance Variation
, (e) Shielding
Miniaturisation, as it Is. moat frequently molt.
nista and applied, involves the reduction In the
physical size land often weight) of,. an Inductor
without degrading its electrical performance. If the
original inductors were deriigned around magnetic
cores, they can freivently be further reduced In site
by utilizing a more efficient core, a novel core
sign, or by utilizing a material having more favor.
able characteristics. Typical examples of this would
be cup-core designs to replace simple windings
having cylindrical cores; even if the same magnetic
material were used, this change would permit using
111 smaller number of turn,s because of the Inr)fe Igo
ficient use of the magnetic material, 40,1 would
therefore lead to s physically smaller assembly
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4,1 ??.?
3.1
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0230009-s
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POOR ORIGINAL
A..
Port I MATERIALS OF CONSTRUCTION ?
with the same or better Q chereeteriatics. A somehai 11;tferent approtich yielding a similar reduction
in ni:.e.would be to uns ti ferrite core in place of a
powdered iron core without reeorting to form factor
modifications.
A more subtle aspect of mininturizutiOn is one
involving the?iniprovement of eleC tricot performance,
geiterally by obtaining a higher Q. without incresinine
the physical site sit the inductor. This., too, Cal
. often be accomplished in the manner just outlined
for reducing size.
IndtActance onritstion in smother important ft.,,u
lion that can. be necompliehed ening mag-
netic cores. This (sun thin, referred to .as perme?
nbility tuning, in baited on chonging the reluctsince
or ? flux distribution in. ihe mognetic circuit of the
coil by physical displacement of the magnetic core.
The simplest illuatratiou of thin is in the use of a
movable cylindrical core in a solenoid winding.
Ilanicolly, the . same concept is used in the more
complex magnetic core structures (i.e. the alumni
completely closed toognetic circuit in cop-co(e as-
rtnblies
Fig, 34) where some portion of the mop
netic core is meile phi, cnlly adjustable.
e
(a) 3 piece assembly. (adjustable center
core)
(b) 1 piece cup core (plain or with eater*
nal ihrtalla)
(c)2 piece cup assembly (nn-adjusiable)
Fi1.34 Typical cup cores an41 cup core asseestlies
3-2
' -?24,44tht4. 4440041000?oom???????aor...../...
'!.
? Permeability tuning is used almost exclusively
In i-f transformers rittil in the' tuners for the broad-
cast band in automobile radios. Oscillator coil",
peaking inductors, filter reactors, and numerous
other coils requiring adjustment after assembly into
an electronic circuit ut his simple and effective
means of varying the coil inductance.
Non-magnetic tore tuning, though somewhat
foreign to the subject matter of this section, never-
theless, should be mentioned in discussing induc-
tance variation since it is an effective method for
coil adjustment in certain cases. This technique
uses a disc or core of silver, brass, copper, or alumi-
num in the magnetic field of the coil. The non-mag-
netic core reducen the inductance in proportion to
the magnetic-flux lines that it intercepts, so ,that
physical movement of such a core in the magnetic
field will cause inductance variation. The losses
introduced by the core can be kept small by limiting
the range of inductance adjustment. Examples of this
type of tuning are high-frequency i-f transformers
having silver plated brass tuning cores and tele-
vision tuners having brass or aluminum threaded
cores .inside spucewound r-f and oscillator coils.
This type of tuning is of significance at higher
frequencies since it reduces instead of increases
inductance as does an iroa tore. Very-high-fre-
quency windings, in general, have only a few turns,
and iron cores for utliosting purposes only -make
such a winding more difficult to manufacture,where-
as the non-magnetic core requires extra turns to
make up for the loss of inductance due to the core,
which is an advantage in many cases.
Magnetic shielding is the third function of pow.
dered iron or ferrite cores. Such shielding confines
the field of a high frequency inductor thereby per-
mittingother circuit components to be placed nearer
without deleterious effects and interaction from con-
flicting magnetic fields.
BASIC PARAMETERS
(a) Permeability
(b) Q
(c) Dielectric Constant
Permeability is defined kw the ratio of the nem-
netic induction to the magnetic intensity and is re-
presented by kz. Mathematically it is
where H is the induction in gausses and II is the
field strength in oeesteds.
The initial (or true) permeability is determined
by the slope of the normal induction curve at 'zero
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magnetizing field. This characteristic is most fre-
quently determined by measuring the inductance of
a coil wound on a toroitinl core of the magnetic ma-
terial and comparing this value with the irshictonce
of a similar toroidill coil having an. air core.
Of greater interest to the coil designer is the
effective permealkolity (p.m) which is usually tie!
fined as the ratio of the inductance of a given ,coil
with and without the core. This is an important
working parameter to the designer since it reflects
the composite effect of the true permeability .of the
core and the geometry of the specific coil and core
combination including distributed capacity effects.
A practical method of measuring i, requires
the use of a Q-Meter. A suitable test coil is reso-
nated (v.itiir?sa the core) at a frequency which is
within at ? t4 the Q-Meter capacitor, say 100
pg. The c is inserted into the test roil Anti the
Q-Nleter again resorinteil by changing the frequency
without changing the capacity value tined ((wale
previous reading. Gall the first reading f nnti the
second reading 13. The effective permeability can
be calculateti from the following formula
ill] 3
14?11 " 2
A practical example:
Coil without core:
Coil with core:
Cs
C3
e 100 pp!
e 100 plif
f 10(X) kc
I 3 500 kc
[Oil a= (2)2 4
500
An alternate Q-Metrr method utilizes a constant
frequency and varies the capacity for resononce.lf
this method is. used a value of C1 mist he chosen
sufficiently high no that C2 will be within range of
the Q-Meter resonating capacitor when the core is
inserted into the coil. This limits the range of
effective permeability that can be measured to
approximately 10, which is relatively low when
ferrite' are considered. The following formula
applies:
Per .. 7:C;i
where C1 s capacity for resonance without t ore and
14
Cs capacity for resonance with core.
A practical example:
Coil without core: II . 500 kc . .. 100
Coil with core: fa . 500 kc CI , 10014
400 . 4
Pell a 1-66
4
MAGNETIC MATERIALS
Effective permeability may .vary from slightly
over one for high-frequency iron-oldile type cylin-
sit ical .cores to nit much as several hmslreil for cer.
lain types of ferrites male into closed cup-core
designs having small air gaps. More specific ex-
amples are 4.0 of 1.5 to 3 for a VW' diu x 1/4"
long cylindrical core in. universal winding and
typical Cores Ut+eil fist brOatleatit 1141111 tunieg (515 to
1650 kc ?.200 tlui x 1 1/-1" long) having an ef-
fective permeability of 9.5 .or greater (see
3-3a-b-c and' 340.
The, permeability of a powdered-iron 4:ore is
determined by the basic powder, the method of in-
sulating and binding the particles together anti the
pressure used in forming the core. It can, there-
fore, vary within it range of sevetal pert eat when
similar cores ore ? Made by different ?fohricators.
Cores made by the sonic fabricator moy vary in per-
y bee Oust molticavsitv presses do not alw ayti
have identical tools in all stations. hieven tool
wear and variation or applied pressnre also affect
permeability. The coil designer must recognize
these fact urn and allow for reasonable tolerances. .
In general, the closer the tolerance, the more ex-
pensive the core. Generally accepted lush ances for
permeability are t 2% or t 1%. Corr5 having closer
tolerances ?generally have to be selecie.1 which
results in a percentage of unusable cores on either
si.le of the nominal value.
It is suggesteilthat t,.e designs., familiarize him-
self with "Tentative Electronic Iron Core Preferred
Dimensional Specification" tio.11,11;1** which
Covers in irldit preferred mechanical awl certain
electrical tolerances as adopted by the electronic
core nuinufact wets.
Because or the newness of the tut, there haii
been no similar Standard set up for ferrite cores.
In general, ferrite materials being cernmic in nature
follow the initial accepted' mechenit n1 tolerances
for electrical-grade ceramics. !Irritate of wider
mechanical tolerances foc ferrite than for iiaa, it is
necessary to allow broader tolerance for perme-
ability. Common tolerances vet 10% with ? '5% oir
? 3 generally ?hel3 only by selection with a re.
nutting higher percentage of rejects..
Q is?a term loosely used to designate the factor
of merit of a magnetic core. Actually this is a non-
existent term since Q is in reality the factor of
merit of an inductor (with or without a core) anti I,s
define,1 as the ratio of the reactence to the equiva-
? Wool r order Aosor Immo, 420 Lastrallon Aveaurro Viso York
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Declassified in Part Sanitized Copy Approved for Release
?
,41????/
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POOR
ORIGINAL
????????????
1
Part I MATERIALS OF CONSTRUCTION
lent series reaiistance.
? 2 tifla
Q4'
Since there 115 no direct way to determine a core
factor of writ without an associated coil, it is
generally .accepted practice to refer to the Q of a
core as if it was an Inherent parameter. It should be
realized that the rare mid coil Q will rarely over
he the same ,for ani. two test coils and that rare Q
therefore, more of at+ effect than a characteristic.
Suitable test coils are in general those comparahle
to a working type of winding. The ?Q obtained is a
relative value for compariaon with other cores of
similar form factor hat not necessarily of the name
material.
? ?
The Q. then, is obtained by inserting the core
In 11 suitable test winding and resonating the coil
on the Q meter di the desired frequency Coen page
3-9 for proper choke of a test coil).
The Q is largely is function of the type of iron
i.lowder used and method of processing. It does ??oi.
vary greatly from core to core due to molding pres-
sure. Typical tolerance* for Q are t 10%, t 7 1/2%
and t 5%. Tolerances eloser than this would nor
-
malty be obtained a 100% test and selection and
might result in a number of rejects thereby in-
creasing the core cost.
Ferrite materials are the result of chemical re-
actions and many factors in their production (such
aa firing temperature and atmosphere) affect the Q.
It is difficult at the prearnostate of the art to manu-
facture them to close 1) tolerance. Larger tolerance
on Q is, therefore, necessary than is generally ex-
pected of similar powdered-iron cores.
Effect of !nitric
Iron cores with iscrcw inserts are frequently
used in r-f coil design. The effect of introducing
the screw is, of Caorms; to reduce the effective Q
and if the 'screw is grounded through the mounting
device and ? shield 'assembly, the :apiseity from
winding to ground also often increased.
The conditions under which cores we used
greatly influences the reduction of Q due to a molded.
in screw, but in graieral it can sun as high as 35%
for steel screws at 10(() kc and 20% at 15 Mc, to as
low as 3% for braes screws at 1000 kc and 2% at
15 mc, Since steel screws generally reduce the
effective Q four or five times as much as fin brass
hereWS, their use 'should be avoided whenever pos.
Thii reduction of Q and added capacity effect
can be minimixeil to a great extent by using cores
which have screws insulated from the magnetic
material, This is accomplished by molding the screw
into a phenolic hushing which is attached to the
end of the iron core. The length of the bushing
governs the proximity of the metal screw to the
kon core and thetefore affects the Q. This type of
core is more expensive than one having the screw
molded directly in the iron and should be avoided
unless required for electrical reasons,
Ferrite corns, by their very nature, cannot have ?
screws molded in during manufacture,but moat have
them cemented into a cavity ,in the end i+f the core.
subsequent to the final firing operation. This in it-
self tends to discourage the use of sorows in
ferrite bodies.'
The dielectric constant of powdered Iron and
ferrite material has been given little attention in
the literature. Manisfactarers ha?a; not hove 41c
produce i. ores having widely different dielectric
constants. Even though isolated project. havc
possibly indicated a need for iron cores of lower
dielectric constant, none are known to be offered
commercially.
The dielectric constant of typical commercial.
Carbonyl E Iron cores varies from as low as 20 to
. as high as 00, or even more. This, of course, is
high compared to coil form mc.terials such as phe-
nolics, paper and ceramics which have dielectric
constants between 2 and 7. Ferrite*, because of
many different chemical compositions, have a wide
cringe of dielectric constant. Measurements taken on
typical ferrite materials indicate the dielectric con-
stant to. be as low as 20 and as high as 460.. The
average value used in commercial production of r-f
and if coils anti transformers is probably between
these extremes. It is known that some commercially
produced ferrite* have dielectric constants as high
as 10,000 and 41:electric constant values 411. high
as 100,000 have been reported, but there Is no in-
formation available regarding the other character.
istics of these special compositions.
Toth e average coil designer, the dielectric con-
stant is not of too much importance if it is rela-
tively low as in the case of iron materials. It is
difficult to reduce the dielectric constant of iros
compositions. Ferrite., because of the almost
limitless body compositions offt. more latitude for
change, if, due to a particular design, a core having
a high dielectric constant should cause undesirable
capacity coupling between windings or circuits
or increase the distributed capacity of the coil to as
r .141. Mr. 10,...../1,/ ? O.., ,
???:?,?????
?
?
S.
unreamonable value. Dermot? each different body
composition usually requires its own tools to allow
for shrinkage from the initial pressing to the final
filing, it is recommended that the coil designer
work is itli established commercial, compositions
for whith tools are availlablo.
The Curie temperature is defined as that tern-
at which a magnetic material reasea to
have magnetic properties. Because, in the ..c..rri_e...of
ferritea, this =ay be in the useful working
is at. important churacteriatie that can be a limit-
to their usage.
Ferrite compositions differ in temperature
orterint lc, Sonic have Curie temperatures as low as
nOF and others greater thau 400F. In general,
bolion having high permonbility and lowt,e have los"
C air temperature and ',odic m having low permeability
and high Q have high Curie to tupecature. Composition.
Intended for use at higher frequencies generally are
of the higher Q type and tend to have higher Curie
temperature.
?
MAGNETIC MATERIALS
. The curves of Fine 3-2 illustrate the chitractcr-
iatic of permeability vs. ?temperature. Some mate-
rials chow little change until near the Cmitt tem'
perature (curve a) while others increase appreci?
ably in permeability over the tntire telnyeratare
range (curve b) until the Curie te mperat We is11111011441.
As an example of the use ful range, materials having
it temperature ,characteristic resembling etaVn "a"
could be use ti lip to 300 or 325F while is material
Illustrated by curve "C" would te.uacful on4 to
250F. A material Nadi as "b" is of little value at
any temperature unless sorer form of compenaation
?pravioeti for is Coll thus sipo
"ion.
? Observations have been made of holieli having
a negative temperaiwe chareo:terimlie allItionigh they
are not believed to. be produced coromfrchilly at the
present time.
DESIGN FACTORS .
In order to +Airier magnetic maIrrial to the
1?000.,??????????
100 200 300 400
TEMPERATURE IN DEGREES F.
Fig. 3-2 Temperature is. permeability characteristic of typical ferrite*
..??? klk,,,e0,1,, 41.. a.ej Vt,,,,,,,01.1.40,44, 11,W 4444,10:4?44 tut 454
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3-5
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MAGNETIC MATERIALS
Part I MATERIALS OF CONSTRUCTION
hest ?nilvantage, certain principles of design must
be clearly understood. Basically, a given type of
powdered iron or ferrite material has an estublished?
true permeability. How needy this cpr, be realized
in, actual practice depends upon tI. and coil
design.
The true permeability is determined by the
cliteetl.core (toroid) me;hod, The effeca4e perms..
al4lity of any particular ',reign of core more nearly
approaches the true permettbility as the co:e con?
figuration approaches the toroidal,. or closed core
configuration. Concentrating the winding near the
voro tends to reduce the stray or leakage flux there-
by 'tette nearly approaching the ideal condition for
nessimum permeability. See curves of Fig.3-3 showing
effective permeability of windings having variocos
formfactora all using the name powdered iron core.
The form factor (length to diameter ratio) of the
cefe' It el( is of extreme importance in realizing the
maximum effective permeability. The curves of Fig.
3-4 illustrate the increasing effective permeability
as the length to diameter relit) increases. Perme-
ability tuners designed to cover the broadcast bond
require a length to diameter ratio in the order of 6 to
1 when using Common types of powdered iron. Fenito
cores having higher true permeability will also have
a higher effective permeability than will iron for the
same length to diameter ratio thereby permitting
tuners to be designed with shorter core travel if
ferrite cores are used.
The proximity of the winding to the core is also
an important factor. The curves of Fig. 3-5 show
the decreasing effective permeability as the ratio
of mean turn diameter to core diameter is increased.
The effect of approaching the toroidal or dossed
core configuration in shown ?by Fig. 3,41 wherein
cylindrial cores ate compared to open and closed
cup cores for effective pezmeability.
Tolerances:
The coil designer should always be cognizant
of practical mechonieal tolerances on all elements.
This is especially true of magnetic cores. Modern
commercial manufacturing methods result in well
established tolerances since little, if any, ma-
chining other than external thread grinding is per-
formed subsequent to pressing. This means that
the core as presseed hats no further sizing operations
I. 50
LID 7.5
2.5 5 75 10
L/0 RATIO
Fig.3-4 Variation of effective perineol,ility with length to ilottoteter
UNIVERSAL
TYPE OF WINDING
rypicul coil form factors with scune core to illustrate variation of
effective permeability.
Fig.3-5 Variation of effective permrahility with varying I04141 of roil to core diameter.
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POOR
ORIGINAL
L ?????????????? ????????????1 ????????????????????? ???????????????
..?????????????????????????????...........4. ..?????????????????????????????????,Tho **ft J ?????????????????????????^?????????? ????????
Port L MATERIALS OF CONSTRUCTION
PERMEABILITY
EFFECTIVE
?
?
?
TYPE OF ASSEMBLY
?
(a) cylindrical core (see
(h) one piece clip (see F?g..1-1b)
(c) !liter 1$irre isAsembly (see Fig..1.1o)
1141i core in adj care out
(d) two juror assembly (see Fig.3-1c)
143-6 Permeolotity for typical assembliee.
with which to correct dimeneionell errors, The folw
lowitig tolerances have become fairly well estab
liabeil for iron core's:
Es lernal Diameter!
Illecauae of die wear core's tend to increase in
diameter No tolerance is always stated on positive
sifICL i.e. .195 .000" .005" (.005" lit gen.
erally accepted regardlena of diameter).
length:
. (This is governed hy pressing on all but milk
pressed ? and requires a larger tolerance)i
up to 13" long + .010"
over 'X' to 11' long i.0IS"
over 1" to long t,020
over 1'4" to Vi" long t .030..
internal Diameter:
Same as for external diameter except as is 110$?
alive tolerance i.e. .110" ? .000 ?.005".
?It is suggested that the Metal Powder Aso?.
"Tentative Eleutronic Iron Core Preferred
Dimensional Spec iftritt ion" No.) )551' be coniiiiltell
for the Littera information an above tolerances. This
specification will be kept up-tiealate wherra U s
beyond the scope of this manual topredirt changaa
that may take place in normal commercial practice,
3-11
. ? ,A.-41.elt,,;ti4-,...,?.;;;"..
?????41.4.? -? .?-?? ? ??? .???? ? ? , ? ? ?
I11111111??????????????????????-?. L. ...L....L....4.. ,,,...................,
Ferrite cores being of a ceramic nature follow
a slightly different tolerance pattern. In general,
the tools wre soilsiect to wear as areiron-ccre tools.
The tolerance to generally stated. as plata or minus
since wider tolerance is required to allow for the
shrinkage involved between pressing and final
firing. Accepted commercial practice is as fol-
lows:
External Diameter +.006" or tilt
which ever is larger
It. .010" or t 2.14
,shich ever is larger
Internal Diameter *.005" or
which ever is !argot
Since industry standards for ferrite core" have not
vet been coot dinated by an agency representing the
majority of producers, it is suggested that the de-
signer consult with the manufacturer of hits choice.
Practical 'shapes. are naturally those that ful-
fill the design requirement,s and are economical to
produce. Sine. most cores, either Ira@ or ferrite,
are wafted, it is in the interest of economy to
utilize readily pressed parts. Round external sad
internal shapes are easiest to tool and maintain.
Blind holes ohoulii have taper, the closed earl being
smaller of diameter than the open end. The length,
in the pressing direction., should bx as short es
Length
?
?
?
?
??
?
??????? 104P ?????,....1,11Mtil,
??????????? . ??????????????? .0 ???????????
?
practical and the length to diameter ratio should be
kept as small as possible. gall sections should be
as thick as possible am) preferably not thinner than
3/64 inch.
hollow cylindrical cores of either iron or ferrite
sometimes Used as external coil shields inside of
metal cans are frequently extruded. It should re?
membered that extruded parts can only be made
with a uniform cross sect ion. There can be iio taper's,
offsets or blind holem. This method of prodection
is relatively inexpensive for those types of cores.
that arc practical for extrasion.
TESTING OF IRON AND FERRITE CORES
'Quantity production of any component can be
riipected to be no more uniform than the imitetials
and rArt s that go into its construction. This is
especiallVtrue if imIto tors am! transformers having
high-frequency n.ii,, it t ores. It is, therefore, im-
portant to the toil design ,trigineer to be crttain
that the specifications prepared for the magnetic
cl yes adequately dencrihe the mechanical . ctn.l
electrical parameters ond that unnecessary teats
or tolerances that sere no useful purpose are no,
also included.
Mechanical:
Mechanical anti phyrsical characteristics are the
easiest to evaluate und should be checked first, If
the mechanical limenaions of the magnetic core
are not within the required tolerances the elec-
trical characteristics are of little importance.
Outside diameter, length and other easily at cesi-
"tilde dimensions are most readily measured with a
micrometer. Inside diameters, blind hole depths and
similar dimtnsiona are hest inspected with plug
gages. Eccentricity a mobled-in ae.rews is me aatged
hy chucking the core in a lathe or other nuitable
fixture and measuring the screw run out with an in-
dicator gage (see Metal Powder Association Ten-
tative Electronic Iron Core Preferred Dimensional
Specifications. No. II-111'). In actual practice just
the opposite is done, since the core is used by hol-
ding the screw and :evolving the core within a coil
form. Measurement al tore eccentricity by chucking
the screw introduces errors that Kre difficult, to re-
concile between supplier and user. For this reason
the former method has been adopted by the majority
of the industry.
E/ectrical:
The electrical parameters require specialized
test equipment. A 0-Meter and a Megohnimeter are
the most useful. Most production anti laboratory
? ?????
?
MAGNETIC MATERIALS
measurenientn Of pernieability tIflhl ,() are made with
the Q-Meter, ,Mosolute measurements are rarely use.1
but more often comparative meamitrentent% are matte
to a previously established standard or reference
core (Selection of ?standards is liencrit,r,1 on page
3-10). ItermeabilitY and ()tolerances ate stated as
.leyiations to per cent from the,eatahlished stand-
ard.
Permeobititt ,.,id
In general .1 test procedure which approaches as
nearly as possible the conditions under which a
core a ill kilt lion has been proven to lie the most
sat i hfoct try. This is not -always possible or prac-
tical. The proctit al approach, then, is to use a. feed
coil %%Lich ii III best show up the most important
parameters. Chat is. if permeability in the most im-
portant t harm teristic for a Oxen application then
the test c oil hitotild be constrwted to best differ.
entiate between small differences in petmenbility.
The fle applies to Q or any other impottant char-
acteris. it.
Et o mph.: -I coil of approx relate/1, the same
length as the CON" u.i.und on a thin wall tube pro-
duces the highest effectice permeabilit,, l'sed as
a test coil, this winding can be etpecteil to hest
differentiate between small diff?rences in permea-
bility.
Cores
broadcast
used for wiile range inning (to cover
hand), having large length to diameter
ratio, frequently have a satisfaiiorx overall tor
total) permeability but do not have is proper dis-
tribution of prrme osh i lit> throughitut the length of
the Core. Such cores are said to be nos-homage scout'.
The maximum ond minimum frequency coverage will
be correct hut they will not track one with another.
It is necessary to classify such cotes latO groups
having similar permeability distrillution if they are
to operate in cascaded or associate(' t ire uta.. The
simplest way to accomplish this is to proviI' siops
in the bottom of the test coil tried foe the metal)
permeohilit y test so that cores can he Watt heel to is
reference core at intermediate points say 1/1. I/2?
and 3/4 insertion,
A somewhat more complicated but also more
satisfactory type of test is to employ itte
tired test windings.. One winding has the reference
core and the other has the core to he lessee'. rach
winding is in the tune,' circuit of an 0014 illator, die
outputs of which are combined to pr.sluce a beat
freqiency. As the cores are simultaneously moved
into their respective coils an audible note is prO-
Aucea if the frequencies of the oscillator's *A there-
3-9
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Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
Declassified in Part - Sanitized Copy A proved for Release @ 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
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Pan I MATERIALS OF CONSTRUCTION
hell, the permeahilities of the cores are not alike. tuning capacity which can be interpreted as percent
lly tier Of a suitable audio f le luency meter the setup of effective permeithility.lt is,of course, necessary
clink, calibratedto irelictite the extent to whichthe when designing the teat winding to make the In.
permeability of the cote under test deviate,' from ductance of the proper value to resonate wit
stendard and the direction of the deviation. at the desirea ,freqiiency.
Sleeve cares such as those used for ehiehling ? The ? teat proveattre is as follows: The 'dewier&
purpopieft are generally tamed for permeability and core is inserted in the test coil which is connected
i.)1,), inserting them inside of a test coil wound on a to the coil termintile of the QsMeter and the main
tulle having an inside ilinmeter which will nccept capacitor dial ii, set ot I.00so1. The vernier dial is
the outside diameter of the sleeve, The winding set at zero. The frequency is then adjusted for
!regal is generally about %%??he cora length and mnximum Q?arel the value. noted. The standard core
the core is centered in this winding, is removed and the cores to be tested insertea into
? Cup cores present a more complex test problem. the tent coil and resonated with the vernier dial
There are ?a numher of types, and each must he (without chnngine the frequency dial or the main ?
treated in a different ?manner. The more common nre capacitor (Ilan, The vernier wi'll accomodate it van-
shown in rig. 3-1. . . ation of -t 3% in effective permeability when the
?Type A, the three piece assembly, is treated as main tuning cupecitor is set et 14-10opf. l,nrAer tievi-
individual parts to avoid having to keep them as ations from standard must be observe(' by leaving
units "luring subsequent nese nbly. The center R.I. the vernier dial at Arra and resonating with the main
jueting core having the screw insert is teste'las capacitor dial noting the deviation from the original
any cylindrical core previously described, The two setting of 10)g40. The percentage can be computed.
halves of the cup proper must be tested as indiviamil (Note that an increase in the value of capacity in-
pieces since there is no means of. conveniently dicates a decreitee in effective permeability). Q can .
handling them in pairs 'luring normal manufacturing be read directly on the meter and compared to the Q
operations. The usual procedure is to prepare a test of the standard core.
coil having the center core and one cup (bottom) ResistancP;
with the winding on the cente: core. The stonilard
The resistivity of a magnetic-core material, es-
cup is used te complete the assembly as a top
pecially powdered iron, is also reptile,' as an ira-
core. After the setup is made the standard cup is
portant charecteristic. Normally, the resistivity
removed and successively e-placed by the cups to
could be determined from simple measurement of the
he tested. ? resistance between the parallel faces of a cube
Type 11 cups are seated by inserting the central
of the material, but this method is not practical
pin into a winding similar to that used in a typical
when dealing with commonly used shapes such as
production assembly.TheC caps are similar in con-
cups and cylindrical cores. A more practical test,
etruction except generally of shorter length awl are
frequently used for production test purposes, is to
commonly used in pairs. This means that the outer .
contact points on the core surface.arbitratily 1/4"
shell and the center pin must be of identical length
apart, or under tertoin circumstances even on oppo-
to avoid air gaps either around the shell or at the
site sides of a core, and measure the resistance with
center pin. A 'jig using one cup as the lower element
? suitable megohmmeter. It is not uncommon for
with a winding on the center pin is the most con-
high resistance cores to measure between 5,000 and
venient. The cotes to be tested are placed on top
50.000 megohms between such test points. Irregular
to complete the clotted cup assembly.
shaped cores may have high density sections caused
New sta.videa a cores will present sliehtly ail-
by conditions of manufacture. The resistance of
ferent test-coil problems which can be nolveil by
these areas should not be permittea to be unto.-
the application of the above principle, and ideas. ,
sonably low. If a core is broken, the resistance
After chosing a saitable test coil and a swathed
should he eulsitantially the same for all sections.
core the test methoil using a Q-Meter must be ea-
tablishe(1. It was previously suggested that IS test SELECTION OF STANDARDS
procedure approximating operating conditions ie After the trot coil is chosen it is necessary to
generally most etstisfactory. This includes the test have a standard cote to use as a point of reference.
frequency. It is common practice to resonate the In most cases this standard core will be furnished
test coil oith 'Woof so that deviations in capacity by the core menufecturerand willhave been selected
from the nominal value will represent percent of as having average -electrical characteritsties. Pros
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auction parts can he expected to fall, within the
prescribed tolerances, on either side to this standard.
If a atandeod core is not available from 1110 corn
manufacturer it cue .1.e selected from a retire-
'tentative group, preferably a reaano047 Wee pro.
auction run, by the following method: An 8 tt 10
cardboard is ruled with lines about 1" apart running
the width of the sheet. The center line is marked
err? and lines to the richt are marked +1%, 03 etc,
and lines to left se s? mnrked ?1%, ?2% etc.
A core is chssen arbitrarily and labeled fennel.).
tar,. stanef.Ard (for permeoliiiity)? and the Q-Meter set
up. using this core. It is thea placed on the irro
fine of the cardboard. 25 or 30 cores are picked at
random and ,measured and then placed on the cord.
hoord in the place. representing their permeahility
with respect to the temporal.), standard. After this
Is completed it will generally he found that the
renjority are in a group which may or may not he
centered around the original temporney stereiord,
the core nearest the imaginary center of this group
Is now selected its the final standard for perme-
ability, providing the Q is about average. If the Q
varies considerably from core to cores suitable
Q standard can be then ',elected from a group of
near nominal permeability cores by the si*Mft method
just described for permeability. Thz standerd ans
leeted should be 'appropriately tagged and several
duplicates selected for future use.
PREPARATION OF A PURCHASE
SPECIFICATION .
16 order to insure that the standard selected is
duplic.ited by any manufacturer who may be .called
upon to produce the cote, a specification Ade-
quately describing the part must be prepared. Mot.y
core specifications have bezn issued which are al.
most meaningless when critically examined, A com-
plete specification should include the following:
(1) A drawing showing all dimensions ami tol-
trances including color coding or other mat.
king.
(2) Electrical specifications to include:
(a) Permeability tolerance (Permeability to
be compared to approved standard)
(b) Q tolerance (Q?to be compared to tip.
proved stendarti)
(c) Resistance (if required) and how mete
cured, s
(d) Test freque nr y or frequencies, especially
to be used for Q. This should toyer the
operating frequency range.
(e) Complete drawing and specification of
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MAGNETIC MATE11143
the test coil unless supplied along 1Nitli
the etettliard core,
(3) Miacellatientot
(a) It wit proofing treatment, surface et bing
or other pipet-foil requirement*,
(b) Physical strength requirement e tied how
measured,
(c) Prevent iosie regarding -resistant e I o pai.?
tient ar solvents Of Coil wiotee,
(d) Lubrication if required (oe threaded
cormo)
(e) Other opecifieetions rn may be requited
shouldhi7e ape t1 E
It e',1idhltpupnlinceacteiso.
snary specilit lit ions
should not tie iacloarki just because the mite
line mentions a spet ific item, i.e., if it gi% applt-
cation does not require the core to lie salijet ti*41 to
high humidity itn(1 if samples submitted by the iendor
:e la little justificetiou ?:? de-
tailed spec ifit at huts on rust proofing Its...flee-la.
It is recommended that r-f core tliittltillititifer a of
their catalogs lee consulted before preparing final
core specificntions so that mechar.i{".11 'Ii ne
and electrical lassode will conform to itema cur-
rently in proloctioa or for which production tooling
is available.Specinl 'shapes amispeciol dimennions
will require new touting or special mechioing which
can be expensive operations with the coontimer
bearing the coot.
TYPES OF IRON POWERS AN1) T111?111
The trial and error method was long %poet for se-
lecting core materiel*. As more and more was learn-
ed about the behevior of iron-dunt totes, iinti 13
iron powders Were improved, the art of pundered
metal. cores het -sone entdblisheil on 4 more. scien.
tific basis. .
The modern e ngiiirer need no longer depend upon:
hit and miss niethoda hut can choose a coir material
based upon proven knowledge of its perfornionce
characte.istica. The majority of the-ifite powders
used in electronic. applications tod.iy calif gimiited
into the following four general typea;? ?
I. Reduced
-2. 1.;11.e
(.troic
lyt
3. 4.11
4. Carbonyl
ore?tio to 11'4.14 tor the general creekrevire *harm 1044401i*
these type? 4i i,w, 11.4 18.s1 Of U OiSC: to Isig.3.10 1.0 .141 '.i.1
cerrenendatione 44 high al **stoma Irequeritley.
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Declassified in Part- Sanitized Copy A ?proved for Release ? 50-Yr 2014/03/27 ? CIA-RDP81-01043R003100230009-9
Declassified in Part - Sanitized Copy Approved for Release @ 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
POOR
ORIGINAL
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Part I MATERIALS OF CONSTRUCTION
Reduced Iron:
This type' ix produced from iron oxide such an
mill scale and chemically reduced b an atmos-
phere of hydrogen or other suitable gas. The final
product which is a reIntively pure iron is pulverized
Ity grinding or boll milling and:r!ansified us to par.
tick?size either by :screening or air-classifictition.
This also incluileft whist is commonly known as
sponge iron which uses ore es the basic material fo.
reduction. This iron is generally recommended for
use under .one megacycle.
Electrolytic lron:
This ,type is produced from plate iron which is
first electroplated on atiiiitable cathode. The plated
iron is then stripped from the cathode and paver-
lied in a manner nitnilat to that described above
for?reduced iron, Electrolytic iron is relatively. pure
anti has .high pertneebility.The frequency range ()la
finished core is somewhat dependent upon the par-
ticle size anti how well the individual particles are
insulated. In general, this type of iron powder is
bent suited for application under 2 megacycles.
Oxide:
Oxide (Fe304) either natural (commonly known
as magnetite) or syntl .ic is frequently used for
r.t cores. The natural oxide is pulverized iron ore
and- is generally of relatively large particle size.
It is relatively inexpensive and can be used for
quite a wide frequency range. It has lower perme-
ability than most other iron powders and is there.
fore not suitable for wide-ronge tuning purposes,
The synthetic oxide? ore extremely fine aid
heve relatively high Q at higher frequencies. Soytr
of these oxides are suitable up to 200 megacycles
or higher.
Carbon"! Powder:
Probubly the most
widely known powder is the
carbonyl group.There are t.everal types, their basic
difference being partiele size and particle hard-
nemo. L..* a definite usage and since at the
prearnt time there are at least ten types it is sug-
gested tl.ot infonratinn regeriling frequency limit.
ations be obtained from the manufecturer* (if the
powder3 able(Fig.3.71 shows values of pen. Q and
frequency range for several of the more common
carbonyl irons.
Briefly, these powders ore prepared from iron.
pentacarbonyl nits , a yellowish liquid with a
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boiling point of 101.5 C. The iron pentucarbonyl is
decomposed at a high temperature and the starting
materials, iron and carbon monoxide are re.formed.
The resulting iron particles are of spherical shape
and vary in diameter from 3 to 20 microns. The use-
ful frequency range varies from 50 or 100 kilocycles
to 100 or 200 megacycles. The smaller particle-
sizes are, of course, used at the higher frequencies.
The spherical nnture of this material result.)
in many desirable characteristics, amosig which
sue ease of insulating and pressing. It is also ex-
tremely uniform and can be depended upon to pro-
duce finished cores to reasonably exiicting
fications.
METHOD OF MANUFACTURE OF MA6NETIC
CORES:
It may seem that the coil design engineer has
Little concern with the problems involved in insu-
lating and fabricating magnetic powders or with the
manufacture of ferrite* but a working knowledge of
theec operations can be extremely beneficial in
choosing the most suitable iron or ferrite core not
only from the standpoint of operation but from the
uniformity to be expected.
Iron Cores:
The manufacture of iron cores essentially con-
sists of the following operations:
a. Insulating the powder
b. Adding the binder (synthetic resin)
c. Granulating and classifying the agglomerates
I. Pressing or extruding
C. Polymcri:stioa of the resin binder
f. Final test
Any tom of particle insuleion tends to reduce
the effective permeability of the fininhed core and
to increase the Q by reducing eddy-current losses.
If the insuinting medium is of the surface-coating
type, i.e., insulating varnish or resin, it lakes up
space that could otherwise be occupied by iron
purtides in a finished core. If the insulation is a
chemical conversion of the particle surface, it re-
duces the pure iron content of the particle and the
converted surface occupies space that could other-
wise be occupied by active iron. The effect is ihrt
34111e in that the permeability is reduced by either
method.
Resign Coating:
The simplest and most elementary methol of
insulating iron powder is to make use of the re-
sin used for binding the particles together. This
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FREQUENCY
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ci
3 3' ta3
z n 3z
axis===r sa. r
Lj 0 '4 0 o 0 0 3t uj It ta
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Figure 3.7 Characteristics o typical iron powders.
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3.13
Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
Declassified in Part - Sanitized Copy Approved for Release @ 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
? Port I MATERIALS OF.CONSTRUCTION
frhiM, generally a phenol-formaldehyde, is applied
day wetting the iron ;tallith. s with resin solution In
a suitable solvent. This mixture of iron powder
and reein is mixed until the solvent is evaparated
stud large agglomerates nre formed,
. Theoretical lee el rte,tse, each particle is there..
? iieoett...3 with a thin leyer of resin. In practive,
It Is impossible to effectively produce a high de-
gree of iestilation by till* process and it is gen-
erolly only used for torus intended for operntion
at loser frequencies, (up to 1000 kc). where high
insulation reeietaner its not of paramount, iin-
portance, Surface remietence between paints lit"
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kg flat surfaces. For milling keyways, slots, or
grooves a side milling cutter is used. Cutters of
this type are ,supplied with teeth not only on the
outer circumference but on the sides 4 its well, thus
having three cutting siirfaces in contact with the
work.
End milling cutters, supported and driven at one
end sand with teeth on bosh the periphery ninl on the
end, .are useful for reaching surfaces that cannot
be reached with conventional cutters. this
type of cutter cannot lore directly into a piece be-
reuse of lack of t;.etli at the center, it can provide
required radii within cavities, machine flat spots
on aliping surfaces, cut away the radius left by a
side milling cutter at the end Of a key.ory, ono, per-
form other similar operations. ?
Fig. 4-12 End Milling
Combinations of various sizes, "'hopes, and
types of cutters are often used to make special
contours in a single operation, while form cutlet.
can be employed to provide curved or otherwic_
special cross-sections.
In the design of parts that must be mile by mill-
ing, it is important wherever possible. to allow for
the uize of standard milling cutters, thins avoiding
the expense and delays involved in procuring
special cutters.
BROACHING
Broaching is a very fast and relatively simple
means of providing a desired contour ? usually in-
ternal, although surface broaching is becoming an
increasingly common operation. The process con-
sists of pushing or pulling the tool, t 'sited the
broach, through /or across) the work. A broach re-
sembles a coarse file in that it is provided with a
large numLer of cutting edges so arranged as to
gradually change the contour of the work from that
of the original Out:e to the desired final form.
Broaching is a fast operation since one pass
over the work is all that is required. The pieces
are left with a good finish because the tool has
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ELECTRONIC HARDWARE
fine teeth in that portion whi.c)ils host in contact
with the work, For the most part. broaching is limit-
ed to Illfge?tiCith: 3perationto since leah the tools
paendnstilvi.
the machineryfor using thcm initially ex-
,
IMPORTANCE OF PROCESS 1:::?ORMATION
It is recognized that the foregoing sire by no
means the only ways in which the .many small, re-
latively pree;se parts uses) elictti,slic components
are machined or manufactured. The primary purpose
of this discussion of fabrication methods is purely
to make an engineer engaged in the design of high
frequency transformers cognizant of some of the -
problems faced by those who must prssloce his com-
ponent parts. It is common knowledge through-out
the industry that far too often a design engineer
will work out sa new design in his laboratory. foe-
getting completely that while there is no psoicular
problem connected with making one or two of almost
anythins. there well may be 'serious problems con-
nected with quantity production of the same items.
It is hoped that this discussion, brief though it may
have been, will kip to prevent issuance of speci-
fications which are not practical and therefore must
be revised at the cost of both time and money be-
fare production can begin.
TERMINALS AND SOLDER LUGS
Terminals and solder lugs are available from ?
number uf sources' in a wide variety of sizes and
shapes. Almost without exception, the material
used in these very necessary bits if equipment is
brass. In the case of small solder lugs or round
straps. copper is sometimes peril; and for those
Canes where successful operation depends upon
spring action, beryllium copper tray lie specified.
As will be pointed out later in this section, the use
of any metal other than one of non?forrous compo-
sition will make soldering difficult even though the
surface ? be electroplated with an easy-to-solder -
metal.
Good trminal design involves ferule practicel
considerations. To begin with. it in best to utilize
existing forms and sizes of terminals rather than to
inaisit upon new designs unless the new terminal
will materially improve the performance or the use-
fulness of the end pro4uct. Terminals which can be
produced by other than lathe or screw machine tech-
niques are highly desirable from a coat angle sad
SAIrcrall-lAarine Products, Inc; Seed Chian tiatudocturtne
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flclassified.P rt SanitizedC
IDY Approved for Release ? 50-Yr 2014/03/27 ? CIA-RDP81-01043R003100230009-9
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Declassified in Part - Sanitized Co .y Ap roved for Release ? 50-Yr 2014/03/27: CIA-RDP81-01043R003100230009-9
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Part I. MATERIALS OF CONSTRUCTION
rarely is there n need for greater necurneles in di-
mensions than can be obtained from upsetting, cold
heading, or, other similar and 'noire economical
processes. ?.
It is importerat to remember that a well-designed
terminal will Rieke it easy to connect lead wires in
a manner such as to make the connection mechani-
cally neCtir0 heforo soldering ? a requirement that
is extremely important. The size end type of the
wire which will . be used for the ctennection must
be consi4eire.1.Generally speaking, the use of termi-
nals with holes through which the wires must be
pushed in not recommended hecamee of the extra
expense involved in this opere:ion,- This fact is
eseee!ally trot) foe those cases where 'stranded wires
are used since Ainly a slight excess of Solder on
the wire following tinning or a bit of binning of
the individual .strands will often be sufficient to
prevent entrance of a lead into a terminal hole.
? In connection with terminal ilessign, it is well
to give some consideration to the means to he em-
ployed in holding the totalitiesl to its insulating
board. The most common methods of fastening termi-
nals can be listed under the four general headings
of fastening by the use of screws, riveting, spinning,
sand staking.
Of the above listed methods, the most expensive
and the least used is probably the method involving
the use of screw?. If a screw iro to he woesl to hold
a terminal in plaee, it means that the terminal must
itself be either tapped or threaded, as the case may
he. A lock washer is required if the terminal is to
remain tight titular normal conditions of use which
means additional parts to handle and a resultant
increase in coal.
Fig. 4-13
Riveting as a means of mounling terminals
Riveting is a process whereby that portion of
the terminal which protroezs through the terminal
board is crushed, rolled, or otherwise deformed in
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such a matter as to prevent withdrawal of the termi-
nal, Properly done, this method provides adequate
bottling power. Two methods of preventing rotation
of a riveted terminal are eaten toted. One method
cattle for the use of square hole in the insulsting
board so. that the riveting action will cause the
metal to crowd outward and Into the corners of the
equate, thus effectively preventing twisting of the ?
terminal. A second method for keeping terminals
from turning requires either a knurl or a set of 'ser-
rations of the ehouldee of the terminal which is in
contact with the surface of the plastic or other insu-
lating rmiterial to which the terminal in attached.
For most applications, either of thent, methods will
be found .satisfactory.
Spinning is a slower, more expensive method
'of anchoring terminals in which that portion, of he
metal which extends through the hole in the in-
sianting board is not. crushed but Instead is actually
rolled by means of a rotating tool until it is in
contoct with the supporting bane. Adopted only to
those terminals which have hollow shanks to ac-
coninuelate the pilot of the apinoing tool, the process
not only anchors the terminals securely but at the
same time eliminates from the deformed portion all
protuberances and general roughness. Closely re-
lated in nature to the ',pinning process described
earlier in this section, when properly performed, it
results in uniform, smooth, well-formed, tight "roll-
over." against the insulation, in the case of com-
ponents which will operate at very high voltages,
spinning in often resorted toe* a means of reducing
the points from which corona may originate..
CPiNNiNG
'tom.
Fig. 4.14
Spinning Qs a means of mountinf. terminalt.
The process of spinning in carried out on ma-
chines resembling dililvenereal and involves the
use of tools of varied designs and nixes according
to the particular terminal whit+ In to be spun. As
might be expected, the nature of the operation is
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such as to require more time than riveting or stak-
ing; hence it is not wine to specify that teresinels
shall he mounted by 04 pinning unless it i.e cobseidar.
ed vital to the performance of the unit to hove all
terminals free from irregutarities and projections.
It should further be noted that common dereign
pravtice often calls for the application of Nobler
to terminals, frequently set the end by which they
are attached, and this Holster. properly applied, can
almost aNvays eliminate completely the need for
spinning terminals to the insulating board.
Stoking is a very quick and generally efficient
means 'of mounting properly designed terminsele.
.general, this proceerse is limited to terminal,* which
are. flat and recta regalia in cross seciion. 1 oper.
ohm is performed in a press and requires the ase
of tools. specially designed for the particular lentil.
net and application. The process of staking consiSts.
of dkplacing a ceriein amount of metal In mm way
that anchors the terminal to its supporting rem-face.
Ilecuuse of a general lack of resilience in both the
terminal- and the insulator, it is difficult to keep
staked terminals eafiviently tight to prevent move-
ment. This feature alone is sufficient to transfer
emphasis from this type of terminal attachment to
one of the previously named methods.
Fig. 4-15 Terminal Mounted by Staiiing
MOUNTING BRACKETS
Mounting bracketoo and similar pieces of hard-
ware are usually stamped from cold-rolled steel al-
though brass is sometimes used, particularly in the
smaller sized pieces. As supplied commercisIlv,
hardware of this sort iv most often cadmium plated
after being punched from 'drip stock.
CORE DRIVE AND TENSION DEVICES
The increased use of permeability-tuned wino-
formers has retreated in a number of fundantentn1
lypes of devices for driving and controlling tension
(torque) on the cares which tune the units. Not only
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