DESCRIPTION OF THE END STATION OF THE THREE-CHANNEL EQUIPMENT TYPE V-3

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP81-01043R001800230007-6
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 114
• Document Creation Date: December 27, 2016
• Document Release Date: March 20, 2013
• Sequence Number: 7
• Content Type: REPORT

Declassified in Part - Sanitized Copy Approved for Release 2013/03/20: CIA-RDP81-01043R001800230007-6
STAT
Declassified in Part - Sanitized Copy Approved for Release 2013/03/20: CIA-RDP81-01043R001800230007-6
 Declassified in Part - Sanitized Copy Approved for Release 2013/03/20: CIA-RDP81-01043R001800230007-6
DESCRIPTION OF THE
END STATION OF THE
THREE-CHANNEL EQUIPMENT
TYPE V-3
0
STAT
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 Declassified in Part - Sanitized Copy Approved for Release 2013/03/20: CIA-RDP81-01043R001800230007-6
CHAPTER I
GENERAL DATA ON THE OV-3 EQUIPMENT
? 1. Purpose of the Equipment
The OV-3 equipment is a device for multiplex high-frequency telephony, designed
for the purpose of increasing the carrying capacity of overhead communication lines
made of nonferrous metals. When this equipment is used, a communication line will
carry three additional channels in the frequency spectrum between 6.3 Icc and 26.7 Icc.
Besides the usual basic components required for transmission of three high-
frequency channels, the equipment contains line filters DK-2.8 and DK-5.7 or balances
BDK-2.8 and BM-5.7.
These filtering components permit the creation of a tonal telephony channel in
the spectrum, from. 0.3 to 2.L kc and a photo-channel in the spectrum from 3.2 to
? 5.2 I:c or, instead of these two channels, a broadcast channel in the spectrum from
0.15 to 5.0 Icc. By means of the picard transformer, which is also part of the e-
quipment, a telephone communication channel in spectrum up to 100 kc may also be
formed.
2. Basic Equipment Data
The equipment operates on a "carrierlessr' principle. The equipment can send
into the transmission line two different spectra of frequencies: either the main
or the additional spectrum. The frequencies of these spectra are shown in Fig.l.
The additional spectrum i.s. ?obtaiftdd from the main one by inverting the side
frequencies of each channel. As a rule, the main spectrum is used; however, when
two systems are operating on parallel circuits, one of the systems must be changed
? to the additional spectrum.
When the level fed into the commutator terminals is equal to the zero level,
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the side-frequency level at the line'terminals of the intermediate and of the terrrr-
inal equipment will be +2 nepers. At the same time, the level in the four-wire
transit points of the end stations will be +0.5 neper at the receiving end and -1.5
nepers at the transmitting end. The amplification of the equipment is such that it
? will compensate for the damping occurring in a 450 ?tea long transmission line made of
copper hires of 4 mm diameter, with 20 cm distance between the wires and under
weather conditions classified as "hoarfrost", d = 10 mm. At the highest transmitted
frequency, the maximum amplification of the intermediate station will be 5.5 nepers,
the minimum level. at the input of the end station will be -4.5 nepers.
The equipment is provided with devices for automatic amplification adjustment,
which compensate for the line damping variations that are caused by changes in at-
mospheric conditions. Besides the automatic amplification adjustment, a manual amp-
lification adjustment is provided for; this ensures greater stability of the residual
damping of channels in long communication lines and under difficult atmospheric con-
A#
?
The equipment is designed so that it is possible to synchronize the carrier-
frequency generator of one station by the carrier-frequency generator of the other
station.
One of the thrri channels may be used for tonal telegraphy. To reduce the in-
fluence of telephonehannels on the tonal telegraphy channel, some amplitude limit-
ers are provided; these operate in the telephone channels.
The call in high-frequency channels is made by a 1000-cycle tone which is mod-
ulated by a frequency of 20 cps. The 1000-cycle frequency may be changed to a
500-cycle frequency, if necessary.
The tonal call device is connected to the two-wire part of the channel.
The end station is supported by two stands, each 2.5 m high and 650 mm wide;
IL
is the-intermediate station is supported by one stand of the same dimensions.
The station equipment is distributed on both sides of the stands; the compo-
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:re:il;s hick req.:ire eorisLarit i?ratcl:in'? arc on tine face of the sLanrl (these are the
conLr_., ele:'.ents and Lite co:: pnnents containin,:? vacuur: tubes). The components that
to not require constant r..olriLorinr (r:ostly fillers) are located on the back of the
sLan,i.
? The equip: cnt is constructed so L:ia.t iL r:a; be disassembled, transported to its
is
?
destination, and re-arse:,blerl there.
"_':he eq' i l ;'curt, uses %acuui:-tube t;rl:es that are standard in wire- co'r-imuni cation
al)]- aratt:s . ien s ,.abilized f i la; ent voltage is available, va.cuirrr-tube types 102,1112C
(T C-1) and 10i 12C (TO-2) are use: w: en a rlolrstabi].ized. fi]a're11t voltare is used,
fire ? actal~'-tl'~)e t;-he; '!;1,12C (10-3) an, 7F12C are er. plo??erl .
in the latter case, the voltaic is stabili^ed b;r rieans of sel aratel,-t-installed
ballast tu:lbas. i'r'bes of 7 ::.12C t rpe require 0.!,.2,5-B5-5-l2 ballast; the 7P12C tubes
regt'i re 0.' 5135.5-12 ba].].ast. iaraneters of bet'' the vacutu.: tubes and the ballasts
will be form' in the Tab] e of Fi--.2.
The eoui.p: en`. -a-- use either direct current (220 'r for plate circuits and 0.. v
for the filar -ent anr' the si:-nal circuits), or alterna Lir1 current (both 127 v and
220 in the latter case, t:.c poker source should have a rectifier to provide
direct-ctrrect ,roltares for the plate and the sirna] circuits and a step-c'oim trans-
for,-,or for filament circtii.ts". Fire power requirements of the equipment. iri.ll be
f G`uru` in the Table ,-i ven in Fi,,.3.
? . r^ sic I) ia rrar: aria Operat?in- Principle of the End Station -C'--3
sir~nlifierl bloc'.; -ra:: of tr:e end station (..) is ' ivon in Fir;./. and one for
the en,d station (3), in Fi-..5.
The eni.ipr:ent of the speech circuits of an end station consists of: the in-
r?ivic'ual c!.annel equipment, the Troup eaui.pitent, the line filters., and the balances.
The power source r- be orderer'. separately.
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The Individual Channel Equipment
The individual channel equipment has a double purpose: It permits changing
over from, a two-wire s,-.-stem of communication to a four-wire system and it converts
? the voice-frequency current into a high-frequency current (in the transmitting part
of the station) and the high-frequency current into a voice-frequency current (in
the receiving; part of the station).
The voice-frequency currents, appearing at the commutator terminals "K"f, are
conducted first to the extender of the two-tirire transit T[J, then to the differential
system DS, and finally to the jacks of the four-wire transit. If the level at the
commutator terminals is equal to zero level, the level at the jacks of the four-wire
transit will be -l.5 nepers. From the jacks of the four-wire transit the currents
will go to the limiter OGR and then to the transmitting system. The transmitting
s,;,-stem consists of a modulator, a pass band filter, a leveler, and a band-filter
transformer. The modulator chances the voice-frequencies into high frequencies. The
? pass band filter separates either the upper or the lower sideband of frequencies :
depending on whether the equipment is operating in the main or in the additional
spectrum. The output terminals of the band filters of the first and third channels
are in parallel and are connected to one aria of the differential system; the output
of the channel II band filter is connected to the other arm of the system. The
function of the differential system is to prevent the occurrence of mutually shunt-
ing effect between the band filters of adjacent channels.
After passing the differential system, the high-frequency currents of all three
channels enter the "group equipment" section.
In the receiving circuit, the three high-frequency currents enter the inputs
of three parallel-connected receivers. Each receiver consists of an equalizer, a
band filter, a demodulator, and a low-frequency filter. The frequencies of the
? given channel are separated by the band filter and are subsequently changed to voice
frequencies by the action of the dei:nodulator.
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is
`r: e voice freot encie3 ta.es t:_?^1 ? t:;e 2^?1'r-frerrenc: ? filter' of t'ie receiver an!
-,nt~ i .e JC' -fl?CCI' et.c- a; p3ifier U C.i tlien tLese frenuei'Cies 'aass t.ie -w c' 3
Cf }:e fr??'t'- ,_.' e '. r_.r?31': i.l ; -.. e .1. eretlvi J 3 ; s2-.e csrl 13 , al.pear d' t:.e
'Ierl i,.4 1s .
en t:.e l e,,-,3 a+_ e co, terl-i n J 3 ^f' + i le ; rir31"1' 1117' i ~.1 icn 1 , ;er 7
f -e level a,. +..e 'ac' s ^f t: e f^1 , -',r] re t?.ra:i3it ' f t,'e recei vi _l- '?ri1 J 1",e
e91-2.- to -0-5 ?ei''crf :.t. r. -e l e-re1 t+ f, .e CO 'r:1 t,Lt^r ter--in.i 3 -)f '.'.e receivin; s ta-
ti r'n 1riJ J 1'e erp-.aJ 1-^ -(.. ' e! er.
,'. e e-n.ipi-en, '-a C c ail-e r-rer 1 i e {?n11'- rire ' el . of oreratirn h'? 3i--
,in -i'1" c^: nec i :1i a. t.-c Jac' 3 rf ' c `'^ I'-;li_^e a;ri s..t -.:' t;:.e T_' ^_f e
_ tin-- -J : 1,l e recei'r` .. cec+,i ,1n. C , a: i in - in e,-1-terrIer3 TI'-, a:;'' T1
^J' ' e 1Ct1= Lire tr..Ln.ii' is, reii"eCT, '?reJ,', .1 :leper-, in 1 7'3 ne;. er.
' e 3?. e ti: e, .3 in j r i::1.3 t1r ~2" ('Z-u;13- it''(-.I-) do-1 :'lr' (receiver) 'r41J be
r c .,r'?ice-freq-enc ri . -ii. -'e-rice is -ire, into t' e t'r^-'sire 1 urt of t!,e c.:a':-
? ..e1, 1;e . rec:: t;:^ -~;C: ?' .e r_ e t a r .
i' 1c 1ia"r-,i it Fir--i.' s^' r, rei resent ia'i'ri-211a1 erh'ip,;.e1:t? of a sin.-1e
c- :.r.:'lei. .mac en I GtJ?ti: . C''.i`ait13 t ref: .ie ..i of inr'ivi ,lld7 cianneJ ecniiy ent ? t:le
,firs.
'iff er ^.11- ir. t C1 . ',a.i fi3 tern an,' t cir rfr ii e
?
i ;een rile free-encies free (.3 I c to c ire
:t'i it t? e '!1rect,icn frci ,1 to 13; t}-e fr orn encie3 fro: 31 .3-'?C to
711 both the- .. and the
r; -,re, 1 ';o tra.,3i if. ire tale 'lirectio i fr '' to
ial r: frcq' e 1(,. 31 ectrl'I ).J c to j!. .'/ ' c) is f1.r11is1lier) h-r the i1l'ii-
'J''UaJ e c:.nne3 er'i~.ir; en', ^!' t' e er') :itation; );i,] s reans that tl.e carrier frequencies
err=-'rin a e r)')1 Jators of t,,.e first, sccolyr', and third; channels of station :1 are
t, S..ir e a3
t, lc carrier frequencies arri'rin,r at t;le t;'o,luJator's r'f II-these _channels of
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station P. The hand filters are also the sane in both cases.
Up,cr: lea?rin!- the individual channel equipment in station '1, (Fib.L), the side
frequencies of the three charnels (located in the spectrum 6.3 kc to 1!x.7 kc) enter
the group equipr ent. here, they pass through the transmission amplifier Us. Per. ,
? turd ugh the -?irect;in ; filter j-16.1,, throu.;r, the line filter K-5.7, and then are fed
i1:to the line. The side frequenc level of each channel (when the level at the
COI dnutdtcr terrinals is zero) is equal to +2 nepers.
The frequencies fed into the line from station B (Fig.5) should be in the spec-
trin-? of if. j l:c to 26.7 1 c. TO obtain these frequencies, a group modulator, con-
vertin frequencies of 6.3 to 11,..7 kc spectrums into the frequencies of 18.3 to
2A.7 Lc spectrur^, is connecte-I between the individual channel equipment and the
transmission ai.rlifier. The carrier frequency of the group modulation is 33 kc.
The band filters of ti,e receiver are tcie same as the band filters of the trans-
mitter, i.e., they all pass frequencies from. 6.3 to 1L.7 kc. The group equipment of
station ,, which receives from the line the upper spectrum of frequencies, must
tl?erefore have a frequency converter to chant. e the frequencies of the 18.3 - 26.7 kc
band to frequencies of the 6.3 - 11-.7 i.c hand. In this case frequencies, received
frorr ti,e line, lass tiircu:-ii tiie line filter K-5.7, through the directing filter
through the ret,ulate-i artificial line RIL and into ti,e group converter
C. Pr. and the receiving ar..rlifier Us. Fr. ; after that, the frequencies of tne 6.3 -
- Jh.7 Lc spectrum enter the equalizers and tree band filters of the channel receiv-
ers. Station 13 requires no ,Troup converter in the receiving circuit, since it re-
ceives from the line only the lower frequency spectrum.
In adrlition to t,.e components discussed above, the group equipment includes a
arrier-frequenc;- generator and a means for amplification ad justment
c .
The Carrier-Frequency Cenerator
.13 seen from the preco iin~, discussion, the operation of the equipment requires
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s5,nchronizinf- trio carrier frequencies. The 9 kc is filtered out by~r.eans of a
narrow-band filter of the receiver ARU of the station B, is amplified and then fed
to the grid of the vacuum tube of the carrier-frequency generator. In this case,
the amplification takes place in the tube of the quartz oscillator,. since due to the
? fact that forced synchronization is being used, this oscillator is not needed for
operation of station B.
.Automatic and 1?anual Amplification Regulation
The group-equipment section of the end station has means for autocratic and for
supplementary manual amplification regulation. These consist of a receiver for the
control frequency of the autocratic amplification regulator 'tPr.ARU", of a receiver
for slopinf- level regulation PIER, of a controlled artificial line RIL, and of a gen-
erator G-50 supplying 50-I:c frequency.
The purpose of these devices is to compensate for the fluctuations of damping
in the transmission line caused by variations in atmospheric conditions. Figure 6
1
' C f 4- 11 d
tr
0
s~~o
s rap
io or . e ampi.n of overhead copper transmission lines, as a function of
the line length and of the weather conditions. The curves in Fig-7 represent varia-
tions in the line damping with changes of the line length and of the :?reather; the
changes of the latter being within the limits : "winter - dry"' and 1 !winter -
hoarfrost" diameter = 10 rr :. These curves show that, at higher frequencies the
?ampin f; variations are greater and that the character of changes in the line damping
is influenced by both the line length and by the vieather conditions,
-
Ti,e curves of Fig.7 show also that, while the increase in line damping at
weather conditions of "isurr.,er - wet" is approximately proportional to the frequency,
,,,.e increase in dar:pin ; at weather conditions "hoar-frosts" occurs at a considerably
higher rate than the increase in frequency. This .fact causes considerable fluctua-
tions in the residual d.ampin, of side channels in instances when only one control
frequenc, is used for autoratic level regulation. This is not the 'case in the
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egtu.r?r o t lm-;cr (l1S CUSS?On, since :.ere the level is re; ;Mated- b?- i:.ea?":s o ;ao Coil-
'si'c ` :frequencies . Crle of t:.ese frem.-.el:Cics contrc-Is t' e C'j:erdtion of at?to; ati c
ar',-'.is ont, t.,e oi,..or perr its a'~r] - cation of porio^ic corrections (b,- r--.cans cf
the slante , level re: tlator) c.,evcr a consiferab].c s. e:r is acCLi;'1.'late::A. Fanual
?
level a7~ Sl.l-en.. is 1r c,.ic.sil" never regLire' -'urin~: the Sinner; ..o:tet-er, in .a:lter
':.i. en area are cc-:ere 0,12?-_rc3 i.:.C a- tc;atic 1C'"el ;,-,:s'rent ''C
lle
is not sa tisiac or-- a. i ' ---us t , nl.. e
h- : al- ..?a]_ c ntro_' r te 1e-.rel., lr-
ea,?3 of t he s'.ante'1 Je-re2. re !a"tcr.
`_1,c, le-.-e3 .:c .`ustr'Cnt is ac ievc, ' - : Cans of t: e contro~- ]e' arti f icia]. line
RUL. .,. si `'' 1.; fie(' s el on %, Of' t% C trj?TTtir is it
F ...
` - - `1O, e T) T
lI? c? :-
J-J1+J t:ro si:: .",.in' artificial lines. (:'^,i' sJ,-,-]'Cit:', tl.ree lin'"s are shown
i:? Fi .f .) 1 .C 'ar.J.lrl - in the 2i.n. s of the first arti_"icia-' ]_inC is a fl.?1Cv1on of
t'+.e _roo'.enc -; t.'-- Ca''j in lin''s Of e oecr,_ ]?,ie is not in'f]fence` b-' fre-
-- an-Co. =o 1 f ia1
Cj" Ci C. e :'. ';1," of 1 i r J. I -t i_ i C J? :]CS 13 C01:' n.11e'' ')--
.cans of variable ce v-citors ca ,
i ( lac K, in L 1'c firs ? an,, car ,cit-?r Fo in t. ~e
? secon-' artificial .'ine). r
=ac' of t CSC ca1r;citors as 3C'rcn st_,tionar'' sections an'' cne r:?ovable section.
7.,P, StG-_i iI sections are locate'' oii a c .rc]o, eaC; section Heel'}', 'in ? 1/k
1' of the
circ 1 o:-cnce of he cir c! e. ff ? C vab3 e sectI is of the same size as '
aJ the s
J ua-
t iora_ - sections an' ..r.. he r to te" to ! es.- .ri~.. either the first or the .event'
sta',io'ar, secti s, (::. on 1cf'; it an ]:" CI".e'l.l~;e position) It 1a' :,C3}1 p r-
';i 1i- it? ': y '
bct' y C ';ior s S t1 7 T. a r? C O ) S
_ ,~, C 3 . .... 'i"C connections })et:?r6Cyr1 the Sta-
car,_.citor 7,Cc'!,ion3 an'' t' e artificial_ line are shown in
?
-a:-.pin'; in I-'-.c ] in' s of t; ae socon, artificiaJ line is in'lepenttent, of }le
frea'.enc--; },eref re, :r:ion the : -ovabI.c section of tie capacitor 1'2 is r'over' fr or:
t^ rr1ci1,;iO1L 60, t} c 'lecrou c in rla,'lpint: 1-rill be r?iforrr: for al] f'regl'.en-
ties (Fi;.;l,). In the liri,-s of tie first artificial line, however, da!npinr will do-
crrase as the is incr.?easer'l: since the statiorrar;- sections of the capacitor
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Li are connected. 'to the links of this line across voltage dividers consisting of
two series-connected resistors, moving the 1,
,l rotor fror;i position, 0 to position 60
will cause the da:pin~,, in the RIL to diminish at high frequencies and to increase
at low frequencies (Fig.'s).
? '!teen the rotors of both t, e I:l and the I.2 are moverl, from position 0 to position
?
60 simultaneously, the dan.pinr in the RIL will chance as depicted in Fig.9a, i.e.,
the !tic-her the frcquenc~r, the --reater will be t}.e damping in the RIL. In this case
the fluctuations in the damping; of the RIL (Fic.9a) obey the sane law that is obeyed
b:r t:.e variations in line dar.-pin,, under average atmospheric conditions.
The capacitors are deli,:ne'i so as to permit either a simultaneous or a separate
rotation of both r-ovahle sections. If the variations in line dar.-ping caused by the
variations in frequency - do not agree with the average curves (this condition ray be
prorh. cerl b-- hoar-frost or icing of wires), the residual clamping curve will be stewed
and the residual dar.pin.; of side channels will clan e. This skew rah; be corrected
b - the rotor of the slant regulator. The rotors of the capacitors are ro-
tated b,-,- an electric rotor located or. the plate which supports the RIL.
R-; Weans of cords and banana plugs, the capacitor rotors can be connected to
corresponding- jacl_s of I.,' air' J.17I;-1 blocks.
:fl on the control frequency of the automatic adjustment at the output of the
amplifier is at a normal level., the rotor does not operate and no adjustment occurs.
.,s soon as the level of this frequency deviates fro:; the normal, the motor is actu-
ated and the damping of the RIL will be chanted until the norr:lal n gnitucle of the
level is re-established. 'lhre direction of rotation of the motor will correspond to
the direction of level deviation.
The rotor is controlled as follows : The motor is equipped with two pairs of
windings', supplied with a 50-ctcle current; to stop the motor, the current in one
41 pair of windings is reduced to zero; to reverse the direction of rotation, the cur-
rent please in one pair of the windings is chanced by 1800.
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`- e ro i i' 13 j ( creel .1 a VaCI'Lli :-L111~4 c.11C: u,,-r f, r a frcquunc ^f j0 cps. One
t.ak", of .Iill.lin-s is C`!u1CCLe'i tC? the (,cilcrator 1ivcctl.;,' an'' the ether, across an
...;U receiver. T. C ...il receiver has a device that !ceps the current in one pair of
win in ;3 cqi:al to ;ero as lot j; as ti, 'e control 1'requcnC,' rel airs at a nor m.1 level..
? r:e11 the colli-,rc] 'real cllc-? level. r cviates fro: norral, this device ~ri11 start the
--,4 -1, 1, 3l p ]: in;- ctn'ren:?. of L:,c propel' 11 ase and ral;nitt!rte to one }.air of :?Iinlin?s.
s1: p11fie'. 1ia;'ral, of this device is ;-,ivc:i in Fib .10. The 50-c; cle voltage is ferl
to the t`ri' ar;' -'f the Lrallsforrer T-1 oC the differential 3`?r-stel^. One arm
of :.':is s"ate: contain:; t:ic re3lstr'r3 R., an'1 H?_, tic other arr contains tl'err~.istor
~. J
T: c t'..er' istr:r is a resist nl' 'I .til a iar-e ter;ucraturc coefficient. In Fi,'.lOh,
' c C::r rC.:t a.:irl rota e in t :c '..or- istor ._s plotte+' a';lil.3t the resistance of t,ie
..cam : ? st or .
Fr,:- t: c I'^t'r a'rlifier, t: c control frcgl enc,- Passes into the narrow-band
ill I'eceiver, i3 a;:p iiic', an'i fe(' O the tl:Cri 1Stor. The `rl trans-
? fi1i,Cr o the ..,.,
for; .or . .e '1iffcrclltia s: ste! i3 31:iJic' -O-c;-cle frequency. The 50-C Cle
v~11?a_e is ta,.eIl C1'f C soec.''ar" win.-'in- -)f to T2 transfor:.er, and is feel to the
_?1Cr '?' r cl tm, is cc.1_cctc., . the 11,1"11 :3 J-~_ of ti he !?otC.r .
.ilc,l t..e :.e-,Tel of t: c cor':.r'ol freed enc - is nor; i.1; t- c -!ifferential s rster is
.. the 1n''1n s 3-' of the rotor. . ten
at en:_iii r11 , a,!'' o ci rrc:It fl-o--d3 '"!I ov ;1
e coatrcJ -i `'2e ' rim e3 '1'r1: t, c no 'r?al_ le-el, the e ril.ihril , in t1,e
"C an,'
c...J arc s
k _c c:,(,-st;a"ion eqi:ire: ant : a
~' ,cr 2 1)C toste:. fi,C i.CTet.cr, C^n3i3ti.1 o` a !102'1 cal sifalal ~'en-
G.'a':^.r :L!1" level :.n'iicaL,^,r, (-r' iLi r.eas-rin, e al ''a: }'iiir' of c.iannels at
a f_-_r;- C;r.c; ni CC c etor is G' ntc' ci: a -;tanr'. _*,.c ixori-.a1:1c tube
s. .
^i on-:,s i,:uat , 1 r3. C _ j / 3:%-_^lc' t n .' Ca3l'1'C %i t''C -})11'?.,0
C' :'rert ^ ti . a ? i)) C; ctirrc:1t in an, _ LIL:.! 'ant cl_Y'cuit 31lr)}1J LC') 1roi a O c
C~ t,~iC r,C:icz'.?O. i;a ti:C: May Cris. vc'1ta.-os fro: ti,cr l101 .1.11a'
v 1) i;or" r a :.i1 1)J" i:i 1'3C')'
C' ` C J ?
c. s s s r _ 1, r v. C 'a Ct'1': -t O)c ca",
)sic )ja ra n f' the Inter: a ' is Lc ?~ta !,ion } 'f-
31i cJ e Ln:, riia, ;rai 0.1. t?o inter , c,'iatc sta Lion TV-.'J Lc ; i-7c11 in
1J
STAT
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ii.t circ it consists of: the 112?e-
~'1_t' :,. e 'irec,ional filte. t.,e ccntrolline' artificial line FtII ,
".:e roi :'lif?er r'1_J, 1'ec ir?i Liter -~ , df^ e line filte'_
? C.. e "irec' ion r .t, tr e circa-it ret' ins 1"?ractica2l" +1:e
e L'-c- ;' e fi-'? .ers Y-11'.' . are Lsec
?
1, r?,' a ~.^{+'.. ~`] C . i -e t.e3t.er.
STAT
0
1 -- '.?^ _ ~,1C le'!ei 3t- en-i. an' he F!'R receiver for the control fre-
"? r' 1C` of ', 'e 3_.tnt ro ?i l.1t^._ are ^.':lec e ' in 1raJ el '.rich the cuts ut of tr:e ^
'r l1,
i - - y`'= ^ f e .~.tU is .Intrere fr a ,0-c? cie freo1:et".C` r'ener,:tcr
' e ; i?.3 -in c - ? p-re.: 3 , - c er . j .err r e inter'-e.aia e Sta :.1 con-
11.., a i t ^
le i cr s la 'cc.) . e i . i -03 9 a^ ci e. uL.i^11 cl the n' e.' .e la
ue
C^' :.e11` 1 are i t' e ? 3 '. 3C r f 1, :ear ce 1 Cr1 drtS 121 %).e er' station.
e,. 3 ](,-,e3 at e c^ Lerrina2 ooi. ''i e en-i 3tcati^I: r'f ''.;ie channel is
e're2. n;^ 3= ie 11. t`e c,.-t"-,t -f +"--c inter., e?'iate statio^;: is
r.. '..r~i er ...wt?i J'! jc tt1.^?. i' t'.e ini.,ei'? e'iato St.ti^?11 is 5.1' nerers at
a
`r? c..3e3, t e Ir. ,Rt receiver for the control fre-
cr c a . ti.e i .:est fre-
~' c ' ' e I r er i. i1 : ent of tl e inter' e?'i_'- e sta-
1i,.1:'. .1 -1 ..... f.f'? '~..:. 'v r' '' e f` cr'' t of a .si3 s of a;;awi-- curate'1 le'-el i r_4ic_-
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BASIC DIAGRAM OF TILE END STATION
?
?
0
Drawing No.P 131.00.20
1. The Transmitting Circuit
The end station may operate either as an A-station or as a B--station. In the
former instance, the station will send into the line the lower frequency group of
6.3 - 15 kc and receive from the line the upper frequency group of 18.3 - 26.7 kc.
In the latter case, the situation will be reversed; the upper frequency group will
be sent and the lower frequency group will be received by the station. To change
station operation from regime A to regime B, certain connections must be resoldered.
In the drawing No.P 131.00.20, the station components are connected to operate
in regime B, and therefore this regime will be discussed first. The circuit of
speech currents begins with the terminals IIID-l and IIID-2 for the second channel,
with the terminals IID-l and IID-2 for the first channel, and with the terminals
IVD-l and IVD-2 for the third channel; these terminals are located at the lead-in
comb of the individual equipment stand. The voice frequencies from a subscriber
are received at these terminals. Behind these terminals, the circuit can be traced
through the contacts of the dividing jacks "Comm." and "Lin.", the two-wire transit
extender, the contacts of the call relay R5, the differential system for connecting
the voice-frequency ringing TDS, the contacts of the voice-call relay R1, the STAT
tacts of the dividing jacks "ISP.TV" and "DS", and through the terminals A3 and B3
of the differential system.
A copper oxide call relay R2 is connected across the choke DR3 to the contacts
of the relay R5 and to TV, in parallel with the main circuit; the purpose of this
relay is to receive the inductor call from the commutator.
On leaving the differential system, the circuit goes through the 0.6 neper ex-
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tender to the transit jacks, thence to the transmission dividing .jacks ""Per" and
into the modulator. The limiter may be either connected or disconnected by means
provided for that purpose. When the limiter is connected, one of the telephone
channels may be used for tonal telegraphy.
? Behind the limiter, the circuit components on the modulator chassis include a
set of extenders, a modulator, an equalizer, and a band filter. The level at the
output of the station can be adjusted accurately by reconnecting the extenders. The
summary damping of the extenders may be varied in the range of 0.0 to 0.6 neper, in
steps of 0.1 neper. The ring-type modulator is assembled of copper oxide elements;
the carrier frequency from the carrier-frequency generator enters the modulator at
the terminals 7-8. The band filter, located immediately after the modulator, separ-
ates the side-frequency band at the output of the latter. If the main spectrum of
frequencies is used, the upper sideband is separated, while the lower sideband is
separated when the supplementary spectrum is used. The frequency bands enter the
band filter through an equalizer.
The second-channel chassis contains, in addition, a block with a differential
transformer tITF PER" to which the outputs of all three channels are connected.
After .leaving the T"TF PER"", the circuit enters the chassis of the group fre-
quency converter. This chassis holds the transformers that feed the control fre-
0
quencies, the copper-oxide ring modulator, the extender, the band filter, and the
amplifier of the group modulator. From the 33-kc amplifier ?"JS-33",-the 33-kc car-
rier frequency enters the terminals A6-A7 of the modulator. The band filter STAT
PF-18-27 at the output of the modulator passes frequencies from 18.3 to 27 kc; only
the lower frequency sideband will pass through-this filter, the upper frequency
sideband and the unbalanced remainder of the 33-kc carrier will be filtered out.
After leaving the group converter, the circuit goes through the transmission
group amplifier, the directional filter K-16.4, the line filter K-5.7, and then
through the line terminals IVG2 and IVG3 of the lead-in comb at the group-equipment
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Some of the K-5.7 filter elements are mounted on the chassis of the D-5.7 fil-
ter; this explains the somewhat peculiar appearance of connections between these
two filters on the diagram. From the line end, these filters are connected in
? parallel.
When a city cable input is available, the equipment is connected to the line
by means of the cable autotransformer ""KT"". In this case, the line is connected to
the terminals IVD2 and IVD3 of the lead-in comb at the group-equipment stand and
the terminals IVG1 and IVG2, IVG3 and IVG4 are connected-by jumpers. The cable
autotransformer is located on the chassis of the lead-in combs at the group-
equipment stand.
A control-frequency inductor IKCh is connected to the output of the group amp-
lifier; this inductor will send out an emergency signal if the transmitting group
circuit fails to operate properly.
? 2. The Receiving Circuit
From the line, the high-frequency currents enter terminals IVG2, IVD3 of the
lead-in comb at the group-equipment stand or, if the cable autotransformer is con-
nected, the terminals IVD2, IVD3. The receiving circuit goes then through the line
filter. K-5.7 and through the directing filter D-16.1..
The controlling artificial line RIL is connected after the directional filter.
As before, the RIL serves the following purposes:
STAT
1. Compensation for line damping changes, caused by changes in-the weather;
0
2. Establishing a proper-(for the given amplification interval) magnitude and
slope of the amplification frequency characteristic, when the equipment is connected
to the line.
The flat adjustment and the slant adjustment regulators are mounted on the RIL
chassis.' Their functions were explained above. In addition, the RIL chassis car-
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ries also a single-stage amplifier BUK, which acts as a buffer between the flat ad-
justment regulator and the group amplifier. Its presence is necessary since the
flat regulator cannot work into a low ohmic resistance. The RIL is followed by the
group-reception amplifier Us.Pr., which is similar to the group-transmission ampli-
? fier. However, since the amplification required in this case should be lower than
that in the transmission circuit, an extender is connected to the output of the
Us.Pr. The other end of the extender is connected to the step-down transformer TP
of the reception filters.
The purpose of this transformer is to match the 50-ohm resistance that follows.
This resistance and the resistors that are connected in parallel with the inputs of
the band filters create t"Ltt-shaped extenders that prevent mutual shunting between
the parallel-connected filters.
Further, the receiving circuit goes to the individual-equipment stand and en-
ters the demodulator chassis. This chassis carries a band filter PF, an equalizer,
a demodulator DM, and a low-frequency filter FPr. The band filter passes the same
? frequencies that are passed by the band filter in the transmission circuit of the
given channel.
The band filter separates the frequency band that pertains to the given channel
and feeds these frequencies first to the equalizer and then into the annular copper-
oxide demodulator. The carrier frequency from the carrier-frequency generator en-
ters the terminals 7,8 of the demodulator. The low-frequency filter will pass fre-
quencies up to 2700 cps, but will filter out the frequencies of the upper siSTAT d
and unbalanced'remainder of the carrier frequency.
The voice-frequency level at the output of the FNCh is -2.8 nepers; since this
level should be +0.5 neper at the transit jacks, the FNCh is followed by a single-
tube low-frequency amplifier UNCh. The amplification of this amplifier may be ad- ~Mw
justed from 3 nepers to 3-4 nepers by means of a set of extenders and by a smooth
-regulator at the amplifier input. Provision is made for mounting the amplification
-3 0
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0
regulator at the four-wire commutation support. In this case, the RU,is connected
to the amplifier by means of the pegs IIIG9 and IIIG10 of the lead-in comb at this
support; at the terminal plate of UNCh-1, the jumpers between E2-E3 and E1, E5 should
be removed and inserted between the terminals E1-E2 and E5 E6. The output of the
UNCh is connected to the reception dividing jacks "Prtt. From these jacks the cir-
cuit goes to the transit jacks and then, through extenders, into the differential
system. The circuit between the differential system and the commutator terminal was
discussed under the heading of "transmission circuit".
3. Changing the Operating Schedule of the Station; Changing from a Twd-Wire
to a Four-Wire Transmission
?
A station, operating as a B station, may be made to operate as an A station by
moving the group converter from the transmission circuit to the receiving circuit,
and by interchanging the filters K-16.4 and D-16.4.. The interchange is made by re-
soldering the connections at the lead-in combs of the chassis.
To shift the group converter into the receiving circuit, the following changes
should be made in the connections at the lead-in comb of the converter: the jumpers
between the pegs G3-V3, G1-V4 , G5-V5, G6-V6, G7-V 7, and G8-V8 should be removed;
these jumpers should be inserted between the pegs V2-B1, V2-B2, V3 -B 32 V4--B4, V5-B5,
V6-B6, V7-B7, and V8-B8.
On the RIL chassis, the jumpers between terminals B2-B3 and B7-B8 should be re-
moved; these jumpers should be inserted between the terminals B3-B4-, B8-B99 BZ B2,
and B6-B7. STAT
The circuits connected to the terminals '-4 and 7-8 of the filter-DK-16.4
should be interchanged.
The change-over from a two-wire to a four-wire transmission is achieved by re-
distributing the jumpers in transit jacks, located in the commutation field at the
0 individual-equipment stand.
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?
h.. Connecting the Spare Amplifier
If necessar,;, the transmission amplifier or the reception amplifier may be re-
placed by the spare amplifier. The connection is made by changing the positions of
the jumpers at the spare amplifier terminal plate. If the transmission amplifier is
being replaced, the control-frequency indicator IKCh should be disconnected from its
output and connected to the output of the spare amplifier. To do so, the jumpers
at the IKCh terminal plate are taken out of the 2-3 and 6-5 jacks and put into the
2-1 and 5-4 jacks.
5. Diagram of the Levels
A distribution diagram showing levels at the individual points of the end sta-
tion is given in Fig.12.
6. Circuits Supplying the Carrier and Control Frequencies
? The carrier and control frequencies are furnished and amplified by the quartz
master oscillator KG, the carrier-frequency generator GEN.NES., and by the 33-kc
amplifier which is equipped with a band filter F-33. The master oscillator and the
carrier-frequency generator are mounted on one chassis, while the amplifier and the
33-kc filter are mounted on another chassis.
In a B station, the tube-of the quartz oscillator operates as an amplifier
tube; the voltage of the 9-kc control frequency, taken off the' terminals 7-8 of the
control-frequency receiver, is conducted to the grid of this tube. To chanSTAT,e
tube from operating as a generator to operating as'an amplifier, the jumpers at the
terminal plate of the quartz oscillator should be redistributed. From the output
terminals of band filters of the carrier-frequency generator, the carrier frequen-
cies go to the terminals 7-8 of the modulators and demodulators. The levels of car-
rier frequencies at the terminals 7-8 are adjusted to be equal to -0.5 to -0.25
neper. The 9-kc and the 15-kc frequencies are also used as control frequencies;
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therefore they are led out of the BZ B2 terminals of the carrier-frequency generator
and into the receiving circuit, across the terminals A3-A4 of the group converter.
The level of the control frequencies at the entrance of the line should remain con-
stant. Since the carrier-frequency generator does not stabilize the frequencies to
? a sufficient extent, an additional stabilization of the level is achieved by means
of thermistors. The thermistors located on the chassis of the carrier-frequency
generator, ensure practically constant level of the control frequencies. The level
of the control frequencies at the entrance to the transmission circuit Is equal to
(5.8 to 5.9) neper. The 33-kc carrier frequency enters the A6-A7 terminals of the
group modulator via the filter F-33 and the single-tube amplifier US-33. The level
of the group carrier at the output of the US-33 is adjusted to be equal to -0.1 to
+0.35 neper.
7. Level-Adjusting Circuits
The control-frequency receiver is connected to the terminals B6-B7, in parallel
? with the output of the receiving amplifier. The control-frequency receiver consists
?
of the receiver for the automatic level adjustment Pr.ARU and the receiver for
slanted (manual) level adjustment Pr.NRU. Narrow-band filters are connected to the
outputs of both receivers. The Pr.ARU filter is tuned to 9 kc, and the Pr.NRU is
tuned to 15 kc. Both the ARU motor (located on the RIL chassis) and the ARU re-
ceiver require a 50-,cycle current for their operation. This current can be obtained
from the station supply, but, to ensure continuous operation of the ARU in the case
when the station 50-cycle voltage is interrupted, this current is furnished 1STAT
50-cycle vacuum-tube generator which is a permanent component of the station. From
the terminals of the generator the 50-cycle voltage goes to the terminals 1-2 of the
Pr.ARU and to the terminals A2-A3 of the RIL. Both receivers are provided with
instruments that continuously measure the rectified control-frequency current. These
instruments permit a continuous check of the operation of the transmission circuit.
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If the pointers deflect beyond the limits of the colored center sector of the dial,
an irregularity in the group circuit'is indicated. Besides the permanently in-
stalled instrument, the ARU receiver has a signal device that sends out an emergency
signal whenever the level of the 9-kc control frequency deviates from the normal
0 level by more than 0.3 to 0.5 neper during a time interval of 5-7 sec. The opera-
tion of this device is discussed in the description of the operation of the control-
frequency receiver.
8. Call Circuit
a) Sending a Call
A call current appearing at the commutator terminals IIID1 - IIID2 will actuate
the call relay R2 on the chassis of the receiver TV; this relay is connected in
parallel to the speech circuit by means of a choke and a small full wave copper-
oxide rectifier. If a direct call current is used, the rectifier may be disconnec-
ted. The method of disconnecting is evident, from the call-receiver diagram in the
? drawing No.135.40.87. Since the contacts of the relay R2 are located in the supply
circuit of the relay R1, the latter is actuated and its contacts 12-13 and V2-V3
connect the channel to the output of the call generator GTV, which, as pointed out
previously, supplies a 1000 - cycle frequency, modulated by 20 cps. The generator
may be readjusted to provide a 500 - cycle frequency. The level of-the modulated
call voltage, at the points where the GTV is connected to the speech circuit, is
equal to -1.1 neper. The output resistance of the GTV is 600 ohms so that the bal-
ance 1
ance of the differential system is not disturbed when a call signal is sent Vou1t
When the relay R1 is actuated, its contacts III1-II12 and.Ii23-II14 will close.
The first pair of contacts is in the circuit of the pilot light ?rpostt (a call is
being sent) at the signal panel; the second pair of contacts shorts out the input
of the receiver TV,,to prevent an unnecessary actuation of the latter.
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 When a call is being received, the current of the 1000/20 or of-the 500/20 call
frequency passes (as all voice frequencies do) through the first differential system
? and into the differential. system that actuates the tone-call receiver TDS; from the
second winding of the transformer of this system the call enters the input of the
tone-call receiver PTV.
The presence of call in this receiver actuates the relay R6, whose contacts
short the winding of the relay R4 which, in the absence of .call, was supplied across
the resistor L-5 and the fuse P35-2, and whose contacts IIIZ III2 were shunting the
winding of the relay R3. -
When the relay R6 is actuated, the R14 relay drops out with a 400 - 450 msec
delay.
The relay R3 is actuated and grounds the winding of the relay R5, which actu-
ates this relay. Through its contacts 1-5 - 1-1;. and V-5 - V-14., the relay R5 sends
voltage from the mechanical inductor to the commutator terminals HID, and IIID2;
the contacts 1-1 - 1-2 connect a 600-ohm resistor on the equipment side. The con-
tacts V-1 - V-2 of the same relay close the circuit of the pilot light "Pr" (a call
being received) on the signal panel. The presence of two relays R1 and R3, one of
which works by dropping in, the other by dropping out, permits to prevent the dura-
tion of call from varying. This question is discussed in greater detail in the
description of the diagram of the tone-call receiver.
The purpose of the differential device TDS, through which the receiver TSTAT
connected to the channel, is to prevent the receiver from being actuated by call
currents coming from the commutator end, when a two-wire transit is used.
This question also is discussed at length in the description of the receiver TV.
? 9. Power Supply Circuits
The station is supplied either from direct-current sources of 24 and 220-volt
23
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voltage, or from an alternating-current source whose voltage is 127 or-220 volts.
When the station works on alternating current, it is provided with a power
unit equipped with rectifiers to furnish the plate and the signal-circuit voltages;
the filament voltages are obtained here by stepping down the line voltage. All
? supplied voltages are led to the individual-equipment stand and from there, by means
of a stand-to-stand connecting cable, to the group-equipment stand. All supply
wires are connected to bus bars and terminals on the plate where the fuse holders
are mounted; this plate is protected by a housing.
When the bus-bar system of supply is used, the bus bars are connected to cor-
responding terminals in the fuse box by means of jumpers. Special jumpers are used
to connect the bus bars of all posts in line.
When the station is operating on direct current, the 21+-volt filament voltage
is connected to the bus bars "Z1411 and 11-24". It is desirable to have a separate
2/L-volt source for supplying the signal circuits. This should be connected to the
terminal "-21_,, sign." and to the terminal 11+2L 11, to which the filament circuit is al-
so connected.
When no separate signal battery is available, the 11-2411 and the -11-2L1, sign."
terminals are connected by a jumper; in this case, however, the indicator of
filament-voltage failure will not operate. The plate voltage is connected to the
terminals 11+22011 and "ZIT. The four jumpers on the fuse panel should be inserted
into the jacks marked "=". When an alternating-current source is used, these jump-
ers should be in jacks marked 1111 and, in addition, the voltage-connecting S4-T ----r
AT'
(see diagram of the power supply, drawing No.P 133.00.17) should be set to the posi-
tion 11127" or 1122011, to correspond to the voltage of the AC power line. This line
is connected to the terminals 11,11 on the fuse panel.
A signal battery should be connected to the terminals 11-24 sign.?' and "+24".
? If there is no signal battery, the terminal t1-24 sign." should be connected to the
terminal 11-24 vypr"; the indicator of AC voltage failure at the stand is absent. The
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 power pack is switched on by means of a tumbler switch on the face of the panel. The
presence of AC voltage is indicated by a neon pilot light. The supply circuits are
protected by fuses: The common circuits are protected by group fuses, and the cir-
cuits of individual blocks of equipment are protected by split fuses. P1 and P20
are group fuses of DC circuits; fuses that protect the AC circuits are located on
the power pack panel. The same split fuses are used for both the AC and the DC
power source. The fuses are provided with means that indicate when they blow out.
The fuses P1 to P15 are in the plate circuits; P18 and P19 are in the circuit of the
mechanical inductor; P20 to P38 are in the filament and in the signal circuits.
Fila.ment Circuits of Tubes
Each filament circuit consists of a split fuse,, a ballast tube (this may be
absent if lOZhl2S and 1OP12S tubes are used in the equipment), a quenching resistor,
a jack for taking measurements, two series-connected tubes lOZhl2S, and one 1OP12S
tube in series with two parallel-connected 1OP12S tubes. The filament-circuit dia-
grams of the end station are shown in Fig.13. The jacks, forming part of each cir-
cuit, are used for measuring the filament current and for interrupting a given cir-
cuit; a special blank plug is inserted into the jack to achieve the latter purpose.
The jacks are located on corresponding panels.
The measurement of current is discussed under the heading 114'easurenentsti.
The plate voltages are connected to each component of the equipment across
split fuses. The plate circuits of most of the elements are provided with protec-
tive filters consisting of a choke and a capacitor. Any plate voltage may be STAT
moved from the panel by removinp, the corresponding split fuse.
10. Sijnal Circuits
The equipment is provided with means to signal the following occurences:
1. Plowing of any of the group fuses or split fuses;
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2. Failure of the filament voltage (only when a separate signal battery is
used);
3. Failure of the plate voltage;
1,.. Failure of the voice-current voltage;
? 5. Failure of the control frequencies at the output of the transmission group
amplifier;
6. Fluctuation in the ARU control-frequency level at the output of the re-
ception group amplifier, if the level changes by more than 0.3 to 0.5 neper
and if the fluctuation persists for a time longer than 5 to 7 sec;
7. Limit of the automatic level adjustment; -
8. Sending out or receiving a call on any channel;
9. Sending out a call from the voice-frequency ringing device or receiving a
call from a disconnected direction, when a voice-frequency ringing device is
being used;
10. Blocking of the ARU;
? 11. Changing from automatic adjustment of the
slope of the frequency amplifi-
cation characteristic to manual adjustment.
The signaling is achieved by means of conunutator tubes mounted on the panels.
In addition, when the cases 1-7 occur, a stand signal bulb OSL, (located at the fuse
panel), will be lit, and a signal bell will ring. A spark quencher is connected in-
to the circuit of the bell, to reduce noises in the channel. Closing of ine bell
circuit takes place simultaneously with the closing of the circuits of the lig]STAT
bulbs of the corresponding transparent signs, namely: ITT' - fuses, "BAT" - battery
voltages, tiff" - mechanical inductor, 1JCCh" - control frequencies. The circuits of
the OSL bulb and of the bell are also closed in the case No.9, if a call is re-
ceived at the PVU. In all other cases, no station-wide or row signaling will occur.
The lamps of the local and of the general signaling circuit will stay lit until
the cause of the signal is removed. The bell and the transparent sign illuminators
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nab- he switched off by pushing the f'Vylc]..Zv.'' button on the signal panel. '.,}hen the
signal indicates an irregularity in the control channel, pushing this button will
only silence the bell; the illuminator of the "KCh" transparent window will. stay
lit until the irregularity is corrected.
When the bell-silencing button is depressed, a signal lamp will light above
? this button; the lamp will stay lit until the cause of the signal is removed.
The signal circuit relays and most of the signal lamps for local signaling are
located at the signal panel.
Signaling of failure of the filament voltage and of the call current is achiev-
ed by means of the relays RVT, RN, and RA; these relays drop out when the corres-
ponding voltages disappear, and their contacts close the signal circuits. When the
fuses burn out, the relay RRP is actuated. All named relays have four groups of
contacts. The contacts II-1 and 11-2 close the local signal circuits, the contacts
11-3 and II-1. close the bell circuit, the contacts IV-1 and IV-2 close the circuit
of OSL, and the contacts IV-3 and IV-, close the circuits of the transparent sign
? illuminators. In the RRP relay, the function of the group II is performed by the
group I, and the function of group IV is performed by the group V. The relay PB3 is
blocked when the button 1'Vyk.Zv." is depressed, which interrupts the circuits of the
bell and of the transparent window illuminators. rl 50-ohm resistor is connected in
series with the signal lamps of the local signal circuits; this reduces the voltage
and prolongs the life of the lamps.
Some signal relays are located on the panels of the equipment correlatPA ?^ th
STAT
their specific function, namely, on the panels of the control-frequency-receiver
and of the control-frequency indicator. Operation of these relays will be discussed
when describing these panels.
11. Speak-Buzz Device and Commutation Field
?
The end station is equipped with a speak-buzz device PVU, which is used for
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service calls and for checking the conditions of the communication channels.
For convenience and to conform with the design of other pieces of standard
long-distance communication equipment, the PVU is divided into separate panels: the
microtelephone panel, the two-wire PVU panel, the four-wire PVU panel, and the con-
trol testing device KIU which is used to test the voice-frequency ringing device.
All these panels and the commutation field (composed of separate panels with jacks)
are located in the central part of the individual-equipment stand.
The principal wiring diagram of the station shows the PVU as separate squares;
the connection of outside circuits to these squares is also shown. The principal
wiring diagram of the PVU is shown in the drawing No.P 134.60.17. Most of the com-
mutation field jacks are shown in the lower part of the station diagram; the commu-
tation field jacks that belong to the transmission or to the reception circuits are
shown in the corresponding parts of the diagram.
Each channel has the following dividing telephone jacks: the commutator-line
jacks "COMA.-LIN." located immediately after the channel input terminal and serving
? the purpose of connecting the two-wire PVU to the channel; the jack ttDTT', used for
the two-wire transit; the jack "ISP.TV.", used when the receiver TV is tested by
means of the control.
testing device; two jacks rTPERrf in the transmission circuit of
the four-wire part of the equipment and two jacks t"PRtt in the receiving circuit,
both pairs serving the purpose of connecting the four-wire PVU when a four-wire
transit connection or an external differential system is used.
The dividing jacks t"TKtt and "FK" are connected to, respectively, the vcSTAT
channel. and the photo-channel. When a broadcast channel is formed, the input is at
the contacts IIB1-IIB2 of the lead-in comb. The jacks t'UUt' are connected to the
input of the level indicator of the neper-meter; the jack t"KIUtt is connected-to the
output of the control testing device. The remaining jacks serve various other com-
mutation purposes.
A two-wire PVU permits to send a call either into the line or into the coirmu-
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tator and conduct a -conversation either in the direction of the line, or in the dir-
ection of the commutator, or in both directions simultaneously. The two-wire PVU is
also a means for controlling the conversation and for connecting the normal generator
or the level indicator to the channel. The two-wire PVU is plugged in by means of a
? double three-prong plug, inserted into the t~CO?~i.-LIIJ." jacks of the corresponding
channel.
The four-wire PW is connected to the channel by means of two cables, each
provided with two three-prong plugs. One plug is inserted into the transmission
jacks, the other into the receiving jacks of the corresponding channel.
The four-wire PW permits sending out calls in any direction, if a four-wire
transit is used. In the case of an external differential system, a voice call will
also be sent toward the commutator; leaving the differential system, the call acts
upon the PTV which then sends an inductor current to the commutator.
In the case of a four-wire PW the conversation may be conducted either separ-
ately toward the line and toward the commutator, or simultaneously in both directions.
? The four-wire FVU permits also a control of the transmission in both directions. Con-
necting the four-wire PW will disconnect the two-wire PW from the system. The
elements of the four-trire FW include an amplification stage that increases the loud-
ness and the transient damping of the PVU circuit between the oppositely-directed
transmission circuits. The four-wire PW permits connecting the normal generator to
the line transmission jack "PER" or to connect the level indicator to the line re-
ception jack ?rprr-.
0
The control testing device serves the purpose of checking the good condition
and the sensitivity of the tone-call receiver. STAT
For testing, the KIU jacks of the commutator field are connected to the
11ISP.TV." jack by means of a two-wire cable. The PTV is tested by a fixed-period
current which is sent by means of a telephone-type dialing apparatus, mounted on the
K.IU block.
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12. Measurements
The residual damping of channels may, be measured by means of the neper-meter
mounted at the individual-equipment stand. The neper-meter consists of an 800-cycle
frequency generator and of a copper-oxide level indicator.
The power source of the generator is controlled by a switch at the neper-meter
panel.
The generator can provide the following fixed levels: -1.5; -0.7; 0.0; and
+0.5 neper. The -1.5 and +0.5 neper levels are used for measurements in transmis-
sion and reception circuits of the four-wire system; the 0.0 neper level is used for
measurements in the two-wire system.
The generator output may be taken off the jack at the neper-meter panel or from
the jack at the PVU panel. Prior to using the generator, the level of its output
should be checked by means of the copper-oxide level indicator; to do so, the rotary
switch should be set to the position "REG.NG." and the zero level adjusted by means
? of the regulator.
The dial of the copper-oxide level indicator has the following ranges: -2.0 to
0.0 nepers and - 1.0 to +1.0 neper and 0 to +2.0 nepers, when the input resistance
is 600 ohms: -0.5 to +1.5 nepers and +1.5 to +2.5 nepers, when the input resistance
is 1000 ohms.
The main purpose of the copper-o..de level indicator is to measure the residual
damping of the channels. In addition, the indicator may be used for measuring the
level at other points of the equipment, where the level is not less than -2.OSTAT
nepers; this will include the station output, the output of the reception or trans-
mission amplifier, and the control-frequency voltages at the modulators. The con-
nections to the input of the level- indicator may be made across the two-wire jack
at the neper-meter panel, across the PVU, or across the "UUtt jack at the commutation
field. The level indicator can be used for measurements in the frequency range
_.
from 300 cps to 3 kc.
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The use of the never-meter and of the station level indicator is facilitated
by n:easurenent jacks provided on most chassis with tubes. These include chassis of
the reception and of the transmission amplifiers, of the RIL, UNCh, PTV, GTV, GEd,
NES, US-33, 0-50, and of the filter D-16-4.
? A portable testing instrument of the IEL type is used for measuring currents
and voltages in the equipment circuits and for testing the activity of the cathodes
of tubes.
The portable testing instrument contains an ammeter with 0.15, 0.5, and 1.0
ampere ranges and a mrailliammuneter whose range is 1.0 milliamp. In addition, the in-
strument contains variable resistors used for adjusting the filament voltage when
the cathode activity is being measured. The ammeter is used for measuring the fila-
ment current; the plate voltage is measured by means of the milliammeter.
The instruments are connected to circuits being tested by means of cables at-
tached to the instrument. The ammeter cable is provided with a three-wire plug that
can be inserted into jacks of the measuring blocks of chassis with tubes.
? The mvatiple switch of the portable testing instrument should be set to a suit-
able position, when the filament current, the plate current, and the cathode activ-
ity of the tubes are being measured. When the test-lead plug is inserted into the
measurement jack of the circuit being tested, the ammeter will be in series withr
the circuit elements. The position of the switch indicates which range of the dial
is to be read.
when the station is powered by alternating current, the portable testing in-
stru ent cannot be used for measuring filament currents. STAT
The mrilliarreter is connected to a cable ending in a two-prong plug; this is
inserted into the cne-wire jac?:s provided for the plate-current measurement and
located at the measurement blocks of chassis. The readings of the milliammeter
? should be multiplied by a factor engraved next to each plate-current jack.
:;hen the portable instrument is used in measuring the cathode activity of
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tubes, it is also connected by cables to the circuit being tested. In this case,
the filament of the tube is supplied by a direct current or by a rectified current
across an auxiliary circuit consisting of: the additional contact of the measure-
ment jack, the sleeve of the jack, the body of the three-wire plug, the filament
? rheostat of the testing instrument, the ammeter, the neck of the plug, and the fila-
ment of the tube. It is possible to adjust the filament current while observing the
changes in the plate current. A more detailed discussion of the cathode-activity
measurements is given in the description of the portable testing instrument.
Filament voltages, plate voltages, and AC voltages may also be measured by
means of the portable-instrument.
In making these measurements, the milliammeter is connected to suitable jacks
at the signal panel. The milliammeter reads tt0.5tt when the voltages being measured
are at their normal level; this is achieved by suitably shunting the jacks and by
use of additional resistors in the circuit being measured. When the voltage devia-
tions are not greater than the allowed ?lO% of the normal value, the milliammeter
pointer should remain within the colored sector of the dial. A full-wave copper-
oxide rectifier is provided for measuring AC voltages; this rectifier receives a
21y-volt voltage from the power-pack transformer.
STAT
?
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CHAPTER III
PRINCIPAL i1IRING DLAGRAMS OF ,THE END-STATION COMPONENTS
? 1. Transmission Group Amplifier of the End Station
Note: It is forbidden to remove the tube grid while the equipment stand is switched
?
?
Principal :,Tiring diagram No.P 135.1:.1.16
The amplifier has three amplification stages. The first two are preamplifica-
tion stages and use lOZhl2S or 7Zhl2S tubes. The third (the output) stage uses
1OP12S or 712SP tubes. The filament of the output-stage tube is in series with the
parallel-connected filaments of the preamplifier tubes. A quenching resistor, lo-
cated at the measurement block of the chassis, is connected in the common filament
circuit. The plate voltage of the amplifier is delivered across a power-supply
filter, consisting of the choke Dr 2 and of the capacitor C15. The amplifier is
provided with negative feedback. The feedback voltage is tapped from the R20 resis-
tor, which is connected in the cathode circuit of the output tube and which is also
connected to the winding of the output transformer T2.
Due to this way of connecting the R20 resistor, the feedback will be influenced
by both the voltage and the current. After being taken off the R20 resistor, the
feedback voltage is distributed to all three amplification stages. The voltage en-
ters the grid of the output stage tube directly; before entering the grid of the
tube in the first preamplifier stage, this voltage passes through the voltageSTAT-
der R6-R4; prior to arriving at the grid of the tube in the second preamplifier
stage, the feedback voltage passes through the voltage divider R10-R7 and through
the capacitor C6.
The amplification may be adjusted within a 0.1p neper range by resoldering the
connection at the D1-D6 terminals of the GUS-1 block. The output resistance of the
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amplifier may be adjusted by resoldering the connections at the B1-BB terminals of
the GUS-1p block. Adjusting the output resistance will not change the amplification
of the amplifier. Both adjustments are made in the course of factory acceptance
tests and should not be made under operating conditions.
? The amplification of the ' amplifier is 11.5 nepers in absence of feedback; when
?
the output of the amplifier.
feedback is present, this figure is reduced to 6.65 ? 0.05 nepers. The character-
istic of the frequency dependence of amplification is shown in Fig.14; the amplitude
characteristic and the clarity damping at the second and thud harmonics are shown
in Fig-15.
The input and output of the amplifier are provided with jacks for circuit con-
nections. The connecting is done by means of jumpers.
The output transformer T2 has a winding connected to the terminals B6-B7 of the
comb; the control-frequency indicator IKCh may be connected to these terminals.
The filament voltage is measured at the jacks "US". The same jacks are used to
turn off the filament voltage. The jacks L1, L2, and L3 are used in measuring the
plate voltages of the tubes. The jacks "VYKH11 are used for measuring the level at
2. Reception Group Amplifier
-Principal wiring diagram No.135.41.16
The reception group amplifier does not differ from the transmission group amp-
lifier.
STAT
3. Reserve Group Amplifier
Principal wiring diagram No.131.1~1.17
In its main part, the reserve group amplifier does not differ from the trans-
mission group amplifier. The only difference is in the commutation blocks of this
amplifier; these are connected in a different way and have a greater number of
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jacks. The transmission of the reception group amplifiers may be replaced by the
reserve amplifier without interrupting the communication, by simply inserting jiunp-
ers into the stare amplifier jacks that are narked with the symbols of the amplifier
being replaced. When the reserve amplifier is connected to the circuit, the ampli-
? fier which is being replaced (and which, in this case, will be connected in parallel
with the reserve amplifier) should be disconnected.
4. Control-Frequency Receiver
Principal wiring diagram No.135.1.0.98
The control-frequency receiver is composed of two independent elements; the
control-frequency receiver for the automatic level adjustment Pr.ARU, and the re-
ceiver for slanted (manual) level adjustment PNR.
A. ARU Receiver
The ARU receiver is the controlling element of the automatic level adjustment;
? in addition, it furnishes a signal indicating that the control-frequency level of
the ARU deviates more than 0.3 - 0.5 neper.
The terminals B5-B 6 of the right-hand comb are connected to the output of the
reception group amplifier. The terminals 1-2 of the left-hand comb are connected
to the output of the 50-cycle generator. Before entering the grid of the tube L2,
the 9-icc control frequency passes through the narrow-band filter. The filter con-
sists of two oscillatory circuits, L1C1 and L2C2, both tuned to a frequency of 9 kc.
STAT
The filter is designed as a sealed unit, with two trimmer capacitors, C'1 and
C'2, attached to its cover. The curves of the relative damping of the filter are
shown in Figs.16 and 16a.
The amplified control frequency passes through the transformer T3 into a therm-
istor which, together with the resistor R/,, forms one arm of a differential system.
The second arm of this differential system consists of the divided resistors R1, R2
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and of the rheostat R3. The values of Rl, R2, and R3 are so selected that, when the
control frequency is at a normal level, the differential system is balanced with re-
spect to the 50-cycle frequency and no 50-cycle voltage is present at the winding
2-1,. of the transformer T2, which is connected to center points of the differential
? system. A change in the control-frequency level will cause the resistance of the
thermistor to change; this will destroy the balance of the differential system and,
as a result, a 50-cycle voltage will appear in the winding 2-13, of the transformer
T-2. This voltage goes to the grid of the same L2 tube, where it is amplified. The
amplified 50-cycle voltage is taken off the transformer T-4. The choke Dl reduces
the shunting effect of the differential system on the thermistor, at the control
frequency. The function of the C3 capacitor is to prevent shunting of the thermistor
by the winding 1-5 of the transformer T3, at the 50-cycle frequency. The capacitor
C1 shunts the transformer T-2 at the control frequency, so as to make the potential
of point (1) of the narrow-band filter practically equal to zero (at the control
frequency). The R4 resistor prevents burn-out of the thermistor during accidental
? surges of the control-frequency level. The tube L2 amplifies simultaneously two
frequencies: the control frequency and the 50-cycle frequency. A highly stable
amplification is required in the case of the former frequency; the amplification of
the latter frequency does not have to be very stable. Therefore, the choke D-1 is
connected in parallel with the feedback resistor R5 in the cathode circuit of L2:
at a frequency of 50 cycles, this resistor is shunted by the choke.
The plate circuit of the tube L2 contains three transformers: T-3, T-1;
T-4. The T-3 transformer supplies control frequency to the thermistor. The T-5
transformer has two functions: Its 6-10 winding supplies voltage to the copper-
oxide rectifier K1 which, after amplification, is used in a permanently connected
device serving as the control-frequency level indicator; the winding 7-9 (for the
? case of the end station B) supplies a control-frequency voltage, to be used for the
synchronization of carrier frequencies. After being amplified by the tube L2, the
36
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50-cycle voltage goes through the transformer T-4 to the grid of the tube L3. By
means of a circuit composed of resistors R-10, R-11 and capacitors C8, C9, the phase
of this voltage is shifted by 90? with respect to the phase of the 50-cycle voltage
which the motor receives directly from the generator of 50-cycle current. The
? transformer T-4 is shunted by the capacitor C7, which is a control-frequency bypass.
Since the power delivered by L2 is not sufficient to operate the motor, a second
amplification stage (using a tube of the 1OP12S or 7P12S type) is provided.
From the A3-A4 output terminals of the ARU-6 block, the 50-cycle voltage goes
through the contacts 111-3 - III-4 of the relay R1 to the terminals 3-4'of the in-
put comb of the chassis; these are connected to one pair of the windings of the
motor.
Operation of the ARU system is controlled by means of the relays R1 and R2. The
relay R2 is connected in parallel with the output terminals A3-A4, through a copper-
o:d.de rectifier Y,2. The relay R1 is actuated by contacts III-1 and 111-2 of the
relay R2. The actuating voltage of the relay R2 is higher than the initial oper-
ating voltage which the motor receives from the terminals A3-A4. Smooth changes in
level will not actuate the relay R2 since, in this case, the level is quickly
brought back to normal by the action of the motor. If, however, the level changes
sharply by more than 0.3 - 0.5 neper, fora time longer than 5 - 7 sec, the action
of the.motor is too slow to return the level to normal and the relay R2 is actuated.
Level Jumps lasting less than 5 - 7 sec are too short to change the resistance of
?
the thermistor; the balance of the differential system remains practically undis-
STAT
turbed and the relay R2 is not actuated. The relay R2 will be actuated if the con-
nection is`interrupted because of faulty operation of the line or of the equipment,
in which case the control frequency is absent: if the damping of the line changes
abruptly, as is the case when, for instance, ice breaks off the line conductors; or-
if the mechanical components of the ARU fail to operate properly. In all these
cases, the relay R2 actuates the relay R1, which then executes the following switch-
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ings: The contacts 111-3 and 111-4 disconnect the winding of the motor to prevent
occurrence of a pseudo-adjustment; the contacts 111-4 and 111-5 connect the output
of the amplifier to the resistor R-19 which is equivalent to the resistance of the
motor windings; the contacts 1-1 and 1-2 connect a DC voltage to the disconnected
? motor winding, to brake the motor; the contacts V-3 and V-4 close the circuit of a
signal lamp on the control panel of the chassis; the contacts V-1 and V-2, III-1
and 111-2, 1-3 and 1-4 then close the circuits of the station-wide signal system.
The HI42 pushbutton is a means for blocking the ARU system. 'When depressed, this
button actuates the relay R1, which then breaks the motor circuit, disconnects the
circuits of the stand-wide signal system, and lights the signal lamp on the control
panel of the chassis.
A test instrument that has the function of a control-frequency level indicator
may be used for adjusting the differential system during the initial installation of
the equipment and for the periodic checkup, in which case the instrument is connec-
ted to the output of the amplifier in series with the winding of the relay R2; this
connection is made by depressing the pushbutton 131-1. ::Then so connected, the in-
strument will indicate the presence of the 50-cycle voltage at the output of the
amplifier; the differential system is then balanced by resoldering the connections
on the resistors R1 and R2 and by adjusting the rheostat R3 until a nmum un instru-
ment reading is obtained. The sensitivity of the ARU receiver is adjusted by re-
soldering the connections at the windings of the transformer T-7.
B. NRU Receiver
The receiver for the slant level adjustment has the following elements: a
15-kc narrow-band filter, an amplification stage, a copper-oxide rectifier, and a
milliammeter. The filter is connected across the transformer T3; the winding taps
of this transformer are used for adjusting the sensitivity of the circuit during the
initial installation of the equipment. When the control frequencies are at a normal
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level, the pointer of the instrument is at the center of its scale, within the limits
of the colored sector. A deflection of the pointer beyond the limits of this sector
indicates a skew in the amplification curve of the group section of the circuit. In
this case, an additional manual adjustment is required. No signaling is provided for
? this instance since, apparently, a skew of the curve is rare so that this phenomenon
cannot be considered an emergency condition of the connection.
5. Regulatin ; Artificial Line RIL
Principal wiring diagram No.P 134.20.40
The three main components mounted to the RIL chassis are: the artificial line
for slanted adjustment, the artificial line for flat adjustment, and the buffer and
amplifier stage DUI-',. The artificial line for slanted adjustment consists of six
artificial line links, RIL-1 through RIL-6, connected to the reception circuit across
the transformer TIL.
The output ends of the individual RIL links are provided with voltage dividers,
? through which these links are connected to 0.60 stator sections of the slanted adj-
ustment capacitor; the output of the last link is directly connected to the capa-
citor section 60. From the output end, the characteristic resistance RIL links is-
equal to 2400 ohms. This resistance is matched to the resistance of the preceeding
circuit element by means of the input transformer TIL.
The rotor of the slanted-adjustment capacitor is connected to the input of the
flat-adjustment artificial line IUD (a capacitor divider). This artificial ]in,- is
STAT
assembled of capacitor links. Each link is connected to stator sections 0.60 of the
flat-adjustment capacitor. The rotor of this capacitor is connected to the grid of
the tube L1 of the buffer and amplifies stage. Structurally, both adjustment capa-
citors and the motor are components of a single unit: the motor-capacitor block.
The motor' capacitor block is connected to the circuit by means of two 16-contact
? strips. The capacitor rotors are connected to the circuit by inserting banana plugs
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?
into the proper jacks.
Thus, if necessary, the block may be removed from the chassis for repair, in
spection, or testing.
The spare-parts set of the equipment contains two shielded cables with connected
transition capacitors. When the motor-capacitor block is removed, the channel con-
nections may be sustained by connecting the 16-contact strips to the corresponding
jacks of the K1) and the BUK-1 blocks by means of these cables; only the automatic
adjustment facilities will be inoperative.
As pointed out on a previous occasion, during the normal operation of the ARU,
the rotors of the flat-adjustment capacitor and of the slanted-adjustment capacitor
are rotated by means of a motor. They may, however, be rotated manually, by means
of two cranks at the face of the chassis, marked "Plosk.Reg."" and "Nakl.Reg.rf.
The dials of the two capacitors are also located on the face of the chassis.
Each dial has seven main divisions, marked 0, 10, 20, 30, 40, 50, and 60. Each main
division is subdivided into five parts. The rain divisions indicate the rotor posi-
tion with respect to the stator sections. The subdivisions show the position of the
?
rotor when it meshes with the two stator sections. The scales are read against the
index line marked on the glass window. The position of the rotor of the flat-
adjustment capacitor is read off the outer scale, and that of the flat-adjustment
capacitor rotor is read off the inner scale. Setting 60 on the flat-adjustment
scale corresponds to minimum damping of the RIL or to maximum station amplification;
setting 60 on the slanted-adjustment scale corresponds to maximum slope of tSTAT
damping curve of the RIL. Normally, whether rotated by motor or by hand, both rotors
rotate simultaneously. They may, however, be uncoupled; to do so, the upper knob
UPloslc.Reg.tf should be pulled toward the operator. In this case, the contact group'
V of the capacitor is shorted, and the signal lamp "Pred.Reg.Tt will light.
As mentioned above, the additional manual adjustment is required during the in-
itial installation of the equipment and during the winter period, when the character-
4.0
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istics of changes in the line damping differ considerably from the average charact-
eristic, and when a skew appears in the amplification curve of the group circuit. In
such a case, it may happen that when the pointer of the ARU instrument (the left-hand
instrument on the panel of the control-frequency receivers) is within the limits of
? the colored sector of its scale, the pointer of the slanted-adjustment receiver (the
right-hand instrument) is out of the colored sector of its scale; this indicates that
the skew of the control-frequency amplification is greater than 0.1 neper. To cor-
rect the situation, the ARU is blocked by depressing the button on the panel of the
control-frequency receivers, and the flat-adjustment regulator is set so that the
pointer of the slanted-adjustment instrument returns to the center of the scale.
This, as a rule, will cause the automatic-adjustment pointer to move beyond the lim-
its of the colored sector of its scale. The pointer is brought back to the neutral
position by means of the slanted-adjustment regulator; after this, the ARU must be
de-blocked. ;then either of the two rotors is in its extreme end position, a signal
is emitted, and the motor is disconnected by means of the contacts of groups I, II,
0 III, or IV.
?
The switch-over of the contacts occurs when the sprint (2) of one of the above
contact groups is depressed b:r one of two cams located on the large drive gear of the
capacitor. The contacts 1-2 break the circuit of the pilot light that signals block-
ing of the ARU [on the panel of KCh (control-frequency) receivers] and close the
contacts 2-3-4. The contacts 2-3 close the circuit of the "TPRED.REG.it (limit of the
adjustment) pilot light; the contacts 2-1~ close the circuit of the relay Rl on the
control-frequencies receiver panel. ;Alien actuated, this relay stops the motorSTAT
connects the station-wide signal system. The station-wide signal may be switched
off by depressing the "BLOKIR" button on the control-frequency receiver panel.
During the autoratic level adjustment, the rotors of the capacitors rotate very
slowly. :1 rotor will move from one extreme position to the other in 20 min. This
will change the damping of the RIL at a.rate of about 0.002 neper per second in the
41
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direction A-B, and at a rate of about 0.001 neper per second in the direction B-A;
both given rates are for the middle frequency of the respective directions. The
buffer and amplifier stage is a single-tube amplifier with a high ohmic input resis-
tance. Besides its main function - that of matching the high-impedance circuit of
? the flat regulator to the low-impedance input circuit of the group amplifier - the
BUK serves also the purpose of smoothing the amplitude distortions caused by the line
and by the directional filters. When transmission takes place in the A-B direction,
these distortions occur in the 6.3 - 15.0 kc frequency range; during transmission in
the B-A direction, the distortions are in the 18.0 - 26.7 kc frequency range. The
?
distortions are corrected by means of the inductances L1 and L2 and their respective-
capacitors, which are a part of the feedback circuit of the BUK tube. The LC cir-
cuits are connected across the autotransformers Drl and Dr2. The CL1 circuit cor-
rects distortions in the 6.3 - 10 kc range, that are due to the filter pair K-5.7;
the CL2 circuit corrects distortions in the 10 - 15 kc range, due to the filter pair
D-16.1.. ;-then its capacitor is replaced by a smaller one, the same circuit is used
for correcting distortions in the 18 - 26.7 kc range, due to the filter pair K-16.4.
Parts of the R7, R8, R9, and R10 resistors of the feedback circuit of the amplifier
are shunted by these LC circuits, which creates a frequency dependence of the ampli-
fication of the amplifier. The elements of the LC--circuits are so selected, that the
resulting frequency dependence of the amplification corresponds to the frequency de-
pendence of the damping of the filters.
The correction is set by proper insertion of jumpers between the BUK-2 term-
STAT
The circuit is provided with facilities for changing both the depth of correc-
tion and he slope of the correcting curve.
In the range 6.3 - 10 kc, the necessary steepness of the curve is obtained by
installing a jumper between the terminal 12 and one of the terminals of the row
F2-E6; the maximum steepness of the curve is obtained when the terminals 12 and E6
1.2
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 are connected by a jumper.
Correspondingly, the depth of correction is selected by placing a jumper between
a terminal of the row E and one of the terminals of rows D and G.'
The max.mum depth of correction is obtained when the jumper is connected to the
Dl terminal.
The correction in the frequency range 10 - 15 kc is adjusted in a similar fash-
ion. In this case terminals of rows B and V, and of rows V and D-G are connected by
jumpers; the former two rows are used in adjusting the steepness of correction, the
latter in adjusting the correction depth. The terminals Al and A2 should be shorted.
To apply corrections in the lower part of the 18 - 26.7 kc frequency range, the
jumper between the terminals Al and A2 is removed. To apply correction in the range
of 23 - 26.7 kc, the jumpers should be inserted between the terminal 12 and one of
the row E terminals, and between the terminals of rows E and D, or E and G (depending
on the required correction depth). No jumper is inserted between K2 and K3. Figure
17 shows correction curves obtained with various relative juniper positions.
1Jhen transmission is in the A-B direction, the amplification of BUK is greater
titan when transmitting in the B-A direction; this is achieved by disconnecting the
R5 resistor at the BUK-1 block:.
6. Carrier-Frequency Generator
Principal wiring diagram No.135.80.25
The following components are mounted to the carrier-frequency generator c''^ -
? STAT
sis: the quartz raster oscillator, the carrier-frequency generator, the band filters
GF-6, GF-9, GF-12, and GF-15, and the control-frequency amplifiers SK-l and SK-2.
The Quartz Laster Oscillator
The tube of the quartz master oscillator (KG) can work either as a generator or
an amplifier. The desired operating; regime is selected by inserting three jumpers
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into the non or into "US's jacks. When the jumpers are in the "GEN" jacks, the
circuit operates as a generator. In this case, the electrode (2) of the quartz
resonator KG is connected to the screen-grid of the tube, while the electrode (4-)?is
connected to the control-grid of the tube, and the electrodes (6,8) to the cathode
? circuit of the tube. The quartz resonator oscillates at 9-kc frequency and is-con-
tained in a glass bulb with an octal base numbered 2. 4o 6. and 80 corresponding to
the numbers of the base pins. The temperature coefficient of the quartz resonator
frequency is 1 x 10-5 per 1?C.
The 9-kc voltage is taken off the secondary winding of the L1, C5 tuned circuit.
The magnitude of this voltage is regulated by changing the value of the resis-
tance R6, which has several taps for this purpose.
When the jumpers are in the ""US"" position, the tube operates as an amplifier.
In this case, the quartz resonator is disconnected from the circuit. The amplifier
input is connected to the winding of the transformer T5 of the control-frequency re-
ceiver ARU. In addition, the resonant frequency of the tuned circuit in the plate
circuit of the tube is adjusted to 9 kc by connecting the capacitance C9. When the
stage operates as a generator, this circuit is tuned to a frequency somewhat higher
than 9 kc, to improve the excitation conditions. From the ARU receiver, the 9-kc -
frequency goes to the terminals B7-B8 of the input comb of the chassis. Since the
filter of the ARU receiver does not completely remove the side frequencies, an addi-
tional filter circuit L2C10C1 is provided at the input of the synchronization amp-
lifier. The voltage at the amplifier output is adjusted by reconnecting the taps of__
the R6 resistor.
Carrier-Frequency Generator
The operating regime of the carrier-frequency generator is so selected that its-
short pulses. The cutoff angle of these pulses is approximately 350; this is
144
STAT
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0 tube works with a large cutoff, so that the plate current appears as a series of
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achieved b,-- so selecting the components of the grid-leak that a large coupling factor
and, correspondingly, a large negative bias value is obtained. When the generator
operates under such conditions, the second to fifth harmonics of its fundamental fre-
quencyr are powerful enough to be supplied directl, ? to individual modulators. The
? fundamental frequency of the generator is 3 kc.
?
The frequenc- of the generator is accuratel,- pre-set at the factory, by means of
the capacitor C5- C7. The resistor R2, in parallel with the circuit, determines the
extent to which the frequency of the generator is covered by the master frequency.
The s--nclhronization is done by r:eans of the 9-1-c frequency., which is the t}iird har-.'
nonic of the fundamental frequenc;, of the generator. All carrier frequencies are
taken off the generator by the prirraryr of the transformer Tl. The primary is shunted
b:- the L1C~? circuit, which is tuned to the fundamental frequency of the generator,
-.e., to 3 1:c. The output lrindirg of the transformer Tl is :aired to the terminals
32-B3. Yrlei c:. are connecter: tc the band filters GF-6, GF-;, GF-12, and GF-15, through
which the channel rorlulators and the control-frequency stabilizers are supplied. The
the
second output .,iinrlin- of the transformer is connected to t};e terminals R -B5 of
left-r.anr' cor.b, to 1,',ich the 33-.:c filter and arplifier are connected.
T'e Carrier-Frequent;- FilteD:,
The carrier-frequent;- fil.ter.s are rlesig;r.eri with a characteristic resistance of
5C c'::.~s, which is a ~prori; el-- equal to the input resistance of two parallel-
connecte' channel o:tlator:,, fro.: .here the carrier-frequent-, is supplied. The
cus?,res cf these filters are plotto''? in Figs.lf; and 11). The resistors R2 in
e fit tors cF-;, serve the purpose of rp enc}hing the power surplus.
T e to , e" res s',r:rs a^,1 are hhserl in a lusting the control-frequency voltage on the
channel. ;-cAulat-,ors to a required value. The R3 resistor in the GF-6 filter is con--
? noc',c ' the filter co F,pu!, 1,, -,cans of a 'rripor inserted between thee tern finals
? i,},i , res- %t.~ r .'c r?lacc,s t, e dihannel :,orl,uaators, wrier the equip. ent is operating
STAT
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in the supplementary frequency spectrum. The resistor R3 of the GF-15 filter serves
the same purpose when operating in the main frequency spectrum.
The circuits that supply carrier-frequency to each of the channels are also
connected to the corresponding t?NEStt jacks at the test block. To control the level
? of the carrier frequency, a level indicator may be connected to these jacks. If
necessary, the carrier frequency of any channel can be removed by shorting its "ANES"
jacks with,a jumper. Usually, this is required only when the modulators are to be
balanced: The balancing process is rather difficult when all three carrier frequen-
cies are present at the station output.
The Control-Freauency Stabilizers
These components are serving the purpose of stabilizing the level of the control
frequencies. The voltage is stabilized by means of a thermistor connected in series
with the resistor R1. The thermistor-stabilized voltage goes through the extender
? R2, R3, R, to the terminals B1-B2 of the left-hand comb on the panel. The magnitude
of the stabilized voltage can be adjusted by changing the value of the resistor R4.
Jacks at the GP; block make it possible to disconnect one or both control frequencies,
by altering the position of the jumpers. Disconnecting one of the frequencies is
often necessary when the level of the other control frequency is being adjusted.
The input resistance of the stabilizers (from the end of the output terminals
B1-B2) is 4000 ohms so that the damping of the circuit rerains practically unchanged
when the stabilizers are connected.
7. The 33-Kilocycle Amplifier
STAT
Principal wiring diagram No.P 135.40.73
The 33-kc amplifier chassis contains both the 33-1:c amplifier and the band fil-
ter GF-33?
The filter GF-33 will pass the eleventh harmonic of the basic frequency of the
46
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carrier-frequency generator but has a high damping at the frequency of adjacent har-
monics. The damping curve of the filter is plotted in Fig.20. The input resistance
of the filter at the 33-kc frequency is low (about 20 ohms), and therefore this fil-
ter is hatched to the output of the carrier-frequency generator by means of the
transformer T whose winding consists of only a few turns. The filter voltage is not
? taken off the load resistance but is tapped from the induction coil L1,, which is a-
part of the last link of the filter.
This voltage is conducted to the grid of the amplifier tube, type lOZhl2S. To
obtain the required magnitude of the 33-kc voltage at the output of the amplifier,
the amplification of the latter is adjusted by means of the feedback resistor R5.
8. The Group Modulator
Principal wiring diagram No.136.20.25
The group-modulator chassis contains elements necessary for converting the lower
frequency group into the higher frequency group and vice versa, depending on whether
? the chassis is connected to, respectively, the transmitting or the receiving cir-
cuit; in addition, the chassis carries blocks that contain a transformer for the
control-frequency feed and a transformer, connected to the output of the band filters
of the reception circuit and also a single-stage amplifier.
:-Then the station operation is changed from regime A to regime B, the group con-
verter should be disconnected from the reception circuit and connected to the trans-
mission circuit; this is done by resoldering the connections at the terminals of the
STAT
lead-in comb. The diagram shows connections of the end station, operating in regime
B, i.e., the 6.3 - 15 kc frequencies are converted to 18 - 26.7 kc frequencies. In
?
this case, filter PF-18-27 is connected after the modulator.
To connect the group converter to the reception circuit of the station A. the-
jumpers should be removed from the terminals G3-V3, G1-V),, G5-V5, G6-V6, G7-V7,
G8-Vg; jumpers should be placed between the terminals B1-V1, B2-V21 B3-V3, B~17V ,-
L~77
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terminals A3-B3, and its output toward the transmission line is wired to the termin-
als A -D3 . The balance of the differential system is connected to the terminals
1 1
D -D of the DS block. The balance is composed of the resistance R = 600 ohms; the
3 1,
rallel or sep-
arately; C3 = l? f, C1, = 0.5 ?f which may be connected either in pa
the capacitors C5 = 0.011.L f, C6 = 0.02?f connected in parallel to the
?
600-ohm resistor. The balance is connected to the differential systems by means of
jumpers between A6 and D4 , and between Al and D3. The capacitors are connected or
? disconnected by changing the positions of the jumpers at the block terminals.
An external balance nay be connected by means of the terminals D3-D1,. of the
differential system, that are wired to the terminals A7-B7 of the comb of the chas-
sis, vouch are connected to the pees of the terminal block of the stand. From the
commutator side, two capacitors, C3 and Ci each having a capacitance of 1? f, are
-
connected in series to the differential system. These capacitors prevent the call-
relay from being shunted by the differential system. In the transmission circuit,
the U extender is followed by a matching transformer TRF whose function is to match
1
the 300-ohm circuit of the middle point of the differential system to the 600-ohm
?
circuit of the transmitting system. The transformer is wound on a toroidal core;
t citors this transformer acts as a high-
8 and C7, C71 C7 capa ,
frequency filter, whose cutoff frequency is 150 cycles. At 50 cps, the damping of
freq ,I
this filter is about 1;. nepers. The filter protects the transmission circuits from
the inductor call current. Extender sets of 0.1, 0.2, and 0.3 neper are provided in
the transmission and reception circuits of the differential system.
The characteristics of the differential system are plotted in Figs.23 STAT,4?
Curve 1 in Fig.23 shows the frequency characteristic of the working damping of the
differential system, measured in the direction of reception between the terminals
T )-D and Dl-D2.1 when the terminals Al-B1 and A7-B7 are connected to a 600-ohm load
5 6
resistance. Curve 2 in Fig.23 shows the frequency dependence of the active damping
? of the differential system, in the direction of transmission from the terminals
'+9
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D1-D2 to the terminals E5-E6 of the DS-1 block, when the terminals A5-B5 and A7-B7
are connected to a 600-ohm load. Figure 21 shows curves for the frequency dependence
of the detuning dapping. Curve 1 represents the case when the reception is directed
from the terminals A5-B5, when the terminals A3-B3 and Al-Bl are connected to a
? 600-ohm load; curve 2 represents the case when the transmission is directed from the
terminals A3-B3, when the terminals Al Bl, A5-B5 are connected to a 600-ohm load. In
both cases, the balance side of the differential system (A7-B7) is connected to a
600-ohm load.
The Low-Frequency Amplifier
The low-frequency amplifier has only one stage and uses a lOZhl2S type tube.
The input of the amplifier is connected to B1 and B21 while the output is connected
to the terminals B5-B6 of the left-hand lead-in comb. The amplification is equal to
3.5 ? 0.05 nepers at 800 cps. The amplification at other frequencies of the fre-
quency range of the amplifier does not differ from that at 800 cps by more than
? + 0.05 neper.
Besides its rr.in function, the low-frequency amplifier serves the purpose of
smoothing the voice frequency used for correcting the curve of the residual damping
of the channel in the low voice-frequency range of 300 - 800 cycles and in the high
voice-frequency range of 2000 - 2700 cycles.
The correction is achieved by means of resonant circuits connected in parallel
?
to the resistor in the feedback circuit of the tube.
STAT
The low-frequency range is corrected by means of the circuit consisting of the
inductance L1, the capacitance Cl, and the resistance R4; the high-frequency range
is corrected by a circuit consisting of L2, C2, and R2.
The correction circuit permits changing both the depth of correction and the
O
shape of the correcting curve. The slope of the curve is changed by means of resis-
tors connected in series to the circuit (RR - for the lower frequencies, R2 - for
50
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the higher frequencies); a minimum steepness of the curve is obtained when the full
value of the resistor is used. The steepness is changed by inserting jumpers be-
tween the terminals of rows A2 to A5 (for the lower frequencies) and between the
terminals 12 to 15 (for the upper frequencies).
The depth of correction is adjusted by suitable insertion of jumpers between
? one of terminals of the rows D2-D6 and G -G6., and the terminals V -V (for lower
2 2 5
frequencies) or E2-E5 (for upper frequencies). Figure 25 shows the correcting curves
that correspond to different jumper positions.
A smooth amplification regulator is connected at the input of the amplifidr; by
means of this regulator, the amplification can be adjusted within a 0.4-neper limit.
The A9-B9 terminals of the chassis are connected to the terminals of the lead-
in comb of the stand, to facilitate connection of an external amplification regula-
tor. ;,'lien this regulator is connected, the jumpers between the E2-E3 and E1,-E5
terminals of the UNCIi block should be removed and inserted between the terminals
E1-E2 and E5-E6 of the same block.
? The amplitude characteristics of the UNCh, plotted as functions of the input
level, are shovm in Fig.26.
The filament of the UNCh tube is connected in series with the filament of the
tone-call receiver tube of a given channel.
10. The Modulator
Principal wiring diagram No.136.20.23
The foll.owin- elements are mounted on the modulator chassis: the limiter, the
Modulator, the equalizer, the band filter, and, in the case of a second-channel mod-
ulator, the band-filter transformer.
To accurately adjust the side-frequency level at the output of the station,` the
damping of the extender connected to the input of the modulator may be varied within
? the limits of 0.1 to 0.6 neper, by resoldering its connections.
51
STAT
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The modulator M is made of copper-oxide elements-, connected in a ring. The
?
potentiometer R2, connected at the output side of the modulator, is used in balancing
the carrier-frequency during factory calibration or, under field conditions, when
the copper-oxide elements have to be replaced. Although the modulator is assembled
from copper-oxide elements that are as uniform as possible, it is always necessary
to additionally balance the carrier by means of the potentiometer R2; this prevents
the ARU from being influenced by the remainder of the unbalanced carrier frequency
in the second channel. The level indicator of the neper-meter may be used in balan-
cing. The level indicator is connected to the output of the group amplifier, and
the balancing is done by adjusting the potentiometer until a minimum level reading
is obtained; the control frequencies should be connected during the balancing pro-
cess.
When the potentiometer is set to minimum, the level of the residual carrier fre-
quency at the output of the group amplifier should be not greater than -1.5 neper.
The carrier-frequency voltage at the terminals A3-A1, of the modulator is adjusted to
? 0.45 - 0.65 volts; the corresponding level should be -0.55 to +0.15 neper.
?
The extender R1, connected between the modulator and the equalizer, improves
the performance of the modulator.
The damping curve of the band filters is plotted in Fig.27. Distortions caused
by filters in the marginal frequencies of their bands, are partly compensated by
means of equalizers provided for that purpose. The characteristic of these equal-
izers is also shown in Fig.27.
An extender that is part of the equalizer permits to vary the correction depth
within a 0.01-neper range. This is done by changing the position of the jumpers at
the terminals of the equalizer blocks.
The distortions, caused by filters, are further compensated in the low-
frequency amplifier.
52 STAT
3(1
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cathode circuit of that tube.
The capacitor C6-C10 set is used when the 20-cycle frequency is'being adjusted
at the factory. The taps E6-E4 of the feedback winding are used for adjusting the
amount of feedback, which is also done at the factory. The grid of the tube L2 re-
ceives the fundamental-frequency voltage from the secondary of the transformer T2,
which is connected in series with the 20-cycle oscillatory circuit. The generator
regime of, the tube L2 is so selected that the pulses of its plate current have a 90?
cutoff; the tube is open during one half-period of the 20-cycle frequency and is
closed during the second half-period.,
Thus, during; the first half-period of the 20-cycle oscillation, the fundamental
frequency will be amplified by the tube; no fundamental frequency will be present at
the output of the GTV during the second half-period.
As a result, the fundamental-frequency voltage at the output terminals 5-6 and
2-2 of the generator is modulated by the 20-cycle frequency. When a fundamental
frequency of 500 cps rather than of 1000 cps is used, the capacitor C15 should be
connected parallel to C16, which is in parallel with the winding of the output trans-
former T3-
The GTV has two outputs: a working output and a testing output. The power,
available at the working output (terminals 5-6) is tapped across resistors located
on the PTV chassis and is used to send the call through the channels. The test out-
put (terminals 1-2) is connected to the control-testing system KIU.
The potentiometer R8 in the working output circuit is the means for adjusting
the output level. The resistance of the Rs is low, which assures constancy of the
output level in cases when the call is to be sent through several channels simultan-
eously. Even in the case when the call is sent through l6 channels at a time, the
level does not drop-more than 0.1 neper (as compared to the output level of a gener-
ator with no load).
Both the tubes L1 and L2 are of the lOZhl2S or of the 7Zhl2S type. In contrast
STAT
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 with the arranrzement in other chassis, the ballast tube used with 7Zh12S tubes is
mounted right on the chassis. This is necessary because of the possibility that the
GTV chassis may sometimes be mounted at the TV stand. Figure 29 plots the generator
output level as a function of the supply voltages and of the load. When the voltages
and load vary within the technical specification limits, the frequency of the gener-
ator remains practically constant.
13. -The Voice-Frequency Ringing Receiver
Principal wiring diagram No.P 135.40.81
The elements mounted to the voice-frequency ringing receiver chassis are: the
receiver itself; the differential system for connecting the receiver; a series of
relays that are part of the voice-frequency ringing circuit.
The receiver is connected to the two-wire circuit of a channel by means of a
differential system, consisting of two resistors R1 and R2, both having a resistance
of 10 ohms, and a transformer TDS.
The terminals A10-B10 of the lead-in comb of the chassis are connected to the
channel toward the commutator end; the terminals A3-B3 are connected to the channel
toward the differential-system end;
Connecting the PTV to a channel does not increase the damping of the latter by
more than 0.03 neper. Damping of the differential device through which the receiver
is connected to a channel varies as a function of the direction of the received sig-
nal; signals received from the commutator end are damped 2.5 nepers more than those
received from the differential-system end. When a two-wire transit is used, thSTAT
situation makes it impossible to use the receiver at the transmitting station: The
call would not pass through the receiver. From the terminals A3-B3 of the lead-in
comb, voice-frequency signals go to the TDS and through its windings 4-2 and 7-9 -
to the primary winding of the transformer T1 of the receiver. When the call is sent.-
by means of a DC current, the possibility of the calling relay being shunted by the
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windings of the TDS and of the transformer Ti is prevented by the capacitor Cl. con-
nected in series to the winding of the transformer T1. The plate circuit of the re-
ceiver tube contains a resonant circuit, tuned to the fundamental frequency. The
tuning may be changed from 500 cps to 1000 cps by disconnecting the winding II; to
? prevent changing of the sensitivity of the receiver, the jumper between the terminals
D2-A3 should be removed and placed between the terminals D3-A3'
The amplified fundamental frequency (modulated by 20 cps) goes to the copper-
oxide rectifier KM-1, where it is rectified. After rectification, the 20-cycle cur-
rent passes through the transformer T2, through the resonant circuits C8-C11,
C3-C12C14? (tuned to 20 cps), and into the copper-oxide rectifier KM-2, which is con-
nected in parallel to the capacitors C12C14. From here, the rectified current passes
into the winding of the relay R6. In the circuit of the first rectifier KM-1, the
R7 resistor (shunted by the C6 capacitor) is connected in series with the primary
winding of the transformer T2. The constant component of the current flowing in the
circuit of KM-1 creates a voltage drop across R7. The magnitude of this voltage de-
0 pends on the strength of the call signal. This voltage shifts the working point of
the copper-oxide rectifier K2?1--2, thus limiting the rectified current that passes
through the winding of the relay R6; such an arrangement permits keeping the required
constant selectivity even during a considerable level fluctuation at the output of
the receiver.
The sensitivity of the receiver is increased by using the telegraph relay R6,
of the RP-5 type, whose actuating current is 0.2 ma. The sensitivity of the receiver
STAT
can be adjusted by varying the resistance of the feedback circuit; this is done oy
resoldering the connections between the terminals of the PTV-1 block. Maximum sen-
sitivity is obtained when the-terminals G5-G6 and G1-G2-G4 are connected; in this
position, the receiver will normally operate with the output level between -2.8
? and -1.8 nepers.
When A2-G6, Al-G1, and G2-G3 are connected, the operating range of the receiver
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will be -2.2 to -0.5 nepers. This is a norn.l position. If the level at the point-
at which the receiver is connected is -1.1 neper with respect to the modulated cur-
rent, a 1.1-neper sensitivity :arrin will be assured. l'inimum sensitivity is ob-
tained by connecting the terminals A2-G6 and A1-Gl. In this position, the operating
0 range of the receiver is -1.1 to 0 nepers.
The second capacitor CL in the plate circuit of the tube, the capacitor set
-C111 the capaci~or set C12-C11.,, and the taps of the choke T3 are used in tuning
the receiver at t e factory. The curves in Pig-30 show the current in the winding
of the relay R6 as a function of the fundamental frequent:; and of the modulating
frequency. The curves in Fig-31 show the dependence of the relay R6 current on the
level received from the terminals A3-B3 or from the terminals A10-B10, when the ter-
minals A3-B3 are connected to a 600-ohr J.oad resistance. The levels listed above
and those found in Fig.29, are compiled relative to the modulated current (0.7 neper
below the nonmodulated current).
The relays operate as follows: 'then a call signal is received, the R6 relay is
? actuated; its contacts short-circuit the winding of the relay R1., which then drops
out, opening its contacts III-1 - 111-2 that had been short-circuiting the winding
of the relay R3. When the relay R3 is actuated in this fashion, the contacts III-1
and 111-2 close the circuit actuating the relay R5; the contacts 1-1 and, 1-2 of the
latter connect RB = 60C oi.m into the differential system, while the contacts
I4, - 1-5 and V-4 - V-5(across the resistors R12 and R13) send a mechanical-inductor
or a DC voltage to the commutator. In addition, the contacts V-1 - 11-2 of the relay
R5 close the circuit of the pilot light "TPR"", located at the signal chassis. when a
call toward the commutator is rrade by means of the mechanical inductor, the call
voltage is connected to the terminals B1-B2; a DC call voltage will be connected to
the terminals B1-Bc,1.
?
The relays R3 and R1, drop out, with a 400 - 450 cosec delay. Therefore, these
relays will not be actuated by a pseudo-call of a duration less than 100 - 450 msec.
57
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In addition, this arrangement permits sustaining the duration of the call.
When a call is received from the commutator end, the relay R2 (connected to the
circuit across the choke DR3 and the copper-oxide rectifier KN--3) is actuated. If
calls are made by means of direct current, the GI--3 rectifier should be disconnected
? by placing jumpers between the terminals Al-A3, A2-A1P of the metering block. The
contacts III-1. 111-2 of the relay R2 close the circuit of the winding of the relay
Rl. When actuated in this fashion, the relay R1 (by closing its contacts I-2, 1-3
and V-2 - V-3) will connect the voice-frequency ringing generator to the differential
system; the contacts 111-3 - III-4 will short-circuit the input of the tone-call re-
ceiver to prevent reception of a pseudo-call; and, finally, the contacts III-1,
111-2 will close the circuit of the pilot light "POSft at the signal panel.
Direct current may be used to send and to receive calls (with grounding) in the
direction of the commutator. Either a two-wire (one wire for sending the call, the
other' for receiving), or a one-wire connection may be used. /
For this purpose, the contacts of the relays R2 and R5 are connected to the
? terminals A2 and B6 of the chassis and then to the pegs IIIB9 and IIIB10 of the
lead-in comb of the stand.
When a two-wire connection is used, the wire through which the call is sent
from the commutator is connected to IIIB-9, the other wire is connected to IIIB-10.
When a call is received from the commutator, the terminal A2 of the chassis be-
comes grounded, and the relay R2 is actuated and sends the call along the previously
described path.
When a call is received from the line, the R5 relay is actuated (by the process-
described above) and its contacts 111-2, 111-3 connect the ground to the commutator.
In the case of a one-wire connection, the call current arrives at the peg
IIIB10 of the lead-in comb of the stand, then goes to the terminal B6 of the PTV
? chassis, to the contacts III-22 III-1 of the relay R5, and finally, across the ter-
minals B3 and A2, to the relay R1.
58 STAT
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A call, received from the line, follows the same path as in the case of a two-
L14.. The Limiter
? The limiter is located on the modulator chassis, and is built as a separate
block. Its cover is provided with four jacks; two are marked TG - telegraph regime
without li iter, the other two are marked TF - telephone regime with limiter. The
input of the limiter is connected to the terminals of the lead-in comb, for connec-
tion to the channel. Essentiall:-, this limiter is an artificial line, whose damping
remains constant so long as the output level is below a certain value; above this
certain value, the damping will increase with increase in level. The limitation
threshold, i.e., the level value beyond which the damping will begin to increase, is
equal to -0.7 neper, as measured at the output of the limiter. This corresponds to
+0.8 neper at the commutator terminals of the equipment.
The damping is made dependent on the level changes by connecting copper-oxide
elements in both the lateral and the transverse arms of the circuit. Across the
resistors Ro and R5, these elements receive a constant bias from the B-battery. The
elements in the transverse arm receive a negative bias, the elements of the lateral
arm receive a positive bias. at low levels, tie copper-oxide elements of the para-
llel arm offer a large resistance to the passage of speech currents, while the re-
sistance of the series arm is low, resulting in a low damping of the system (about
0.15 neper). At levels greater than the limitation threshold, the resistance of the
transverse-arm elements will drop sharply, while the resistance of the lateral-arm
elements will increase, which in turn will increase the damping of the system. The
circuit parameters and the operating states of the copper-oxide elements are so se-
lected that the input resistance of the system is practically the same, at levels
? both greater and lower than the limitation threshold.
Due to the presence of the copper-oxide elements, some nonlinear distortions
59
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'01
The IKCh has an amplifier tube of the lOZhl23 type, whose plate circuit contains--
the transformer Ti. The secondary winding of this transformer works into a copper-
oxide rectifier and the R1 relay, which is of the RP-5 type. The grid of the tube
is connected to the winding of the output transformer of the transmitting amplifier
across the resistor R1. ..When control frequency is present at the amplifier output,
the relay R1 is actuated and its contacts L-Ya close the circuit of the relay R2.
The contacts 11-3, V-4 of this relay open, connecting the resistor R14 into the cath-
ode circuit of the tube. This causes the negative grid bias of the tube to increase
considerably, which will prevent the appearance of grid currents in the tube; these
currents are undesirable, in view of the fact that the tube is connected in parallel
to the main transmission circuit. Despite increased bias, the relay R1 will continue
to operate so long as the level of the control frequency remains normal. If the
control frequencies disappear, the relay R1 will break the circuit of the R2 relay,
whose contacts will then close the circuit of a suitable indicator lamp at the sig-
nal panel.
?then the main amplifier is replaced by a spare, the jumpers should be removed
from the "OSLO? jacks and inserted into the "rREZ" jacks. The jacks are located at
one of the blocks, inside the G-50 chassis housing.
16. no Power Suppl:,-
Principal wiring diagram PIo.P 133.00.17
To satisfy the AC requirement of the station, a power-pack is provided. S i
rower source is assembled on a separate chassis, located in the upper part of the
220-volt rectified voltage for the plate circuits, 21,--volt rectified voltage for the
face of the stand.
The power source provides 211~-volt AC voltage for the filament circuits,
.
signal circuits, and 19-volt rectified voltage for the microphone. The station can
be adapted to operate either from a DC or from an AC source, by changing the connec-'
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tions at the fuse panel.
The AC power line is connected to the terminals AgA9 of the lead-in comb of the
chassis. From here, the voltage goes to the fuses and contacts of a toggle switch.
From the tumbler contacts, one wire goes to the terminal (7) of the power
? ? transformer and the other, to the center-jack of a three-jack cluster by means of
In the first case, the winding, III is connected, while in the second case both the
if the line voltage is 220 v, the jumper should be moved to the jacks marked"-22011.
line voltage is 127 v, the jumper should be inserted into the jacks narked"-1271t;
which the rectifier is set to correspond to the voltage of the power line. ,then the
windings III and IV are connected. Further, the power circuit goes through the
It is not necessary to change the voltage adjustment under field operating condi-
individual circuits are adjusted while the power chassis is checked at the factory.
from the winding I. All these windings have taps by means of which the voltages of
The filament voltage is taken off the winding V; the winding II supplies voltage
to the signal-circuit rectifier, and the plate-circuit rectifier receives its voltage
compensating device is controlled by means of a 'mob at the face of the panel.
their positions. Line fluctuations of -29,F-, uo ensated. The voltage-
short-circuiting of the transformer windings during the time that the brushes change
tions. The resistor R1 (or R2) is connected between the brushes, which prevents
brushes of a device whose function is to compensate for the line-voltage fluctua-
the rectified 2!~-volt voltage: I = 0.3 to 1.0 amp; the rectified 19-volt voltage:
The 2J.,.-volt AC voltage : I = 6 anip; the rectified 220-volt voltage : I = 200 ma;
The rectifier is intended to work with the following rated current values.
sisting of a choke and of electrolytic capacitors,
selenium rectifiers BSl and BS2. Both rectifiers are provided with filters, con-
The plate voltage and the signal-circuit voltage are rectified by the full-wave
I= 20 ma.
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?
When the current consumption is 300 na, a 0.5% ripple is present in the 220-volt
rectified voltage; the ripple of the 21~ volt rectified. voltage is ?l; to 15;x, depend-
ing on the current consumption which nay vary from 0.3 to 1.0 amp.
The efficiency of the rectifier is 55`,.
17. The neper-1,~eter
Principal Tiring diagram No.13C.80.1.5
Two independent r::easurinr instruments are mounted on the neper-meter chassis:
a "normal" generator and a level indicator. These instruments permit periodic mea-
si;rcments of the residual ciampirr, of the channels and check tests of the levels
throughout the equipment. Either a 10Z1il2S or a 7Zh12S tube ray be used in the gen-
erator; facilities are provided for adding a ballast tube, which is required in the
latter case. When no ballast tube is needed, the terminals 7-8 f the lead-in comb
are connected by a juniper. The supply circuit of the tube is controlled by the key
I~:5 at the face of the panel. The generator furnishes a fixed C00-cycle frequency.
? Power is taken off the output winding of the R.F. transformer Ll through an extender
Ill whose clamping is 1.0 neper and Z = 600 olu;hs. The presence of this extender as-
sures constancy of the output resistance of the generator. When the generator is
connected to a 60C-ohm load, one of the three fixed levels (0.5, 0.0, or -1.5 neper)
may be selected by means of the hey K1.
In addition, a -0.'i neper output level may be obtained by connecting the 1.2
neper extender U2 (this is done by depressing the pushbutton marked ft-0.7 nep.").
The output of the generator is connected to the jack "VJYKh.GI?" at the face of the
panel and also to the terminals 3-4 of the lead-in comb, through which the generator
is connected to PVU. The fine acl~,ustment of the output level is done by means of the
potentiometer t'REG.PNIG", using a level indicator. This adjustment should be made at
? the beginning of each measurement series.
The level indicator employs a simplified circuit and is essentially, a copper-
63
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1 5 1
oxide full-wave rectifier connected to a meter of 100 ii amp sensitivity. The input
resistance of the level indicator may be equal to 600 or 10,000 ohms.
Either of the two input resistances ray be selected by means of the key Y,1+.
In the first instance (600 ohms) the rectifier is connected to the terminals
? 14-8 of the secondary winding of the transformer TR-1. In parallel with the primary
winding is resistor R20, which rakes the total resistance of the indicator equal to
600 ohms. The points of the device is set to the end of the scale by means of the
rheostat R23. In the second instance, the rectifier is connected to the terminals y
?
in parallel to the primary winding, make the total resistance of the level indicator
equal to 10,000 ohms. The pointer of the instrument is set to the end of the scale
by means of the rheostat R18.
The low-resistance input measuring ranges are: 0.0 to -2 nepers; +1.0 to -1.0
6-5 of the secondary of the transformer TR-1. The resistors R21 and R22, connected
neper; and +2.0 to 0.0 neper. The high-resistance input measuring ranges are:
+1.5 to -0.5 neper; and +3.5 to +0.5 neper. The ranges are switched by means of the
key K3. With the low-resistance input, the indicator fray be used in the frequency
range from 300 cps to 10,000 cps; with the high-resistance input, this range is 200-
cps to 3000 cps. The measurement is 10.05 neper.
18. Directional Filters DK-16.
Principal wiring diagram No.P 135.01.11
The chassis of the directional filters carries tie following elements : STAT
filters DK-16.14 (blocks from NFD-1 to NFD-8'); the filter K-16.1. (blocks from I1FK-1
to NFK-5); and the circuit for parallel operation (blocks NiFK-o and NFK-So).
The filters ray be connected to the station circuit (from the parallel-
connection erid) by means of the dividing jacks located above the cover of the chas-
sis.
The filters are of a special type: all inductance coils are ground on toroidal,
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rrai;rietic material cores. To crake nonlinear distortions as small as possible (:?rhich
is especially important in the case of directional filters) the cores are grade of
hi;h-perr:eability material with a low hysteresis loss. Because of these cores and
also because of the properly-desif;ned circuit, it was possible to obtain high clear-
darnpinr- in the filters. The damping curves of the filters are shown in Fig-33.
19. Line Filters DI:-2. P
Principal vriring d i agrar, i'o. P 135-00.9"
The chassis of the filters DI:-2.8 contains the following elerents: the filter
D-2.8 (blocks 0--2.8-1 to D-2.8-5); the filter I:-2.8 (blocks K-2.8-1 to I'-2.2-10); the
parallel-operation circuit; the bloc; K-2.f-0; and two relays, RSh-1 anri RSh-2, used
for switching the filters when a broadcast channel is formed. Both relays are actu-
ated b:- depressing the 'TVY_L.ShV'f push-button. The contacts of the relay RSh-2 dis-
connect the filter DK-2.8; the contacts 11-2, II-]. and II-4, 11-3 of the RSh-1 con-
nect the terminals 5-6 of the lead-in comb of the chassis to the terminals 7-8, thus
? creating a circuit that by-passes the filter DY-2.8.
The damping curves of the filters DK-2.E are shown in Fig.34. The inductance
coils of all filters are wound on toroidal cores, made of ragnetic materials.
20. Line Filters DK-5.7
Principal wiring diagram No.P 135.01.22
AIo . P 13 5.01.20
STAT,
The filters DK-5.7 are located on two chassis; the chassis diagrams are given
in the above-mentioned drawings. In Fig-35 the filters D-5.7 and K-5.7 are shown
together, to simplify the diagram. Each of these filters has one ''K'"-type link and
one bridge link. In order to increase the clear-damping, some of tre'inductance
oils of both filters are wound without rrar;neti.c cores. The coreless coils are
Ll, L2 coils of the filter D-5.7 and 1,0, Ll., L2, LIH coils of the filter K-5.7. All
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coreless coils of each filter are located within one copper housing. All other coils
are wound on toroidal magnetic cores. The damping curves of the filters are shown
in Fig-36.
? 21. Balancing Filter BDK-2 8
Principal wiring diagram No.P 135.01.07
lbe balancin- filter consists of the follovring components: Blocks BDK-2.8-5
to BDK-2.c-1 which reproduce the filter D-2.8; the block BDK-2.8-6 which repeats the-
circuit used for connecting in parallel the filters D-2.8, K-2.8; and'the block
BDK-2.8-0 which balances the filter K-2.8. The terminals of the left and of the
right lead-in combs of the filter are connected to the terminals of the lead-in comb
of the stand.
22. Balancing Filter BDK-5.7
?
Principal wiring diagram No.P 135.01.25
The blocks BDK-5.7-1 to BDK-5.7-6 of this filter reproduce the filter D-5.7;
the block BDK-5.7-B balances the filter K-5.7. t'1ith one exception, all inductance
coils are wound on toroidal magnetic cores. The coreless coil L1 is located within
a separate housing.
23. The Call System and the Corimutation Field
The 'No-Wire PV;U
?
Principal wiring diagram No.P 131.60.17
STAT
The two-wire PVU is connected to the channel by means of a double three-wire
plug, through the t'LIN.C0I2' jacks of the two-wire PVU block. The PVU may be con-
nected either in the direction of the line or in the direction of the commutator, by
placing the, key K1 in a corresponding position. The call is sent by depressing the
key K2 toward the IVYLOVtU position. This creates a circuit consisting of: the split
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fuses MI, the terminal A6 of the micro-telephone block, a section of the resistor RI
the contacts of the keys h2, Kl, and K3, the contacts of the ?LINIYA'" jack, the con-
necting cable, and, finally, the channel input. The return path of the circuit may
be traced through: the ilLIWIYA11 jack, the contacts of the three above keys, and the
? terminal A7 of the two-wire PVU. Depressing the key K2 will actuate the relay R3,
which is connected to the resistor Rl through a copper-oxide rectifier. This relay
closes the circuit of the ""POS.VYZII signal lamp. To send a call toward the coimnu-
?
?
tator, the key Kl is set to the position t1KOMMI.. When the key K2 is depressed, a
circuit differing from the one described above only in having a series-resistor R3,
will be created. :Ten the key Kl is in the position ?R1ZG.LIAI? or "RAZG.K0I- MP, or
when the key K2 is in the position t"OBShch.R:1ZGut (this corresponds to the two-way
call circuit), the R2 relay is actuated. The contacts I-1, 1-2 will close the micro-
phone supply circuit, and the contacts V-1, V-2 will connect the microphone (across
the contacts of the keys K2 and K1) to the corresponding jacks of the PVU. In addi-
tion, this relay will switch the telephone from 'tcontrol"" to s'conversationu.
When the PVU is connected from the line end or from the commutator end, the dis-
connected end is loaded with a resistor R1 = 600 ohms and a capacitance of Cl = 1?f;
in parallel to these, the relay Rl is connected, across a copper-oxide rectifier.
This relay is actuated when a call is received; its contacts send a 2L-volt voltage
into the winding of the relay R1, which receives +21~ v across the contacts of the key
K1. The contacts V1-V2 of this relay close the circuit of the t"PR.VYZ" signal lamp
and of the station-wide signal circuit. The. circuits will open when the ke;rSTAT'
moved to another position.
When the keys are in their center positions, the telephone receiver, across the
transformer TR, is connected in parallel to the call circuit, for monitoring. The
norrral generator or the level indicator of the neper-meter may be connected to the'
TvLIn;IYAT1 jacks by means of the hey: K3.
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 The, Four-Wire PVU
?
?
The four-wire PVU is connected to the channel by means of two cables, each hav-
ing two double three-wire plugs. One cable connects the jacks "PER1' at the four-wire
PVU block with the jacks "PER" of the commutation field of one of the channels; the
other cable is used for connecting the "PR" jacks of the two equipment pieces. To
make a call in the direction of the line or in the direction of the commutator, the
key K2 is depressed. When a call is sent toward the station, depressing the key will
close the circuit that goes through the terminals B7-B8 (to which the tone-call gen-
erator is connected), through the contacts 9-10 of the key K2, through the extenders
U1, U2, through the contacts 15-16 and 7-8 of K2, through the contacts of Kl, through
the "PER.LIr1" jack, and finally through the connecting cable and into the "PER" jack
of the channel.
When a call is sent toward the commutator, the signal originating in the tone-
call generator goes through the same terminals B7-B8, through the contacts 1-2 of K2,
through the extender Ul and the contacts 3-4 and 11-12 of K2, through the
"PRIYEM.C0M.:' jack, through the connecting cable and into the "PER" jack of the chan-
nel. After passing the differential system, the call current will act on the tone-
call receiver, which then will connect the mechanical inductor to the commutator. In
a four-wire transit, the tone call from the "PR" jack is sent into the transmission
circuit of the second end station.
When a plug is inserted into the "PE." or "PRMi" jacks, the relay R1 is actu-
ated; its contacts V1-V2 close the filament circuit of the amplifier tube, connect
STAT
the telephone receiver to the output transformer T3 of the amplifier, and connect the
microphone to the input of the extender U3. The amplifier tube is of the heater
type, with about 30-40 sec warm-up time, and therefore the four-wire PVU (when the
plugs are inserted into the above jacks) will not be ready for use until this time
is is over and the tube has warmed up.
When the line is used for conversation, the key K4 should be in the "RAZG" pos-
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Wm_
ition. The contacts 11L-15 of the Ivey will close the microphone supply circuit, the
contacts 3-?; and 17-18 will shunt the resistors R5 and R6; the contacts 19-20 *.-rill
connect the microphone circuit (through the extender U3) to the differential trans-
former T1. Through the transformer T1, the speech currents of this circuit will go
? to the contacts 7-C and 21-22 of the key K3, and into the "PER.C0I?71 jack; through the
transformer T2, these currents will go to the contacts 2-3 and 16-17 of the key K3,
to the contacts 2-3 and 8-9 of the hey Kl, and into the TTLINIYA PRIEI?PT jack. Thus,
speech currents will be simultaneously conducted in both directions of transmission.
Incondmg speech currents will to through the transformers Tl and T2 to the grid of
the amplifier tube; the plate circuit of this tube is connected to the telephone re-
ceiver across the transformer T3.
The differential transformer Tl separates the opposite-direction transmissions,
and also reduces the loudness of the outgoing call as heard at the sending station.
In case a separate call (toward the line or toward the commutator) is to be
sent, the key K3 should be set to the proper position. The contacts of this key will
disconnect the unused transmitting direction and charge it into the resistors R3 and
R1F, of 60C ohzs each. The amplifier tube is required for increasing the loudness
and for balancing the differential system.
:Then t::e keys K2 and K4 are in their center positions, both directions are mon-
itored. In this case, speech currents
pass through the resistors R5, R6, the trans-
formers T1, T2, into the amplifier and then into the telephone receiver.
The Control Testinr Device
STAT
The device is used for checking the performance of the tone-call receivers. The
terminals B7-138 of the KIU receive voltage from the voice-frequency ringing genera-
tor. This voltage goes through the resistors Rl and R2 to the key K2. The function
Of this key is to vary the testing level at the TTKIUTT jack at the commutation field.
;Then the key K2 is in its center position, the level will be at its normal magnitude
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?
of 1.1 nepers. When the key is shifted upward, the level will increase by 1.0 neper;
I
moving the key downward will redupe the level by 0.7 neper. When the ley K1 is in
the 11TV" position, the TV generator is connected to the 11ICU11 jack. In the position
of the key Kl "TV TRI11, the generator is connected to the 11KIU11 jack of the spring-
relay R, operated by means of the dialing mechanism. Depending on the number dialed,
the duration of the signal sent by the dialing mechanism may vary from10.1 to 1.0
sec.
To check the PTV of its own station, the 11KIU11 jack is connected by a cord with
the "ISP.TV" jack of the corresponding channel. The receiver should operate when
the level is at its normal value, as well as when it is higher or lower than normal.
During the test, the 11LIII" jack of the channel whose receiver is being tested should
be connected with the jack marked 11600 bhm".
In testing by means of the dialing mechanism, the PTV receiver should not oper-
ate when 11111 or 11211 is dialed; the receiver should, however, operate when "311 or any
higher nu:,ber is dialed.
? The PTV of the opposite station is tested by means of the two-wire PVU which,
in this case, should be connected to the jacks t1D3" and "ISP.TV1t. In addition, the
ttKOIJTRi1 button at the KIU panel should be depressed for the duration of the test
24. The Lead-In Combs
The lead-in panel of the No.1 stand carries four 60-contact combs and also the
channel extenders of the station. The interstand cable is connected to the fSTAT
comb; the circuits of the first channel are connected to the second comb and those
of the second channel, to the third comb; the circuits of the third channel are con-
nected to the fourth comb. The types of circuits connected to the terminals of the
lead-in combs of the stand No.]. are listed in the Table given in Fig-37.
? The lead-in panel of the JJo.2 stand carries two 50-contact combs, and also the
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 line and the balancing autotransformers, together with the capacitor sets. The
riflit-hand comb is used for connecting the external and the line circuits; the in-
terstand cable is connected to the left-hand comb. The circuits connected to the
terminals of the lead-in combs of the No.2 stand, are listed in the Table given in
Fig-38.
The cable autotransformer is connected by 'wiring to the terminals IVG2-IVG and
the terminals IVG3-IVGI,. The frequency characteristics of the operating attenuation
and of the reflectance of the autotransformer (when connected to a 550-ohm and to a
]J.0-ohr- load) are riven in Fig.40.
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CHAPTER IV
INSTALLATION OF THE EQUIP1?ENT. INSTALLATION TESTS AND NEASUREME ITS
? 1. Installation and Wiring
0
The stands of the end station are erected in accordance with the general dravring
No.P 330.00.56. The first stand is at the left and the second stand, at the right
side.
The stands are attached to the floor by means of bolts set in concrete blocks.
They are also fastened to the wall or to the next row of equipment by means of steel-
angles. In addition, the stands are bolted together at the base, and their upper
parts are interconnected with straps.
Panels that were removed to facilitate transportation of the equipment, should
be mounted in their proper place in accordance with the drawings No.P 330.00.54 and
No.P 330.00.55. The installation panels should be connected as indicated in the
stand assembly diagrams, drawings No.131.00.21 and No.P 131.00.23. The wires of the
interpanel connecting cable are spaced to fit their respective terminals, which sim-
plifies the wiring. The interstand cable is also constructed in this fashion.
If the stand is the last or the first in a row, its open side should be covered-
by protective plates (see general view, drawing No.P 330.00.56). Instead of the up--
per plate,?a.signal transparency panel may be installed.
STAT
The transparency panel is connected to the corresponding terminals of the -Lead-
in comb of either stand, in accordance with the diagram of drawing No.131.00.20.
After the panels and the interstand cable are connected, the vriring should be
tested by ringing the station components.
If the vriring is found to be correct, the supply lines may be connected to the
? stand No.l. The 1t-24 v? and "ground" are connected to bus bars and all other supply
voltages, to terminal blocks at the fuse panel.
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The wires to be attached to the terminal blocks are provided with lugs that fit
under the nuts of the terminal posts.
2. Preparing, the Equipment for Connection to the Line
':bile connectinr? the equipment to the line, the following procedure must be
?
?
1. Install the tubes lOZhl23 and 1OP12S (if the filament .voltage is stabilized)-
or the tubes 7Zhl2S and 7P12S (if the voltage is not stabilized). Also, in the case
of nonstabilized filament voltage, install a ballast tube 0.4.2585.5-12 for 7Zh12S
tubes or a ballast tube 0.8585.5-12 for 7P12S tubes. All ballast tubes, except those
used in the PTV, GTV, and GNCh, must-be installed on the ballast chassis.
If the filament voltage is not stabilized and ballast tubes must be used, re-
move the connections between the terminals Al-Bl to AC-B8 of the right-side lead-in
comb on the ballast panel, and also between the terminals A3-A5 of the lead-in combs
on the PTV and GTV panels and the terminals 7-8 of the lead-in comb of the neper-
meter. The location of the tubes and ballasts is shown in the filament circuit
diagram, Fig.l3.
2. Mount the quartz resonator at the KG-l block on the chassis of the carrier-
frequency generator. The jumpers in the quartz oscillator blocks of both stations
should be in the position "GL111t.' Until final adjustment of the control-frequency
levels of the A-B direction is completed, the station B generator should operate in- rv
dependentl;r of the station A generator, and. its frequency should be controlled by
STAT
the quartz resonator of the B station.
3. Install thermistors on the chassis of the carrier-frequency generator and on
the chassis of the control-frequency receiver. The -TP-2/0.5 thermistors are in-
stalled in SYl and S1':2 blocks on the G1: chassis. A T-2/2 thermistor should be
mounted to the ARU-2 block of the PKCh chassis.
1I.. Connect the voltage supply lines.
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5. Install group fuses and split fuses, first in the filament circuits and then
in the plate and signal circuits. Consult Fig-52 for establishing the jumper posi-
tions.
6. Test the filament and plate circuits of all tubes by measuring their fila--
ment and emission currents. Use the portable measuring instrument IEL-11.for this
purpose. Compare the instrument readings with the data listed in the Fig.1-l Table.
If there is a considerable difference between a measured value and the tabulated
counterpart,-find and correct the cause of this discrepancy.
7. Adjust the filament currents of all tubes (see Fig.13).
This adjustment is possible only if the mean filament voltage of the given sta-
tion is 1aiovm beforehand. The filament voltages are measured by means of a portable
0-30 v voltmeter, connected to the 21+'...11 and 11-2411 terminals of the fuse panel. The
current adjustment should be performed as follows:
First case: the filament voltage is stabilized.
? a) Measure the current in the given filament circuit by means of the portable
instrument IEL-1..
b) Measure the filament voltage at the stand (within an accuracy of 0.1 v) by
means of the portable instrument and calculate the difference between this
voltage and the mean filament voltage of the given station.
c) Using the Table of Fig.1~ 1, find the filament current value -that should
correspond to this calculated difference between the measured and the mean
filament voltage. Regulate the filament current produced by changes STATie
value of the quenching resistor, mounted to the test block. Change the posi-
tion of the sliding- contact of the quenching resistor at the test block of the
chassis until the filament current is equal to the tabular value. Re-tighten
the slide of quenching resistor.
d) The filament current should be within 0.29 - 0.35 amp for the lOZhl2S tubes
and 0.58 - 0.70 ainp for the 1OP12S tubes.
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Second case: the filament voltage is not stabilized.
a) In parallel with the ballast of the circuit to be adjusted, connect a sec-
ond 0 - 15 v portable voltmeter to the terminals of the ballast-tube panel of
the PTV, GTV, or of the neper-meter (see Fig.13).
? b) Within a 0.1 v accuracy, measure the voltage at the stand; calculate the
difference between the measured value and the mean filament voltage of the
given station.
c) Adjust the ballast-tube voltage until it is equal to 8.75 + AV, where AV
is the difference between the measured and the mean filament voltage. If the -
measured voltage is greater than the mean value,A V should be taken with the
"plus" sign;' if the voltage is less than the mean value, AV should be taken
with the "minus" sign. The ballast-tube voltage is adjusted by means of the
quenching resistor, located at the test block of the chassis.
8. Measure the emission currents and the cathode activity of the tubes.
The emission currents and activities are measured after the filament current of
? a given tube is adjusted. The measurements should be made in accordance with the
instructions found in Appendix No.2.
9. Adjust the power supply.
This adjustment is. necessary for the following reasons:
The power supply is factory-calibrated so that, at normal load, a 220 v,recti-
fied voltage corresponds to a 21+ v filament voltage. However, under operating con-
ditions, the mean filament voltage may be not equal to 21~ v; therefore, when a DC
STAT
power supply is replaced by an AC supply, the tubes nay happen to be operating under
abnormal supply conditions. If the mean filament voltage of a_given station is with-
in the 23.5 - 24.5 v range, the power supply does not have to be adjusted; if the
mean voltage does not fall within the mentioned limits, adjustment is necessary.
? The adjustment should be made in accordance with the following procedure:
a) Change to AC power supply. To do so: install group fuses on the power-
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supply panel; on the same panel, move the jumpers to the jacks marked ",.,If;'
set the voltage selector to the 11127" or "22011 position, to correspond to the
voltage of the power line; switch the system on by means of the toggle switch.
b) Using the portable IEL-4 instrument, measure the voltage at the "Anod"
? jacks. Adjust the regulator on the power-supply panel until the pointer of
the instrument is at "0.5"; this will correspond to a 220 v plate voltage.
c) Measure the voltage at the 'L" jacks and compare it with the mean voltage.
obtained when the station is operating on a DC supply. If the two values
differ by more than 51'0, the positions of the jumpers between the terminals of,
row A of the left-side lead-in comb of the power-supply panel should be
changed. The positions of the jumpers are given in the basic diagram of the
power supply, drawing No.P 133.00.17. When a jumper is moved to the next
terminal, the voltage will change by 5%.
10. Check the performance of the signal circuits.
? a) Test the signal system for blown fuses. Closing of the signal contact of
any fuse should light up the "PRED" lamp on the signal panel and the light
bulb of the "PR" transparency; it also should ring the signal bell.
b) Test the signal system of the battery-voltage failure, by removing the
fuses P1 and P2, one at a time. In both cases, the "BAT" transparency should
be illuminated, the bell should ring, and the signal lamps "ANOD" or "NAKAL"
(respectively) should light up. In a similar fashion, the circuit which sig-
nals failure of the mechanical-inductor voltage is tested. In this case, re-
STAT
moving the fuse P18 or P19 should-light the "? I"t signal on the signal panel
and on the transparency panel; the bell should also ring.
c) Test the signal system of the adjustment limits on the RIL chassis, by
moving the RIL capacitors (by means of the "PLOSK.REG." knob) first to one
and-then to the other extreme position.
In both instances the "PRED.REG." lamp at the RIL panel and the "KCh" transpar-
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 ency should light up, and the bell should ring. When the slant-adjustment capacitor
is disconnected from the motor drive, the t"PRED.REG.tt signal on the RIL panel should
light. Depressing the "I3LOKIR" button should light a signal on the PKCh panel. When-
ever the transparency signals are illuminated, the general-signal lamp OSL should
? also light. When the transparencies and the bell are disconnected by means of the
tIVYKL.ZV.tt knob, the t"VYKL.ZV.tt lamp should light; the OSL lamp should stay lit. In
the case of the circuit signalizing failure of the control frequency, only the cir-
cuit of the signal bell but not that of the ttKChtt trans rency is interrupted when
the rIVYKL.'7V. tf button is depressed.
11. Check whether the operating regime of the station corresponds to the direc-
tion of communication. If the Liven end station is transmitting southward or east-
ward, the station should operate as an A station, i.e., the lower frequency group
6.3 - 15 kc should be sent into the line. If the station is transmitting northward
or westward, it should operate in a B regime, i.e., the upper frequency group should
be sent into the line.
If the operating regime of the station does not correspond to the above condi-
tions, the connections should be changed to remedy the situation.
12. Make certain that the station is operating in the required regime: either
is
station may be selected by changing the connections at the blocks GF-6, GF-9, GF-12,
and GF-15 on the chassis of the carrier-frequency generator. When the main,spectrum
of frequencies is'used, the terminals E2-E3 of these blocks are connected. When the,
E2-E1 terminals are joined, the station will operate in the supplementary frequency
spectrum.
13. Check the carrier-frequency voltages at the modulators, demodulators, and
at the group converter.
The level of the carrier frequency fed to the modulators and demodulators is
measured at the left-side test block of the carrier-frequency generator panel; the
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in the main or in the supplementary frequency spectrum. The operating regime of the
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SO, `10 tl MR W
V. TV, OWN A,
level of frequency supplied to the group modulator is measured at the test block of
the US-33 chassis.
The carrier-frequency voltage at the modulator and demodulator should be
0.46 - 0.65 v (-0.55 to -0.2 neper); the modulator carrier-frequency voltage of the
? group modulator should be 0.7 - 1.0 v (-0.1 to +0.35 neper). The voltages can be
measured by means of the level indicator of the neper-meter.
14.Check the level of the unbalanced carrier frequencies.
The measurements can be performed by means of the level
?
indicator of the neper-
meter (600-ohm input), connected to the jacks at the panel of the filters DK-16.4.
Prior to measurement, the control frequencies should be disconnected. This is'
done by setting the jumpers at the carrier-generator block to the position 1tVYELtt.
The carrier-frequency level at the terminals IVG2-IVG3 should be not less than
-2.0 neper. A higher level would require balancing of the modulators. When one
modulator is being balanced, the carrier frequencies should be removed from the other
two modulators, by short-circuiting the proper jacks at the left test block of the-
carrier-frequency generator. The balancing is performed by means of a potentiometer
located at the test block of the modulator; the potentiometer is adjusted until a
minimum level (read on the level indicator). is attained.
15. Measure the control-frequency levels.
The measuring instrument should be connected-to the jacks located on the panel
of the directional filters DK-16.4. When the level of-one control frequency is be-
ing measured, the other control frequency should be switched off. The levels of
both control frequencies should be within +0.4 to +0.6 neper limits. If the STATrol-
frequency levels are beyond these limits, they must be adjusted. The adjustment is
made by changing the connections between the terminals A2-A5 of the blocks SK-1 and
SK-2.
? 16. Measure the output level of the side frequency in each channel.
For convenience, this level may be measured at the jacks of the DK-16.4 panel
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instead of at the output terminals of the stand. The output terminals IVG2-IVG3
should be connected to a 600-ohm load. One of the connecting lines SL-9 - SL-12 and
the 600-ohm resistor (wired to the "600-ohm" jack of the commutation field) are used
for this purpose. In addition, high-resistance input of the level indicator should
be used.
0 When a zero-level 800-cycle frequency is connected to the +rLIN" jack of a chan-
nel, the level of the side frequency at the jacks of the filter DK-16.4 should be
?2.05 ? 0.1 neper. The side-frequency level in the first channel of the lower band
should be 0.15 neper higher than the side-frequency levels of other channels (thus
the transmission damping of the filter K-5.7 is being taken into consideration).
?
17. Measure the output level of the tone-call at the jacks of the filter DK-16.4
of each channel.
In order to send a tone-call along a channel, the commutator terminals must re-
ceive a mechanical-inductor voltage, or else the armature of the relay R1 at the
TV-receiver chassis must be moved by hand. The level of the side frequency of a
tone-call, as measured at the jacks in the filter DK-16.4, should be +1.25 to +1.45
nepers.
18. Check the performance of the tone-call receivers of all three channels, in
accordance with the procedure discussed in Section 13, Chapter III.
3. Measurement of the Circuit Parameters
Before the final connections to the long-distance line are made, the main para-
meters of the circuit, whose carrying, capacity is to be increased by the equipiSTAT
should be measured. These parameters are: insulation resistance between wires and
also between each vrire and ground; circuit resistance; resistance of each wire;
asymmetry of the circuit and the operating damping of the amplifier section in both
directions of communication.
? The frequency dependence of the circuit damping should be
uniform.
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The B-3 equipment cannot be used in lines whose damping curve has an undulating
shape, several maximums, or sharp breaks. Such shape of the damping curve is indica-
tive of distortions due to detuning between the resistance of the circuit and that of_
the cable inserts, or'to absorption in parallel circuits. The causes of distortions
should be found and corrected before the equipment 1s connected to the line.
4. Ad
iustments to be Made After the Equipment is Connected to the Line
I. Austing the Control Frequencies in the Direction A-B and Testing the
Performance of the ARU
1. Check the control-frequency levels at the jacks on the panel of the filters
D-16.4 when the station is under line load. The level of each control frequency
should be from +0.4 to +0.6 neper.
Before measurement, disconnect the control frequencies and measure the interfer-
ence level at the jacks of the filter DK-16.4. This level should be not greater than
-1.5 neper.
? 2. Block the ARU by pushing the tBLOKIRtt button on the PKCh panel and set the
flat and the slanted regulator of the RIL to the ttOrt position; this will correspond
to maximum damping of the flat regulator and to minimum steepness of the slant-
regulator curve.
3. Adjust the control-frequency levels at, the output of all intermediate sta-
tions (starting with the first station) and at the output of the reception amplifier
6f the B station. The sequence of adjustment should be the same in intermediate
stations and in the end station. STAT
right-side instrument on the panel of the control-frequency receivers (the 15-kc
? control frequency) to the colored segment of the-dial.
4. Decouple the regulators. Rotating the slant-regulator alone,tthen the flat-
The adjustment is made as-follows:
First, by simultaneously rotating both RIL regulators, bring the pointer of the
80
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amplifier of station B; transit jacks of the receiving part of the channel of sta-
tion B; "LIN" jack of the given channel at station B. The level of the side frequen-
cy at the jacks DK-16.4 of the end station A and of all intermediate stations should
be +1.95 to +2.15 nepers; at the output of the reception amplifier in station B, this
? level should be +1.8 to +2.0 nepers. When the amplification regulator of the UNCh
is in the position 11511, the voice-frequency level should be: -1.6 to -1.4 neper in
the transmission transit jacks; +0.1r. to +0.6 neper in the reception transit jacks;
-0.9 to -0.7 neper in the 11LIN11 jacks of the channel.
In a similar fashion, the residual damping of the channels is measured and the
level diagram is checked for the direction B-A. The direction A-B of transmission
should be disconnected during the test. When the residual damping measurements are
completed, the connections of both transmission directions should be restored.
III. Testing the Stability of the Channels
At both end stations, remove the load from the commutator terminals of the chan-
nel being tested. Set the level indicator to the 11-0.5 to 1.511 range and connect
the high-resistance input of the instrument to the "LINIYAtt jack of the station which
will be adjusted. All other channels must be connected to 600-ohm loads. Disconnect
the motor drive on the RIL panel and slowly rotate the flat-regulator knob in the
direction of increasing calibration numbers until an abrupt movement of the pointer
of the level indicator is observed.
Reverse the direction of rotation of the amplification regulator, to find the
position when the generation loss occurs. Leave the regulator in this position STAT
measure the residual damping of the channel. The difference between this reading
and -0.8 neper will give the stability margin of the channel. This margin should
be -0.6 neper or higher. When the stability test of all channels is completed, re-
turn the flat-regulator to its original position, i.e., one at which the pointer of
the ARU instrument will return to the 11011 mark. If the stability margin of a channel
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 happens to be lower than 0.6 neper, the frequency dependence of the residual damping
of the channel will have to be measured.
IV. Testing the Tone-Call in All Channels
Perform the following tests:
1. Test the performance of the TV receivers receiving tone-calls from the gen=
erator of the station; conduct the test at normal,reduced, and increased signal
level.
2. Test the performance of the TV receivers receiving a normal-level pulse of
a fixed duration from the generator of the station.
3. Test the performance of the TV receivers of the opposite station.
V. Supplementary Tests and Measurements
3. Measure the amplitude characteristic of the channels.
2. Determine the frequency dependence of the residual damping of all channels.
ment in the frequency range of 6.3 - 15 kc, for both directions of communication:
1. Determine the frequency dependence of the amplification. of the group equip- ,
tests be made:
testing instruments are available, it is recommended that the following supplementary
? by means of testing devices forming a component part of the equipment. If additional.
The above-described tests and measurements are mandatory and can be performed
test block of the panel, with the jumpers removed), and at the output,of the recep-
at the input of the group converter of station B (jacks "rVkh.GT" on the left-side
ception amplifier of station B; the measurements in the direction B-A should be made
the input of the transmission amplifier of station A and at the output of the re-
amplification circuits, the amplification in the direction A-B should be measured at
STAT
The test should be conducted in accordance with the conventional diagrams for'
measuring the working amplification and the operational damping. In the group-
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 tion amplifier of station A.
Figures 1.3 and 45 show frequency characteristics and amplitude characteristics
frequency characteristic of the group section of both end stations has a similar
has been smoothed by the correcting circuits of the BUK) is plotted in Fig-46. The
characteristic of the intermediate-station amplification (both before and after it
Figure 44 shows typical characteristics of the group equipment. The frequency
of the channels.
the capacitors of both the flat and the slanted adjustment are rotated simultane-
Figure 47 shows the frequency dependence of the RIL damping for the case when
caused by the resistor R5, which is connected across the output transformer of the
by 0.4 neper upward with respect to the curves for the A-B direction. The shift is
curves for the B-A direction will have the same shapes, but will be parallel-shifted
All above curves are for the A-B direction of communication. The corresponding
tion;of the position of the slant-adjustment capacitor.
the flat-adjustment capacitor only; in Fig.49, these changes are plotted as a func-
Figure 48 shows the changes in the RIL damping as a function of the position of
BUY.
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 CHAPTER V
2.-UMTE LANCE TESTING OF THE EQUIPI1~IT
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The'quality of performance of the equipment .is, to a large extent, determined
by its tubes. One damaged tube in the main part of the equipment will disrupt oper-
ation on all three channels; for this reason, the operation of the tubes should be
closely controlled. The present equipment uses new types of tubes, designed espe-
cially for long-distance wire corvnunication systems. Although under normal condi-
tions the life of these tubes is very long, 5000 hrs or more, they still require
systematic maintenance testing.
a) The service life of tubes will be much shorter, if the filament voltage is
too high; therefore the filament-voltage sources must be closely controlled.
As was pointed out on a previous occasion, when the equipment is being in-
stalled, the mean filament voltage of a given station must be known beforehand; the
initial adjustments of the filament-circuit voltages are made on the basis of this
mean tralue. If, for instance, these adjustments are based on a voltage value that
is, lower than the actual mean filament voltage, the filaments of the tubes and bal-
lasts will be almost continuously overheated; this will greatly reduce their service
life. If the mean filament voltage of the station changes for any reason, all fila-
ment circuits of the equipment should be re-adjusted. These re-adjustments do not
disrupt the operation of the equipment in the least, since they are made by merely
changing the resistances of the quenching resistors in the filament circuits; this
is easily done without disturbing the operation of the filament circuits. In making.
these adjustments, connect a voltmeter across the quenching resistor and, by moving
the slide of the resistor, change the voltage drop in accordance with the known
86
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change of the mean filament voltage.
If one or more tubes have to be replaced, adjust the filament circuits in ac-
cordance with the procedure outlined in Chapter IV, Section 2, Cases 1 and 2.
b) As a rule, a tube will break down not only when its filament is burned out,
but also when it loses emission; therefore, the emission of tubes must be periodic-
ally tested. The emission current of tubes should be checked daily. Should the
emission current of any tube start differing from the specified values, the cathode
activity of this tube must be tested (see procedure for measuring cathode activity).
In addition, the cathode activity of all tubes must be measured once a week. Tubes
with an abnormally low cathode activity must be replaced. The cathode activity is
tested without interrupting the operation of the equipment.
2. Testing the Distribution of Levels in Group Equipment
A systematic control of the control-frequency level is necessary for maintaining
a proper level distribution in the group-equipment circuits. The ARU circuit is not
? provided with means for signaling irregularities in the operation of the slant-
adjustment; under adverse atmospheric conditions, the performance of the slant ad-
justment must therefore be controlled by means of the slant-adjustment instrument on
the PKCh panel.
It is recommended that the level of the ARU control frequencies at the jacks of
the filters DK-16.4 of the transmitting end station and of intermediate stations,
and at the 11V.YKH?T .jacks of the reception amplifier of the end station be checked
STAT
once a month. This level should not deviate from the originally set value by more
than 0.1 neper in the case of the transmitting side of the end station, or by more
than 0.14. neper in the case of the intermediate stations and of the reception side of~
the end station. When the control frequencies are at a normal level, the pointer of
the PKCh instrument will stay within the colored segment of the dial. If the pointer
? goes beyond the limits of the colored segment, the tuning of the narrow-band filter
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of the PKCh must be tested. The testing and re-tuning of this filter are performed
as follows: Slowly change the capacitance of one trimmer at the narrow-band filter
block, until a maximum reading is obtained at the PKCh instrument; repeat this step
by changing the capacitance of the second trimmer. The tuning should be done with
utmost accuracy. If the pointer of the PKCh instrument stays out of the colored
segment of the dial even after the narrow-band filter is re-tuned, the sensitivity
of the receiver must be adjusted by changing the connections at the TUF block.
Other measurements required for maintenance of the equipment (such as measure-
ments of residual damping of channels, etc.), must be performed in accordance with
the pertaining maintenance instructions.
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 BUK acts as a buffer between the flat regulator and the group amplifier. Its pres-
ence is necessitated by the fact that the flat regulator cannot vrork directly into
the low-resistance input of the group amplifier.
The RIL stage is followed by the group amplifier US-A, which has the function
of sustaining a required transmission level at the line terminals. The US-A is fol-
lowed by the directional filter D-16.1r.A. From the points of parallel connections of
the filters D-16.11 and K-16.14.A, the circuit goes through the terminals 5-6 of the
directional filter panel to the dividing jacks t"LIN-All., located at the commutation
field. Further, the circuit goes through the line filter K-5.7 to the terminals
IVG2-IVG3 at the lead-in comb of the stand. This end of the circuit is also provided
with a cable autotransformer AT. If it becomes necessary to connect this transformer,
the terminals IVG1-IVG2 and IVG3-IVG4 are joined by jumpers, and the line from the
direction of station B is then connected to the terminals IVD2-IVD3.
The circuit of the communication direction B-A is analogous to that of the dir-
ection A-B with one exception: facilities are provided for connecting the filter
D-30 between the RIL and the group amplifier US-B.
This filter is required when the present equipment is to be used in lines al-
ready utilized for operation of a 12-channel equipment.
The intermediate station is provided with a spare amplifier US.REZ. which, if
necessary, can be used for replacing the main amplifier of either direction; the re-
placement is performed without interrupting the communication. When the spare ampli-
fier is to be connected, the position of the jumpers at the terminal 'blocks of-both
the spare and the main amplifier should be altered. First, the jumpers at the spare
block of the amplifier must be inserted into the jacks t"US-Att or "US-Btt, (depending
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on which amplifier is being replaced). Then, the jumpers that connect the main amp-
lifier to the circuit are removed.
3. The Level Diagram
The distribution diagram of the levels at individual points of the intermediate
stations is shown in Fig.12a. The side-frequency levels are denoted by a continuous --
line, the dotted line indicates distribution of control-frequency levels.
1.. The Circuits For Level Adjustment
In parallel with the output of each group amplifier, a control-frequency re-
ceiver is connected to the terminals B2-B5. The control-frequency receiver consists
of a receiver for automatic level adjustment (Pr.ARU) and of a receiver for slanted
(manual) level adjustment (Pr.NR). The control-frequency receivers operating in the
communication directions A-B and B-A differ only in the narrow-band filters connected
to their outputs. These filters are tuned to frequencies of 9 kc and 15 kc for the
A-B direction, and to 18 or 21+ kc for the B-A direction.
The 9-kc and the 24-kc frequencies are used for the automatic level adjustment;
the 15- and 18-kc frequencies are used in the manual level adjustment. The ARU re-
ceiver and the ARU motor (located on the RIL chassis) require a 50-cycle AC current
for their operation. This current could be obtained from a station source; however, -
in order that the ARU will continue to operate during breakdowns of the station
voltage, each station is equipped with a separate vacuum-tube 50-cycle generator for
each direction of communication. The 50-cycle voltage, delivered by the generator,
goes to the terminals 1-2 of the Pr.ARU and to the terminals 3-4 of the RIL. Both
control-frequency receivers are provided with permanently-connected instruments for
measuring the rectified control-frequency current. These instruments permit a con-
stant control of the level of communication. When communication in one direction is
interruuted, the pointers of the instruments of the control-frequency receiver, op-
91
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The plate voltage is connected to the terminal "+220tt and to the grounded bus
bar. The four jumpers on the fuse panel must be inserted into the jacks marked rr=rr?
When an AC, rather than a DC source is used, the said jumpers should be'moved
to the jacks marked rt-It and, in addition, the voltage regulator on the power-supply
? panel should be set to the position "1271" or "220", as the case may be. The AC
voltage is connected to the terminals t? on the fuse panel. Also, a signal battery
should be connected to the terminals marked "24 SIGN" and "+24". If such a battery
is not available, the terminal It-24 SIGN" is connected to the terminal "24 VyPRrr; in
this case, the signal system for AC voltage failure (at the given stand) is inopera
tive. The power supply is controlled by means of a toggle switch located at the face
of the panel. When the AC voltage is on, a neon indicator lamp will Light. -
The supply circuits are protected by fuses; group fuses protect the common cir-
cuits, and split fuses protect the circuits of individual equipment sections. The
fuses P1 and P16 on the fuse panel are group fuses for DC circuits. The group fuses
of the AC circuits are located on the power-supply chassis. The same split fuses are
? used for AC and DC. The fuses P3 to P11 protect the plate circuits while the fila-
ment circuits are protected by the fuses P1S to P27; the fuses P14 and P15 are in
the mechanical inductor circuit; the signal circuits and the PVU are protected by the
fuses P2, P172 P281 and P29. All fuses are provided with contacts that signal their
burn-out.
Filament Circuits of Tubes
?
Each filament circuit consists of a split fuse, a ballast
(which is disconnected
when the equipment uses tubes lOZhl2S and 1OP12S), a quenching resistor, a test jack,
two series-connected lOZhl2S tubes, and one 1OP12S tube, in series with two parallel-
connected lOZh12S tubes. The test jack is used in measuring the filament current;
this jack also acts as a circuit-breaker, when a blank plug is inserted. The jacks
are located on each individual panel. The method of measuring the filament current
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was described in the "Measurements" Section.
The_plate voltage reaches individual components of the equipment via corres-
ponding split fuses. A protective filter,, consisting of a choke and a capacitor is
included in the plate circuits of most of the chassis. To break a plate circuit, its
split fuse must be removed from the holder.
?
7. Signal Circuits
An intermediate station is provided with means to signal the following events:
1. Burn-out of any of the group fuses or split fuses.
2. Filament-voltage failure.
3. Plate-voltage failure.
4. Failure of the call-current voltage.
5. Changes in level of the ARU control frequency at the output of the group
amplifier of either communication directions; the changes are signaled when-
ever their magnitude is greater than 0.3 - 0.5 neper and their duration longer
? than 5-7 sec.
6. Instant at which the automatic level regulator approaches one of its de-
flection limits.
7. Blocking of the ARU.
8. Change from automatic to manual adjustment of the slope of-the amplifiea
tion-frequency characteristic.
The signaling is achieved by means of commutator bulbs located on panels. In
addition, when cases 1-6 occur, a stand signal lamp TTOSLtt will be lit and a signal
bell will 'ring. The closing of the signal-bell circuit occurs simultaneously with
the closing of the circuits of the light bulbs of the corresponding transparent
signs, namely: PR - for the fuses, BAT - for the battery voltage, NI - for the
mechanical inductor, KCh - for the control frequency. In all other cases, the all-
stand and the row (transparencies) signal system remains inoperative.
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The lamps for local and for general signaling will stay lit until the cause of
the signal is removed. The bell and the transparency illumimtors may be switched
off by depressing the "VYKL.ZV" button located on the signal panel. The button has
no caging mechanism; when this button is depressed.,' the iamp above
? will light and stay lit until the trouble is corrected.
?
The signal-circuit relays and most of the local signal JJ nps are located on the
signal panel. Failure of the filament voltage and of the call. current is signalized
over the relays'RVT, RN, and RA; these relays drop out whenever the corresponding
,voltages are interrupted and their contacts close the corresp?ohding signal circuits.,
Burn-out of fuses, is signaled by means of the relay RRP. EacI:h of the named relays
has four groups of contacts. The contacts II-1 and 11-2 closee the circuits of local
signaling; the contacts 11-3 and II-4 close the circuit of thee signal bell; the con-
tacts IV-1 and IV-3 close the circuit of the "OSL"" bulb; the ocircuits of the trans-
parency light bulbs are closed by the contacts IV-3 and IV-4 *. The relays RBZ are
blocked when the button ""VYKL.ZV" is depressed; this closes the circuits of the sig-
nal bell and of all transparency illuminators. Several 50-ohim resistors are connec-
ted into the local signal circuits, to reduce their voltages aired thus to increase
the service life of the signal lamps.
Some of the signal relays are located on the control-freq? ency receivers chas-
sis. These relays are discussed when describing the operation. of components on whose
panels they are located.
8. The Voice-Frequency Ringing Device and the Commutation Field
STAT
The intermediate station is equipped with a two-wire voice-frequency ringing
system, which is used for making service calls. The system is Composed of two stan-
*The functions of the contact group II of the relay RRP are p eer for-med . bY the con-
tacts of group I; those of group IV - by contacts of group V.
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The control-frequency level and the level of side frequencies at various points
of the circuit may also be measured by means of the level indicator. To facilitate
this measurement, most of the tube-containing stages (among these: US-A, US-B,
RIL-A, RIL-B, and G-50) are provided with special test jacks. In addition, these
? measurements way also be made at the jacks 'OLIN-All and "LIN-B". A portable test in-
strument, consisting of an ammeter (having 0.15, 0.5, and 1.0 amp ranges) and a mi-
croammeter (1.0 milliamp range), is provided for measuring the filament voltages,
emission currents, and emf of the electric supply sources. The instrument also con-
tains variable resistors for regulating the filament voltage when making cathode-
activity
measurements. The ammeter is used in filament-current measurements; the
plate currents are measured by means of the milliammeter.
The test instruments are connected to tfe circuits by means of test leads pro-
vided for that purpose. The ammeter lead ends in a three-wire plug which can be in-
serted into the test jacks of the chassis containing vacuum tubes.
The portable instrument is provided with a switch which, by changing connections
? in the instrument circuit, makes it
possible to use the instrument for either mea-
suring the filament and plate currents or the cathode activity. In the former ins-
tance, the ammeter of the instrument is connected to the neck and head of the three-
wire plug; when this plug is inserted into the test
jack of the circuit to be tested,
the ammeter is in series with the other circuit components. The value of the current!
is then read off the ammeter dial, in the range selected by the range switch. The
portable instrument cannot be used for filament-current measurements when the station'
is operating on AC.
0
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The microammeter is wired to a two-wire cord, ending in a two-prong plug.
making measurements, this plug is inserted into one-wire jacks of the plate circuits..
The numbers engraved above each of these jacks, are conversion factors; the reading..
of the microammeter must be multiplied by these factors.
In this instance, a cord with a three-wire plug on one end and with-a two-prong
98
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plug at the other end must be used. The three-wire plug should be inserted into the
jack "IZN" and the two-prong plug, into the test jacks of the plate circuit to be
tested. The same test leads are used when the circuit of the test instrument is
changed to suit the conditions under which the cathode activity must be measured.-In
this case a temporary circuit for supplying the filament of the tube with direct cur-
0
rent and with rectified current is formed. This circuit consists of: additional
contact of the test jack; body of the jack; body of the three-wire plug; filament
voltage rheostat, located within the test instrument; ammeter; neck of the plug; and
filament of the tube. Such arrangement permits simultaneous adjustment of the fila-
ment voltage and observation of the plate-current variations. The filament, the
plate, and the AC voltages are also measured by means of the portable instrument. The
instrument, in this case, is connected to suitable test jacks on the signal panel,
and its microammeter is read. The "0.511 reading of the microammeter will correspond
to normal values of all measured voltages; this is made possible by suitably shunting
the test jacks and by inserting an additional resistor in the circuit being measured.
If the voltages of the electric supply sources deviate by not more than the
allowed 110% from their nominal normal values, the pointer of the microammeter should
remain within the colored segment of the dial. A copper-oxide rectifier, located on
the signal panel and supplied with 2L-volt AC voltage from a power-transformer wind-
ing, is used in measuring AC voltages.
STAT
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 _APPENDIX.No.2
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THE IEL-4 VACUUM-TUBE TESTZR
(Description of the Instrument and Operating Instructions)
I. Pi:rpose of the Instrument
is
0
from 0 to 100 ma
from 0 to 0.5 amp
from 0 to 1.0 amp
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The vacuum-tube tester IEL-4 is a supplementary portable testing instrument to
be used with the long-distance equipment; the instrument is intended for testing
vacuum tubes under actual operating conditions. The instrument may be used in the
following types of equipment: SUTU; V-3; NUS-3; V-12; K-12; TT-12/16, and others.
Since all necessary additional resistors, shunts, rectifiers, and other special
devices are built right into the long-distance equipment parts, the following measure-
ments may be made by means of the IEL-4 instrument:
1. Filament-current measurements in circuits, supplied by direct-current
voltage.
2. Measurements of total filament voltage of tubes, supplied with either direct
or alternating current.
3. Emission-current measurements.
4. Cathode-activity measurements.
5. Measurement of plate voltage, as delivered to the stand.
II. Technical Data
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The vacuum-tube tester is equipped with two magnetoelectric instruments:
1. An ammeter, to be used for measuring the filament currents. The instrument
has three ranges:
 2. A microammeter, to be used for all other measurements. The instrument has
two main ranges:
from 0 to 1.0 ma
from 0 to 100%,
and a supplementary range, from 60 to 100%.
Test leads, provided with the instrument, are used in connecting it to the fila-
ment and plate circuits of the equipment.
III. Structural Data
The vacuum-tube tester IEL-L. consists of a metal box with a cover and with an
internally-attached metal panel.
The following components and controls are located under the cover, on the metal
panel; two measuring instruments; two rheostat knobs; a range switch; a switch for
changing the circuit connections of the instrument.
Leads for connecting the tester to the test jacks of the equipment components
are brought out through openings in the panel.
IV. Description of the Basic Diagram and of the Operating Principle of the Instrument
The basic. diagram of the vacuum-tube tester is shown in the drawing
'Ido. P 133.80.53
1. Measurements of Emission Currents of Vacuum Tubes; Measurements of the'Emf of
the Voltage Sources
To measure the emission currents and the voltages, the switch 1~2 must be STAT
irizm. toka i napr" (measuring current and voltage) position (Fig.No.1).
The measuring circuit which is formed when the switch K2 is in this position
consists of the microammeter "rmAlf (200 p amp movement), and of a supplementary resis-
? tor R10 that brings the total resistance of the circuit to 2000 ohms. The dial of
the nicroammeter is graduated from 0 to 1 ma.
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By means of a test cord ending in a two-prong plug (distance between the prongs:
?
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13 mm), which may be inserted into the test jacks of the long-distance equipment, the
instrument is connected to low-ohmic resistors (shunts) of the tube circuits. As a
rule, these resistors are between the ground and-the cathode of a tube; the resistors
carry the full emission current of the tube, equal to the sum of the plate and the
screen-grid currents.
In some cases, when it is impossible to have shunt resistors in the cathode
circuit, they are located in the plate circuit of the tube.
The emission current is determined by measuring the voltage drop on these shunt
resistors.
The voltages of the supply sources are measured in a similar fashion and by
means of the same microammeter. These measurements are facilitated by a marked sec-
for and. an index line on the dial of the instrument.
Because of the additional resistors and shunts incorporated into the test cir-
cuits of the long-distance equipment for this purpose, the pointer of the microamme-
ter will remain at the center of the marked-off dial sector as long as the voltages
being measured are at their normal values.
The limits of the sector correspond to a ?10% voltage fluctuation.
The measurement of the 24-volt AC voltage is facilitated by copper-oxide recti-
fiers in the test c.-rrcuits of the long-distance equipment.
2. Measurement of the Filament Currents
The circuit for measuring the filament current is formed when the key K2 is in
the nizmer. toka i napr." (meas. curr. and voltg.) position (Fig.2)., This circuit
consists of the ammeter amp/ma, the range key K1, and the ammeter shunts R4, R5,
and R6.
The R4 shunt is connected for making measurements in the 100-e range; the
0.5-amp range is covered by connecting the R4 and R5 shunts; all'three shunts are
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used when making measurements in the 1.0-amp range.
The 0 - 100 ma scale is used for measuring'the filament currents of the 12Zh1L
and lOZhlL tubes; the filament currents of the 10Zh12S and 7Zh12S tubes are measured
with the 0 - 0.5 amp dial, while the 0 - 1.0 amp scale is used for measuring the
,current of the 1OP12S and 7Pl2S tubes.
The test cord used in filament voltage measurements is connected to the neck
and head of a three-wire plug (6.5 mm dia.); this plug fits the special jacks pro-
vided for the purpose of filament current measurements.
When the key K2 is in the position "'vykltu, the ammeter is shorted; this prevents
an accidental breaking of a filament circuit while inserting the plug of the test
lead into the jacks for the filament-current measurement.
3. Cathode-Activity Measurements
When the instrument is used for measuring the cathode-activity, the key K2
should be in the "izm. akt. katoda'? (meas. cath. activity) position (see Figs-3a
and 3b).
As seen from the diagram in Fig-3a, the resistors R3 and Rg, operating as volt-
age regulators, are in series with the ammeter. The pointer of the instrument is
aligned with the 100% rrark by means of the fine-tuning rheostat R9 which is in series
with the microanQneter (Fig-3b).
In conducting cathode-activity measurements, the three-wire plug of the instru-
ment is inserted into the filament test jack, while the two-prong plug is used for
making connections with the plate circuit of the same tube. STAT
The cathode activity is measured by reading the relative (percent) changes in
the plate current that correspond to a reduced filament current.
First, the filament current is adjusted to the nominal value by means of the
rheostats.R3 and RS, and the pointer is brought to the 100% nark by means of the
rheostat R.9. Next, the filament current is given a predetermined decrement (again,
103
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y means of R3 and Rg), and the corresponding plate current (in percent) is read.
_V. Operating Instructions for the IEL-4 Instrument
-- s
e
?
?
For making emission-current measurements, the instrument is connected to the
corresponding jacks by means of the two-wire plug; the key K2 should'be in the nizm.
toka i napr." position.
The microammeter reading, multiplied by. the factor marked next to the test jack'
to which the instrument is connected, will give the omission current in milliamperes.
1. Emission-Current Measurements
2. Filament Current Measurements
To measure the current in a filament circuit, the instrument is connected to a
special test jack by means of the three-wire plug. The proper measurement range of
"100 ma", "0.5 amp", or "1.0 amp" should be selected by means of the key Kl; the key
K2 should be in the "izm. toka i napr." position.
The current is read off the scale selected by the key K1.
Note: the emission current and the filament current of a tube may be measured
at the same time.
3. Cathode-Activity Measurements
To measure the cathode activity, the instrument is connected by means of the
three-wire and the two-wire plugs, inserted into the corresponding test jacks of the
equipment components.
Before connecting the instrument, set the "grub. reg. nakala" (coarse filament
adjustment) to the mark 3-4. Set the key K2 to the "izmer. akt. katoda" position;
by means of both the "grub. reg. nakala" and the "plavn. reg. nakala"'(continuous
filament adjustment) rheostats, adjust the filament current to a value equal to the
mean filament current for the given circuit.
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?
After waiting not less than 3 min, bring the instrument pointer to the 100%
division on the main scale, by means of the 'lust. na 100 prots.ff (set to 100%) rheo-
stat.
By means of the "plavn. reg. nakala" and the "grub. reg. nakala" rheostats, re-
duce the mean filament current to a value given in the description of the long-
distance equipment.
Wait until the cathode is stabilized at the new temperature (not less than 3
:min), then read the relative decrease of the cathode activity from the main scale. If
it is impossible to set the instrument to 100% on the main scale, the 100% division
of the auxiliary scale must be used.
In the latter case, the relative decrease in cathode activity should also be
read off the auxiliary scale.
Note: All above measurements can be performed while the equipment is in opera-
tion;.the test instruments cause no interference.
STAT
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105
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 APPENDIX No-3
CONNECTING THE VOICE-FREQUENCY RINGING SYSTEM IN A FOUR-WIRE CIRCUIT
I. Connecting the GTV and the PTV to the Four-Wire Part of an End Station
NIT a Differential System
1. Connecting the GTV
a) On the left-side of the PTV chassis, move the jumpers from the terminals
A2-A3 and B2-B3 to, respectively, the terminals A2-A1 and B2-B1.
b) On the left-side comb of the PTV chassis, move the jumpers from the terminals
A5-A4 and B5-B4 to, respectively, the terminals A5-A6 and B5-B6.
c) On the lead-in comb of the stand I, remove the jumpers joining the terminals
III G1-III G3 and III G2-III G1.
'? d) On the lead-in comb No.1 of the stand, insert jumpers between the terminals
III E3-III G3 and III E3-III G4; III E1-III G1 and III E2-III G2.
Note: The jumpers between the terminals V3-V5 and V3-V6 of the left-side comb
of PTV chassis should be removed.
2. Connecting the PTV
a) On the left-side comb of the PTV chassis, remove the jumpers between the
terminals V9-A9 and V8-B9.
b) On the left-side comb of the PTV chassis, place jumpers between the termin-
als V10-B9.
c) On the left-side comb of the PTV chassis, place jumpers between the termin-
als A3-A8 and B3-B8-
0 d) On the left-side comb of the PTV chassis, place jumpers between the termin-
als A4-A7 and V4-V7.
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e) On the No.l lead--in comb of the stand, place jumpers between the terminals
!III V9-III G5 and III V10-III G6.
U
II. Connecting the GTV and the PTV to the Four-Wire Part of an Find Station Whose
?
Differential System is Disconnected
is
In this case the call may be sent by means of direct current only. There are
two possibilities:
a) Two separate wires may be used, one for sending, the other for receiving
the call. The call is sent by grounding the terminal III B9 of the No.l
lead-in comb of the stand.
The incoming call will ground the III V 10 terminal of the No.l lead-in comb of
the stand.
b) A single wire may be used for sending and receiving the call. In this
case, the terminals A2-B3 of the right-side comb of the PTV chassis should be
connected by a jumper.
The call is sent out by grounding the terminal III B 10 on the No.l lead-in
comb of the stand.
An incoming signal will ground the same terminal.
1. Connecting the GTV
a) On the left-side comb of the PTV chassis, remove the jumpers joining the
terminals A4-A5 and B4-B5.
b) On the left-side comb of the PTV chassis, place jumpers between the termin-
STAT
als A5-A6 and B5-B6.
c) On the No.1 lead-in comb of the stand, remove the jumpers joining the term-
inals III E9-III D9 and III E10-III D10?
d) On the No.1 lead-in comb of the stand, place jumpers between the terminals
III E9-III V1 and III E10-III V2.
e) On the left-side comb of the PTV chassis, place jumpers between the termin-
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 Declassified in Part - Sanitized Copy Approved for Release 2013/03/20: CIA-RDP81-01043R001800230007-6
Zi.
als V3-V5 and V4-V6.
Note: The III E1 and III E2 terminals of the No.1 lead-in comb of the stand are
assumed to be the transmission input terminals.
? 2. Connecting the PTV
a) On the left-side comb of the PTV chassis, remove the jumpers joining the
terminals V9-A9 and V8-B9.
b) On the left-side comb of the PTV chassis, place jumpers between the termin-
als AL,-A, and B1,7131.
c) On the left-side comb of the PTV chassis, place jumpers between the termin-
als A9-A7 and B9-B7.
d) On the No.1 lead-in comb of the stand, place jumpers between the terminals
III E3-III V5 and III E4-III V6.
Note: The terminals III V9 and III V10 of the lead-in comb of the stand are
? assumed to be the reception output terminals.
The lead-in comb designations quoted in the present Chapter correspond to the
second channel (comb III). The appropriate connections for the first and the third
channels should be made on, respectively, the comb II and IV, in agreement with the
procedure outlined above.
41
109
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TABLE OF CONTmTS
Page
Chapter I. General Data on the OV-3 Equipment .............................. 1
? 1. Purpose of the Equipment ............................................ 1
2. Basic Equipment Data
.......................??......................? 1
3? Basic Diagram and Operating Principle of the End Station OV-3 ....... 3
4. Basic Diagram of the Intermediate Station PV-3 ...................... 13
Chapter II. Basic Diagram of the End Station ............................... 15
1. The Transmitting Circuit ............................................ 15
2. The Receiving Circuit ............................................... 17
3. Changing the Operating Schedule of the Station; Changing from a
Two-Wire to a Four-Wire Transmission ................................ 19
4. Connecting the Spare Amplifier .... .................................. 20
5. Diagram of the Levels ............................................... 20
6. Circuits Supplying the Carrier and Control Frequencies .............. 20
~? 7. Level-Adjusting Circuits ..........................................
.. 21
8. Call Circuit ............................................ ............ 22
9. Power Supply
Circuits ............................................... 23
10. Signal Circuits ..................................................... 25
11. Speak-Buzz Device and Commutation Field ............................ 27
12. Measurements ........................................................ 30
Chapter III. Principal Wiring Diagrams of the End-Station Components ....... 33
1. Transmission Group Amplifier of the End Station ..................... 33
2. Reception Group Amplifier ........................................... 34
3o Reserve Group Amplifier as 0*0 090000 0000 0000 0000*00 000000 0 000000 assess 34
4. Control-Frequency Receiver .......................................... 35
? 5. Regulating Artificial Line RIL ...................................... 39
6. Carrier-Frequency Generator ......................................... 43
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7. The 33-Kilocycle Amplifier ? ........................................? 46
S. The Group Modulator .............................................:... 47
9. Low-Frequency Amplifier ............................................. 48
? 10. The Modulator ....................................................... 51
11. The Demodulator ................................ ........ ............. 53
12. Voice-Frequency Ringing Generator ................................... 53
13. The Voice-Frequency Ringing Receiver ................................ 55
11+. The Limiter ......................................................... 59
15. The 50-Cycle Generator of the End Station ........................... 60
16. The Power Supply .................................................... 61
17. The Neper-Meter ..................................................... 63
18. Directional Filters DK-16.4 ......................................... 64
19. Line Filters DK-2.8 ................................................. 65
? 20. Line Filters DK-5.7 ................................................. 65
21. Balancing Filter BDK-2.8 ............................................ 66
22. Balancing Filter BDK-5.7 ............................................ 66
23. The Call System and the Commutation Field ........................... 66
2La.. The Lead-In Combs .................................................. 70
4pter IV. Installation of the Equipment. Installation Tests and .
Measurements ........................................................ 72
1. Installation and Hiring ............................................. 72
2. Preparing the Equipment for Connection to the Line .................. 73
3. Measurement of the Circuit Parameters 79
4.. Adjustments to be We After the Equipment is Connected to
the Line ............................................................ 80
~pter V. Maintenance Testing of the Equipment ............................ 86
? 1. Tube A4aintenance .................................................... 86
2. Testing the Distribution of Levels in Group Equipment ............... 87
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Page
Appendix No.l. Basic Assembly Diagram of Intermediate Station .............. 89
1. The in Route ...................................................... 89
2. Connecting the Spare Amplifier .................:.................... 90
? 3. The Level Diagram ................................................... 91
4. The Circuits for Level Adjustment ................................... 91
5. The Tone Channel, the Phototelegraphy Channel, and the
Broadcast Channel ................................................... 92
6. The Power Supply Circuits ........................................... 93
7. Signal Circuits ..................................................... 95
8. The Voice-Frequency Ringing Device and the Commutation Field ..~..... 96
9. Measurements ........................................................ 97
Appendix No. 2 . The IEL-4 Vacuum-Tube Tester ................................ 100
I. Purpose of the Instrument ........................................... 100
II. Technical Data ...................................................... 100
III. Structural Data ..................................................... 101
IV. Description of Emission Currents of Vacuum Tubes; Measurements
of the Emf of the Voltage Sources ................................... 101
V. Operating Instructions for the IEL-4 Instrument ..................... 104
Appendix No.3. Connecting the Voice-Frequency Ringing System in a
Four Wire Circuit ................................................... 107
I. Connecting the GTV and the PTV to the Four-Wire Part of an
End Station (with a Differential System) 107
II. Connecting the GTV and the PTVto the Four-Wire Part of an
End Station Whose Differential System is Disconnected ............... 108
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