SOVIET TECHNICAL MANUALS ON THE R-250-M SHORT WAVE TELEGRAPH/TELEPHONE RECEIVER

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80T00246A069100410001-9
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 272
• Document Creation Date: December 27, 2016
• Document Release Date: February 20, 2013
• Sequence Number: 1
• Publication Date: January 20, 1963
• Content Type: REPORT

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50X1-HUM
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CONFIDENTIAL
50X1 -HUM
R-250M RECEIVER
Part I: TECHNICAL DESCRIPTION
Part II: OPERATING INSTRUCTIONS
GROUP 1
Excluded from owtornatic
downgrading and
elaelosaaigsvgawas
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10 ?
U.S.S?E?
50X1-HUM
"P-25 CU" RE CP, I'VE rt
Parta I ?Ind II ?
? OriCTINICAL Dr,f3C:ZI"TIC?ii
Part I
CoNFIIMITIAL
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? h.
Is MSTINATION
50X1 -HUM
.The "P-250:4" receiver is destined for receiving signals of
transmitting radio stations working both on the telegraph and to-
? lephone (with the amplitude modulation) regimess
Possibility is provided for double and triplex reception du-
ring diversity reception -using spaced antennas and translating
operation on lines
With the accessory terminations the receiver can be tined for
reception of teletyping (with frequency and amplitude manipulation)
ondulator recording and for phototelegraphy, and also for reception
.
of'multighannel and multiple telegraphy.
? P:igh accuracy of receiver calibration, high stability of its
frequency and high sensitivity and selectivity make it possible
to establish commaniOntion without search.
? Possibility iaprovided.20r.receiver operation with automatic
frequency control (if.thero is a special notor and an accessory
device - and APC adapter).
' Variable selectivity in the channels of intermediate and low
frequencies makes the operation in conditions of different kinds
Of interference easier.
The receiver completely keeps its capacity for work:
, a) when changing the ambient air temperature from ?10?C to
+50?C (from +14?11 to +122?4;
b) at the air relative humidity up to 98%;
e) while varying the supplYing ascsmains voltage to +15%
'and the current frequency to+ 2r/J.
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2
1
;? d) when varying the accumulator battery voltage (if the r3-
1
,
operation, ?!-
Ks
.? ?
*
MINICAL PAPA
The overall continual frogthency range is within 1.5-25.5 me
? (200-11.75. m). ?
The overall frequency range is divided into a2 bands with
?
? ; overlapping tor each band:
? I b 1.5 -.9.5 mc/s. VII b 13,5 - 15.5 mas
?II b 3*5 - 5.5 7 . " 15;5 - 17.5 *
50X1-HUM
colvors is supplied by accumulatoro) to Jr 10.
.The receiver 13 designed for continuous twonty-feur-hour ?
J
In b .5.5 ?? .7.5 " to '17.5 19.5
" 7.5 9.5 " a ?9.5 - 21.5 ?
,., ?
: *
L ? i ? -VI " 11.5 13.5 "
XII a 23.5- 25.5 a
Switching from one band to another is carried cat by means
* of a dram-typeavitch. The overlapping margin on the ends at each
; 1 ?
band is not loss than 50 M/s; except the second -bands the over-
, 1
,
lapping margin of which is provided by the adjacent bands.
The reolver Innuto. The,rocoiViag device has the following
?
inputaC ?
- I) the antenna, input of the receiver;
:(7* 2) the. second intermediate frequency input;?
3) the input. for driving the A.11,0, motor.
The input automat: circuit of the receiver s.designed for.
?
?Operating fro. one Of four '.antenna. types: '
1
?
?
F
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a) symmetrical antennas ending with feeder line the charac-
terstic impedance of which is within 60- 400 ohm;
b) asymmetrical antennas ending with feeder the characte-
ristic impedance of which is within 60- 400 ohm;
c) type "inclined beam".entennao with such parameters: the
capacitance being within 100 300 pi' and the native resistance
about 100 ohm and whip- antennas with such parameter: the capaci-
tance ie 50 pf and more.
Per operation with antennas the 1:npedance of which differs
from those pointed mit in "a" and "b" the trimming of the roceiver
input circuit is provided.
' Then operating with symmetrical antennas the degree of asym-
metry of input etage does not ezceed 10/0.
Receiver Outnuts
The receiver has:
a) output for operation on two pairs of low-resistance head-
phones of TA-56U type. Berme' voltage on one pair of headphones
is 145 V; .
b) output for operation on line with characteristic 4 pedan-
ce about GOO ohm; receiver line output power is not less than
0.5 w (the output is made on terminal-sockets on the receiver
front panel and an output plug on the casing lett wall);
c) automatic gain control (AGO) output intended Lor combined.
work of receivers during operation with spaced antennas (the out-
put is on the single-vire .plug on the receiver front panel and
on the outputs plug on the casing left wall);
CONFIDENTIAL
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as 5 ad.
50X1-HUM
d) high-resistance output of the second intermediate fro-.
. quoncy (on the single-wire plug on the front panel), is carried
out from the AGO amplification stage.HRigh-resistance output vol.',
_
tage of the intermediate frequency is not less than 0,2 It when
capacitive load is 100 pf (with the nominal sensitivity of the,
receiver); ?
e) low-resistance_ output 02 the second intermdiate frequency (on the eingle-ouire plus aa the front panel) is carried out
- from the second amplification stage .of the second intermediate
.freqUency. Low-resistance output voltage of the intermediate:ire-
quency is not loss than 25 mV when the capacitive load is 1000 fl
_(with the receiver nominal sensitivity);
? 2) detector load output intended for connection of different
? .s
terminationsazd for combination -during operation of receivers
_
with ePaCed antennas (the -output there is on the casing 'left wall),
Receiver JonaltWays
The receiver sensitivity at telegraphy reception is not .
worse than 00G IN when the signaIsto-noise ratio is 5:1, pass-band
at the intermediate frequenc:Ric 3 *c/s and at the low frequency
is 2.5 70/.5,. with the antenna equivalent being 100 ohm. The re-
ceiver sensitivity at telephony 'reception on the came conditions
with the modulation frequency 1000 c/eec and modulation depth ?
3070 is not worse than 3 UV,
CONFIDENTIAL
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50X1-HUM
Receiver ss,leativILL__
At the second intermediate frequency the receiver has.a .
tinUOUaly variable pass?band from 2. to 14 ggis.With the pass?band
control position 12 32. 6 and 12 Keis the frequency characteristice?,
-have'got'the following data: ;
bandwidth I Y.cis ? while rejected two times is 0.7 ? 1.5KCis;
when rejected 1000 times is not more.
than 6.5 Ks/S;
bandwidth 31(cis while rejected two times. is not less than
2.5 RC/si when rejected 1000 times is not
more than 12 eis;
bandwidth 6. Kcis ? while rejected two times is not less than.
5 Kc/s; when rejected 1000 times is not
more tfl 20 7;"cis;
bandwidth 127cis ? while rejected two times is not less than
11Kcis;when rejected 1000 times
than 30Zols;
At lov. frequency the receiver has four 3witched pasd ands'
with nominal values 82 5 '2.5 and 0.3 Weis.
.At operetion an line with resistance GOO ohm:
bandwidth SICcis'? while rejected two times :is limited with
frequencies not more than SO cis= and
not less than 7000 cisec;
? bandwidth 57.cis ?while rejected two times is limited with ,
frequencies not more than SO ciao() and not
? less than 4000 cisec and rejected 10 times?
? ?not more than 6500 c/seci
La not more
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bandwidth 2e5n/s
while rejected two times
50M-HUM
limited witht,
te,
?-frequencies not more than 80.c/see and
not less than 2000 e/sec and when re-
jected 10 times not more than 4000
c/sec;?
bandwidth 0?37c/a.- tone. filter with the mean frequency
900 1100 cisec, and the pass-band re-
jected two times is 200 400 asee; -
when rejected 10 times - not more than
800 0/soc,
The frequency characteristic of the complete receiver at ope-
ration on line with resistance 600 ohm, the modulation depth
boins 30 per cent over the :cense 100 - 4;00
asec is flat within
2 times with pass-band on the intermediate fror:aency 12-Tto/s and
on the low frequency 5. '70/s.
For aural operation on headphonee, frequency characteristic
is made with procreoeive rise of high frequencies an is charac-
terized with the 2011ov:ins data while operating, on one pair of
headphones:
bandwidth 5 Kau - maximum Eain is within 2000 - 5000 esec,
lower\frequeney of the pass-band (at re-
dueinc 2 times) is within 600 - 1200 asec
? and upper frequency of the pass-hand is
within 4000 - 7000 c/se0;
bandwidth 2,5Kas -maximum Cain is within 1500-3300 e/sec,
the lower frequency of the pass-band is with.
in 300-1000 c/oec and the upper frequency
- of the 'pass-band is within 2000-4000e/see5
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bandwidth 0,3 Xas maXimum gain at froquency 300-1200c/s4,
while rejected two time the pew/a?band
Is within 200-400 else?, when rejected
tea times 13 not more that 800o/sec
Rejection of sensitivity at the Image frequencies of the
first and second conversions is not loss, titan 4000 times, Rejec?
tion of sensitivity of the first and second intermediate frequen?
cies Is not less than 10000 times,
.?1
'Automatic Gnin Control
??
When ACC is acting', the output voltage is increased not more
than 2.4 tines, input voltar,e being increased 10000 times (with
respect to its nominal value equal to 3 ,r7).
Amnlitu-e Olirnctorlotie
Receiver amplitude characteristic at operation on line with
? characteristid impedance about 600 ohm ib practically linear 'up ?
'to 17 Volts and up to 4 Volts at operation on one pair of head?
phones,.
nsar nintortions
?. The receiver nonlinear distortions coefficient does not exce?
ed 4 per cent at operation on line with characteristic impedance
600 ohm when maximum power 0,5 W in telephone regime, with nodu?
lation frequency logo eine and modulation depth 30 per Cent, or
? dolIFIDENT/AL
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50X1-HUM
under the Some Conditions at the work on one pair of headphones
:(voltc44 on phone? is 1,5 V) Zoos not exceed 4 por cont.
.1112,4knev Tomerature Ceofficiont
'PreciuencY tethporatzra. coefficient Of the recoiver it the tem-e
porature:dttervalfrem1+500 to 90?C (+41?P to +:122?2) does not
4740004:15107 on the root oned. ,
?
Prom, env 3tabi1l,ty
PrequonO:drift of the first, second and third osoillators
of the receiver Goes not . 500 c/sec while'tho malts voltage
" ? ?? ?
is Chaneed'by:t 10%,
Total frequency .drift of the roceiver.osoillatorn because of
.self-hesting :deed not exceed 1000 c/sec for 2-4 hours (beginnits
, - ?
Hwith:30 minutes from switching on). Durint:! tho following time the
frequency 'is chatzod.not more than by 2CC c's-o for any hour?of one-
.
_ L. ?
rationzYcon condition of censtant ambient tomperature, moisture and.
. _
Atains voltages).
LeSkurro of Onc51Irt,ei Vo)t-ros Ji
Circuit
LeakatieYof-the firet, second and third receiver oscillators
voltages 'and tilt:ir harnlOnioai moasurad at the r3ceivor inputoload?
.ed on the contenAS?oqUiValent to 200 ohm, does not exceed 10 W.
-
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_ 50X1-HUM
NOTE: Tho ex:a-3'4;011CD Of 5 ..fixoa points_ with the level up
to ona one point vath the loyal up ? to 50 MI
lei allowed.
Inner Crrbinaticin_Trkterforence ?
Boats of.the first and seconf o cille.ters harnonics -result in:
Inner combinatin interference I:7111th is hea2.-8. Alt 0070 points of
the .re co iver frequencies range
As a .rulet .the :level of this ?interference is mush lower thsn
the nominal sensitivity of the roc,?.:iver the telegraphic regime.
. ? ? I . ? a . ?
Calf!F!ration Accur:c7
Under the nercal operation consUtiens at the tac:poratu.re. 2u C-
?,9?I7 (63?0 + the total orrorc2the calibration =a frequency
? ?
sot-up of the 1..ceiver .does net excced I7as after scale_ correc-
tion uoinr,
the
inner crystal cztlibrater; at other tor:peratures .1.7?02
-10?
to -:5000 (-144?11/ to ,r122?0) the error does not =coed 1.57e/s,
'Mire _correcting the scale at the point situated near the
ro?
co?vci fro1uency2 the error of calibratiOn can be cons:Li:let-ably
? created comparing with. the ,inflicated values (approximately to
. .? I I
;CO asec).
..?
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-.1.1 -
lcale Dev:Ico ?
50X1-HUM
The receiver calibration is performed directly on -the read-
ing scales, The scale device consists of a 'coarse tuning scale
and of a fine tuning scale.
1arl.cs are plotted on the coarse tuning scale on 0.1 mc/0
and figures in 0-5 mc/s. The fine tuning scale is.optical, each
part of 0.1 mc/s of the coarse scale is divided into 100 divisions,
14e3 the divisions are plotted in I Kase 1:igures On the fine calib
ration scale are. plotted. in 10 70/31.
Bands Indicator is matched with the coarse tuning scale.
Correction of C,041:.rnt4,
To diminish possible calibration error:: -nder the influence
of different .destabilising factors on the reccHwr (charp chanros
of temperature and moisture, tubes replacement others) the re-
ceiver is provided with the correcting system and a special crystal
.calibrator, the fundamental frequency of which is 100 Kas (vacuum
crystal is placed in thermostat).
'Correction of calibration is carried out by means of:. .
a).trimminG capacitor in the second oscillator circuit
wicimputlecimil voppolmon" ("electrical corrector");
b) displacement of optical scale sight frame - " EoppeitTop
=am ". ("scale coreectorl)
.c) the first. oscillator trimaing capacitor (correction of
the first oscillator crystals frequency),
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ta--au-c-osr-
50X1 -Fium
The Recoivag_contvls
.The following details bolong to the receiver controls:
1) the main tuning knob with two stages of deceleration
1:5 and 1)45;
2) band selector;?
3) the first and second intermediate frequencies gain,control.
knob;
4) low frequency gain control knob;
.5) .control knob of intermediate. frequency pass-band;
.6) knob with a vernier control to the third oscillator fre-
quency;
7) low frequency. pass-baad switch;
8) switch for checking the main tubes currents, supply volteze
output voltage.levelef audio frequency, and for tuning indicator
and thermostat operation indicator;
9) knob for the input circuit alignment;
10) antennas switch;
11) switch 'of.AGC time contact;
12) mains tUtbler switch;
? 13) switch of kind of operation;
14) tumbler switch of crystal calibrator for the first oscilla-:
tor frequency correction;
15)tumbler switch of crystal calibrator for the second '
lator frequency correction;
16) the second oscillator froquency.electrical corrector (with
the slot);
17) mechanical corrector of the scale (with the slot);
CONFIDENTIAL
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50X1THUNA,.,
18) the third oscillator frequency electrical collector (with,
the slot);
19) slain morals control (with tho slot);
.20) tho. first oscillator frequency electrical corrector;
? 21) the crystal calibrator frequency electrical corrector;
.:22) half?duplex operation switch tumbler;
23)the 'second Intermediate frequency input switch tumbler;
.24) .the A.F.O. motor switchinc?in knob;
The Receiver Tubes
? ..The total number 0i :receiver elettronio tubes is 19) from
which: 10. tubes? 63, 3 tubes ? 6a4 3.tuhes GA?, . 2 tubes -!?
?64C1.1 tube tr, 6116c.
H?To stabilize plate voltace of the second oscillator tubes
. .
gas stabilizer. cr-30 is applied),
The Receiver. Voltee7e
. ;
i HIPorHsuPply. froM,the. ains'the set of the receiver contains a
rectifier.:
HA vibropack of Bil-I4-I2M:' type as included into the supply
devices set by means of which the entire :supply of the receiver
31,110D1Y 'System
The fundamental. receiver'supply source is the altornatinc
current mains)-the'voltagPbeinc either 127 or 220 Tend frequency'
..50 c/sece
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-.14
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from the emergency sources (the 12 V battery) io carried QUI:.
It io added by. a special order.
..Power Data of,the Receiver
Normal plate voltage /3 160 V. Normal heat voltage is 12.6 V.
/17ith the normal supply voltages the current consamption by
the receiver does not exceed 120 ma for anode and 6 A for heater.
.Tho consumed mains power does not exceed 130 VA.
Overall Dimeneione.of the Receiver and its
.0verall. dimeAsioneef the raCeiver,with the closed cover
without dampers but including the projecting parte are: width -
.? 67p mm. (26.3/8 inches); height 450 mm (17 23/32 inches); depth-
'480 mm (18 57/64 .incheo); its dimensions with aympers are 670 mm
x520mM x 540m (26. 3/8 a. x 20 15/92" x 21,17/64").
The receiver weight in,the working set (with tubes and dam-
,
pars) does nOt'exceed 95.kg (2C9,25 1bs).0
Vibronack ? .BIT-1.4-1.2M H
?? ?
The BR-I4-I2M vibropack (Eig.55) serves to convert direct'
.voltage :12V into direct voltage 145 V. Supply
cource of the vibro-
pack may be storage battery with voltage 12 V, capacity not loss
thaa 100 a.111.. or direct current main 12 V.,
'
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a.
?15?
50X1-HUM
The vibropack data:
Supply voltage is 12+1.5 V,
Output voltage is '145+10 V
Load current is 100 ma
,is not lower than 65%
.Ckatput power is 15 W ?
Overall dimensions of the vibropadk
Width is '15 mm (4.17/52")
Length is 210 mm (8 17/64")
? Eeight is 160 mm (6 19/64 ")
Weight ? STI-14?I2M with spare vibrator is 4.7 kg (10,35 lbe)
The type of the Vibrator is BC-12 (hermetic). .minimum life-
-time is not less than 500 hours.'
ITT, SZT CO1PCNENn
The following components are Included into the receiver de?
vice cot:',
a) receiver with the working sot of tubes;
b) rectifier with the working pet of tubes;
c) vibropack of Bil?I4-12M type (delivered at special
agreement .with thecustomer)3
d) spare and accessory equipment;
e) documentations,?
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.tiNCIPLE OF OPMATION
)
50X1-HUM
? Receiver is a superheterodyne with deable.froquency cancer-,
. ?
slon on all bands, besides the first one, On the first band the
receiver has one frequency convex-elan as in this case the first
? Intermediate frequency range is the range of the.raceiyed frequency
The peculiarity of this receiver circuit consists in usi4g
crystal control ofthefirst oscillator at operation on the con-
tinual range of received frequencies, This makes it possible to
ensure in the receiver rather high frequency stability and calib-
ration accaracy because in this case the highest frequency reed-
(
'-'ver oscillators are crystal controlled,
?The essence of the superheterodyne method of radio reception
with the crystal control of the first oscillator 13 as follows:
the whole range, of the superheterodyne received frequencies is.
'divided- in such a way that on all bands -ah'equal number of kilo-
cycles is overlapped (j$ the Case in question it is 2000 1Ccia).4.
Por each band one invariable frequency of the first oscillator
(which is switched'simultaneously rith the band change) is
established, and it. iz crystal-controlled,
In consequence of it the intermediate frequency after the
first conversion (the difference between the rqcoived frequencies
and the first Oscillator fixed frequency) is not constant, as
usual, but variable according to tho.Chaage of the received fre-. rTh
\re.
quency (in the case in question the first intermediate frequency
change is by 2000 74/0)..
323--
See basic diagram
, CoNFIDENr2IA.;
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an-
50X1-H UM
Since the equal .number of kilocycles la overlapped on all
bands- (according, to the .condition of their division)*
the change
of the firet intermediate freqUency will be equal on all bc1.21az.?.
Choosing the firet crystal controlled oecillator frequencies Co
that the .frequency on one band r :!iffers from the frequency 02
anotherband by the value o2 overlapping an frequency (in our
case it. Sc 2000 Kc/s)a. we shall get change limits of the first
intermediate frequency for all bands which will be equal not
only in overlapping bUt also in their absolute value. So the amp-
lifier or thd first intermediate frequency is a range one (in this
case-it is with frequency.change lieits from /500 to 3500 re/s)4
The second receiver oacillator La made as a range one in A
'order the intermediate frequencY (which is the difference be?
? twoen the second oetillator frequency ana the firct intermediate
? frequency) after the second conversion should be constant (in '
the case in question It is 215 gc/s)4
The next pert of the superheterodyne receiver circuit is
made as,usual.
irrnut otatze
The inputeircuit of the receiver is a singletUned?circuit
preselector connected before the zria of the first tube. The re? ,
ceiver input is deeigned for operation from four antenna typos.
/ 1 simplified 'diagram of the receiver input circuit at opera-
tion from asygmetrical antennas is shown in Pig.10 the one during
operation :rem symmetricaLantennas is shown in Pigall, and the
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CONFIDENTIAL
18-
50X1-HUM
One during Operation from Open or rod antannas is shown on Pig.121
Switching from one antenna type.to:anotheris possible?by?means
of the switch (it,5)..When operating with symmetrical'andtcym-
metrical antenna types an inductive coupling of. antenna network
with circuit is used for creation"of input balance a balance-to-
-Unbalancejbalun) transformer is sot, when operating with rod:
Qr-4)Pen:.en44s:it is'a capacitive one,
::POr-14takage.of static changeS. Which are formed on symmetrical
' antennas and cause ixterforencel.the resistors (it.3 end 4) are
provided at the receiverinpute. ?
By
means of (?t018) the prose:lector circuithasget
an alignment in small limits, The aligntent ensures matehingthe
receiverinput.at-the operation with different antennas, If the
antenna has purely active. parozater3 CR within 60-400 ohm), input '
alignment at' operation it usually not zaceded,
-^.00, protect input Circuits from overvoltarfe by high frequency
'signals (in the ease of operating hear a powerful transtitter) a
neon discharger is connected parallel to the precolecter circuit
(it019)* With voltage increase on the circuit up to ignition
threshold of the discharger, that is approximately up to 50 Vo a
' glow discharge appears In the neon lamp; the dischater conduct-
ance shants the circuit, removing the possibility of further ?
voltage increase ,on the input circuit and in the subsequent cir-
_cults.
UtIn circuit elements of the preselector are; inductance
coil,
coil, variable capacitor and padding 'capacitor (besides the first
band where the necessary overlapping is carried out with the .main
variable capticitor)40
'
OC NFIDENTIAL
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CONFIDENTIAL
50X1-HUM
Por
For oxamPlei for the third band the main circuit elements
.are:.circuitcoa and.antennecoupl Coil (it42), variable
?
capacitor (it.17a)4 padding 'capacitors (it.14)*
Circuits-fcircuit coils, coupling coils, paddins capacitors
? and so. on) are chanted in bands' .(cee basic diagram).
The receiver cot Contains a 'special radar-proof gilt-mr sup-
pressing the frequencies VaP and unto reaps. In the case Of radar
interference the filter it to be connected to the receiver.input '
?"- P12,14 chows' the eircuit'of the filter. Pig'', shows the connec-
j-?
7:tion of the radar-proof tilt:gr./co the receiver*
'a? set,224.6r:SIer ?
After the preeeloctor the =calved c:!snals of high frequen-
cY'are amplified with two radio frequency stages. The first eta-
to operates on jp114...7 tube, the second ono is on the. 6R3 tube.
.Sheistagee aredesisned with the transformer circuit An
inductive-capacitive coupling, which improves the stage gain con-
!, ? .
stancy Within the band, is applied te come bands (from the first
to the fifth inelaciaa)t.'
A simplified circuit ?tithe first otage of the radio fro-
.
? quoncy amplifier is shown in 218.19.
The main elements of amplifier statea circuits are: cir-
cult coils, plate cells, variable capacitor and padding
tors. .Por instance, the main elements of the first amplification
stag() 'circuit_fOr.the.thira 14ksad are; plate.ar4 circuit coils
(it,79)>.variable capacitor (itfr17 c ), coupling capacitor (it.
80), padding capacitor (it.a2)..
CoNFIDENTIAL
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CONFIDENTIAL
50X1-HUM
The First 7.2,ixer ?
?H-fl..Aftor:.the two-stage amplifier the received hien frequency
- signals are fed.to the grid of.thelirot mize.m.dosicned on the
GA? thbe The basic diegram?of the first pixer Is shown in Pic,16,
. The miter Plate eirOuit is loaded on the first intermediate fre-
quency circuit (transformer connection) which operates in the
Continually-changinsfrequency range within 1,5 - 3.5 me/s..
At operation on'the.first band the first mixer becomes an.
amplifier(the first oscillator is switched off), and only one
-frequency conversion is used on.this band, The main elenents of
the first mixer plate circuit are: coil (it .286). and variable.
? capaditor (it.171r)
The First Oscillator
The receiver first oscillator (type c7Atabc) operates ,
Hwith crystal without tuned Circuit as Is shown in 2iss, 17, 18
and 19.:Thefirst oscillator does not operate on the first band
-? .and ,with that the control .i24.7id.iemoarthed". Two crystals are used
on the second band: on frequency 2,02 mc/s (it,240) and on fre-
quency 1.93.no/6 (it.239). Crystals operate in tura; on one part
of the scale operates the crystal 2,02 me's, on the second one
operates 1,98 mas,
? Thc. using crew?. crystals'makeS possible to exclude the af-
fectod?zons:ef the band in the receiver, which could appear while
using ono crystal on frequency 2 mc/s, In this case crystal
CONFIDENTIAL
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50X1-HUM
queney would colncide with the frequency of the first intermediate
'frequency which changes continuously from 145 to.3.5.mc/s (and,
consequently passes through tuning. on 2 mc/e)..
? The crystal commutation system on the second band coupled ' ?
with tuning capacitor is designed ia such a way that at operation
an one crystal the scale ends with the received frequency 4 moist
and:at operation on the other, one it begins with four mc/s (tho
frequency margin near each point 4 mac ia not less than 20 r:cis*? .
Coarse tuning scale and optical scale have a marked non-ope-
rating area in whieh crystal switching takes place. The switching
(=Cue by means at two contacts set in a free section of the lower
unit of the variable capacitors. The crystals of the second band
are installed in. the came?placee
' The first oscillator basic diagram on the 11 bend is chown
Pig. 18? 4
On the third .band the first oscillatorfrequoncy is 4 mc/e,
on the. 17 band - 6 mc/s, on the V - 8 tic/s, on the VI - 10 mc/s,
on the VII .12 mc/Suon the VIII 14 Mc/c (cristal 7 mc/e , the
second harmonic is used), on the IX - 16 mas (crystal /8 mas v
the second harmonic is used), on the X - 18 me/s (crysta1.5 mc/s
- the oecondharmonic lanced)' LIU -'20'mc/s (crystal 10 mcis
the second harmonic is used), and on the XII band the first oscil-
lator frequency 12.mc/a (crystal II rWs - the second harmonic
12 used).
The basic diagram of the first oscillator at operation on ?
-the In band is shown in Fig4174 At operation on the X band it is
shown. in Lugar .
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50X1-HUM
Time, the difference between the frequency of tho received
signalat.any point of any band.and-tho firstoscillater frequen-
cy .rosults-in frequency within:116.- 3'45'me/3y'that is the first
intermediate froquencyS.
. Altegether.12'erystals are 'used in the first oscill.tor,
of the receivers
For the. first oscillator equenc correction (when the tube
changoo'consIderable.fluCtuations.of t! ambient te-riperaturet,
crystal."ageine andso.on) the circuit is provided 7tith special
triming camIcitors_hy means le' which the oscillator frequency
can be changed within certainlimits (200 1000 c/scos)s ?or
each band a .seperate.trimmer is ucad, besides theII band where
there's's. Only one trimrcer for 2 cry:;tals,
The Pirrit 7nte-modiate Prormoncy Alfier
The receiver first intermediate frequency &naes within
115 - 345 me/a, ?
The firdt intermediate frequoncy amplifier has one? sta e on
6X3 tuhe.(its300).
The basic diagram.of the first intermediate?frequency ampli-
Tier is.,hovn In ei6si,20..'
Plate load of the stage is a double-circuit tuned filter ths
main elements of which are two inductance coils (it .307 and 317)i
and two variable cap.:!citers (1)417 ana lye).
Coupling between filter eireuits as Intel-nal and exto?nal
?
?
capacitive; it is correspondingly carried out with capacitors
. CONFIDENTIAL
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?23
50X1-HUM
(it.312,313 and 314). Coupling system between the circuits on
this stage is adjusted In ouch a way that stage amplification de-
creases with Intermediate frequency increase, and thus .compenea-
tier. of gain increase in other receiverotages is achieved.
. Together with the first converter circuit three tuned cir-
cuits operate in the. intermediate frequency channel.
.As it-was already pointed .cut, amplifier stage of the first
intermediate frequency operates on the first.bdnd as an amplifier
?
of the received:frequency,,:Thus
r
circuits,-tuned.te the received
at this band the total number of
frequency, ,equals to six.
The :7,econd 119.x07,
The.second mixer operates on the 6::7 tube. A simplified basic
diegram.of the second mixer is shown In. Pigo21, The plate load
o2 the mixer is the selective multisection filter tuned to the se-
send intermediate. frequency, that
combination frequencies which are due to the harmonic beats of the
first and second oscillators, the mixer plate circuit includes
filter consisting' of choke (it0322)3 and capacitor (it.323).
la' to 21,5 Xe/s. To diminish the
On the first band the second mixer -is the: first mixer, and
on this band the receiver operates with one frequency conversion.
Secona Oocillator
The receiver second oscillator operates in a ocmtinual fre-
quency range within 1?.715 - 37l5 mcis (two tubes of 0;c3 typo).
The casic diagram of the second oscillator is given in Pic,22.:
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50X1-HUM
. Thus. the second intermedioto.frequency which is .the difforen?\.
ec of the second oscillator frequcacy :ma t110 $irst Illtermcdiate
frequency is constant and equals to 215 Wo/s,
The oscillator is assembled according to the oircuit.with
back- coupling throuf,h an additional atolifying stage,. .recause of
rather Slight coupling of the tubes with oscillation circuit this
circuit is notable for good frequency.stebility (while the change
of supply voltages and oelf?heating of oscillator tubes),
La order to increase frequency stability a .type cm Gas sta?
bilizer. of oscillator tubes plate voltage is employed,.
Second oscillator voltage delivered to the second mixer is
taken off from the grid circuit of the oscillator arnlifying tube
from re3istor.(it.540) throuGh the capacitor (it0320).
The main elements of the second oscillator circuit ara: tir?
,
cult coil (it,349), variable capacitor (1t,:17. and Paddin&
pacitor (it0515),
For. calibration correction a special trimMing caoaciter
3-51) 13 included (7 anefuNgoczlin Itoppel=m
ca-
? ? "clect--;cal corm.:
rector" the axle of.which ip brought cut to the frentHanci (With
the slot)* 4
Variable cap2.citors.cf the preselecter,
amplifier ofthe.fir,'
-intermodiate frequency and the second oscillator aro united
into
one common capacitor unit (seven capacitors of-variable cap:city),
the rotor plates-of which ara
;
r ?
rotated by
double. 1.!nob
tunings
When the secend intermediate frequency
input
of rocc.?vor,
is ewitcheca pia,
pfate_ve/tSge of second oscillator is 37:itched off. (see
, CONFIDENTIAL
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50X1-HUM
? Crystal Calibrator
The receiver calibration correction is carried out by the se-
cond oscillator circuit trimminc, scale eight ?line displacement,
and the first oscillator frequency chance by means of the trimminc
capacitor.-
For calibration correction. a special crystal calibrator is
installed in the receiver which operates on the type ?Z4 tube in
the circuit without tank. The calibrator basic diacram is shown
in riZ*23. Crystal used is vacuum one with basic frequency 1007c/a
(reference points follow,ig 100 Rc/s)a
th th
For calibration correction harmonics from 15-- to 255 ? are
used. Harmonics voltaco is fed to the tube plate of the second
stace of radio frequency amplification.
In order to increase calibrator froquetcy stability the
eryetal reeonator is placed into the thermostat, the temperature
it which is maintained within -1-100 utd the operatitc temperature
4 600c (4140011)4
? The thermostat operatiot proceeds as followo. then the re-
. ?clever is switched on thermostat, heat windinc (see basic clic:cram,
.its357), Cots its supply froz. heat'voltaco of the receiver tubes..
With that mercury thermecontecter (it.358) is broken and 40
,current is fed to the relay of heating (it.363)* When some tire
which is necessary for temperature rise in the thermostat up to.
6000 has passed, mercury thermocontactor will close. supply relay.
? circuit (relay is supplied from the rectifier on crystal diodes),
CONFIDENTIAL
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Relay will switch off the thermostat heating-winding
4-
.L0X1-H ti
switch on ballast resistor (114394), na/last rSolJtor is nocoasa1
ry to keep heat voltage constancy in the receiver when the loud
is changed (in case of switching 0.22 the thermostat heating wind-
2,213)*
Thermbstat is getting Cold, .Whon the thermostat is coolisrt
dews the temperature lower then 60?C, the mercury thermocontactor
will be 'broken which Causes the relay switching off. At that the
thermostat Leafing winding gets the feed.: If the mercury thorme-
contactor; rectifier or relay is incorrect, the process of thermo-
stat heating is not stopped at tire ter1De-ature +60?C. To avoid
inadmissible .Overheating the thermostat circuit contains a fuse .
therthoprotoctor (it,35e)breaking supply circuit of heating wind-
ing if the temperature In the thermostat rises up to 80 - fee
(176 - 185?P),
'Nigh Stability and accuracy of frequency Is secured by usi-c,
in the calibrator a thermostat' and 'crystal with small frequency
temperature coefficient,
Calibrator frequency deviation after 30 minutes from the =-
mint Of the receiver switching on does not exceed 60c/seo on the
XII band (on other bands the 'error is proportionally less), ?
Whet the calibrator tube is replaced the frequency error does
net exceed 100 asee on the XII band (without frequency correction
To correct the frequency of the crystal calibrator (in case of
crystal ?ageing" $ tube replacement
arid
se on) in the circuit is
y provided with a special trimmer (1t03G7)$ the control of which is
carried out from the teeing roar wall,
_?
CONFIDENTIAL
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-27?
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50X1-HUM
Tho Second InSoryeeClisteyronaenev AiTnliner
The receiver second intermediate frequency is 215 Xasece
The.aMplifier of the second intermediate frequency is a throe-
stage ends
.:The basic diagram of the first, the second and third stages
of the cocond Intermediate freqnency amplifier are flown in rigs,
.24, 25, and 260
Tho:firet stage (typo 6X3 tube) is loaded on the selective.
multisection filter.
,
The socend and third stages (6X3 tuba) are realised as the
- rosOnant amplifiere with transformer connection of tank in the
'plate circuit. The coupling of the plate coil end the tank i0
1nductivotcapacitive one
VariablescelectiVity in the receiver is achieved by means of
.continual change of pass-band in two selective multicection filters
cc acted In the plats circuits of the second mixer and tho first
amplification stage of the second intermediate frequency.
.2ach selective multisootion filter iacludes four circuits
'coupled one with another by means of. external capacitive coupling;
filters outputs are loaded with resistors.
Thbn the pass-band changes, coupling capacitors valueS aaa
filter lead isolators change. acCordinglyo
As the filter with external capacitive couplinc rives banZ
expansion to one side of the mesn.frequoacy of pass?bend (ryhon c.
pacitive coupling 13 increased), the circuit capacitances chazIce,
in. the receiver simUltancously with coupling capacitances values
CONFIDEZITIAL
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54
-HUM
?
?
change; the-results in constancy of pass-band mean frequency,
? Filter coils with fundamental capacitances are placed into
special hermetic screens*
?? ' The elements of the second stage circuit of the Second Inter
?"mediate frequency amplifier are:. coupling coil and oscillatory Cir
cult coil (1t.465). 'circuit capacitors (it.474 and 475)s and coapl
Hing capacitor (it.459)*
t'-. Circuit capacitoram(it.474 and 475) for a capacitive divider
-
from which low-resistance output of the 'second intermediate fro-
--:quency is realized..
- - The third stage amplieler'Circuit has coupling coil and
? ?
. .
'Circuit coil (it.492)0 circuit capacitor (it.705)sand coupling
capacitor (it:478).
:An%additionel can control "gain twarvia"-n
?3anac yeti=
is, carried Out by means of voltage chance on the acreoninc.grids
of the three tubes of-the second Intermediate frequency amplifier.
The secondaad the third amplificatioa ?Auger; of the second
'intermediate freqUency preCtically have no influence Upon the re-'
'suiting receiver selectivity and fulfil only the necessary ampli-
ticatioa of the second intermediate' freqUency.-
7 :
? ;
C.:: ? . ,
r
.After the second intermediate frequency amplifier the second
.intermediate frequency voltage is fed to the diode detector (ono
.cliodenf.the typo &Ilia tube is used).
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50X1-HUM
The basic diagram of the detector i3 shown in Vig.27.
The second half of the-diode is used for teat voltage vneelurtt
?
cent (see aection "Current and'Voltacca Control").
The load of detector ia the resistor (it.483 ). Prom this
resister audio frequency voltage is taken of: end it is fed to the
grid of the low frequency amplifier first stage. This is carried
out through the'intez:lediate frequency filter consisting of two
high frequency chokea?(it.434 and 435) and capacitors (it.48G
and 437). Voltnge rectified with detector which can be used for
addition a operation. of several receivers is fed to the output
plug situated on the belt wall of the receiver casing (detector
output)4
Audio Pi'cluenc-A Am11,f:ser
.Audio frequency amplifier is the three-ste one and has the.
following pass-bands: 8, 5, 2,5 and 0.5 Ii.c/sec.
In order to get pass-bands 5, 2.5 and 0.5 Kcisee aifferent
low frequency filters are switched on the plate circoat of ?
the tube of the amplifier first stage.
:7be fundamental. filter elements are four chores (it.54235S3,
564 and -56'5) and fixed capacitors. Or. bands 5 and 2.5 Fasec the
filter consists of thme sections of n -type. Capacitance values
egla V arc chanzed with overswitching from the be:nd 5 Ic/s3.,0 to the had
2.5 Fc/sec. -
CONFIDENTIAL
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-HUMS.
'. A simplified diagram of the audio frequency amplifier first
stage for bands 5 and 2.5 Kas is shown in fig.20. "!ith the over- C
switching to the band 0.3 Xas the filter Cireuit'acquires the view
shown in pis.29,
With the setting of the pass-band $ "rfc the _37/frequency'
filter is switched .off, the amplifier first stage has the view
shown in Pig050. ? .
. The second state of the audio frequency 13 a resistive ampli-
fier on the 673.tube. This stage secures getting of the necessary
voltage of audio .frequency for the receiver outpat stage operation.
Frequency characteristic of. this stare does not.pr%ctically
.influence the resulting frequency charscteristic of the Whole QM,-
plifier. Tube operating regime is chosen from the condition'of
getting minknum distortions.
. Negative back Coupling voltage te.i;cen off from an output trans-
former special wind1n57 is fed to the second
to.ocie
tube cathode.
A basic diagram of the second stage is shown in Pig .31,
, The third stage (the output one) of the audio frequency
amplifier is designed for operation:
' ? aYoa one pair of low-resistance headphones of TA-56r type.
with normal Voltage 1.5 V on them;.
' b) on line with characteristic impedance 600 ohm with out
power 005 Wo
' . Tube operating regime is chosen se that the output stage
amplitude characteristic at operation on one pair of headphones :is
practically limear.up to 4 V, and at operation on lino - up to 17V.
CONFIDENTIAL
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? 50X1-HUM
The audio frequency output* stage is made on MG tube with..
transformer in the plate circuits A special winding (see Vig42)
on the'outputliransformer is utilized for the negative coupling.
To diminish the supply mains'alternatinc?current hum level
(which' is due'to.the voltage leakage from the tube cathode heater ?
into cathode circuit)in the first. P.A. stage a,Fipecial bias.
is realized between the cathode and heater for hum loc'r!ing.
Locking %Lae is a certain :direct currant voltage between the
tube heater and the cathOded?
In the circuit of the Aolv, first stage bias voltage develops
on the resistor (it.708)*.
The Third Oscillator
-
6k? tube which performs the functions of oscillator and de?
' toctor'is employed for continuous vfavea, telegraphy reception by
the beat method.
The basic diagram of the third oscillator at operation with
the resonant circuit is shown in Pi3.33; and at operation with
crystal ? in Pig.34.
The third oscillator resonant circuit includes the variable
capacieor (it0517) which gives possibility?to chanye oscillator
frequency by 5 Kc/soc.
Seat:tone frequency. can be determined by the sonic natchc-d
with the knob of the third oscillator variable caonciter which is
situated on the receiver front panel..
cONFioziniat
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50X1-HUM
Vor oscillator scale correction trimmins circuit (it.G16)
used, Control of this circuit is carried out Zr= the receiver
front panel with the set*:
Circuit correction is used alSo? for getting ,beat tone up to
10 Reis* Per this purpose zero heat? are adjusted by means of the
circuit corrector, when the beat tone ?scale ..1.2 in. +5 or -57c/s
position.
. To avoid the third. oscillator frequency leakage. an, the re-
ceiver audio frequency input, a filter is placed on the converter
plate circuit*
In order to diminish the e...c* hum caused by the third-oscilla
tor, 6117 tube cathode possesses certain positive potential in
relation to the filament due to voltage drop on resistors (it.'
693 and (55), when tube Cathode currant passes throush them,which
isenalogous to the effect of resistor (it.703) in the audio fre-
quency amplifier*
, .
The possibility 6.11. the third oscillator a-perstion on crystal
(t = 215 Kcis),in the receiver practically excludes the third osci
later frequency error ,at the calibration' correction of the whole
receiver (freouency correction!: the second and first oscillators
? and gives possibility to 'carry out the third e-eciilater scale cot'-
rection when it operates without crystal stabilization.
? The switching on of the third oscillator is carried out by
means of switch. of kind of operation- (it.507).
, CONFIDENTIAL
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coNFEErna
33 -
AuSnm7tio OcIr; Cnntrol
50X1-HUM
The receiver automatic gait control system (AGO is delayed
and amplified.
Pig, 35 show's the AGC basic diagram, regulated tubes are eive
The control voltage is applied to the control grids of five
tubes of the following otages:.tho.second'stsge of radio frequency
amplification (6K3 tube) s the first mixer (GA?),
the first inter?
mediate frequency amPlificaticn stage, the first and the second ,
amplification stages of the second intermediate frequency (61(3
? tubes),
The amplification .stage is realized on the 61