THE SOVIET LENINGRAD T-2 TELEVISION RECEIVED

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80-00809A000700100182-7
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 28
• Document Creation Date: December 22, 2016
• Document Release Date: October 24, 2011
• Sequence Number: 182
• Publication Date: January 17, 1953
• Content Type: REPORT

Declassified in Part - Sanitized Copy Approved for Release 2011/10/25: CIA-RDP80-00809A000700100182-7
INFORMATION FROM
FOREIGN DOCUMENTS OR RADIO BROADCASTS
CLASSIFICATION S-E-C-R-E-T
CENTRAEINIELLIG'&E AGENCY REPORT
COUNTRY tTcSR
SUBJECT Scientific - Electronics, television
HOW
PUBLISHED
WHERE
PUBLISHED
DATE
PUBLISHED
LANGUAGE
1951
Russian
CD NO.
DATE 0c
INFORMATION 1951
SUPPLEMENT TO
REPORT NO.
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D. kheyfeta, V. IQibson
Leningrad
ffhis :repo_'t plea?-nl s information on the Leningrad T-2 televiei.on
receiver, taken from an article In Radio, No 9, 1951, and also a cir-
cuit diagram and a .list of component_ a v as the enclosure
to Air Attache tl'SSR Report No iR-68.52 A general
deecriptic,n of th= receiver can be found
Figures rsfe red to are appendea. Numbers in parentheses refer to
append ed 301: ie:7
Picture Channels and Sound Accompaniment
The .-thematic diagram of the telev.eion receiver is given in Figure 1 and
a block diagram of the video and sound accompaniment channels in Figure 2.
As may be seen from the block diagram, the rf amplifier stage, tube L1,
is a 6Zh4 {{(6AC7), the mixer, tube 12, Is of the same type, and the oscillator,
tube L3, is a 6528 6Z5). These tubes are common to both channels. The pic-
ture and sound accompaniment channels are separated at the intermediate frequency.
The average int w mediate freluency of the Bound accompaniment channel is
29 Mc and that of the picture c.banuel, 35.5 Mc.
The i-f values were selected to el'minate interference which may arise
in the picture channel due to the beats betveen the i-f harmonics of both chan-
nels with the carriers and aide bands of the video signals.
STATE
ARMY
NAVY
AI R
Declassified in Part - Sanitized Copy Approved for Release 2011/10/25: CIA-RDP80-00809A000700100182-7
 Declassified in Part - Sanitized Copy Approved for Release 2011/10/25: CIA-RDP80-00809A000700100182-7
The video amplifier has two stages, tubes L7 and L8. Its amplification
factor is 120. This makes it possible to apply a low-value video carrier (0.5-0.7)
to the. detector input and still obtain a linear detection characteristic. At
the video channel output, the signal polarity is negative.
For the i-f values selected, the oscillator frequency must vary from 85 to
115 Me. At such high frequencies, frequency stabilization becomes difficult be-
cause of fluctuating supply voltages and self-heating,
The schematic diagram of the oscillator is shown in Figure 3 and its equiva-
lent circuit in Figure 4.
The oscillator uses capacitive feedback; capacitor C4 is connected in series
with inductance Lk. This circuit, even without heat compensating elements, pro-
vides sufficient stability so that the oscillator. need not be tuned for several
hours.
Tests of the receiver showed that there was practically no frequency drift
for 30 min after a 10-min warm-up.
From the mixer's plate circuit, the audio signals are fed through capacitor
C15 to the i-f amplifier of the sound accompaniment channel, using tubes L9, L10,
and Lll, all 6zh3's, These signals then pass through an amplitude limiter, tube
L12 of the same type, and enter the discriminator, a duodiode L13 type 6im6s.
We will point out certain features of the receiving part of the circuit. The
input of the receiver is aperiodic. An active resistance, Rl, of 75 ohms is con-
nected between its input terminals. This insures good matching of the input cir-
cuit with the antenna feeder, which is loaded by an impedance at the receiver
terminals snot to the --
- ..?.a.oc,.uinLic impedance.
Dc reinsertion is accomplished with the help of a peak detector in the grid
circuit of the video channel's output stage (right half of the twin triode L16).
This stage can be connected to the cathode-ray tube without blocking capacitances.
This considerably simplifies the problem of correcting the amplifier for lower
frequencies.
The picture contrast is controlled by varying the bias on the grid of tube
L1 of the rf amplifier with pote'Itiometer R3. This adjustment permits a 100-
fold change in receiver sensitivity, while maintaining the resonance curve prac-
tically unchanged.
In addition to the ordinary sensitivity control in the rf amplifier, control
of the amplification of the sound channel in the i-f stage is provided by potenti-
ometer R45. This adjustment is made once when the receiver is installed and reduces
the voltage of i-f harmonics of the audio signal at the limiter. Thus, it prevents
interference on the raster from combined frequencies created by beats of harmonics
of the i-f audio signal with the oscillator harmonics.
The band of frequencies amplified at the rf and i-f band is 4.5 Mc, and the
band width in the video amplifier reaches 5-5.5 [ic, which provides the proper fi-
delity curve.
The rejector :alter at the video amplifier output consists of choke coil Dr 12
and capacitor c143 and is tuned to 6.5 megacycles. Its purpose is to eliminate
parasitic modulation which appears as dots on the raster lines. These are caused
by detected beats between the i-f sound and video carriers which reach the modu-
lating electrode of the kinescope.
The Scanning Unit
Line scanning is accomplished with a separately excited saw-tooth oscillator.
This oscillator is used to obtain a high voltage for supplying the plate of the
cathode-ray tube:
Declassified in Part - Sanitized Copy Approved for Release 2011/10/25: CIA-RDP80-00809A000700100182-7
 Declassified in Part - Sanitized Copy Approved for Release 2011/10/25: CIA-RDP80-00809A000700100182-7
S-E-C-R-E-T 0 50X1-HUM
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