A SUMMARY OF SPECIFIED TESTS OF THE RS/C-11 RADIO SET

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78-03424A002400060003-8
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 8
• Document Creation Date: December 22, 2016
• Document Release Date: September 20, 2011
• Sequence Number: 3
• Publication Date: July 30, 1957
• Content Type: MISC

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I
A SUMMARY OF SPECIFIED TESTS
OF THE RS/C-11 RADIO SET
DATE: 30 July 1957
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Page 1
The RS/C-11 Radio Set prototype model developed by the 25X1
has been received 25X1
by the R&D Laboratory for preliminary tests of receiver sensitivity,
selectivity, calibration, and over-all drift characteristics.
The radio set is comparable to the RS/A-11 and RS/B-11 prototype
models in size, weight, printed circuitry, and electrical and
mechanical characteristics. The exception being that the RS/C-11
units operate in the 4 - 16 me frequency range.
During initial tests, the receiver failed to function due to an
intermittent short in the audio section board and to the HFO board
being cut too short so that it did not line up with the correct pin
receptacles on the main printed board.
In the following summary of the test results, the RS/B-11 Specifi-
cations No. 54 A-1029 A are cited for ease of comparison.
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2. SUMMARY OF RECEIVER TEST DATA
2.1. AM and CW Sensitivity and Raw Noise Output
AM'
Sensitivity: Raw Noise Output:
Minimum - 19.0 microvolts at 16 me 0.525 microvatt at 12 me
Maximum - 4.2 microvolts at 4 me 3.6 microvatts at 4 me
Average - 11.0 microvolts 1.265 microvatte.
CW
Minimum - 11.0 microvolts at 16 me 15.5 microvatts at 10 me
Maximum - 1.3 microvolts at 4 me 36.0 aicrovatts at 4 me
Average - 4.6 microvolts 21.7 microvotts
Specifications: AM sensitivity to be 15 microvolts into 300 ohms for
0.5 millivatt audio output. CW sensitivity to be 5 microvolts into
300 ohms for 0.5 milliwatt audio output. The raw noise output not to
exceed 20 microvatts under any conditions.
2.2. Range and Calibration
Range: 3.917000 to 16.444500 me
Calibration:
Minimum error - 0.12625% at 6 me
Maximum error - 0.4935% at 12 me
Average error - 0.208%
Specifications: The dial calibration shall be within 0.1% of the
tuned frequency.
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2.3. Receiver Over-all Drift
Average Drift:
Minimum - 10.9 cycles per minute (0.000091%) after 2j hours
maximum - 95.5 cycles per minute (0.00079%) during first 20 minutes
Over-all - 62.2 cycles per minute (0.00052%) during 3 hour test
The drift curve appears on page 6.
Specifications: The rate of frequency change shall not exceed
0.0004% at any point of the curve.
2.4. Selectivity
Receiver bandwidth - 4535 cycles at the 6 db points
Shape factor - 5.0
The-selectivity curve appears on page 7.
Specifications: Bandwidth 5.4 kcs at the 6 db points
Shape factor - 3
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3. CONCWSIOAS AND RECOMMENDATIONS
3.1. Conclusions
The RS/C-11 receiver performed satisfactorily in two of the speci-
fied tests. The unit meets the specifications regarding sensitivity
except at the high end of band 2 (16 mc). The receiver bandwidth
was found to be 4230 cycles, rather than 5400 cycles as required in
the test specifications. The receiver calibration and over-all
drift characteristics are not satisfactory.
Page
Future acceptance of the receiver as a prototype model is considered,
primarily, to be based on specific improvement of the RS/11 dial
mechanism. The receiver fails to meet Section 4.3.1. of Specifications
No. 54 A-1029 A (dial).
3.2. Recommendations
(1) The receiver drift should be reduced by improvement of the UFO
circuit and its operating parameters.
(2) The calibration of the receiver should be improved. This defect
is considered to be a function of the dial mechanism reliability.
It is requested that consideration be given to the possibility
of using a counter to select frequency. An alternate solution,
which may be considered, is the initiation of a new development
to produce a reliable dial mechanism.
(3) The receiver bandwidth is narrow and is not considered to be
representative of other RS/11 receivers tested. No recommenda-
tion is given.
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3.3? Malfunctions
The following malfunctions occurred during testing of the RS/C-11
(1)
(2)
(3)
Earset receptacle broke.
Audio printed board shorted to the tape roller lip on the
receiver case inner wall.
The HFO printed board was cut too short so that it is possible
to mismatch the board pins and pin receptacles on the main
printed board.
BFO tube (lAK4) defective.
IF tube (lAD4) defective.
Page 5.
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Page 6
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