INFORMAL MONTHLY PROGRESS REPORT NO. 4 FOR THE PERIOD 16 APRIL 1955 THROUGH 15 MAY 1955

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP81B00878R000200120027-3
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 5
• Document Creation Date: December 15, 2016
• Document Release Date: June 16, 1999
• Sequence Number: 27
• Publication Date: May 15, 1955
• Content Type: PERRPT

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Informal Monthly Progress Report No. 4
For The Period
16 April 1955 through 15 May 1955
Contract No. A-101
25X1A
Copy L of 7
This document contains information affecting the
National Defense of the United States within the
meaning of the Espionage Laws, Title 18, U.S. C.,
Sections 793 and 794. Its transmission or the
revelation, of its contents in any manner to an
unauthorized person is prohibited by law.
SECRET
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1.0 This report reviews the progress on System No. 1 for the period
of 16 April 1955 to 15 May 1955, inclusive.
2.0 ANTENNA
The waveguide dipole feed at X-band was matched to the dish and
gave good performance over the band. The cutler feed was abandoned
in favor of the simpler dipole design.
Free space pattern measurements and pattern measurements with
the antennas installed in a full-scale mock-up of the nose of the air-
craft have been made for S and X frequency bands. The major effect
of the mock-up was a small increase in the magnetic plane side lobe
response at the high frequency end of the S band.
3.0 INFORMATION AMPLIFIERS
Recent activity in amplifier development has been directed at in-
creasing the dynamic range of the amplifier from 33 db to approxi-
mately 46 db to equal the recording range of the tape. To obtain this
added dynamic range, the plate-voltage supply was increased from 28
volts to values of 250 volts and 125 volts. These d-c potentials are
obtained from a vibrator-type power supply operating from. a 28 volts
d-c source. The high-voltage supply weighs about one pound.
A pulse transformer is to be added between the last video stage
and the cathode follower driving the pulse-stretching circuit to invert
the phase and step-up the pulse amplitude. This increases the ampli-
fication by a factor of two or three with very little increase in the
power requirements. A specially designed transformer will be deliv-
ered in the near future.
A pulse-width limiting circuit was added to the information ampli-
fier to make the amplifier-output amplitude independent of input-pulse
widths. This circuit consists of one cathode follower and a 0.2,5 micro-
second, delay line. This change and the new power supply are indicated
On. the revised block diagram, figure 1.
4.0 INFORMATION RECORDZR
Parts are machined or are on order for four prototype recorders.
A fibreglas cover has been received. The base plate and gear assem-
blies are being assembled. All parts will be received by the second
week of the next progress period. Some parts will be hand fitted until
proper tolerances can be determined for the production model. Test
tapes, dubbing tapes, and the 1/2 mil Mylar tapes are either on. order
or have been received.
The circuit design and physical layout of the bias oscillator, timing
oscillator, and monitor amplifiers are about 90% complete.
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The bias oscillator uses a silicon transistor and operates at a
frequency of approximately 20 kc.
The timing oscillator is a silicon-transistor, crystal-controlled.
oscillator supplied by Hill Electronics. The packaged unit operates
at 1 kc and weighs 3 1/2 oz.
The monitor amplifiers are silicon-transistor amplifiers. The
required gain and noise figure will be determined during the next
progress period after more complete tests are made using the proto-
type recorder.
Tests were made to check the effectiveness of the motor-speed
governor as the supply voltage, the load, and the temperature were
varied. The initial speeds of five motors operating at rated voltage,
room temperature, and with no load varied from motor to motor to
within 3. 2% of 7000 rpm. The following table shows the effects of
supply voltage, temperature, and load on motor speed.
Conditions Percentage Change
In Speed
No Load, Room Temperature, Supply
Voltage Varied From 23 volts to 30 volts 0.5%
No Load, Constant Supply Voltage, Tempera...
ture Raised from Room Temperature to 80?C ? ? 2.5%
Constant Voltage, Room Temperature, Load
Varied From Zero to Full Load (O. 3 in-oz) 0. 6%
A tape-transport mock-up using the capstan-drive motor and gear
box has revealed flutter on the order of 4% as measured on a 3-kc
carrier frequency. The nature and causes of this flutter are being de-
termined. The noise induced into the reading heads by the motor mag-
netic fields has been reduced to a usable value by double mu-metal
shielding of the heads and capstan drive motor, and single shielding of
the reel-drive motors.
The production design of the recorder was started during this pro-
gress period. This design will eliminate use of the magazine and will
result in repositioning a number of the recorder components. The final
design for the recorder will offer the following advantages over the
present magazine type:
A. The recorder will become a single-unit structure and will therefore
exhibit gr eater rigidity and more advantageous placement of certain
component parts.
B. The recorder may be loaded or unloaded from one side only.
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C. Recorder tape-threading will be simplified.
0. Noise pickup by the reproducer heads from the driving motors
will be reduced greatly.
E. Greater freedom. in. choice of recorder mounting will be pro-
vided.
F. Slightly higher tape speed (2 1/4 inches per second vs. 1 7/8
inches per second) will extend proportionately the recorder fre-
quency range.
G. The operator may observe the tape motion to be certain the
tape is threading and moving correctly.
5.0 TEST EQUIPMENT
All circuits are designed and preliminary tests have been made
on a breadboard model. Design of the chassis, case, and front panel
were started during this period along with the layout and wiring of a
prototype unit.
6.0 DUBBING EQUIP1vIENT
A visit was made to Bing Crosby Enterprises to observe the square-
wave response of an Ampex 350 recorder operating with a tape speed
of 7 1/4 inches per second. Non-linear phase response caused considera-
ble distortion of the reproduced pulse. The dubbing amplifiers will be
modified so that the amplitude of the output is proportional to the amp-
litude of the pulse input. Four of these recorders have been ordered.
Delivery of the first unit is promised for early in June.
7.0 CONCLUSION
Flight testing is scheduled for mid-Jane and a large part of the next
interval will be devoted to assembliing and testing the two complete
systems and the spare antenna assemblies which are to be used for these
test flights.
Design of the production model of the system will be started during
the next reporting interval.
A total of 5565 man-hours were expended during this reporting period.
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S OR X-BAND
ANTENNA
ASSEMBLY
X OR S-BAND
ANTENNA
ASSEMBLY
S OR X-BAND
CRYSTAL
DETEC TOR
X OR S-BAND
CRYSTAL
DETECTOR
4 STAGE
VIDEO
AMPLIFIER
PULSE-WIDTH
LIMITER
PULSE
-
PULSE
STRETCHER
STRE TCH
LIMITER
1-STAGE
AUDIO
AMPLIFIER
250 vdc,
60 ma
125 vdc,
60 ma
INFORMATION AMPLIFIER
PULSE-WIDTH
LIMITER
4-STAGE
VIDEO
AMPLIFIER
CHANNEL
CHANNEL 2
INFORMATION AMPLIFIER
STRE TCH
LIMITER
---9-1110?1
PULSE
STRETCHER
CHANNEL 3
1 - S T AGE
AUDIO
AMPLIFIER
D- C
SUPPLY
-4? 28 vdc
Input
TIME-
REFERENCE
OSC ILL ATOR
BIAS
OSCIL-
LATOR
FIG. 1 AIRBORNE MONITORING SYSTEM, BLOCK DIAGRAM, REVISION NO. 1
INFORMATION
RECORDER
CHANNELS 1, 2, 3
MONITORING
AMPLIFIERS
TO SYSTEM TEST SET
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