THIRD PROGRESS REPORT DEVELOPMENT OF AS-3 PORTABLE RADIO STATION

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78-03330A004200010010-9
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 4
• Document Creation Date: December 23, 2016
• Document Release Date: April 28, 2014
• Sequence Number: 10
• Publication Date: January 1, 1957
• Content Type: REPORT

STAT
Declassified in Part - Sanitized Copy Approved for Release 2014/04/28: CIA-RDP78-03330A004200010010-9
THIRD PROGRESS REPORT
DEVELOPMENT OF AS-3 PORTABLE RADIO STATION
January 1, 1957
This report covers the progress in' the development of the AS-3
Radio Station for the period of November and December. The work
has been directed towards completion of the bread-board phase of
the transmitter and preliminary bread-board of the other com-
ponent units.
The schedule as outlined in the First Progress Report has been
revised in accordance with the contract so that paragraph g should
read: "Delivery of nine preproduction units and final report due
March 1, 1958." Delete paragraphs f arid h.
Transmitter AT-3
The bread-board stage was completed to a point where the initial
steps of packaging were begun. As proposed in the second report,,
the tuning of the entire frequency range (3-30 mc) in one band
has now been achieved using for the tests a commercial condenser
and a specially constructed rotary coil. The use of a powdered
Iron core and variable-pitch winding in this coil provided the
required inductance range of 10:1 with a very compact structure.
A special miniature condenser is now being designed using a number
of available standard parts to achieve the required '10:1 capacity
range in a minimum volume. The coil and condenser will be gang
tuned at approximately one to one ratio between coil and condenser
worm.
The oscillator tube is the 6417 which provides apple output through-
out the frequency range. This is accomplished using 250 volts on
the plate and 140 volts on the screen which will hold the crystal
current below 30 ma. The crystal oscillator is a modified Pierce
circuit employing grid, cathode and screen, and the output 16
taken at the crystal frequency or multiples of the crystal fre-
quency in the gang tuned circuit connected to the plate.
Grid keying of the final amplifier has been tested. : Experimen-
tally, a punched tape keyer was used to facilitate atudy of the
keying waveform for keying rates up to 200 cps.
For purposes of studying modulation methods a 150 cps square wave
oscillator was constructed and applied to the grid or to the screen.
Both methods were adequate; however, further investigation may
prove that the oscillator could be modulated.
Declassified in Part - Sanitized Copy Approved for Release 2014/04/28: CIA-RDP78-03330A004200010010-9
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Declassified in Part - Sanitized Copy Approved for Release 2014/04/28: CIA-RDP78-03330A004200010010-9
Third Progress Report, AS-3 - 1/1/57 -2-
An extension of this idea, which would still further conserve
power and perhaps reduce the number of components required, would
be to perform both modulating and keying at the oscillator. .This
might allow the use of transistor keying circuitry, which could
not be used in the amplifier due to the higher voltages. Circuits
are under construction to investigate the possibilities of this
approach.
Keyer AK-3
Two methods of driving the tape cartridge are being compared ex-
perimentally.- In one the keyer unit will contain a 12v motor
operating through a slip clutch to drive the cartridge. A motor
is available and is being incorporated in the bread-board model
of this system. A voltage regulator will have to be incorporated
so the motor will have a fairly constant 10" applied to it, thus
making the speed nearly independent of battery supply voltage.
Along with the above development, a spring type of drive will
also be bread-boarded so that an evaluation of the two methods
can be.made. This unit will use the negator type motor, hand
wound by the operator prior to message sending. The advantages of
the spring type are (1) quiet operation and (2) independence from
batteries.
The manufacturers of magnetic tape are performing evaluation tests
on their. tape to determine the characteristics of square wave
pulses at a repetition rate of 150 cps. Their degree of magneti-
zation is adjusted to that which we expect to obtain from the
permanent magnets located in the coder. . This magnetization is
approximately 1000 gauss which should substantially saturate the
tape. -Their results will indicate the effect of print-through,
if any, cross-talk between pulses, and noise effect and residual
noise level using a permanent magnet type erase. This last effect
will determine a lower cutoff point for the keyer pick-up ampli-
fier so that it can not be triggered by random noise on the tape.
The manufacturers will also investigate the completeness of erase
which will be necessary since no previous coding should be left
on the tape.
Coder AC-3
The mechanism for the coder operation has been partially, completed
in a bread-board stage. The complete mechanism has been sketched?
and drawings are being made for fabrication of this system.
Declassified in Part - Sanitized Copy Approved for Release 2014/04/28: CIA-RDP78-03330A004200010010-9
Declassified in Part - Sanitized Copy Approved for Release 2014/04/28: CIA-RDP78-03330A004200010010-9
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Third Progress Report, AS-3 - 1/1/57 -3-
A spring clutch has been incorporated so that both directions of
travel of the push buttons may be utilized. The magnets are
brought against the tape near the completion of the down stroke,
and then released. The advance of the tape is performed during
the return motion of the button. Tests conducted on the first
model have indicated the feasibility of this type of motion.
A direct gear drive to the cartridge Will be necessary so that
positive advance of the tape can.be obtained.
Battery Charger ABC-3
The battery charger can be made to charge in two ways. The
battery can be charged in two hours or less by maintaining a
voltage of 15.5v across the battery. This method, however, re-
quires careful supervision during charge, for an overcharge or a
too rapid rate of charge will cause the cells to gas and loose
electrolyte.
The second method would be a modified constant potential so that
as the cell approached full charge the charging current would
drop off to a value which would not cause gassing or loss of
electrolyte. This end potential, which is the open-circuit voltage
of the charger, should be adjusted to a value between 14.0 and
14.5 volts as recommended by the battery manufacturers.
This latter method of charging does not give the 2 amperes charging
rate as called for in the specification; however, it does afford
protection against damage to the batteries in the event the
charger can not be turned off at a specified time interval. This
method of charging is sufficient to bring the batteries back nearly
to full charge overnight. Preliminary tests with such a charger
Indicate a charging rate of .250 amp. for discharged batteries
and this current holds constant, until very nearly the end of charge.
It is believed that the charging method chosen for the final equip-
ment should be decided on by your group since it will involve
equipment operation methods.
Further tests will be conducted relative to the two types of
charging methods, and combinations thereof. A regulated charger
using -Zener diodes for reference voltage and transistor output
control has been constructed.
Battery ABA-3
Two sample 12-volt batteries of Ni-Cad cells have arrived and are
undergoing tests. These tests are being conducted on the ACT8X
(3 ampere hour) and ANC8Y (2 ampere hour) cells respectively.
Declassified in Part - Sanitized Copy Approved for Release 2014/04/28: CIA-RDP78-03330A004200010010-9
Declassified in Part' - Sanitized Copy Approved for Release 2014/04/28: CIA-RDP78-03330A004200010010-9
Third Provess Report, AS-3 - 1/1/57 -4-
Preliminary tests based on present system power requirements of
approximately 75 watts on Transmit and 20 watts on Receive indi-
cate at least three continuous cycles using the ACT8X and approxi-
mately one cycle of operation using the ANC8Y battery. Continuous
discharge tests at ?8 watts (single cells) show the ACT8X good for
30 minutes and the ANC8Y for approximately 12 minutes of trans-
mitter operation. It would appear that for the small added volume
and weightidifferential between the Actex and ANC8Y, it would be
worth using the ACT8X cell, thus achieving greater capacity and
dependability.
Plans for the Next Reporting Period
All effort will be placed on completion of the first engineering
models of the transmitter, keyer, coder and cartridge. Similarly,
sufficient components should be available so models of the AC
supply, DC supply and battery charger can be completed.
Prepared By:.
Approved By:.
STAT
?narinccifipri in Part - Sanitized Copy Approved for Release 2014/04/28: CIA-RDP78-03330A004200010010-9