RESEARCH ORDER #2 PHASE I - PROGRESS REPORT #5

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78-03300A001600020083-0
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 23
• Document Creation Date: December 22, 2016
• Document Release Date: December 28, 2011
• Sequence Number: 83
• Publication Date: September 7, 1954
• Content Type: REPORT

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1 CONFIDEN I 1AL
I
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Research Crder #2
Phase I - Progress Report #5 7 6eptember 1954
3 copies to:
1 copy to:
1 copy to:
5 COPIES DIST. 'BUILD AS Faldlie
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CONFIDENTIAL
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NIFIDENTIAL
Research Order #2
Phase I - Progress Report #5 7 6eptember 1954
OBJECTIVE:
To develop a traneistorised receiver in the frequency range 5-7 mc,
with a sensitivity of 30-60 uv/m and total input power of 80 milliwatts or less.
DATA -
The use of junction transistors as local oscillators and mixers was
investigated, suitable circuits were developed, and a breadboard layout of a
cose,plete receiver was constructed.
rATA. - DETMLED:
Various types of oscillator circuits were tested using both crystal and
LE resonant elements. Of the several transistors immediately available,
type CK721 was chosen for the first investigations. No limitation 25X1
was place on input power since the initial aim was to determine the maxi-
mum stable operating frequency. Using a Colpitts circuit (Figure 5) and a
45-volt center tapped battery, three different CK721 transistors were tried
with the following results:
Transistor A
Transistor 13
Transistor C
2.95 mc/s
2.2 mc/s
2.0 inc/e.
since 45 volts is higher than would be desirable for equipment of this nature,
further investigations were made but with a battery voltage limited to 3 volts.
i\gain a Colpitts circuit was employed, yielding a maximum frequency of
1.78 mc/s. Several other circuits similar to those used in broadcast
transistor receivers developed by
were also tried; however the maximum frequency obtained was
on y 1. mc/s.
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During this period we were able to obtain two Cli7ti2 transistors. 25X1
These were used in a Colpitts circuit similar to that used with the CK721.
This combination resulted in stable operation of frequencies as hAgh as
12.8 mc/s. The crystal oscillator circuit shown in Figure 13 in ccessbinatian
with a CK762 gave good results at 6.4 mc/s.
aimultaneous with the above, work was done with regard to tne use of
transistors as mixers and as detectors.
Information from outside sources claimed greater conversion gain at
broadcast frequencies than at intermediate frequencies with the result
CONFtDENTIAL
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CONFIDENTIAL
that double conversion was considered. "A'ests made using a CK762 as a
mixer resulted in slightly less gain as a mixer than as an amplifier. These
tests were later confirmed by outside sources working on broadcast receiver
development. As a result the double conversion was abandoned.
To keep oscillator radiation through the antenna to a minimum it was
decided to inject the oscillator on any element other than the input.
Tetrode type itDX302 WAS tried as an i-f amplifier and as a mixer.
The gain as an amplifier exceeded that of the CK762 by greater than 6 db,
feeding signal into the essi, ter as recommended by the manufacturer. How-
ever, using oscillator injection on either base resulted in 10 db less
conversion gain. Conversion gain approximating that of the Ci.762 could be
obtained by injecting both signal and local oscillator into the emitter. Since
this was not an improvement and would result in increased oscillator
radiation, the tetrode was abandoned as a mixer at these frequencies. All
mixer tests were conducted at approximately 5.45 me.
Base injection of the oscillator was chosen since the necessary
oscillator voltage is approximately 1/3 that of emitter injection for similar
conversion gains. The final circuitry resulted in k..onversion gams of 15 db
to 18 db.
To achieve an input frequency range of 5-7 mc, advantage is taken of
the oscillator being above or below the desired signal, and the me illator
range is now 4.755 mc to ;).745 me enabling reception of 4.3-7.2 mc.
The second detector circuits shown in Figure and Figure E were
investigated with regard to output, eurrent requirements, simplicity and
transistor interchangeability. In all cases the inpui signal 'was 455 itc/s
with 1U00 cps - 30% modulation.
The secondary of the output transformer was loaded with a 1000-ohm
resistor to simulate the following stage, and the output measurm ents taken
across this load.
Using a Cfc.721 connected grounded base (Figure A), approximately
4 times the output was obtained as compared to the grounded emitter connection
shown in Figure B. The input signal was the same in both cases. The
current requirements for the grounded base conneetion however, was about
4 times that of the grounded emitter connection. The grounded base
connection also requires a greater number of components and a tapped power
source.
Vten changing transistors, fil had to be readjusted to obtain ri,..wcinutita
power output. The grounded emittet connection exhibited good stability
of output and current requirements with various transistors. The circuits
shown in Figures ).? and B were both tested with a CK70 and a CK762
_2_ .n.CONFIDENTIAL
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s'k
CONFIDENT1A,
transistor. The circuit of Figure B showed the greatest improves ent of
the two, with no appreciable increase in current requirements. Utili?..ing
the above results, an essentially complete receiver was constructed and
tested. The oscillator circuit was ,_hoeen since it resulted in constant
output over a wide range of frequencies. .Ihe circuit of Figure B was
selected for the detector because of its simplicity, low power requirements,
and stable characteristics without the use of selected transistor.
he-receiver is a superheterodyne, tunable from 5 nac/s to? mc/s,
with mixer, local oscillator, two stage i-f amplifier at 455 kc, second
detector -Ind one audio stage. Six transistors are used as follows:
, Mixer
Oscillator
I-f Amplifiers
Power Detector
Audio
rlype 700
Type 762
Tyke 760
Type 762
Type 721
I-f stage gable of 3.i db were obtained with commercially available i-f trans-
formers (Automatic Mfg. Corp. 4EXO 3315). Mixer conversion gain is
approximately 15 db. Audio output with 5-volt supply is approximately 0.6 mw.
Total current drain from 5-volt supply is 2.1 ma.
Seneitivity measured at mixer input (base - 50-ohm source) is 4 uv
for rated audio output (signal modulated 30% at 10)0 fss ). With an 8-inch
ferrite loopstick resonant at 5 mc, a sessitivity oi i0 mv/m was meaeured.
Limited field tests of this receiver with the loop transmitter described
in Report #4 gave adequate eignal at 0.5 mile range, corresponding to a
fie,ld strength of 11-15 uv/m.
automatic gain control was tried on this receiver, but could not be
developed satisfactorily in time for this report. A simple r-f gain control
is used in the emitter of the let i-f amplifier, giving about 4J ub range.
Considerable work was done with audio ty,?e junction transistore at
100 kc/e as self-excited and crystal controlled oscillators in an attempt to
determine maximum power output and efficiency without a frequency hesitation.
Various combinations of single ended and push-pull oscillators, and push-
pull, class C final amplifiers were tried.
Best results.: were obtained with a single ended zelf-exciteel oscillator
using a CK721 with a 6-volt suety. Power output was 50 raw at 37%
efficiency.
Somewhat similar performance has been obtained with type CK702
transistors, at 5 mc to date. Vork is continuing to determine opticeum
circuitry. It has been suggested two type CK702 ransistors in a push-pull,
(..,&1\iii:IDENTIALI.
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CONF
DENT
class C oscillator are capable of 250 mw input and 60% efficiency at 5 mc.
CCNCLUSIONS:
It is felt that a satisfaaory basic receiver design has been azthieved.
The addition of AGC and stabilization for temperature and battery voltage
remain to be done.
jince the receiver performance is better than expected and can be
further improved, the transmitter problem is simi.lifiect to the extent that
the required carrier power is much reduced, and can be obtained from
existing transistors, with the powerful advantages of common battery
operation.
ViC:AK PAOGAAM FOR NEXT INTERVi
Completion of receiver circuitry, determination of transistor limita-
tions as r-f power generators at 5 mc, field comparieons of Ferrite loop-
stick antennas and air loops on existing receiver are part of the work program
for the next interval.
Report prepared by
Iteport approved by
F!DENTI
i
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X03015
Signal frequency 5 MC
IF frequency 455 KC
Output Impedance 1000--n-
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TRAtTsisToit cpmp*scirl: cutcpT FOE 15tTECTOR USE
Input. 455 kc
Modulation 1000 cps 30% -
CK762 Transistor
Input
1
2000 uv
3000 .09918,v noise
5000 .0005 v,:t'-,v11,:e
40090 . oo;
t120000? . .01 v- '?`
30000 " ' .026 v '
10000 uv
20000
\30000
60000 ?
CK721 Transistor
Collector Current "
15 ua
15 ua
16 ua
17 ua
21 us.
29 ua
;; 0003
v noise
4 ua
:0014
v
?4 ua
.904
v
'5 us.
.028
18 ua
-
'
?
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, t
InputOutput ' CoCollectorgurrent
.
500 u'v. - .0001 v liaise 40;ux,
1000 - . 0001 v noise 40,sua
2000 .00013 viip ... ' .
5900 - .'0005 -:v ' 40 U4
40 ta '
10000 . 0021, V. 40 ua
, 20000 .0078 'v-i 4:. e 40 pa
?
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FIOURE 13. DETECTOR CIRCUIT
.001 uf
E-2717
6K721
UM113
Input 455 ke '
Modulation 1900 cps 30%
Input
output
... Output Collector Current
........... ?_,
500 uv . 0001 v noise 8 ua
1000 . 0001 v noiSe *4 wi,
2000 . 00011 v 8 usl,
5000 . 00014 v - 8 ua
. 10000 ? . 00042 v ?; 81 .ua. '
20000? :0018 v 8 ua
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? L
? Type CK721*
? f max approx. 1-1./5 me
A, C2 =To 30:uuf
L = 200' WI
1 Miller Type 72-13
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22.5V ; 226V
FIGURE 4.
....7.,
it lilt Lill 1 11.worim...
225V 225V
..,..;--
FIQURE 5.
74.,P:1
,
With same specific 721 parts same as
Figure 1.
?
f max = 2.35 mc
Same CK 721
f max = 2.61 mc
? Removal of C1
f max =.2,8 mc
- CK721S ?tested
? all oscillated above 2.0 mc.?
Q of Li =?20 -25 at 2 MC
C uuf Q meter = 110
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-6V
-6V ?
7
FIGURE 6.
L Same as-in Figure
C 325 uuf Var.
1
Max. f = 950 KC
Output low at high end
Took specia1,CK721 to operate
L 11 T feedback , ?
T secondary
#36 Nylon,: iron cote.
3/8: L.
With 91T Tap at 63 for collector. Q = 44 1=950 KC
2 other CK121 allow operation to,1200 KC.
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OSCILLATORS
' FIGURE 7:
FIGURE 8.
. 370 uuf max
C2 = 465 uuf
L2--
100T 7-44
? .
3/16 D Form
C shorted ,F max 1.2 MC
? . 400 uuf '
f max = 1.78 me
f max limited by coil
I = 8.7 mc -
C-2 7. 0 uuf
Range restricted by C1
(squegging)
? Eo L3 = 15 V PP
Smaller L3
C min,ca.p
C3 = min cap
f = 12.8 rnc
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,r -..,
CRYSTAL OSCILLATORS
FIGURE 9.
FIGURE O.
? FIGURE 11.
+6V
+6V
FIGURE 12.
XTAL 1-5 MC or more
R1 1M
C1 400 uuf
C4 .002 uf
RFC - 2.5 mh
e (XTAL) = 16 V PP
e 6 V PP
Output from collector may be loaded
R to reduce possibility of L. F.
oscillation - 47K
RFC 500 uh
RFC 500
XTAL 5 MC
ee 0.7 V
e = 2.2 V
L
ec = .0.5V
I = 0.5 ma
Eo = Same
, .
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RECEIVER OSCILLATOR AND MIXER
FIGURE 13.
?
XTAL 3910 KC
RFC 0.5 mh
= 6.5 V with good
regulation
XTALS tried up to 6.4 mc
C approx. 10-20 uuf
may be to load
BC 348 Mixer
AVC Read. IQ FQ uv
4 V 2.1
3.8
6.8
donv. at
5.5 MC
8.8 uv
5.8
5.8
9.0
- ?
Comments
Adj C and C4
(45 uv at Recdiver)
(46 uv at Receiver)
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'MIXER CIRCUITS C\411itIC 2
G2
?'.+To BC 348
5 MC - 200 uv
5.455 MC
0.5 ma
AT Rec
38 uv
36 uv
2.uv. .
1.3
51
.05 51
+6V
? CK762
2-3M 6.5 uv 45 uv
11 uv 0.5 ma.
13 uv 0.25 ma zi
-FIGURE' 13.
1.,
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TETRODE TYPE RDX302
As an Amp1ifier
1 uv = 4 V- AGC on 8C348
R1 any value greater than 0
R2 1K
R3 adj for O. 25 ma
*Ai i..ritixer
--
osc in 132.
; 30, uv = 4 ,V AGC
Comment - poor mixing
?
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300 uuf
.003u
FIGURE 19.
FIGURE 20.
L 24T 3/4" D 32T/in
etap 2 1/4 T
C tap 12 1/4 T
ol approx. 158.uuf,,-.4.,
f Mixer 4.6 me
?
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..,04.441.4e4707(4444.o.4.1,4414P.oC01
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uaiariawv
CILLATOR STRIP - EXPERIMENTAL
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