FOURTH BIMONTHLY REPORT ON THE MINIATURE IF AMPLIFIER PROGRAM

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78-03424A000500050028-3
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 21
• Document Creation Date: December 22, 2016
• Document Release Date: February 15, 2012
• Sequence Number: 28
• Publication Date: January 1, 1960
• Content Type: REPORT

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Fourth Bimonthly Report on the Miniature
IF Amplifier Pro~am
-~_
~~
Period: 1-Jan-'60 to 1-Mar-'60
25X1
25X1
Prepared by:
ORIGINAL Ct_ EY ~-3'~
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I
Purpose 1
II
Abstract 1
III
Factual Data 2
1. Ceramic Resonator Program 2
2. Crystal Filter Amplifier 3
IV
Conclusions 4
V
Future Plans 5
VI
Identification of Key Technical Personnel. 5
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I Purpose
See Bimonthly Report No. 1.
Measurements have been made to determine the behavior of the
ceramic transformers as a function of load capacitance and temperature.
Curves are included in this report which show the variation of center
frequency and bandwidth of the individual transformers as well as the
variation of power gain of the complete amplifier over the temperature
range from -~OoC to +40?C .
The schematic diagram of the high IF (2.281 mc) amplifier is shown
witr. the associated crystal oscillator and mixer stages. Results are
included showing overall power gain, impedance levels, etc.
In preparation for the arrival of the crystal filter for the secors~?
IF amplifier design work has been started on the transistor circuitry requ.ir~~a.
for this unit. A brief description is given in this report of the work carrie::?.
out so far on this portion of the program. Results are given of tree various
measurements which have been made to determine the characteristics of the
ferrite material to be used for interstage coupling transformers. Cu3?ves
are also shown indicating the impedance measurements made on the 2N27~- d,rif't
transistor.
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III Factual Rata
1. Ceramic Resonator Program
Complete environmental testing of representative samples of PZT
and ANA type ceramic resonators has been completed.
Individual resonators have been tested in the test circuit shown
in Figure 1 of the Second Bimonthly Report for center frequency variation
versus load capacitance {Figure 1), bandwidth versus load capacitance
{Figure 2) and center frequency and bandwidth versus temperature (Figures
3 and 4).
The latest ceramic resonators made of the ANA material have the
required bandwidth of approximately 20 kc per individual resonator in order
to insure the overall amplifier response will be in the neighborhood of 5 kc.
The schematic diagram of a three stage 455 kc amplifier is shown in
Figure 5. The circuit is essentially the same as Figure 6 of the Third
Bimonthly Report except for better power supply decoupling and slightly
increased bias on the last stage to prevent overloading.
The variation of power gain over the temperature range of -40?C to
+40?C is shown in Figure 6 to be -3 db, +2 db Prom the room temperature
value of 77 db. The shift in center frequency is approximately +2.5 kc at
-40?C and +1.5 kc at +40?C (Figure 7). The change in bandwidth from the
room temperature value of 9.2 kc is +1.0 kc, -3.0 kc over the temperature
range of -40?C to +4d?C. The shape of the response curve of the three stage
amplifier at various temperatures is shown in Figure 8. It should be noted.
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X470
Y
ANA
X
X
~
MATERIAL
PZT MATERIAL, ~
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20 40 60 80 100 120
OUTPUT CAPACITANCE (p.?f )
CENTER FREQUENCY OF CERAMIC RESONATORS YS. OUTPUT CAPACITANCE
FIGURE I
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a~
Y 40
20 40 60 SO 100 120
OUTPUT CAPACITANCE (??f)
BANDWIDTH OF CERAMIC RESONATORS VS. OUTPUT CAPACITANCE
ANA
X
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MA
TERIAL
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_ .
PZT MATERIAL
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?
PZT
MATERIA L
ANA
MATERIA
-40 - 20 0 + 20 +40
TEMP ?C
CENTER FREQUENCY VS. TEMP. OF CERAMIC RESONATORS
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+
+
J
+ a
Q ~
2 W
Q ~
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Q
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` ~ ~. ` PZT MATERIAL
BANDWIDTH VS. TEMPERATURE OF CERAMIC RESONATORS
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3 K ~.,,
;,
ALL TRANSISTORS 2N274
TRANSFORMER +14I - PZT #2
TRANSFORMER # 2 - QNA #3
TRANSFORMERS 3 - ANA#7
TRANSFORMER #' 4 - ANA+1t 6
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?
POWER GAIN VS. TEMPERATURE OF A 3 STAGE AMPLIFIER
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Y
V460
r
v
z 9
W
O
W
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~ TEMP.?C
BANDWIDTH AND CENTER FREQUENCY OF A 3 STAGE AMPLIFIER VS. TEMPERATURE
FIGURE 7
?
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?
X
0
P~ /
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ao
0
m
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+ 40 ?C
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20?C
-20?
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450 460
FREQUENCY (KC/S1
GAIN VS FREQUENCY OF A 3 STAGE AMPLIFIER
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-3-
that there is a tendency for the response to show a double peak on the low
aide at the higher temperatures and on the high side of resonance at the
lower temperatures.
The schematic diagram of the 2.281 me IF amplifier, the 2.736 me
crystal oscillator and the mixer stage is shown in Figure 9. A lumped
element LC filter will precede the 2.281 me amplifier stage. This is
inserted in order to provide adequate image Frequency rejection in a
double conversion system.
The two interstage transformers feeding the base of the mixer are
wound on ferrite, toroidal cores of .25 inch OD of CQ-61+ material. The
optimum oscillator voltage of 70 my is injected in parallel with the signal
input to the mixer stage. The output of the mixer is fed directly to the
first ceramic resonator in the three stage x.55 kc amplifier.
The overall power gain of the complete amplifier.is 111 db without
tre 2.281 me input filter. It is expected that the insertion loss of this
filter will be about 6 db so the required gain figure of 100 db can be
obtained. The input impedance of the 2.281 me amplifier is 6.8 K ohms.
Crystal Filter Amplifier
Preliminary design work for the 2.281 me crystal filter amplifier is
now being completed. A satisfactory ferrite core material (CQ-64) has been
found (see Figure 10). Since the bandpass of the amplifier is to be
entirely determined by the narrow band 2.281 me crystal filter, each
amplifier stage may be designed to be wideband so that any shift in centea:?
frequency due to the ferrite core interstage transformers can be tolerat~:d.
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?
?
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?
0
W +4.0
d
Z
Q
V
F, +3.0
z
W
v
a +2.0
UPPER EXTREME
-AVERAGE
LOWER EXTREME
?
AVE. OF 10 UNITS, 60 TURNS~36 WIRE
+20
TEMPERATURE - ?C
INDUCTANCE STABILITY OF CQ-64 CORES AT 2.28 MCS.
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Four amplifier stages will be required to provide 100 db overall
gain. A restriction on the gain per stage arises from the necessity of
conserving battery power. Curves of input and output resistance and
~~aps.cits.nce are shown in Figures 11 - 14 for the 2N274 drift transistor .
T'~.P irr.~ividual, interstage transformers will be designed for optimum match
on t1~fl basis of the material presented in these graphs.
A breadboard design will bE available for preliminary testing in
the next report period.
The electrical. design of the ceramic transformer amplifier is
eF~~~ent,ially r.omplete. Soule difficulty is being encountered due to feed
through of tte 2.?~ iac oscillator frequency which appears at the output
of t:~e x+55 kc section. W.~i1e this phenomenon does not directly effect
the pE:~formance of the amplifier, efforts are being made to reduce the
amplitM,~de of this 7requency component at the output due to its undesirable
effe~:ts on any ACf.' detector that might ultimately be used in conjunction
with an amplifier of this type. In other. respects the behavior of the
amplifier appears to be quite satisfactory.
T",~e start to be made on the design of the circuitry for the