THIS DOCUMENT CONTAINS THE COMMENTS REQUESTED FROM (SANITIZED) CONCERNING THE A&A REPORT NO. 285 ENTITLED, "AN ANALYSIS AND APPRAISAL OF THE (SANITIZED) CERAMIC RESONATOR AND CRYSTAL FILTER IF AMPLIFIERS."

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78-03424A000500050005-8
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 7
• Document Creation Date: December 22, 2016
• Document Release Date: February 15, 2012
• Sequence Number: 5
• Content Type: MEMO

Declassified in Part - Sanitized Copy Approved for Release 2012/02/15: CIA-RDP78-03424A000500050005-8
CONFIDENTIAL
This document contains the comments requested from
concerning
the AaA Report No. 285 entitled, "An Analysis and Appraisal of the
Ceramic Resonator and Crystal Filter IF Amplifiers." The report
was written in connection with Project D1o. 200l~-181 and is dated 16
September 1960. Due to the interdependence of various measurements and
operating conditions, the comments below are organized in the following
manner. The sequence used is 3.ri accordance with the page mzmbering of the
subject Report. Each comment is then given an Item Number which is sub-
sequently used for cross referencing purposes throughout this memorandum.
The Ceramic Resonator IF Amplifier is discussed first, followed by the
Crystal Filter IF Amplif ier.
Ceramic Resonator IF Amplifier
Page ~.. Under "3.1.2 Techanical Inspection" it is stated
Item 1 that the amplifiers are housed in "fragile thin wall copper
cases." It is important to recall that these amplifiers were
not intended for use as separate pieces of equipment but were
designed for incorporation, with other circuitry, into an
outer receiver case.
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CONFIDENTIAL
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Page 6 The block diagrarl shown under "3.3.2 Output Impedances" in-
Item 2 dicates the use of a GR1I~,32A Resistance Decade Box and a
IIPI~OOD~ITVr? at the output of the amplifier. The GR11~32A adds
30 to I~S~F while the IIP400D with 2 feet of, for example, RG58
coaxial cable adds a further 85~,}~F. The resultant load would
be highly capacitive (130~~uF approx.). The amplifier was de-
signed for use with a resistive load.
Page 8 The Test-Setup with which the over-all gain was measured shows
Item 3 the use of a HPI~OODVTUT2. This instrument, in conjunction with
2 feet of coaxial cable, will place 8~u~a.F across the output.
This trill cause severe distortion of the pass band. See also
the Spurious Response data and the Selectivity measurements.
The apparent gain falls as the input level is increased due
to increasingly severe clipping. This should be expected in
an amplifier operating at minimum power drain without the bene-
fit of AGC. Although AGC was to have been included in the
design, as described i_n the Proposal, it was omitted in the
actual design with concurrence of the Technical Representative.
Page l1c:12 The b1ocl: diagram showing the test set up for measurement of
Item 1.~ Image and IF Rejection and Spurious Responses indicates that
the input to the amplifier under test was fed from a 10 or
50 ohm source, defending on the output termination of the
G21001A Signal Generator. The correct source
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impedance is 100 ohms. This mismatch will affect the selecti-
vity curves as well as the spurious responses.
Carrier distortion of the GR type 1007..A Signal Generator
is listed as "on the order of 7~" by its manufacturer. Its
output can be e~.rpected to contain appreciable amounts of 2nd,
3rd and lath harmonic. Increasing the output level of the
signal Generator will result i_n a considerable percentage of
harmonics being introduced into the amplifier under test. This
is indicated by the spurious responses measured at 569.9 lcc.,
759.9 lcc. and 1139 icc. The ~.th harmonic of 569.9 ltc. is
2.28 mc., the 3rd harmonic of 759.9 kc.is 2.28 mc. while the
2nd harmonic of 1139 kc. is 2.28 mc. The high input levels
necessary to produce the remaining spurious responses shown on
Pate 12 could lead to a combination of amplifier saturation
and direct feed through of the signal due to the very close
physical spacing of the various stages.
The image rejection was originally measured with a con-
stant input level at 2.28 mc. and 3.19 mc., under matched input
and output conditions. The com'oined effect of overloading and
mismatch resultinb from the method described irl the report
probably accounts for the different in Image Rejection data.
Page 13 The test set up used for measurement of selectivity,
Item 5 as shoti~rn under 3.3.6 would lead to very heavy capacitive load-
ing. Specifically:
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H.P.52]~P counter: !~0}z~F + lead capacitance
HPI~OODVTUPI: 25u~af + lead capacitance
5i5A Scope: 12 to 3~F + lead capacitance
(if probe is not used)
Under this t~Tpe of capacitive load considerable alteration of
tl~e bandpass characteristics must be expected.
Cr~?stal Filter Amplifier
Pane 3 In the Report, the "Contractor's Final Test Data" con-
cer~u.ng gain variation tirith temperature appears to have been
misquoted. Reference to page 7 of the Sixth ar~3. Final ~ i-
monthly Report will shoT~r that the gain variati on at +1~0?C was
reported as +1.5 db and at -L~0?C as -10 db. Consequently
there is closer agreement between the Final Test Data and the
~~D Laboratory 1`Ieasurements than is indicated in the Report.
Page 6
Pa^e 10
See Item 3.
It i,rould appear that the wide discrepancy between the
Final Test Data and the IUD Laboratory Teasurement of gain can
only be attributed to the development of a fault subsequent to
delivery. It would be of interest to '.:not-T whether the gain
measurement i~ras made after the amplifier was partia7_ly dis-
assembled. A fault causi nL such a reduction in gain would
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doubtless, cause ccnsiderable changes in other per:?ormance
Page 11 See Item Ia.. In summary, spurious responses can be at-
tributed to one or Wore of the following:
( i) Grverloading the input by the h%gh generator out-
put level.
( ii) Heavy capacitive loading of the output stage due
to th.e metering tecYinique used.
(iii) The use of poor signal generator with high harmonic
content. (7~ accordi.nv t.o its manufacture)
Page 12 The first six spurieus responses occur at signal levels
from l.C my to 1~.8 my where the amplifier trill overload. The
fo1lo~Ji~ig six responses occur ir_ pairs corresponding to the
peala at either side of the pass barn.. The first pair coincide
with the nth harronic present in the signal generator output.
Tl~e secorxl pair coincide with the 3rd harmonic while the last
pair represent the 2nd harmonic content of the generator out-
put .
Pa;e 13 See Item 5.
Abstract It is stated that the Crystal Filter IF Amplifier did not
meet the target specification with regard to its output fre-
quency. This observation can probably be attributed to the
list of specifications on Page 2 of the Proposal. This is,
admittedly, c~~nfusin~ and, as has only no~?r become apparent,
suffers from a typographical error. The output frequency is
r v air
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quoted as 1~1~5 lcc. It was, of course, intended to read L.G55 lcc.
for the ceramic resonator amplifier. The output frequency of
the Crystal Filter Amplifier was always intended to be the
same as its input frequency since the purpose of this approach,
as described in the Proposal, was to eliminate the need for
a second converter stage in a superheterodyne receiver. In
summary the following factors appear to be responsible for the
various performance discrepancies.
1. Due to the absence of AGC a.nd the mirLimum power con-
sunptior. design of the amplifiers ar.y measurement tecrnique
used must not be allowed to cause overloading.
2. The amplifiers i~rere designed to operate between es-
sentially resistive terminations. Measurement procedures
cannot be allowed to place a large amount of capacitance across
the terminations.
3. Spurious response measurements must be made with a
signal generator having an absolute minimum of harmonic content
in its outpttt.
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`. Contract Ali-].07, T.O. 12
l+liaiature I~' A~lif iers I L L E G I B
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Thee evaluation of the tvo miniature u' aa{pJSr~.ers cue.wpea, ~
has been coa~leted~ dad the results indicate pertorernoe bela- that 25X1
specified sa deei,6n goals in the contractors prowl. A copy of this report
is 'being subaitted to for his coawneats. This contrast vas re? 25X1
quested to be terminated by August 1960.
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