COMMENTS ON (SANITIZED) PROGRESS REPORT NO. 1 "ON MEASUREMENTS OF TRANSMITTER SPURIOUS RADIATION" NOVEMBER 1957

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78-03330A004100030006-3
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 2
• Document Creation Date: December 22, 2016
• Document Release Date: February 14, 2012
• Sequence Number: 6
• Publication Date: December 11, 1957
• Content Type: MEMO

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Declassified in Part - Sanitized Copy Approved for Release 2012/02/14: CIA-RDP78-0333OA004100030006-3
Office 2~rd~rn.uNITED STATES GOVERNMENT
TO : The Files (R&D Branch)
DATE:11 December 1957
SUBJECT:i Comments onl (Progress Report No. 1 "On Measurements
of Transmitter Spurious Radiation" November 1957)
1. The following notes and comments on the referenced report
are forwarded for whatever value they may have in considerations
involving this project:
a) Some of the transmitters mentioned will not
tune to 50 ohms.
b) Peak measurement of key click type interference
will produce extremely high values which will
not be an indication of the actual nuisance value
of the interference.
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c) Conducted interference measurement conforms very
closely to our tests. We have the line impedance
stabilization networks ordered to conform to the
Mil Specification. Previously we have used the
line adaptors provided with the Stoddart equipment.
d) Case radiation has been skipped over very lightly
in the report. Most installations do not have a
screen room that will accommodate a 30 foot dipole.
Is it proposed to make low frequency readings with
a loop and then change to a dipole for the harmonics?
The readings would probably be meaningless. In order
to duplicate the readings at a different installation,
the distance of the pickup from the case would also
be necessary information. Shouldn't case radiation
at lower frequencies also be checked with a whip
antenna to check both polarizations?
e) Key click radiation should be taken at short distances
and absolute readings should be made in order to check
against maximum allowable radiation specifications.
f) On the antenna terminal interference radiation set up,
the source impedance for the tuned rf voltmeter will
vary considerably from the fundamental frequency to the
higher harmonics. Would not this mismatch give readings
which would not be proportional to the actual funda-
mental to harmonic ratio. Most meters of this type
require from 50 to 100 ohms resistive source impedance
Declassified in Part - Sanitized Copy Approved for Release 2012/02/14: CIA-RDP78-0333OA004100030006-3
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Declassified in Part - Sanitized Copy Approved for Release 2012/02/14: CIA-RDP78-0333OA004100030006-3
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for proper operation. Another source of
error which would be self correcting with the
substitution method would be in the fact that
the transmitter output could be tuned to
compensate for the capacitive voltage divider
while such would not be.the case for the signal
generator. The resulting mismatch would require
a larger input from the signal generator than
from the transmitter.
FAU
Declassified in Part - Sanitized Copy Approved for Release 2012/02/14: CIA-RDP78-0333OA004100030006-3