[Milsurplus] Whazzit - MD-209/UC HF transmitter phase modulator

[Nick England]

Info at
http://www.navy-radio.com/xmtrs.htm#md209

What was this used for? - adds audio freq phase modulation to an HF
(4-20mc) transmitter. 1955 manual. OK, I give up - what was this used for
and who was receiving such signals? Fax?

=================
The MD-20 9/UC is a device for electronically
shifting the phase of a radio frequency
signal at an audio frequency rate. Its use
permits audio frequency transmission by an
A-1 emission type transmitter. Audio frequency
modulation signals used for this purpose
must be in the frequency range 250 to
6000 cps.
The modulator is designed to phase modulate
 n RF signal in the range 2 to 5 mc. It is
intended to be used with transmitters whose
output frequency is in the range 4 to 20 mc.
A "MODULATION RANGE" control is provided to
reduce phase shift in proportion to the frequency
multiplication used. The RF input is
terminated in a 51-ohm resistive load. An RF
input level between 1 to 20 volts is required.
The nominal maximum modulation capability
is ±1/2 radian of RF phase shift at
all modulating frequencies within the above
limits. Audio modulating signals should be
between -20 dbm and a +10 dbm to satisfactorily
modulate the RF signal. The audio output
circuit matches a line of 600 ohms impedance.
===========================

Cheers,
Nick England K4NYW
www.navy-radio.com
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