Watkins-Johnson Listening Post
This is an LP construction project in process. I will be adding a complementary Preselector (RFP-1), and an Audio
Control panel (ACP-1). I will place reports of the progress on the index page as they occur.
Note that both WJ units now have meter lights - yellow LEDs - this is something I could never figure out about their
design team's intentions ... maybe it just wasn't in the government spec ... dunno.
This phase of the project adds the WJ DMS-105A-2 Demodulator. This unit connects to the WJ-8718A-9 (shown
above) IF Output. It demodulates and filters all signals from the receiver's IF therfore making the receiver a tuner of
sorts ... utilizing only its front end and pre-455kHz IF filters.
The basic advantages are: greater filter selection and control, BFO flexability, and Pass Band Shifting. Additionally, by
utilizing both audio outputs -- from the receiver and from the demodulator -- a kind of Diversity Reception is possible.
Not to be confused with "Signal Diversity" from multiple, phased antennas, this arrangement might properly be called
"Receiver Diversity" Whatever we call it, it works. To effect that feature, the audio from both the receiver and
demodulator will be fed to separate inputs of the ACP-1 where they can be selected and/or mixed for feeding to the
audio power amp.
Closeups of the
left and right
sides of the
panel details and
Thanks to Jake at
JHI Auctions who,
experience, I can
recommend as a