[time-nuts] Old xtal filter

Bill Hawkins bill.iaxs at pobox.com
Mon Mar 7 01:48:41 EST 2016


Look up the Collins CV-157. This 1950s unit converted the IF output of
an R-390 receiver into upper and lower sidebands, which could be further
demodulated by existing land line multiplexing techniques, such as 4
RTTY on each sideband. It heterodyned the R-390 IF to 100 KC and
filtered that with a 10 CPS bandwidth filter. A mechanical servo tuned
the heterodyne oscillator to hold 100 KC. It was a marvel of technology
at the time. Didn't use the Knights filter, though. Possibly the
heaviest converter Collins built. Had 44 tubes.

Had one once, but time passes.

Bill Hawkins

-----Original Message-----
From: Joseph Gray
Sent: Sunday, March 06, 2016 1:32 PM

Assuming I made the pictures small enough, attached are two images of an
very old crystal filter that a friend found. The strange thing about it
is the bandwidth - 100 Hz. What could this have been used for, with such
a narrow bandwidth?

Joe Gray
W5JG



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