"Dale Parfitt" ) writes:
"Tom" wrote in message
news:YBvjd.2272$bH2.1471@trnddc09...
Don't know where you can buy a passband filter. Maybe be able to find some
cavity type filters for 50 MHz, but probably only surplus. Building from
scratch
is easy but takes a network analyzer to tune.

A coax stub can be either open or shorted, your preference. Cheapest way
is
to
start with an open stub slightly too long and trim it to length. If you
can
borrow
a signal generator and power meter, then you can tune it that way.

It's practical to get about 25 dB of loss with a stub, better is difficult
due to losses
in the conectors, cables, etc.

You may achieve -25dB loss at CH2 video, but unfortunately you will also
have high loss at 50MHz, and a VSWR that is out of sight.
Build one and see for yourself.

Dale W4OP


So you get a crystal cut for the channel 2 carrier frequency, and find
a place to connect it in the receiver chain. This sort of thing was done
apparently in repeaters forty years ago, to keep the transmitter out of
the receiver. I do think one would have to modify the receiver because
the crystal might not be able to handle the transmitter signal.

Michael VE2BVW