FM receivers are designed to not respond to amplitude variations. CW is
about as pure an example of "information conveyed by variations in
amplitude" as one is likely to find. To cut to the chase, what you
propose won't work.

Sure it will! Open the squelch up all the way. You'll hear the
background noise from the band and/or the front-end electronics when
there's no carrier being sent. When the OM at the other end keys up,
the FM receiver will lock onto the carrier, and happily demodulate the
(nonexistant) sidebands - it'll go silent. No CW filter needed... in
fact it'd make the noise/silence difference harder to hear.

Admittedly, trying to copy "negative noise" CW is likely to be a real
hassle at first, but I imagine that one can train oneself to do it
(just as one can train oneself to read a book held upside-down).

For _conventional_ CW reception, you need something rather different.

;-)

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
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