"Michael Black" wrote in message
news:alpine.LNX.2.02.1308251248110.28924@darkstar. example.org...

Same with a crystal filter, it allows only one sideband to pass so
anything on the other side of zero-beat is knocked down in strength
significantly.

Except in the case of CW through a single-Xtal filter, when the carrier
and BOTH sidebands***** pass through, but an interfering signal
on the other sie of the BFO is phased out.


***** very close in, eg 12WPM is 10baud.