"Michael Black" wrote in message
news:alpine.LNX.2.02.1308251307180.28924@darkstar. example.org...
On Sun, 25 Aug 2013, gareth wrote:

"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.

No, you put the BFO on the slope of the filter, no different from some
fancier filter, and so the image is attenuated because it's outside of the
filter bandwidth.


That's not the case with a single-Xtal filter because of the notch caused by
the parallel resonant frequency.