On transmit, you need to get some of the carrier
suppression by means of the filter. Most balanced
modulators are not able to get good enough
carrier suppression when operated at low enough
levels to have good IMD. This is main reason
why phasing rigs went out of fashion.

Rick N6RK

"Tom Holden" wrote in message
.. .
ARRL Handbook says that the BFO frequency should be at the -20dB point
down
the skirt of the SSB filter. Pete, KE9OA, says -24dB.
1. What is the reasoning behind these choices?
2. How critical is it that the BFO be so positioned?
3. Wouldn't the shape factor have some bearing on where it should be?
4. Is linear interpolation between the -6 and -60dB points accurate enough
to determine the BFO freq?

TIA,
Tom