Hi, Gang,
I suspect that the reason that some are not bothered by strong signals inside
the roofing filter is that the AGC kicks in and knocks the signals down enough
so that the interfering signal does not seem to be a problem. With weak signal
work this could be devastating, but may work fine for
everyday applications.
There is another way. I removed the source bypass resistor from the 1st IF
JFET amp in my RX-320 to cut down the front end gain, and have been pleased
with that approach, i.e., reducing the gain before the DSP filters are applied.
On the RX-320 I made a modification to allow a 6 kHz wide filter to be switched
in at 455 KHz for SSB and CW use. If you try a filter much narrower than
that, then some of the signal is lost due to the split tuning duties between
the VCO and DSP. Since my 6 kHz filter was not
particularly sharp, the difference between the standard filter and the narrower
filter was not that great.
Regards,
Jack, KE4ID
Electrical Engineer, but mostly an all round tinkerer.
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