[Lowfer] narrow filters

[Douglas D. Williams]

Since LF activity really seems to be picking up, I went ahead and
ordered the 250Hz 455kHz IF filter for my R75. This, combined with my
current 500Hz, 9MHz IF filter, should give the receiver good
selectivity. In your opinions, would I see any additional benefit in
getting an even narrower external audio filter? Some of the DSP units
can provide selectivity down to 20Hz! I'm not sure if this amount of
selectivity would help when trying for QRSS signals. I suppose it
could be of benefit when listening for NDBs. Opinions?

-Doug KB4OER