Terry
It's just the usual removal of adjacent signals, no big "click" or
anything like that, just a smooth transition with an improvement in
skirt selectivity - much as you would expect with a narrower filter.
Under low signal level band conditions as here at 2230 local time on
80m, there's not much difference, under contest conditions when 40m is
pounding in it's more noticeable. It's hard to describe, the K3 just
does what you would expect a decent receiver to do without fuss, filter
ringing or any other artefacts. I guess the only real test is to have
two K3s side by side, one with filter "A" and the other with filter "B"
as the DSP bandwidth is linked to the roofing filter, so it's hard to
open one IF leaving the other "narrow". Suffice to say I think the $120
for the 400 Hz 8 pole CW filter is money well spent, as to whether it's
necessary to use 8 poles rather than 5 is something I can't answer, as I
only have 8 pole filters.
73 Dave, G4AON
K3/100 #80
===============
Dave,
Perhaps you can comment on what sort of improvement was noted when
the 400 Hz filter was switched in. Noise? Steeper skirt
selectivity? Impulse response (ringing)? IM products?
Thanks & 73,
Terry N6RY
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