Darwin, Keith wrote:
Let's widen the question to make it KAF2 or KDSP2 or NOTHING? Does the
basic K2's crystal filtering work well enough that you (any of you)
would be happy with no AF filtering or does the AF/DSP filtering add
enough that you wouldn't want to be without it?
Selectivity has two functions: to reject QRM and to increase the
signal/noise ratio by narrowing the bandwidth. The crystal filter in
the K2 is usually sufficient for QRM reduction, with the help of the
"built-in wetware filter" in the human brain.
However, it *is* advantageous to have the narrowest practical bandwidth
when receiving a weak CW signal; the signal's energy is concentrated in
a very narrow range of frequencies -- maybe 50 Hz is required for usual
CW speeds -- while the noise is evenly distributed over the bandpass of
the receiver. I find it useful to have a narrow audio filter available
for this reason.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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