[Elecraft] K3: KFL3C-200 filter

[Jim Brown]

AGREE!  There's also some serious science behind Eric's observation -- 
the skirts of filters made with real components cause phase distortion, 
often described as "ringing." Noise excites that ringing at the 
frequency of the filter slopes, and confuse the brain when trying to 
decode CW.

The same thing happens when the crystal filters in the K2 are aligned 
for RX bandwidths narrower than the TX filter -- the amplitude response 
is a bunch of peaks, and the resulting phase distortion makes SSB hard 
to copy. At full RX bandwidth, the K2 uses the TX filter, which sounds 
very good.

73, Jim K9YC

On Wed,11/30/2016 9:00 AM, Eric NO3M wrote:
> I find the 200Hz filter most useful to knock down adjacent QRM, ie. 
> during crowded contest conditions, not so much dealing with QRN. Try 
> opening up the bandwidth to 500-700Hz when QRN is bad.