[Elecraft] APF For K3

[Ron D'Eau Claire]

When dealing with very weak signals in the absence of really strong QRM, I
use the widest bandwidth possible for just that reason. At least 2.8 kHz is
typical for me and I almost never drop below 1 kHz. The more pink or
white-ish the noise, the easier it is to hear a very weak CW signal down in
it. 

That's why I vastly prefer the notch filter to help my gray matter filter in
case a really strong signal appears in the bandpass. 

On stronger signals mixed in a lot of heavy QRM I'll crank in the bandwidth
so the desired signal is the only one I hear. Then I can pretend I'm
listening to a code practice oscillator - it sure doesn't sound like a
"radio", Hi

Now that Wayne's implementing APF I'm curious to see how it sounds. I'm
prepared to be astonished if it sounds any different than a decent active
audio filter with some gain at the center frequency.  

Ron AC7AC

-----Original Message-----
On 10/25/2010 12:29 PM, Merv Schweigert wrote:
> but never found them useful for CW.  The filter in my head always seems
better at picking out the desired signal than the audio filter

That's usually been my experience too, primarily because the skirts ring 
on QRN, and the narrower the filter, the closer those skirts get to the 
CW note.  The closer the ringing is to the CW note, the harder it is for 
the ear/brain to separate them.  This is pretty well known by scientists 
working in the psychoacoustic world.

73, Jim K9YC