[Elecraft] APF Primer?

[kevinr]

I have used APF a number of times.  Sometimes it worked, but often the 
ringing makes it hard to hear anything intelligible.

I have a two families of questions to hopefully remedy my problem.

1) What are the best band conditions to try APF?  Does it work under 
medium QSB against medium to high noise levels?  Is it better on 80, 40, 
or 20 meters?

2) What are the procedures to use APF on your K3, KX2, KX3, etc.?  How 
should I set the bandwidth of the filter I'm already using?  How do I 
peak the APF performance?  Does the set up change on a per band basis or 
does one setting fit all cases?

As I mentioned, I have gotten it to work well a few times, but usually 
the signal sounds buried in a hard walled well.  Then I get emails 
telling me how well it worked during ECN.  My interest is renewed, hence 
my questions.

Help?

    Kevin.  KD5ONS

-