Fwd: no8v: APF Primer? - 2020-08-25

Here is John's method for using the APF feature on his K3.

    73,  Kevin.  KD5ONS




-------- Forwarded Message --------
Subject: no8v: [Elecraft] APF Primer? - 2020-08-25
Date: Tue, 25 Aug 2020 12:20:14 +0000
From: John Gibson <[hidden email]>
To: kevinr <[hidden email]>



Hi Kevin,

I have used APF to find you on ECN/20. When QRN/QRM was high and signals
were weak, APF sometimes enabled me to hear and recognize you by the
rhythm of your sending. Without APF, I could not hear you at all.

Normally I tune for you with a WIDTH of about 25 Hz, but when I switch
to APF, I also broaden WIDTH to its default CW value of 400 Hz to help
minimize ringing. I also change the tuning rate to FINE to avoid missing
the APF peak. It should be possible to automate both of those changes on
the K3, although I have not yet done so.

APF is no panacea. It does ring, which makes copy difficult. But
sometimes it saves the day.

73,

John, no8v

________________________________________
From: [hidden email]
<[hidden email]> on behalf of kevinr <[hidden email]>
Sent: Monday, August 24, 2020 10:33 PM
To: Elecraft Reflector
Subject: [Elecraft] APF Primer?

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

-

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[Bill Frantz]

APF is not a cure all. It is an alternative to narrowing the
bandwidth to the minimum to try to improve the signal to noise
ratio. If there are strong signals near the one you are trying
to receive, from a crowded band or DQRM, then it isn't going to
help. If the band is reasonably quiet around the signal, it can
make reception possible.

73 Bill AE6JV

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Bill Frantz        | Concurrency is hard. 12   | Periwinkle
[phone]      | out 10 programmers get it | 150 Rivermead
Rd #235
www.pwpconsult.com | wrong.      - Jeff Frantz | Peterborough,
NH 03458

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