I chase very weak CW signals on 160M 80M and 6M many of which Iwould not have 
been able to hear unless I turned on the APF feature.
I have a 400kz filter as my narrowest CW filter and tune like this: 
    1) Zero beat exactly 
    2) Hold the XFIL/APF button    3) Narrow the width as far as it will go  to 
.05 which I interpret as being 50hz    4) it might help to change tuning to 3 
digits by taping the FINE button    5) Tune ever so carefully +/- a few hz and 
sometimes shifting slightly until the best signal is heard
A weak signal often pops right out of the noise, but be you will find there may 
be unpleasantringing, popping in the noise you might not like.  Point is u can 
pull a signal out and work himwhen it would otherwise be impossible to copy.
73Dave N4DB  K3s 10223
 

    On Sunday, October 16, 2016 12:56 PM, Robert W5AJ Wood <wood...@gmail.com> 
wrote:
 

 I'm curious about others BW (width) setting on CW
If weak, really weak  using 20 to 15 hz 
Going narrower to 10 or 5hz setting doesn't seem to do much 
Really helps on weak 160 signals, generally APF off 

73 Robert W5AJ



-----Original Message-----
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of brian
Sent: Sunday, October 16, 2016 9:43 AM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] (K3) APF and selected bandwidth

Part of the problem with narrower bandwidths is making sure the signal is at
the APF peak.

I had fits trying to use APF with 200-400 Hz dialed in until I launched
Spectrogram and made sure the signal peak aligned with the APF peak.
Weak signals still show even when you have trouble hearing them.  This
alignment helps with pulling them out.  One can tune either the K3 shift
knob or K3 main tuning if it is set at 1 Hz steps.

Works every time.

Spectrogram can be collapsed to a small rectangle for this purpose an
permanently left on the display.  HSDR also has a narrow bandwidth display.
Other spectrum display programs would work as well.

73 de Brian/K3KO




On 10/16/2016 13:03 PM, Chip Stratton wrote:
> I seem to recall a recommendation to use a 400 Hz bandwidth with APF. 
> In my own exerience, narrowing DSP bandwidth much below this does not 
> seem to help APF function and rather muddies it.
>
> Chip
> AE5KA
>
> On Sat, Oct 15, 2016 at 11:44 PM, Brian Hunt <huntin...@coastside.net>
> wrote:
>
>> On the other hand, when used in conjunction with NR a wider DSP BW is 
>> desirable since NR works on uncorrelated noise. Try:
>> BW= 700-1000 Hz,
>> NR= ~ 5-3
>> APF= ON
>> Great for pulling out weak signals on an uncrowded band. The NR 
>> settings of 5 and above mix processed and non-processed data so the 
>> APF has something to work on.  My theory, anyway.
>>
>> 73,
>> Brian, K0DTJ
>>
>>> On Oct 15, 2016, at 19:52, Ken Arck <k...@arcomcontrollers.com> wrote:
>>>
>>> The narrower the bandwidth, the better signal to noise.
>>>
>>> That should answer your question :-)
>>>
>>> Ken
>>>
>>>
>>> At 07:39 PM 10/15/2016, Robert G Strickland wrote:
>>>> When using the APF, does it make a difference which bandwidth has 
>>>> been
>> selected? Or in other words, does APF work better on top of a narrow 
>> or wide bandwidth, or is selected bandwidth irrelevant? Thanks.
>>>> ...robert
>>>> --
>>>> Robert G Strickland, PhD ABPH - KE2WY rc...@verizon.net.usa 
>>>> Syracuse, New York, USA
>>>>
>>
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