Re: K3/KX3 Operating Tip: APF (audio peaking, filter) for weak-signal CW work

[G3XDY]

I find the K3 APF invaluable for weak signal work on the microwaves. In
the microwave NAC contest last night I worked three stations over 600km
on 2.3 and 3.4GHz by aircraft reflection, and the APF really helped pull
the weak signals out of the noise. I generally use 1kHz width for CW and
my ears for the rest of the filtering, but the APF makes a really big
difference on those signals that seem just too weak to copy.

The only disadvantage is the hold rather than tap to switch it on/off -
I often find I end up having to reset the filter width when I try to
cancel the APF .

--
73

John G3XDY
K3 #0689

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[Bill W4ZV]

G3XDY wrote

I find the K3 APF invaluable for weak signal work on the microwaves. In
the microwave NAC contest last night I worked three stations over 600km
on 2.3 and 3.4GHz by aircraft reflection, and the APF really helped pull
the weak signals out of the noise. I generally use 1kHz width for CW and
my ears for the rest of the filtering, but the APF makes a really big
difference on those signals that seem just too weak to copy.

Coming from a totally different operating perspective (low band DXing), I agree with John.  For signals in white noise (i.e. at or below the noise floor), I use a wide XFIL (e.g. Inrad 500 with DSP setpoint at 600) and then carefully peak APF in 1 Hz steps using FINE.  With any other signals in the XFIL passband including impulse noise (e.g. lightning), I do better without APF.

73,  Bill

[drewko]

Just wondering if there are others who would prefer that the APF state
NOT be remembered by the WIDTH I/II preset? For some reason that has
always rankled me a bit. Would prefer to have APF changed only by
means of the DUAL PB button.

73,
Drew
AF2Z



On Thu, 28 Jun 2012 03:27:00 -0700 (PDT), you wrote:

>
>G3XDY wrote
>>
>> I find the K3 APF invaluable for weak signal work on the microwaves. In
>> the microwave NAC contest last night I worked three stations over 600km
>> on 2.3 and 3.4GHz by aircraft reflection, and the APF really helped pull
>> the weak signals out of the noise. I generally use 1kHz width for CW and
>> my ears for the rest of the filtering, but the APF makes a really big
>> difference on those signals that seem just too weak to copy.
>>
>
>Coming from a totally different operating perspective (low band DXing), I
>agree with John.  For signals in white noise (i.e. at or below the noise
>floor), I use a wide XFIL (e.g. Inrad 500 with DSP setpoint at 600) and then
>carefully peak APF in 1 Hz steps using FINE.  With any other signals in the
>XFIL passband including impulse noise (e.g. lightning), I do better without
>APF.
>
>73,  Bill

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