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

[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



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