[Elecraft] APF (audio peaking filter) on the K3/K3S/KX3

[F5vjc]

Well actually I prefer copying CW with a certain amount of noise present.
 Pure tone, no noise CW, as from a practice oscillator or an S9++ signal
quickly becomes boring and I loose concentration(or something).
It's perhaps why I prefer to dig out weak signals (ESP) from the noise on
the band.
However I do really appreciate the tools available in the K3 to do this :)
APF works great if you really learn how to use it.

Any one else?


73,  Deni - F5VJC



On 6 February 2016 at 12:19, Bill W4ZV <btippett at alum.mit.edu> wrote:

> N1EU wrote
> > I suspect that when the K3 APF was first engineered, the Yaesu FT-1000D
> > APF
> > (original hi-Q version) was used as the model because many prominent
> > dx'ers/topbanders always raved about it.
>
> I lifted the "original" FT-1000D APF from the schematic in 2009 and Al W6LX
> did a circuit simulation on it.  Al's description provided the roadmap for
> what Elecraft eventually implemented in the K3's DSP in 2010.
>
> http://www.mail-archive.com/elecraft%40mailman.qth.net/msg105227.html
>
> As Wayne has suggested previously, APF works best if you use a relatively
> wide DSP setting (I use 400 Hz).  I trick my K3 into using my 200 Hz XFIL
> at
> DSP=400 by setting the XFIL BW to 400 (similar idea to what Wayne recently
> suggested with the 2.7/2.8 XFIL for better NB).  The wider DSP BW keeps the
> ringing down and gives your ear/brain a better background to discriminate
> signals through the 30 Hz APF without ringing while the wide (5 pole) 200
> Hz
> XFIL still gives good protection from nearby strong signal overload.
> Setting the VFO is not as critical compared to narrow DSP settings, and I
> use APF virtually all the time...even in contests.  This signal path may
> help visualize what I'm doing:
>
> signal >> 200 Hz XFIL >> 400 Hz DSP >> 30 Hz APF >>  ear/brain
>
> 73,  Bill  W4ZV
>
>
>
> --
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> Sent from the Elecraft mailing list archive at Nabble.com.
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