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

[KENT TRIMBLE]

Stephen is correct.

Several of us lobbied for an APF feature shortly after the K3 debuted in 
2007, drawing on our experiences with the FT-1000D. There /were/ two 
firmware versions that Wayne developed, and the consensus among some of 
us was that the first one was better than the second.  As I recall, the 
second version cleaned up some artifacts and unintended consequences, 
but, we felt, at the cost of diminished "peaking."  Wayne was adamant 
that the APF part of the code was not touched.  We eventually chalked up 
the difference between the two versions to subjectivity among the 
testers and left it at that.

Barry, by the way, is also correct in saying there were two versions of 
the APF circuit in the FT-1000D over the years.  It has been the 
consensus of owners that the earlier version was superior to the later 
version.

The APF in both the K3 and KX3 is excellent, in my opinion.

73,

Kent  K9ZTV
K3/KX3  s.n. 21



On 2/5/2016 10:03 AM, Stephen Prior wrote:
> I've seen it written that it helps to offset the IF slightly, although to
> be honest I have never myself got the APF to work to my satisfaction.
> Oddly, and I communicated with Wayne about this at the time, the first beta
> (I think) implementation of it was stunning, but a later release lost it
> for me.  Wayne told me there had been no change in code, but I have never
> understood that.