[ICOM] APF filter question

[Dave 'Doc' Corio]

     John, I recently switched from the IC-746 to the IC-7200. The APF 
on the 746 was excellent, but I believe the DSP on the 7200 is a bit better.

     On the 746, I always had to "fiddle" with the APF, especially if 
the other station was a bit off my zero beat. In narrow (80 Hz) mode it 
did eliminate a lot of other signals. However, being able to adjust the 
DSP filter from 3600 Hz down to 50 Hz, is much easier to use in that 
same situation.

     For example, I always had the APF on the 746 tuned to my 600 Hz 
sidetone. If conditions warranted I could turn that on in one of the 
three bandwidths easily, But if the other station was at 750 Hz, tuning 
the APF in one of the narrow modes got tricky.

     On the 7200, I can turn the DSP in very small steps, instead of 
only three choices, until only the noise is eliminated. I haven't yet 
used it in the narrowest (50 Hz) width, but have stopped it down to 150 
Hz with good results. It doesn't have the "ringing" quality that the 746 
had using the APF.

     The DSP on the 7200 also works MUCH better on the digital modes 
than the optional filters (500 Hz and 250 Hz) I had in the 746.

     I operate very little SSB, so my opinion only apples to CW, and as 
most "opinions", it's impossible to quantify! This is just my 
preference. YMMV!

73

Dave KB3MOW

On 2/22/2017 2:40 PM, John Geiger wrote:
> One of the more useful CW tools on some Icom rigs is the APF filter where a
> thin slice of receive (where the CW signal is) can be increased to boost it
> out of the noise.  This feature is found on the 746 and 756 original, and I
> think it reappeared on the 7600.  The HF/VHF/UHF radios like the 7000 and
> 7100 do not have it.  Since they have IF DSP does narrowing the CW filter
> down to 150hz or so pretty much replicate this feature, or are you still
> missing out because you don't get the "boost" that the APF gives?
>
> 73 John AF5CC
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