[Elecraft] K3 Auto Notch distortion

[Nate Bargmann]

* On 2012 26 Jan 08:18 -0600, NZ0T wrote:
> After a firmware update quite a while ago (I don't remember which one but it
> was more than a year ago) I have had bad distortion using the Auto Notch on
> SSB.  I have heard others say the same - is there anything that can be done
> about this?  Mine is bad enough to make the Auto Notch unusable and I use
> the manual notch instead.  I'm primarily a CW op but my SSB use is for local
> nets on 75 meters and with a group every night on 160 phone and those are
> bands that Auto Notch would be very handy to have!

While watching the effect of the autonotch on USB a CW signal in
the passband on 20m with Fldigi, I see an interesting set of audio
frequency bands that appear to be notches on either side of the desired
notched signal but not on the signal itself.  Meanwhile the manual notch
is a nice ~200 Hz wide band of notched audio.

First, a screenshot with no notch enabled:

http://i197.photobucket.com/albums/aa106/N0NB/Ham%20radio/k3-no-notch.png

Second, the auto-notch:

http://i197.photobucket.com/albums/aa106/N0NB/Ham%20radio/k3-auto-notch.png

Finally, the manual notch:

http://i197.photobucket.com/albums/aa106/N0NB/Ham%20radio/k3-manual-notch.png

It must be noted that the sensitivity of the waterfall is affected by
the values in the lower left corner of each image.  The -16 sets the
upper signal level in dB and the 60 sets the range of the display.
Adjusting the upper signal level higher (more positive) makes the manual
notch appear wider and adjusting it lower (more negative) makes it
appear to be more narrow.  These controls are analogous to the P3's Ref
Level and Scale settings.

73, de Nate N0NB >>

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