Re: K3 on-channel strong signal overload?

Posted by wayne burdick on May 05, 2009; 9:01pm
URL: http://elecraft.85.s1.nabble.com/K3-on-channel-strong-signal-overload-tp2785612p2806235.html

Mike,

The AGC mod is definitely preferred. The old AGC circuit allows in-band
signals as low as S9 to activate hardware AGC. This would cause desense
if you were using a wide crystal filter but a narrow DSP filter. The
new AGC circuit has an in-band desense threshold of more like S9+20 to
+30.

Of course we also recommend that you have at least one narrow crystal
filter (e.g., 400 or 500 Hz) if you're using CW or narrow data modes.
This changes the definition of "in-band" to such a small value that
desense due to adjacent signals becomes very rare.

Those really pushing the envelope should consider our 200 Hz filter.
Ask a few 160 m contest operators about this :)

73,
Wayne
N6KR

On May 5, 2009, at 1:29 PM, Mike Harris wrote:

> Hi Geoffrey,
>
> I guess there are no simple answers to this apart from proper operator
> intervention.  I guess that is why the buttons are there.  I've no
> intention of adding any diode clipping, I don't have a problem even
> with
> my S-9+60++ neighbour.  One thing to note is that #1400 doesn't have
> the
> hardware AGC mod installed so it is cutting in approx 20dB before the
> latest versions.  I was on the verge of doing it before this thread
> started but I've put it away again....

---

http://www.elecraft.com

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