Re: K2: RF Feedback Distortion Problem

Posted by Don Wilhelm-4 on Jan 11, 2011; 3:29am
URL: http://elecraft.85.s1.nabble.com/K2-RF-Feedback-Distortion-Problem-tp5908625p5909512.html

  Jon,

Thanks for that preliminary information.
Try two things, testing again for the distortion after each one.
First, remove the right side panel and tuck the KPA100 ribbon cable up
in the space near the top of the control board.  Do the same for the
speaker cable - in other words, dress those cables as far away as
possible from the SSB board.  Put the side panel back on and re-test.

With the KPA100 still connected, set the power at 20 watts and use an
external wattmeter to measure the KPA100 output.  Is it near 20 watts or
is it over 110 watts?

If the first step does not cure your distortion, then remove the KPA100
completely and test only the base K2.  Try it at 5 watts, 10 watts and
at maximum power.

Let us know what you find.

73,
Don W3FPR

On 1/10/2011 9:53 PM, Jon Perelstein wrote:

> Don,
>
> As always, thanks for your reply.
>
> I can confirm that I *DO* get distortion when operating into a dummy load.  I
> can also confirm that I have the distortion when operating with nothing but the
> microphone and antenna connected to the K2.
>
>   The K2 itself is Rev G dated May 2007, with errata to G-5 (March 2008).  The
> KPA was purchased with the K2 in July 2008, and is Rev E, dated Jan 2007.  The
> KSB2 was also purchased with the K2, and is Rev E dated Jul 2004.  According to
> the Elecraft web site, the KPA100UPKIT is for KPAs prior to Rev D.
>
> ALL cables used for my testing were exactly the same for the K2 and the FT-897
> and the IC-746.  That includes the power supply cables, the coax from the
> antenna to the tuner, and the coax from the tuner to the rig.  I used the same
> Signalink with the same USB cable (although, of course, the mic cables were
> different).
>
> I have not added any additional components to the Elecraft products.  They
> contain only those things that Elecraft included as specified in the Elecraft
> assembly instructions.
>
> Jon
> KB1QBZ
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