[Elecraft] Re: K3 Audio

[Leigh L. Klotz, Jr WA5ZNU]

I have noticed this effect in recent beta firmware revisions as well.  I 
spent quite some time looking at a busy band and chasing ghosts 
everywhere, trying to find out what was up.  I searched the archives and 
saw others had the same problem; the harmonics do seem to be recent, as 
I've not been troubled by this effect before.  Before I wrote I was 
waiting to see if someone did just this experiment you describe.

One point: I have the HAGC mod on my desk still, though, so it's 
possible, especially after Lyle KK7P's last email about the HAGC mod, 
that my problem is related to the undone HAGC mod.  However, if others 
with more recent K3s have the problem, then it isn't just that.
Leigh/WA5ZNU
K3#51
> I see the same extra stripe using mixw  and an RF generator. I had to 
> turn down the line out of the K3 to 001 and crank up the sound card to 
> max inorder to eliminate it. The level is a bit weak now and needs 
> more gain. There is something not quiet right here.
> Steve Ellington
> N4LQ at insightbb.com
> ----- Original Message ----- From: "Jim Brown" 
> <jim at audiosystemsgroup.com>
> To: <elecraft at mailman.qth.net>
> Sent: Friday, August 08, 2008 1:19 PM
> Subject: Re: [Elecraft] Re: K3 Audio
>
>
>> On Fri, 08 Aug 2008 09:30:55 +0100, Andrew Forrest wrote:
>>
>>> It appears that this effect is nothing to do with clipping or
>>> transformer saturation but some kind of mixing.
>>
>> I'm also not convinced that this particular screen shot is non-
>> linear distortion. It could be aliasing in the FFT software that's
>> part of the decoder.
>>
>> On the other hand, the pdf below DOES show both harmonic distortion
>> and IM distortion on the Line Output when the Line Out level is set
>> too high (driving the transformer being driven beyond it's ratings).
>>
>> http://audiosystemsgroup.com/K3FilterStudy.pdf
>>
>> 73,
>>
>> Jim Brown K9YC
>>