Fred,
I would have to have a lot more specific information about that K2 to make
an educated guess regarding the cause.
Here are some 'uneducated' guesses (in order of higher to lower
probability):
1) the VCO is operating on the edge of its stability range (check the
voltage at the left end of R30). That should be noticable on receive as
well if one knows what to listen for and there is a signal on just the right
frequency.
2) The BFO has a spur - this should be noticable on receive by careful
listening (as above).
3) The PLL crystal is causing a spur (should be noticable on receive too).
4) The operator is using AFSK to generate CW through the SSB option and his
driving solftware is generating 2 audio tones.
There could be others as well, but I ran out of possibilities. I would have
to have the K2 on the bench under controlled test conditions before
commenting further.
73,
Don W3FPR
> -----Original Message-----
>
> Was reading where with a spectrum analyzer form a 781, signal was
> seen as very clean. I little less precise, I have listened to my
> K2 with an MP adjacent to it, and there are no spurs to be heard.
>
> BUT...
>
> A few days ago I worked a K2 built and used by an OT in his 80's.
> He had a very strong spur about 2 khz up from the fundamental.
> I suspect this is caused by an adjustment mistake such as the VCO
> adjustment that leads to chirp on 40 meters.
>
> Can anyone tell me what adjustment mistake might likely lead to that spur?
>
> TNX, 73, Fred - kt5x
>
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