[Elecraft] CW signal raspy, underwater, motorboating

[Don Wilhelm]

Scott,

I was not able to hear your mp3 - I could not get the long URL to work, but
...

Since TUNE is OK, but your CW is not good, the only thing I can think of is
the components for the 'keying waveshape' mounted on the back of the Control
Board may be giving you some problem.  Check the soldering on all the
components on the back of the control board first (one monolythic cap and an
electrolytic cap).  If these components are not properly in place, 'funny
keying' can result.

73,
Don W3FPR

> -----Original Message-----
>
> I got a "heads-up" this weekend in the New England QSO Party that
> my K2 was sounding pretty awful on CW. I skip the part where I
> claim, "it used to work fine!"
>
> I could use some help diagnosing the problem. Here are the symptoms:
>
> 1. The sound for the CW is raspy, almost like it is underwater with a
> motorboating buzz.
> You can hear it in this mp3:
>
> http://homepage.mac.com/WebObjects/FileSharing.woa/wa/default?
> user=bsandersen&templatefn=FileSharing11.html&xmlfn=TKDocument.
> 11.xml&sitefn=RootSite.xml&aff=consumer&cty=US&lang=en
>
> This was recorded by a friend about 15 miles away. You first hear the
> tone
> when "tune" is used. Then you hear the dots and dashes. Tune is OK;
> CW dots and dashes not OK.
>
> 2. The signal produced by "tune" sounds great. I can adjust the power
> to minimum or full
>     and it continues to sound OK.
>
> 3. It is independent of band selected.
>
> 4. SSB works.
>
> 5. The problem does not seem to get better (or worse) with variations
> in power out.
>
> 6. I looked through the Elecraft email archives and found this:
>
> http://www.ac6rm.net/mailarchive/html/elecraft-list/2003-09/
> msg00550.html
>
> This seemed very promising! So, I just replaced RFC15. No change. :-(
>
> 7. I have taken off the lid so we are nearly back to the original K2
> (no autotuner, internal battery, rs232) and I've removed the DSP
> stuff. The only add-on now is the SSB board (which will come out next).
> Nothing I've removed made the problem better or worse -- which is
> what you'd expect.
>
> =-=-=
>
> This radio has been moved around a lot. It has been to SF, Hawaii,
> Maine, and used several times very recently "picnic table portable."
> I'm sure airport TSA people have shaken it to see if I need to go
> on the next "no fly list". I mention all this because it is not
> inconceivable that something has rattled loose or a cold solder
> joint has finally reared its ugly head.
>
> I've looked at the parts around the PLL, TR switch, and a few other
> places but I've come up empty so far. It is probably something
> stupid but I'm just not seeing it yet.
>
> Any ideas are appreciated. Thank you.
>
> -- Scott (NE1RD)
>