[Elecraft] CW signal raspy, underwater, motorboating

[B. Scott Andersen]

Fellow K2 builders:

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)

B. Scott Andersen    | "Magic is real, unless declared integer."
bsandersen at mac.com   | -- The collected sayings of Wiz Zumwalt
Acton, Massachusetts | Ham: NE1RD, QRP ARCI#11588, FP#910, NEQRP#634