K2 intermittent CW fault - help!

[Solosko, Robert B (Bob)-2]

Hi All,

        I have an intermittent problem with CW on my K2 (ser 5309).

        My K2s been on the air for several months now on SSB and everything works fine. Several weeks ago, I attempted CW (not having had a CW QSO in 40 or so years), and it work OK for a few minutes -- then when I pressed the hand key (my trusty old J-38), I would get the side tone for a very short time followed by 2 shorter high pitched tones, then nothing (no receive either). Releasing the key, I got receive but pressing the key again, the same thing happened. After a while, I gave up, assuming that I had some wiring problem with the key or the key plug (it was rather a jury-rigged affair). Yesterday I re-wired the key with new wires and a new plug and tried again. Every thing worked OK for a few minutes (except the band was dead) and then the same thing happened. I have an iambic paddle (even though my code speed isn't quite good enough yet to use it) and I plugged that in. In hand key mode, the same thing happened. Putting the K2 into paddle and iambic B mode, the same thing h!
 appened when the side of the paddle connected to the center connector of the plug was pressed, but the side connected to the plugs middle ring worked fine. Reversing the paddle using the menu changed the sides for the dots and dashes, and the paddle side connected to the middle ring work, giving either a string of dots or dashes and expected. For the side connected to the plug's center, I would still get the short side tone followed by the two high pitched tones and then nothing. I the reversed the wiring of the paddle, and the same thing happened, the paddle side connected to the middle ring worked and the side connected to the center didn't.  On the K2 schematic, the center is labeled as DOT/PTT. When running SSB, PPT worked fine.

        So, can anyone suggest what the problem might be and where to start looking?

        Thanks.

Bob Solosko
W1SRB

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[Masleid, Michael A.-2]

Bob, is the Mic plugged in when this happens?  /DOT-PTT is wired to the Mic input, and perhaps picks up
RF if the shield ground on J2 Mic isn't working.

Michael AB9GV

--Hi All,

-- I have an intermittent problem with CW on my K2 (ser 5309).

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[Solosko, Robert B (Bob)-2]

Michael,

        Yes, I had the mike plugged in, so that's a possibility. However, I tried reducing the power from 10 watts down to 2 watts or so and it had no affect (I don't have a KPA100). I also changed from my antenna to a dummy load, which also had no affect on the problem.  But  there could be some interaction problem with the mike PTT. The mike cable shield is connected to pin 8 on the connector, but the front panel chassis mike connector is not grounded. When this happens again, I'll remove the mike and see if that cures the problem.

        Thank and 73.

Bob
W1SRB


-----Original Message-----
From: [hidden email]
[mailto:[hidden email]]On Behalf Of Masleid, Michael
A.
Sent: Tuesday, May 16, 2006 11:25 AM
To: [hidden email]
Subject: RE: [Elecraft] K2 intermittent CW fault - help!


Bob, is the Mic plugged in when this happens?  /DOT-PTT is wired to the Mic input, and perhaps picks up
RF if the shield ground on J2 Mic isn't working.

Michael AB9GV

--Hi All,

-- I have an intermittent problem with CW on my K2 (ser 5309).

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