[Elecraft] K2 transmit power instability on 20 & 12 meters

[Don Wilhelm]

David,

You are correct that the only thing common to 20 meters and 12 meters is 
the relays for the VFO Range Select.
Put the internal counter probe in TP1 and see if you have a steady 
frequency on each of those bands.  The low end of 20 meters should have 
a VFO frequency of 18,915 kHz and at the low end of 12 meters the 
frequency should be 19,975 kHz.

If the VFO frequency is correct, then relays K13, K14 and K15 are 
working correctly for those bands.

Fluctuating power is usually associated with the power control loop or 
RF feedback is another possibility.
Just how much does the power fluctuate?  "Wildly" is not an adequate 
description to provide troubleshooting information.
If you have a KPA100, does the power fluctuate if power to the KPA100 is 
removed and only the base K2 is powered?

73,
Don W3FPR

David C Dawson wrote:
> My K2 (05386) has developed a problem affecting the 20 meter and 12
> meter bands only. When I key up, the power fluctuates wildly. On the 20
> meter band rx seems normal, on 12 there is a chorus of birdies.
> My assumption is that a common component was cold-soldered or has
> failed.
> I note that in the relay table, K13,K14 & K15 are energized together
> only on those two bands.
> Before I start the troubleshooting, I'd like to know what components
> could be the culprits?
> Or any other (helpful) suggestions. (I have an rf probe still)
> Thanks.
>   
>