[Elecraft] Strange K2 Failure Mode

[Ron D'Eau Claire]

Jim, K9YC, wrote:

I bought a k2/100 from someone on this list several months ago...Just got
out here to play with it 
last weekend....

Tuning knob is VERY stiff compared to my own K2.

tuning knob tunes makes the frequency readout change but the transmitted
frequency (as observed 
on another radio) doesn't.  The readout said 7002 kHz, but the 
transmitted (and receive) freq was around 7070. 

Strong transients when the RF gain knob is turned (sounds like DC on 
the pot from a leaky cap).  Causes the AGC line to essentially mute 
the radio for a second or so, then recovers to where the knob sets 
it.
----------------------

Ouch!

Re: Stiff Tuning. A problem that hasn't been mentioned in a long time now
that caused the K2 optical encoder to become very stiff is that some of the
fine "hairs" from the felt washer can get tangled in the shaft bearing.
They'll show up where the rotating shaft passes into the bushing around the
c-clip retainer. I was able to tease mine out tugging each strand with
tweezers while rotating the shaft to "unwind" each one. It took me about 15
minutes or so of patient work but, in the end, the encoder ran as smoothly
as before. I put a little "super glue" on the inner edge of the felt washer
to hold the hairs together. That fixed the problem for me.

Re: Frequency readout.  Assuming you aren't in SPLIT mode (in which case you
should see the xmit frequency on the K2 when you transmit), I'd run CAL PLL
and see how it behaves. If the firmware has been changed without doing that,
all sorts of strange tuning behavior can occur.

Re: Noisy RF Gain. Sounds like an abused pot. 

Ron AC7AC