Strange new drift on my K2

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Strange new drift on my K2

Andrew Moore-3
I recently noticed some drift on my K2, but it's not happening the way
I'd expect.

This morning it happened again, as follows.

I turned the K2 on the K2 with volume turned down almost completely
and left it that way for a couple hours, tuned to 7040 kHz.  Then I
turned volume up to a normal listening level and immediately tuned
down to a CW signal at 7024 kHz.

Tuning resolution was set rather course at 100 Hz.  When I let go of
the main tuning dial, within seconds the frequency starts climbing up
the band at a rate of about 100 Hz every 10 seconds (rough estimate).

I changed tuning step to 1000 Hz, and the apparent drift kept
happening, but this time in a 1000 Hz step *within the same time
period as before*.

It's almost as if my encoder is drifting... not the radio.

After a few minutes things seemed to stabilize.

I just tweaked the main dial again, and drift started, this time in
the other direction.

The rig seems to go into these drift fits only when I tweak the knob.

I've never seen this behavior on my K2 before.  It's been very stable
since I built it more than two years ago (serial number 4958).

A couple weeks ago I did a very thorough realignment of everything
(peaked inductors and caps, tuned filters, calibrated S meter,
measured MDS, etc.) using test oscillator and calibrated noise
generators ('til I fried my N-gen.. D'oh!).  Top to bottom tune-up.
I'd swear it sounded better than ever -- or maybe that was just the
conditions on 40... but this drift seems to coincide roughly with that
realignment.  Maybe a complete coincidence.

Help?

--Andrew, NV1B
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Re: Strange new drift on my K2

Vic K2VCO
Andrew Moore wrote:

> When I let go of
> the main tuning dial, within seconds the frequency starts climbing up
> the band at a rate of about 100 Hz every 10 seconds (rough estimate).

There *was* a problem like this with an old version of the firmware. If
this is the cause you can update the firmware or make a simple hardware
mod. See <http://www.elecraft.com/Apps/Alert16.html>.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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Re: Strange new drift on my K2

JT Croteau
Drew,

Have you ruled out the simple obvious?  Felt washer is no longer
putting enough friction on the VFO knob to keep it still?

--
JT Croteau, N1ESE - Manchester, NH (FN42gx)
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