[Elecraft] Realign xtal filter for changed sidetone frequency?

[k6se@juno.com]

Hi, Sverre,

You wrote:

"I envy those of you who can realign those filters quickly and accurately
though. This is the one single issue with the K2 that I never seem to get
comfortable with. I have tried Spectogram and other methods."
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Usually the BFO settings that the manual gives in the tables for the
number on the pack the BFO xtals came in is close enough for SSB.

For CW you should set up a marker in Spectrogram at the frequency of your
sidetone pitch and adjust the filter BFO settings (on noise only, using
either the 0 to 255 readout or the actual BFO frequency readout) so that
the center of the filter passband is at the marker.  Do this for all 4 CW
filters on both CW Normal and CW Reverse (8 times).
==========

"My filters may be fine when aligned, but I get the feeling that they
drift out of tune after a while - even after I installed the reduced
drift-modification for the BFO."
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Temperature drift of the BFO oscillator was a big problem in my K2
originally.  It would drift enough so that the received signal (when
tuned in at the sidetone pitch) was no longer in the center of the CW
filter passbands when the temperature inside the cabinet was not where it
was when I set up my filters.  The new toroid in the BFO circuit
eliminated any noticeable temperature drift in my K2 and I no longer have
that problem.

73, de Earl, K6SE