[Elecraft] K2 filter attenuation

[James Hammons]

I followed the instructions for the setup of the filters provided in
both the manual and SSB manual.  The recommended setting for FL4 is
0.10 dc. or 100 cps.   If this setting is not recommended then why
specify the setting.   I would bet most K2's are set up this way.

I recently changed the setting to 0.20 to keep the drift within the
passband.  I removed one of the PLL crystals and found that one
crystal would pull 11.5 kc, not the recommended 12kc but it worked and
it reduced the drift of the PLL to .5 ppm/degree C an improvement of
better than half.  The BFO still drifts more than 1ppm/degree C.  How
is the recommended mod coming along.  Could we have a few more hints
of what is involved with the BFO mod.

I was thinking along the lines of if an output could be found which
only happens  on the reverse cw or LSB setting then the signal could
switch to a second crystal or insert a fixed cap to pull the crystal
and thus reduced the voltage change required or eliminate the two
crystals in parallel.  perhaps there is a output at the LCD that would
be usable for this?