[Elecraft] Equalizing pitch on filter switching

[Vic Rosenthal]

After installing the Elecraft frequency stability mod, replacing my crystals
with new matched ones, and installing the firmware and I/O controller compatible
with the KAT100, I had to do a complete recalibration of the PLL and BFO.  I
used Spectrogram to center the BFO in my 1.5, 0.8, 0.4 and 0.2 KHz bandwidths,
and it happened that the pitches came out all the same except for the narrowest
filter, which was 10 Hz high.  

I discovered that by changing the width from 0.2 to 0.22 KHz and moving the BFO
one click to the right, the K2's PLL-shifting algorithm rounded down instead of
up (or whatever) and the pitch came ou exactly right!

So if you are trying to equalize pitches, try changing the bandwidth slightly
and re-centering the BFO.  The difference between 200 and 220 Hz. bandwidth was
negligible.

Of course, don't even think about adjusting the BFO without using Spectrogram.

Vic K2VCO