Brian,
Since the K2 preserves pitch, you CAN freely change the sidetone pitch as
long as both the old and new pitch both fit inside the audio range of the
filter. The signal being received will not be centered in the passband, but
positioned off to the side of center, but that makes no difference if it
still fits inside the passband (and ideally somewhere within the relatively
flat portion of the passband).
If you want to initially set up the filter (particularly the narrowest) to
operate with a variable sidetone, I suggest that you first decide what the
lowest and highest sidetone pitches will be for you. Then use Spectogram
and set 2 markers, one at the lowest sidetone and the other at the highest.
Then change the BFO to place the center of your narrow filters between these
markers. If the flattop portion of the narrowest filter does not fully
cover these frequency extremes, you may widen the filter or simply accept
the fact that you will see some attenuation when using this filter (the tone
you want will be demodulated on the filter slope).
Watch the wider filters too - do not center them - be certain the low
frequency slope of the filter appears to the left (lower frequency) of your
lower sidetone pitch marker and be certain that the filter stopband occurs
before you get to zero frequency (if it does not, you will have signal
detection on the opposite side of zero beat and loose the single signal
tuning capability.
Extra note - anybody now want to resurrect discrete passband tuning? I
think many of us have gotten hung up on 'setting the BFOs for no frequency
shift between filters', but that is NOT why the shift occurs, any shift is
due to firmware digitizing error. You can set the BFOs almost anywhere and
there will be little shift between filters. What I have discovered (after
all this time) that the BFOs shift the passband, but does not change the
pitch - the firmware changes the pitch. So now I am contemplating using the
CWr filters as a set of discrete passband tuning filters using a fixed
filter width of 400 or 500 Hz and changing the BFOs so the audio range of
each filter is positioned offset a bit from each other (to cut either the
low frequency end or the high frequency end). Also, I seldom use the
reverse sideband for CW, and there is no reason that the BFOs have to be set
for sideband reversal - I will use the side where the pitch increases with
increasing frequency - that way my brain knows which way I am tuning without
looking at the frequency readout. This K2 provides more flexibility than I
thought before!!!
73,
Don W3FPR
----- Original Message -----
Now if only the sidetone pitch could be changed without having to redo
the filter calibration... I like to change the sidetone pitch
occasionally when I'm on the air for long periods as I find my ears tend
to get less "tired" that way. I can't do that with the K2 without
recalibrating the filters.
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