For narrow receive SSB filtering (crystal and DSP) for contesting and other
crowded band conditions, use the HIGH CUT control rather than WIDTH and
SHIFT.
In an earlier post, I reported that the K3 1.8kHz crystal filter is
excellent for SSB contesting and had no degradation of audio quality over
the 2.1kHz filter, at least to my ears. I noted that the IF needed to be
SHIFTed lower by 500Hz with the 1.8kHz crystal filter for best sounding
audio. Wayne just pointed out to me that rather than having to adjust two
controls (WIDTH and SHIFT) to go from 2.8 to 1.8kHz in SSB, that the HIGH
CUT control could be used instead to move from 3.0kHz to 2.1kHz, at which
time the 1.8kHz crystal filter automatically kicks in.
Carrying this one step further, I reduced HIGH CUT to 1.2kHz, yielding an
overall 1.0kHz bandwidth and causing my 1kHz crystal filter to kick in for
IMD protection of the DSP IF. (NOTE: I had to enable FL3 = YES for SSB so
the 1kHz crystal filter was available.) The audio was still quite
intelligible, entirely adequate for contesting, but was a little low for my
taste. I found that at a 1kHz SSB bandwidth I prefer to stop HIGH CUT at
1.3kHz and move LOW CUT up from 200 to 300Hz. Individual preferences may
cause different operators to prefer slightly different combinations of LOW
and HIGH CUT settings to achieve the desired bandwidth, especially at the
narrowest bandwidths. But, for me it is simple by adjusting HIGH CUT
downward until the bandwidth is about 1.3kHz or so, then I like to narrow it
further by raising LOW CUT. YMMV, as its said.
If you are on the fence about what narrow crystal filter(s) to install for
SSB, spend some time listening around the bands by setting your HIGH CUT to
2.3kHz (2.1kHz bandwidth) or 2.1kHz (1.8kHz bandwidth) or even 1.2kHz (1kHz
bandwidth). This will show you exactly what the K3 sounds like if want to
use a narrower crystal filter. You'll be surprised at how narrow you can go
and still have excellent readability.
73,
Ed - W0YK
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