I have a home brew speaker passive filter. One choice of cutoff
frequency is about 1850 Hz. Its quite useful for enhancing weak signals
and hiding QRM.
2 KHz spacing works with fine radios having super front ends. Tentecs do
that. Many others don't do that well and need greater spacings.
For sure, moving 3 KHz is fine courtesy. There are many in this world
who aren't courteous. It seems as if some see the digital dial reads
differently from when they copied the signal, which they can't copy, but
they still hear, but since the digital dial shows a different frequency
they MUST be away from that QSO frequency so can use this frequency
(even though its only 500 Hz away). Some have little perception of
bandwidth and numbers. Like some (satellite users) who want to run FM on
the edge of their satellite band and grumble about terrestrial FM 10 KHz
below that overlaps their receiver on the band edge.
In my 40 years of SSB, I've used filters of 2.1 and close to 3 KHz
bandwidth, and now the Corsair II with 2.4, and I find I tend to narrow
the Corsair probably down to about 2. And sometimes to narrow further
with the audio filter. Its much less about fidelity and much more about
interference reduction. Or enhancing the signal to noise ratio of the
weak signal by limiting the unneeded frequencies, both highs and lows.
Lows in the transmitter are good for sounding like a radio announcer and
showing up watts on the output meter, but add little to understanding,
unless the voice box is gone an speech comes only from croaks with very
low bandwidth, all low frequencies.
73, Jerry, K0CQ
--
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.
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