250 would probably be narrow for pactor. The more important feature is
the relative phase response of the filter. A Tentec 250 Hz filter may
pass pactor unharmed while a 250 Hz Kenwood filter would destroy the
data due to the filter's rapid phase change near the band edges (also
demonstrated by its tendency to ring on noise and fast CW). A Collins
mechanical filter probably will ring at least as much as the Kenwood
filter, though my 300 Hz S-line filter sounded decent on CW the last
time I used it.
500 Hz is a more reasonable filter, the pactor detector does a lot of
its own filtering at audio and after detection.
73, Jerry, K0CQ
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Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.
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