[TenTec] Re: N4LQ and the 2.8kHz Pill

[Dr. Gerald N. Johnson, P.E.]

The phase delay of a crystal filter changes rapidly at the knee. A
little frequency shift could easily be magnified by that phase shift to
sound like a wider chirp. It would seem to me to be best to make sure
the CW signal was inside the filter a ways to get away from that. Either
by selection of CW carrier frequency or filter frequency. Maybe it would
be better to introduce a totally separate CW crystal oscillator that
didn't need to go through the filter. I don't have any idea what that
would do to the switching, but ought to make it sound perfect. Though
its not easy to key a crystal oscillator without either clicks or
chirps. The crystal doesn't like stopping and starting... Probably
better to key a mixer to get a better on/off ratio that just keying a
straight gain stage with the oscillator running continouously.

73, Jerry, K0CQ

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