>
>
>> Cuting off the tubes intermittently during speech with RF-actuated bias
>> results in switching rapidly in and out of linear-bias during
>> soft-syllables. For this reason, Alpha 77s are well-known for their
>> harsh-sounding audio and spit-spit sound on adjacent channels +/- c.
>> 3kHz. [note -- this sort of thing does not appear with a 2-tone test].
>> The fix is to sync the bias with the coil-current in the RF-relays.
>>
>> //I agree I've never found the "cutoff between syllables" thing to do much
>> for me. If you make it sensitive enough to really work, then the
>> slightest background noise modulation trips it and you're back to standard
>> biasing again. If you make it insensitive, so background noise modulation
>> doesn't trip it, then operation is choppy is you describe. On CW, it
>> seems to work okay (I think).
RF-actuated bias switching works as advertised on CW/FM/AM/RTTY. The
problem area is SSB.
>>
cheerz, Steve
- R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
www.vcnet.com/measures.
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