> 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).
>
> -WB2WIK/6
>
>
> >
> >
> >
> >> The problem with a 50w zener is that its Vz is not adjustable. A
> >> fwd-biased Si diode string can be adjusted by changing taps.
> >>
> >> //'Tis true. However, I don't know why I'd need it to be adjustable.
> I
> >> suppose for an amp having two HV taps (CW and SSB) this might be a nice
> >> feature, however my amps don't. Using signal-activated electronic bias
> to
> >> cut off the tube(s) between words, etc, is a cool feature that would
> >> require more than tap changing.
> >>
> >> -WB2WIK/6
>
>
> - R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
> www.vcnet.com/measures.
> end
>
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