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.
>
>
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>> 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.
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