>Hi Rich,
>
>> ** RF-actuated EBS is an idea that looks workable on paper but one
>> which doesn't work acceptably in practice because the EBS switches in
>> and out of non-linear bias during soft-syllables. Synchronizing the
>> EBS with the RF-relays is clearly the best approach - even though it
>> requires two, additional wires from the transceiver to the amplifier's
>> RL Control circuit. As I see it, even with a radio that had no
>> overshoot and pristine IMD, RF-actuated EBS would still have the
>> problem of generating IMD (and harsh-sounding audio) by rapidly
>> switching in and out of non-linear bias during soft-syllables.
>
>Yep. The Aussie amp maker, Emtron, is VERY proud of their EBS,
>because it holds dissipation down.
** This is true for those who still use PTT. However, many people
(including me) currently use VOX and transceiver-controlled bias
switching. Whenever I stop talking, within a fraction of a second,
ZSAC dissipation is zero.
>I have had quite a bit of
>experience with these amps (several different DX-2's with the now
>scarce-as-hensteeth 4cx1600b), and have experimented on-the-air with
>setting the threshold. When set as the factory suggests, on SSB the
>best report I got was "your signal sucks!" It sounded fine when I
>backed the bias down to where the resting anode current was... guess
>what!?... equal to the value with the EBS turned off! It would be a
>good energy saver on CW, RTTY, etc.
** chortle. In other words, when adjusted for minimal suckiness in the
Tx audio, RF-controlled EBS Increases average dissipation for SSB. It
still puzzles me why anyone would promote a T/R system where the
bias-switching was not always in perfect sync with the RF-switching.
>
>There are many things I like about the Emtron amps, though.
>
** As do I. He seems to have done his homework on VHF suppressors.
>
cheers, George
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