Gentlemen,
In reading the posts below do I detect a tendency to use a HV relay
to switch the HV on and off every time the amplifier is keyed?
Using the 3CPX5000 scenario posted before, would then the
sequence (abridged) be:
1. Apply HV- (B- as Will espouses, below).
2. Apply Bias.
3. Trigger antenna relays.
4. Apply drive voltage.
5. Remove Dive voltage.
6. Remove Bias.
7. Remove HV-
8. Unpick antenna relays.
This sounds like a switching sequence nightmare!
If I'm running 4KV at 2 amperes on the plates, I need to
run serious vacuum relays (and I do, I do!), but they
are huge and slow. I could see all this in a setup that
had long turn-around Tx/Rx, like RTTY bulletin stations,
but what happens to PSK31, AMTOR and contesting
operators when they want to "get up and go?"
Hal Mandel
W4HBM
> >Is this true even when the tube is biased into cutoff? I've owned
> >four commercially-made amps and all of them apply HV as soon as the
> >power switch is turned on, but all four have the tube biased into
>>cutoff. Are you saying that is a design error?
>- Bill
> In any amps I've made, I did kill the B- lead for the HV until the
> antenna relay pulled in even though it was biased to cutoff on idle.
> The reason being is that if the bias ever failed while the amp was at
> idle, you'd have a run-away situation that would happen fast.
>-Will
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