[Amps] input matching question on the YC156?

[Harold B. Mandel]

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