Chad Kurszewski WE9V wrote:
>
> >If one actually did build these amps with one common power supply (Ok, I
> >know you can't run multi-single or multi-multi) how is the power supply
> >switched between amps...given the fact that you could use one P/S for all
> >the amps? What do these people do to accomodate 3500 volts at an amp? Of
> >course yu would be foolish to swich filament power, but just the HV.
>
> We have tried this, with two major requirements:
>
> 1) No HV present without filament voltage, both turn on and turn off.
> 2) No requirement to have all RF decks on at once.
>
> We ordered large Dahl XFMRs to handle double the current and tried using
> 2 RF decks per supply. With the above requirements, the solution I came up
> with was to have the RF deck control a Jennings RJ-1 HV vacuum relay to
> switch the HV to the deck.
>
> For reasons unknown (Rich, Tom, Karl comments??) we had terrible luck with
> this. A high percentage of the time, for turn on, the RF deck would draw
> a TON of current, blowing up all of the RF deck annode components up to the
> tube, a fuse resistor in the power supply, and most expensivly, the vacuum
> relay.
Chad:
You can not open a vacuum relay with voltage present at the contacts, as
an internal arc will ionize metal off of the contacts in the process of
opening same. The result is a conductive ionized cloud inside the relay,
which shorts all theree contacts to the case/ground. Bad news.
Jennings has some very good application notes in this respect. In the
end, your solution of separate supplies can be used, or you can use a
high-voltage ceramic switch, as Phil has recommended, with large
interposition spacing (45 degrees).
Best of luck,
Vince Fedele
WA2PKE
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