[AMPS] Single band amp construction query

[Chad Kurszewski WE9V]

>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.  I don't know how many hundreds of dollars were spent on replacement
relays, but we finally went back to 6 power supplies for 6 RF decks.

>From hindsight, it appears as if the tube (single 8877) wants to see a ramp
in the HV, not the instant-on 4kV.  The relay was used so the PS could be
on without all the RF decks/filaments being on.

p.s.  330 uF at 4kV is a LOT of energy...it makes quite an explosive sound!
p.p.s.  127363 Joules.  Isn't a defibrilator only like 300 Joules?

---
Chad Kurszewski, WE9V         e-mail:  Chad_Kurszewski@csg.mot.com
The Official "Sultans of Shwing" Web Site:  http://www.QTH.com/sos



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