> The ramping is a lot easier to do
> with DC supply than AC (which might use variacs, saturable reactors, or
> other ancient technologies). I use an SCR regulated mains supply with
> good filtering.
Filaments can just as easily be ramped up on ac, this way with no
fuss. I have seen ferro-resonant regulator feeding the filament
transformer, the size was carefully chosen so the low resistance of the
cold filament "bogged down" the regulator to a few % out, as the heater
warmed, the resistance rose as did the output of the regulator until
opium temperature, current and solid regulation were achieved.
I first saw this on 8.5 Volt 25 Amp Varian klystrons.
--
Ron KA4INM - The problem with socialism is that eventually you run
out of other people's money.
[Margaret Thatcher]
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