> My big interest though, is in a plate transformer that I've acquired.
> The HV winding reads 5316 VAC and 106 Ohms.
>
> My thought is to disassemble the unit and rewind the primary with
> twice the turns using slightly smaller wire, as there is plenty of
> room. Thus I would hope to have a 240 V primary.
>
> My questions are:
>
> Does a 240 V primary vs. 120 V give significantly better voltage
> regulation , such that it is worth the trouble to rewind?
Regulation in that transformer will be terrible especially if you
draw anything over a few hundred mA. ESR is far too high for a
capacitor input supply. You need to rewind all the windings, or find
a better transformer.
> My open circuit DC voltage with a "C" filter will be nearly 7500
> Volts. Can anyone recommend a tube that will operate at that voltage
> without an enormous price tag? I'd prefer grounded grid and 100 w
> drive, but will build a screen supply if need be.
Voltages like that are major headaches unless you also run big
current to keep the impedance reasonable. You could use a 4CX5000 or
something similar, or perhaps a 3CPX5000 at two or three amperes
plate current for reasonable plate impedances.
Myself, I'd get look for another transformer or completely rewind
that one, pick a more reasonable voltage, and do something to have
low secondary and primary resistance.
> Although I can operate the transformer at lower voltage taps, I'd like
> to use all of the available voltage to keep the current at a minimum
> for the purpose of good voltage regulation.
>
> Thanks again for the help provided.
>
> Jeff - K1LE
>
>
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73, Tom W8JI
W8JI@contesting.com
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