Re: Vacume tube TC

I just use any kind of transformer in place of a filament transformer as long
as voltage and current is correct.  A  dropping resistor can be used in
series with the transformer input to reduce the output voltage if needed, or
use a variac.  If transformer is overrated in current--that's OK.  Two or
more transformers can be placed in series or parallel to give the needed
voltage and current, but be sure to observe proper phasing.   These
techniques are useful when you just don't  want to wait for the exact spec