Back to back trafo's

[Cornelius]

There was some talk of this subject a while back, but i'll put out the question here with my parameters...

I got 2 identical trafo's; initially unknown specs, but i've got these numbers:

Primary: 230v
Secondary open AC voltage: 20V
Physical size: around 2"x2"x2"

I need High Voltage for a couple of preamp tubes (12ax7).

I've measured the mA at secondary for one trafo to be 500mA with a 35ohm load; the voltage at that load was 14.3VAC - 7.15W. After 10minutes at this load, the trafo was just under fingerwarm to the touch.

Watt being Watt, this should correspond to 31mA at 230V after connectong these two trafos back to back.

Does this seems to be ok to use as HV for 2 preamp tubes?

[Cornelius]

Just to clear up the question; i plan to use these two to get 230VAC by connecting the secondaries together, and input 230VAC on one primary, and get 230VAC out on the second primary...

[Phil_S]

With all those mA, you could build a doubler and that would get you into the 500v range for plate voltage.

You will need to supply filament voltage separately.

Interesting idea. Go for it!

[Cornelius]

Yes, i do have a 6,3v trafo separate.

I just need HV for a preamp tube or two, so i think i'll try.

I do not believe i need a voltage doubler for plate voltage for those preamp tubes... (It's for a experiment; a tube preamp for a transistor amp-block i have... )