5E3 power transf no center tap

[benito_red]

I would like to build a 5E3 clone.

I know that a power transformer with the secondary high voltage rated at 320-0-320
Volt (that is 640 Volt with center tap) 120 mA should do the job.

However I would like to use a transformer at 320 Volt without center tap.
Of course I will not use a vacuum tube rectifier but SS bridge rectifier instead,
by means four 1N4007.
I also will add a series power resistore to simulate the voltage drop of a vacuum
tube rectifier.

Question is:
what current rating must I have with 320 Volt no center tap?
120 mA or 240 mA?

I suppose I still should have 120 mA, can somebody confirm?


thanks n regards

benito_red

[loudthud]

Center tapped high voltage transformers tend to be rated for DC current "on center" meaning in the typical arrangement seen in tube equipment. The actual RMS current in the high voltage winding is not really specified and you can exceed it if there is too much filter capacitance. If you are having a transformer custom made, you should either tell the winder that you need 120mA after rectification and filtering or an RMS rating of perhaps 200mA.

You can still use a tube rectifier. Just use a 5Y3 for two of the diodes in the bridge that go the the standby switch and two 1N4007 diodes for the other two that go to ground.

[benito_red]

thanks Loudthud for your answer.
I already have in my drawer a tranny 320 Volt unfortunately rated at 170 mA. In this case I'll have to get a new one.
regards
benito_red

[jmaf]

If your transformer is well built, the 170mA will do. I have some italian transformers here, they are built like tanks and their rating has lots of headroom.

I would test the one you have, but then again it shouldn't be too expensive to get a new one.