rectifier tube filament

[dBel84]

This is probably a very dumb question but here goes.

I am going to build the Baby Huey EL84 and picked up an Antek transformer with HV and heater windings. I learned that the PSU board is optimal for the EL34 and am thinking I may put some rectifier tubes I have to use. I have a 5A DC power supply - can this be used for the filament in the rectifier like the 5U4G or will I be trying to electrocute myself.

My gut instinct is no but I have tied B+ to DC heaters for heater - cathode bias as the heaters float. It has just been a while since I built a real tube amp and solid state doesn't have these problems.

thanks..dB

 

[rayma]

The rectifier filament must float at the B+ level, so you would not want to use
an external power supply for that. It would fail in very short order.
That's why tube amplifiers' transformers have a separate isolated 5VAC winding for the rectifier.

 

[astouffer]

It's probably frowned upon but you could do it with a switching power supply. They usually have a good voltage rating between the input and output. Of course check the datasheets and don't attempt it with a Chinese eBay deal.

A real transformer however would be better.

 

[dBel84]

Thanks. I should trust my gut. I will hunt down a suitable ac supply.

 

[rayma]

It will need voltage isolation of twice the B+ value to be safe.

 

[PRR]

It will need voltage isolation of twice the B+ value to be safe.

Plate to cathode, yes, 2X Vpeak. And Vpeak is a little more than B+.

Cathode to ground is different. Vpeak will do.