PY 81 as power rectifiers?

[Amie]

Is there a reason its not a good idea to rectify the ground side of the mains transformer.
Anode to chassis, cathode to transformer secondary, other end of secondary to smoothing for HT+
( I have some transformers that would suit this idea nicely)

Nothing intrinsically wrong with the idea but why would you want to do it? And what is so special about your transformers which particularly makes them suitable for this application?

It's a good question! The transformers have a 230volt primary, 230 volt 330mA secondary tapped at 15 volts, the tapped part of the winding can't be separated..there is also a separate centre tapped 12volt 2A winding.

The tapped 15volt section gives just over 17VAC when running the heater of a PY81.

I don't see another way to do it.

The transformers were intended for some piece of medical equipment.

The PY81's because I've got 50 new in box Mazda ones in the parts pile, the only other rectifier diodes I've got are UU4's and I think they need to be saved for preserving vintage equipment, they're huge, and, I haven't got any sockets

As for the PY81 suggestion, the live top cap(s) could present a danger risk - particularly as your 'glow' comment suggests that you aren't intending to hide them away safely!

Clear poly carbonate back panel on the case I thought. Also when the heaters are lit the top cap should only be at 10volts or so from chassis, (doesn't make it safe, I know).