[ChristianFletcher]

Thanks so it looks like the single wiring for the heater may not be such a bodge after all. I am just waiting the arrival Of the output valve on Saturday hopefully before I can power the set up but I may give it a try using my signal tracer as the PA. funny that I have done quite a lot of domestic radios Restorations and I have never seen the one wire heater Circuit using a chassis return Line. Great thing about the hobby every day is a school day. I can experiment with the heater wiring. Just to clarify it isn’t using an auto transformer it’s a conventional transformer with the primary isolated from the secondary.

Thanks for all the great comments always food for thought. Best regards Chris