"Ian Bell" wrote in message
...
David Looser wrote:

You could use a separate heater
transformer and use the relay to switch the primary of the HT
transformer.


The current (sic) design does have a separate heater transformer so that
is a viable alternative

Then that is what I would do. It is a technique that was often used in
valve-based industrial equipment, such as broadcast transmitters.

except I want to ensure the HT is discharged when the mains is turned
off.


Bleeder resistor?

David.