For the plate supply, consider the $5 boost converter available on ebay (search term "390v dc boost converter").? I used this to provide B+ for a vintage receiver from a LFP battery.? The output voltage is regulated, but it has some LF noise.? If that matters, add a resistor or choke plus another filter capacitor after that.? Also, load it at 5 or 10% of full current between key-up and key-down.? Note: the output is not electrically isolated from the input.
Halden VE7UTS
