Pentode - triode switch, DC rating of miniature switch?

[David Root]

I am working in a small chassis (BFPR) and need to use a miniature switch on the rear apron for this application as a full size switch interferes with the power tube socket and there is really no other close location to the socket. I don't want to run the plate/screen wires across the chassis to the front plate and back again, it's messy and could lead to oscillation.

So I started looking at miniature switches (not sub-min) and the best rating I can get seems to be 3A @250 VAC/6A @125 VAC. Since my plate/screen voltages are about 365/320 DC respectively, I think I will come up a bit short on current capability as the amps derating factor for even 125 VDC with an inductive load is 0.03. I.E. 0.03 X 6 = 180 mA. I need 75 mA at 365 VDC, but with a 250 mA HT fuse this switch has to be good for >250 mA as I don't want it acting as the HT fuse. Plus it will be a SPDT on-on situation so the switch will be hit with plate voltage in either position as soon as it comes on.

I know one option is to use a suitable solid state relay, maybe FET-based, but I need some assistance with that as I'm not real good on relays, have only used them for SPST footswitching.

Any experienced EEs out there who can suggest a safe solution to my problem?