P-Series Valves, what to do with them?

[BusyBee]

I have a small number of P series valves, but seldom use any. I do however use DC supplies for all of the circuits I build. As such I don't have too much of an issue with different voltages within reasonable limits. It's maybe just having a spare to hand which occupies my thoughts more. I can see problems with replacing E series with P, but, except for keeping things original, it wouldn't bee too much of an issue.

Tracy