Good question. Nope, no doubler.
According to this
handy website we have the following.
CRT, Typical, Max
19AP4, 14 kV, 16 kV
5AXP4, 14 kV, 19 kV
8YP4, 16 kV, 22 kV
I'm a little surprised. I though the 19AP4 would be a little higher than that. I need to rig up an anode cap, but otherwise should be OK.
I'll find out for sure soon I hope
