Thanks. I'll have to see about ordering one before something goes pop.
But, I'm surprised that Ameritron didn't put in higher voltage power supply capacitors in this amp. I was under the impression that the design rule is to rate the capacitors 1.5 times the working voltage. In this case the capacitors should've been rated at least 600 volts each (instead of 450 V) - since the 4 caps are in series this would allow for voltages as high as 2400 VDC across the capacitor string.
However, from what I've read on an 811A spec sheet the maximum plate voltage should be 1500 volts for class AB2 but Ameritron says the HV should be a nominal voltage of 1700V. Oh well, I'm not a design engineer so I don't know what the engineer was thinking when the amp was designed. I should just go buy 572B's and eliminate this issue also. Looks like the 572B can handle 2400V plate voltage - plus I could run RTTY at max amp power with this tube.
But, I'm going to leave things pretty much the same as original - otherwise by the time I get done redesigning/improving the amp I might as well as go buy another amplifier that's "properly" designed.