[Amps] The maximum amount of 811As and 572Bs in parallel

[Peter Chadwick]

Tom said:
>Output capacitance of the tubes is not an issue at all. 
Adding tubes increases capacitance in the same proportion as 
it reduces optimum load impedance, and tank operating Q 
isn't a critical parameter at all as long as it exceeds a 
certain amount.<
Not only that, but the stray capacity around the tuning cap, bandswitch etc generally doesn't go up in proportion, so you can end up with less of a stray capacity problem. As Tom says, feedback capacitance is a problem, and there's also the possibility of some interesting parasitics - you can get several tubes going off in a ring oscillator, a bit like the original XAM US Navy radar power oscillator. I think that was 250TH, 6 off, from memory of the article, but they may have been 100TH.

73
Peter G3RZP