[Amps] Plate Impedance, ARRL

[Peter Chadwick]

Will said:
>Everything I've read says AB is around 60% efficient, not less.<
I think you'll find that's the theoretical tube efficiency, and the real world has to take into account tank circuit transfer efficiency, too.
>From memory, the old Mullard data sheets provided measured values with tank circuit efficiencies stated as around 90%. I've always worked on a rule of thumb of 50% efficiency, and haven't been let down that much, especially when you consider the measurement uncertainties involved.
And if your tank circuit when you've tuned and loaded for optimum ends up with a working Q of 15 instead of 12, I doubt if any of us has equipment with enough resolution to tell the difference, let alone make an absolute measurement.
I guess we can get too hung up calculating (or worse, simulating) for the last fraction of a dB that can't be achieved in practice. Makes you wonder how they ever got radio to work in the first place!
73
Peter G3RZP