All these points are well and good about screen peaks, within the limits of
the screen dissipation etc.
Heck, we could even add a grid current meter to make things really
interesting, and pray never to see it move (much).
If this discussion was about a 4CX350, 600J/JB, 800A, 1000A, or 1500B, we'd
be winding up with a pretty well-tuned amp, AND capable of some pretty
decent 3rd and 5th order distortion products.
Unfortunately, however, we're sort applying lipstick to a pig here.
The 250B is just not a very 'worthy' tube at -22db; hard to gain BFF among
your neighboring six meter guys.....
Might as well run an old model brick with no active bias (closer to class C
than AB anything).
If someone knows some tricks for adding 10db or so of distortion
improvement, well then, now we're on to something.
Otherwise, a 350A or re-socketing to a 800A would be a better choice.
IMHO, 73
Dick, K5AND
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