> My feeling is that 572Bs are a bit close to the edge
> anyway once you get to 28MHz.. They have very long grid
> leads, especially when compared with a 3-500Z. Even a
> copper strap to ground from the grid pin won't reduce the
> inductance that much, because it's such a small fraction
> of the total inductance, although it's worth trying.
> I've never understood the raison d'etre for the
> introduction of the 572B. I gather it was meant as a cheap
> SSB tube: just how much would it have cost to put it on
> the same base as a 5894? that would have given it much
> better performance, and it wouldn't be such a bear to tame
> parasitic wise.
I tried to get a custom 572 manufactured with both grid
leads extended into the socket, but it never happened.
That alone would have been a major improvement.
73 Tom
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