[Amps] 572B grid

[Tom W8JI]

> 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