[Amps] AL811, AL811H or AL572 mods to 6m

[Peter Chadwick]

Bill said:
>As I mentioned, this technique is covered in any recent ARRL handbook
in the HF amplifiers chapter.<

That deals nicely with the output side. But 811s and 572s have very long grid leads, which make them awful bloody things at 30, let alone 50MHz. So personally, I wouldn't touch them with a barge pole (as the saying goes) on 6. I suppose you could series tune the grids to resonance, but I have doubts about the resulting efficiency at the end of the day. The spacing is enough for, I suspect, transit time to start coming into play, as well as the gain dropping because of cathode lead impedance.
73
Peter G3RZP