> 1) Is the AL-811H the same copy of AL-811, but
> has an extra matched tube.??
No. The AL811H is neutralized and has a few other changes. I'd go
for the AL811H.
> 2) Can i buy an AL-811 and then later, when i
> retube it, drop in a matched quad of 572B's to
> make it a AL-811H. I assume the 811 will have an
> unused tube socket.
You can drop in 572B's, but it would be a bear to add a fourth tube
to the AL811. Three 811's are just on the edge of not needing
neutralized, add a fourth tube and you would need to neutralize
otherwise you'd have the Clipperton Syndrome.
Even the Collins 811 amps with four 811's are not totally stable
because they lack neutralization.
572B's are a good mod to the 811 amp, they make it almost bullet
proof. It is a cheap way to pick up the most power gain per buck. If
your signal is marginal, the first few hundred watts more makes the
biggest difference.
> My setup has a TA-33 with the 2KW traps, a TS-440 exciter
> and a MFJ-969( 300W tuner).
The MFJ 3KW tuner is a good fit with the AL811, but the 969 is
certainly not. I would NOT use the MFJ-969 with any amplifier.
73, Tom W8JI
W8JI@contesting.com
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