I don't have the magazine now, but there was an article by a WB2 in Brooklyn
who pulled the 811A's and swapped them with 572B's. You could ground the
grids rather than run minus 4.5 volts bias, plus you had to short across the
power supply choke to increase the B+.This was from 73 Magazine in 1966.
Joe W4AAB
----- Original Message -----
From: "Vic K2VCO" <vic@rakefet.com>
To: "Amps reflector" <amps@contesting.com>
Sent: Sunday, July 23, 2006 12:49 PM
Subject: Re: [Amps] 572B grid
> Vic K2VCO wrote:
> > kenw2dtc wrote:
> >> "I've never understood the raison d'etre for the introduction of the
572B.
> >> I gather it was meant as a cheap SSB tube"
> >>
> >> Perhaps this tech bulletin from 1964 will explain:
> >>
> >> http://w2dtc.com/1964-waters-tech-bulletin.jpg
> >
> > This is very interesting, because it contradicts what I've believed:
> > that the 572B offers no additional power output over the 811A unless you
> > raise the plate voltage. But this bulletin says that simply plugging
> > them into a 30L1 and increasing drive will increase power output by 33%.
> > What's the truth here?
>
> I take it back. That's 33% *without* increasing drive. It's 75% if you
> increase drive!
> --
> 73,
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco
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>
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