Yep, two 572's in a Heathkit SB-200 will deliver about the
same output power (600 - 800 watts) as four 811's in a
Collins 30L1.
Mike, W4EF..............
----- Original Message -----
From: "John T. M. Lyles" <jtml@lanl.gov>
To: <amps@contesting.com>
Sent: Friday, April 26, 2002 9:40 AM
Subject: [Amps] 811/572 triodes
> Erick, K8LV, says:
>
> >Despite its higher voltage and dissipation rating, this tube is identical
to
> >an 811A when operated in the 1-2KV plate voltage range. Many of the
> >applications for this tube fall into this range - the familiar 1500-2000V
> >4x811A desktop KW. My old 30L1 is exactly such a beast, and is what
started
> >this whole thing. Anyway, within that range the operating characteristics
and
> >interelectrode capacitances are virtually identical. Also, it is not
possible
> >to drive the tube hard enough to require that higher (160W) dissipation.
> >Above about 600ma. the Gm starts to drop like a rock . Hence, my original
> >statement that it quacks just like an 811A.
>
> I see your point now, that at the 30L1 operating conditions, they two
> triodes play almost the same. If you had a blank sheet of paper to
> redesign and wanted to utilize the 572 for more whoopie like it could
> make, you can do so. Crank up B+, and driver 'er harder. But
> substituting them into a fixed design doesn't buy you anything.
>
> The vacuum tube Tesla coilers used to put 572s in place of 811s for
> more discharge, and push them until they were orange.
>
> 73
> K5PRO
> --
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