SB-200 users: a question.

[Wilson Lamb]

Won't 811As run in that thing?  They are nearly indestructable and you'll 
never notice a little powr loss. When I was a kid, I ran them at 1500-1600V, 
zero bias, in a modulator for several years.  You'll need some bias, I 
expect, but that's not hard.

If you run a lot of CW, it would be good to add a grid leak, maybe that you 
can switch in/out, and drive them into class C.  Your output would be 
increased somewhat over the linear case.
Wilson
W4BOH
----- Original Message ----- 
From: "Kenneth G. Gordon" <kgordon2006 at VERIZON.NET>
To: <HEATH at LISTS.TEMPE.GOV>
Sent: Monday, April 19, 2010 12:11 AM
Subject: SB-200 users: a question.


> Well...since I have had both my SB-200s, I have been
> having considerable difficulty obtaining 572Bs that are
> reliable and will output what they are supposed to for more
> than about a month.
>
> I run them as I am supposed to, keeping the grid current
> well below 100 mA, but they seldom last. I don't abuse
> them, and run mostly CW. I never allow them to show
> color.
>
> I am very seriously considering replacing my 572Bs with
> 813s, or some other heavy-plate tube of about the same
> physical height.
>
> What do others use? How long do they last in normal
> service?
>
> I am NOT pleased... :-(
>
> Ken Gordon W7EKB
>
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