[Amps] Replacement tube for 4-1000a

Carl km1h at jeremy.mv.com
Wed Dec 8 12:45:09 PST 2010

A couple of GU-81M's would make some smoke if you added some air cooling


----- Original Message ----- 
From: "Dennis Goebel" <radios1236 at yahoo.com>
To: <Amps at contesting.com>
Sent: Wednesday, December 08, 2010 3:21 PM
Subject: [Amps] Replacement tube for 4-1000a

>I have found it increasingly difficult to locate good 4-1000a tubes. Just 
>wondering what would be a good replacement tetrode for the 4-1000a in grid 
>driven service. Not grounded grid.
> Obviously it doesn't have to be the same socket or filament voltage as the 
> 4-1000a.
> It would be nice to come close to some of the other parameters so 
> recreation of the entire amp wouldn't be needed.
> I have thought of the russian GS-23 or GU-74 series tetrodes. Or home 
> grown variety like 4CX1000 or the like. Most of these have pretty wimpy g1 
> and g2 parameters compared though.
> Anyway I would like to get some opinions from the experts on the 
> reflector.
> thanks
> Dennis
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