Boy, that brings back memories. I ran 4 of them at over 200 watts input for
over a year. Never replaced any of them. I still have them and the amp. I
only ran 1,000 volts, though. All driven by a single 6AG7 hb.
Big problem was that you could never see the plates - so I still do not know
if they were abused or even ran red hot.
I probably should get the old 6AG7 tubes out and put the fins from an old
4X150 on them, then use them for replacements for the hard to get and
expensive 8874 tubes. They never got proper cooling when I used them so an
air socket and a lot of air might surprise someone. 3x6AG7 sounds like a
nice fit for retrofitting the old Alpha. If the first three would not take
it, I could put the entire Alpha in an oil bath.
Reminds me of a story by Bill Orr about the hams who went a bit wacky during
the lull of the sunspot cycle and cooled the 304TL tubes in an oil bath.
73, Colin k7FM
----- Original Message -----
From: Larry Kayser <kayser@sympatico.ca>
To: Xu <salers@hamal.freemail.ne.jp>; <amps@contesting.com>
Sent: Tuesday, February 26, 2002 5:09 PM
Subject: Re: [Amps] Oil cooled
> Xu:
>
> >Does anyone heve expermence in oil cooled vacuum tube rf amplifier?
>
> I don't think this is what your looking for, but when we were kids we used
> to run 6AG7's (at 10 for a Dollar in those days) in GG and invert them in
a
> can of oil to cool them. 1600V on the plates and all was well if you
> didn't sneeze....
>
> Larry
> VA3LK
>
>
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