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833A for tube TC
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From: FutureT-at-aol-dot-com [SMTP:FutureT-at-aol-dot-com]
Sent: Wednesday, February 25, 1998 12:59 PM
To: tesla-at-pupman-dot-com
Subject: Re: 833A for tube TC
In a message dated 98-02-24 23:48:03 EST, you write:
<<
> I lucked up on an 833A triode (for free!). I have no experience
> with the big tube. Is it OK to mount it horizontally? I plan to
> run mine pretty hot using a 1KVA MOT for +B. I'm thinking about
> removing the old magnetron filament winding & rewinding it for the
> filament supply. This would certainly make for a cheap, compact
> power supply. The same dead oven that provided the transformer also
> yielded a nice, open-frame 5" blower--suitable for cooling the tube?
> Any advice on care & feeding of the 833A would be much appreciated.
> Greg
>>
Greg,
Nice find on the 833A. It can be mounted horizontally only if the plate
is kept in the vertical plane. You can use the filament
winding idea but the limitation of that is as you vary the
input power with your variac, your filament will
vary also, so it forces you to run at full power which makes tuning kind
of difficult. The 833A tends to run very hot at the center of the plate,
proper tuning and loading is required to keep it happy. I just posted a
design for a small tube TC that gives 20" sparks from an 833A, and
an MOT, using the doubler diode and cap from the oven. I never even
bother blowing any air on the tube, but I guess it's not a bad idea.
The 833A can withstand up to around 5kV AC on the plate, but at
higher voltages it can arc and be destroyed. A plate lead choke helps
to protect it in case this happens.
John Freau