[Amps] H2O cooled tubes

[Steve Thompson]

Barrie Smith wrote:
> John:
>
> Several years ago I ran a single 3CX100 in a cavity for 1296.  The
> tube was/is fitted with a water cooling device.
>
> On the recommendation of "someone", I used mineral oil instead of
> water. The theory was that mineral oil was less of a conductor than
> water, and had better heat transfer capabilities.
I think I remember a design in VHF Communications that used oil.

A tiny bit of conductivity might not be a bad thing. One place I worked
(just before my time unfortunately) prototyped a really compact high power
hf amp for mil mobile use by using a tube and having the whole of the tube
electronics and anode cooled by circulating Freon instead of air. It worked
a treat thermally, but also worked as a Van de Graaf generator. When the
heat exchanger finally discharged, it was quite destructive. I guess the
lesson is to add some bleed resistance.

Steve