> Liquid cooling has become quite mainstream. Heck, even liquid cooling
> overclocked PC CPU's and GPU's isn't uncommon. I can walk into the local
> MicroCenter and buy everything I'd need for liquid cooling a PC. Granted,
> an RF PA would have higher dissipation than a PC, but we're not talking
> about giant heat exchangers, copper plumbing, redundant pumps, flow
> meters,
> etc. like we have in broadcast.
Or...vapor-phase cooling of a heatsink? I could see the heatsink resting in
a filled boiler without the need for a pump, using only convection currents
caused by water heating and a small whisper fan for assistance and to keep
positive air pressure in the cabinet. My Alpha 70V works this way. The
tube anode contains a boiler. As the tube heats, water vapor is created and
moved to a condenser about the size of a motorcycle radiator. The vapor
condenses, cools, and becomes the supply to the same boiler, creating a
continuous cooling loop.
Vapor-phase cooling requires only 1/17 the required amount of water volume
passing through the system when compared to water cooling. Less water volume
means less water stored in a reservoir, minimizing cabinet size. The only
real drawback to vapor-phase cooling is that it's not a 100% closed system.
It requires air venting for water to circulate without the need for pumps.
Venting presents an opportunity for evaporation and as such, one must "top
off" the condenser with distilled water every six months or 3,000 miles in
DX, which ever comes first :-)
The Alpha 70V uses the same cabinet size as the original 77 model, which is
about 2/3 the size of the 77Dx/Sx. I can key the 70V to 1500W and put the
proverbial brick on the key. As long as there's enough air mass around the
rear condenser, water temperature never comes close to the boiling point --
a point at which bubbles form on the surface of the water in the boiler.
Bubbles mean more insulation and more insulation translates into higher
water temperature to the point where the cooling system becomes a heating
system. Without ample air circulation, the cooling system can cycle out of
control to a full boil like a filled pot on the stove.
Paul, W9AC
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