F. Veitch wrote:
I used and have worked with water cooled amps and oscillators for
years. We used De Ionized (DI) water for years with systems up to
multi-hundred KW. Either DI or distilled water should work fine. Most
tap water is far too conductive. Just put your ohm meter on the high
scale and stick the probes in a half inch to one inch apart. As long as
it shows 50-100K it should be fine. I used a probe that had 1 CM
square plates separated by 1 CM to measure Ohms per cubic CM , or
resistivity.
The only thing to remember about DI and Distilled water is they are
corrosive to copper and brass. However the amount of flow in
intermittent amateur service should show no degradation in years of
use. You might need to replace the water every now and then as it picks
up ions from the metal in the system. Others have commented on how they
monitor this. If there are no indications of lower conductivity there
is no need to replace the water. In systems that ran almost steady 24
X 7 we had to replace copper and particularly brass fittings every 3 or
4 years. Based on that I'd expect the normal amateur system to last a
lifetime. Water replacement which was around a thousand gallons was
about twice a year, but it ran through a lot of equipment and in an
industrial environment. I'd hate to tell all the stuff that went into
that, but a half a salt shaker in a thousand gallons shut the whole
system down. That was expensive in the 100's of thousands of dollar
range, but we never did find out who did it we were fairly certain. Just
rumors from the crews running all that equipment. Word was someone
remarked, "I never thought that little would do that much". <:-))
Look into "Vapor Phase" cooling as well.
73
And good luck,
Roger (K8RI)
> I am in the process of getting a water cooled GS-15B cavity on line and I
> wonder if the group has any recommendations on coolants. Distilled water is
> typically of unknown provence, so you are never sure if it is really low
> conductivity unless you measure it. Somehow the idea of 1700-2000V on water
> of unknown conductivity just bothers me. (silly me!) I have heard that some
> Radar systems and high power lasers use a special ethylene glycol for a
> coolant. I wonder if anyone in the group has any experience with such
> coolants and if they can recommend a source for same.
>
> Thanks and regards
> Fletch
> K3JYD
> FM18
>
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>
>
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