"John Smith" wrote in message
...
wrote:
Transformer oil.

Try your local power company. typically they will either sell it to
you, or, sometimes when they find out that you only need a gallon or
so, they'll just give it to you. Mine did.
- 'Doc

No one knows about silicone oils? Break down is a few hundreds of
degrees, good thermal conductivity, ... benign to all components,
including any gaskets, I can possibly think of, etc. Also, if you are
into health/toxic concerns, purchase a food grade ...

Regards,
JS


Silicone oils are excellent from a health standpoint and usually very good
from a flammability standpoint. However, the Cantenna relies on natural
convection of the oil for cooling and the higher viscosity of commonly
available silicone oils will limit the power handling capability of the
Cantenna. Remember that the Cantenna must be de-rated when used for long
duty cycles, and a high viscosity oil will lower the power rating still
more. Also remember that silicone oils are not cheap (and my buddy at Dow
would only send me small samples).

I would suggest using modern RF terminations made by Bourns and other
companies. These are designed to be bolted to a large heatsink. The
CHF9838CNF series is rated for 50 ohms, 250 watts, VSWR below 1.1 from DC
to 2.2 GHz. It only costs $27.50 in single lot quantities. I think this
is higher than the continuous rating of the Cantenna. I don't know for
sure as I disposed of my Cantenna years ago. Digi-Key sells these Bourns
terminations if you want one.

I had used transformer oil given to me by the local electric cooperative.
I didn't learn until a few years later that the oil was contaminated with
Aroclor, a PCB oil. Proper disposal was easy for me as I then worked in
the research labs of a major chemical company that had an EPA licensed
incinerator specifically rated for PCB destruction. Even so, I had to
repackage the oil into special disposal bottles and give the incinerator
operators instructions that only one of the bottles could be burned daily.
Before anyone asks can they send their oil to me for disposal, I left that
company over 10 years ago and am now retired, so the answer will be no.

I did quite a bit of research on trade names of PCB containing oils. In
fact, the EPA's list found at
http://www.epa.gov/epawaste/hazard/t...bs/aroclor.htm is partly a
result of my study. About a third of the trade names on this list were
unknown to the EPA until I provided them to the Atlanta EPA office.

Barry L. Ornitz, PhD WA4VZQ