Here is a wild idea for a cheap Beverage termination. When
I visited the MIT Super-Cooled Linear Accelerator as a
Tektronix Sales Engineer, I learned what a "brine load"
was. It was a large plastic garbage can filled with salt
water that had a couple of electrodes inserted into the
solution. These were used as dummy loads for the stages of
high powered VHF/UHF RF along the length of the accelerator
during tune up and testing for each stage independently.
They had several advantages:
!. Cheap to construct.
2. Handled LOTS of power.
3. Impedance adjustable by varying the concentration of
salt in solution.
4. Non-inductive.
One disadvantage was that the water would evaporate (or boil
off!) over time and the impedance would go down as the
concentration of salt increased. But it was easy to check
for that and fix it. I think they just measured the
resistance between the electrodes with a VOM and added water
or salt.
Perhaps a 1 liter plastic pop bottle with salt water in it
would make a good, cheap Beverage termination. You could
seal the bottle so the concentration of salt would not
change. You could make these for virtually no cash outlay
and they should be able to dissipate a lot of power if
necessary. Might even survive a lightning hit, and even if
they didn't, what is the replacement cost?
The one piece of info I do not have is what the electrodes
inserted into the salt solution were made of . . . probably
strips of some sort of metal, but I don't know.
If somebody decides to try this, I would like to know if it
works.
Stan
w7ni@easystreet.com
________________________________________________________________________
Where do you get ICE bandpass filters & beverage matching boxes? The
same place that pays for the hosting of this list: The eHam Store.
Order online at http://store.eham.net.
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