On 8/30/2011 10:30 AM, ZR wrote:
> Did you open up a Cushcraft balun to discover that method? I believe
> some other companies do similar and Teflon wire is used so it doesnt
> char as does THNN.
There are baluns and there are common mode chokes. I'm talking about
common mode chokes. Some so-called "current baluns" are really common
mode chokes. Some baluns are wired as auto-transformers, so they depend
on flux coupling through the core to transform the impedance. More
important, the core sees ALL of the transmitter's power. A common mode
choke sees ONLY the common mode voltage/current, which, if the antenna
is reasonably well balanced, is a tiny fraction of the transmitter power.
This makes common mode chokes FAR less subject to overheating than a
balun operating as a transformer.
73, Jim Brown K9YC
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