>From K9SGQ:
I was looking for real world experiences on how severe the problem is
when an
insulated antenna wire touches a tree limb.
------
Two considerations that bear:
1) There is likely to be wear of the insulation. Teflon will likely
last best in such a situation, but will eventually succumb if laying
across a branch, due to constant abrasion. Further, sunlight and
weather will weaken some insulation, accelerating breakdown.
2) Breakdown will occur quickest with QRO and quickest if the touching
is near a voltage high. Voltage at the ends of a dipole (or unfed end
of endfed wires) can be surprisingly high, well into thousands of
volts, even running 100 watts. Some insulating material will not
withstand QRO at a voltage point and breaks down immediately.
If the touching is occasional, I have had success with a layer or two
of teflon on the wire in the area where touching can happen.
I currently have a supply of silvered stranded #12 with teflon
insulation, and get the second layer with high temp teflon shrink
tubing. I have run that right through thick bushes without problem,
and at QRO levels. This is not a wire for strength however, and will
not substitute in a situation that calls for copperweld. I only use it
where contact is expected.
Teflon insulated wire can be seen on eBay from time to time at
reasonable prices. Just search on "teflon" and "wire".
73, Guy.
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