On 12/16/2013 5:52 PM, GeorgeWallner wrote:
On Mon, 16 Dec 2013 14:32:41 -0500
"Charlie Cunningham" <charlie-cunningham@nc.rr.com> wrote:
Many black plastics are "blackened" by the addition of "carbon black"
that
can make them rather lossy at RF! "Been there, done that" in my work
- at
900 MHz.
I have been using 3" black Derlin (Acetal)insulators at the base of my
160 m vertical. Because the antenna is only 91 foot tall, there are
substantial voltages on the insulators at legal limit. Indeed, one
them caught fire just after a rain-shower, when water got between the
insulator and the metal. I replaced the burned insulator with the a
new one and covered all the insulators with high voltage putty. That
was about two years ago and I had zero trouble with any of them since.
George
AA7JV
Hi George,
I had the same experience with black delrin insulators for one of my 160
meter vertical antennas. It was fine until it got wet, then forget it,
it would breakdown. I kludged up a shroud to keep the rain off it. It's
been fine ever since.
BTW, I have never heard of high voltage putty. Where do you get it?
73, Mike W4EF.....................
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