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[TowerTalk] Clicking? & F-12 antennas

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Subject: [TowerTalk] Clicking? & F-12 antennas
From: (Bill Hider)
Date: Mon, 22 Jun 1998 17:15:36 -0400

I had a similar problem with my Force12 EF-180A (80M rotatable dipole). 
The bird feces (droppings) would saturate the fiberglass insulating rod
at the center of the driven element causing conduction of RF energy
across the element, first at high power, then at lower power levels down
to below 50 Watts. I never bothered to notice the effect in a lightning
storm. I made a fix for it, detailed below.  But, with the fix,
eventually, it would arc across the PVC to the U bolts.

My fix for all this, after replacing the EF-180A with the EF-180C due to
mechanical failure in a storm, was to totally insulate the fiberglass
rod with non-conductive RTV (RTV#162).  That stopped the bird dung from
affecting the conductive property of the fiberglass.  I then insulated
the portion of the element boom directly under the PVC with Scotch
Mastic HV insulating tape (I don't remember the exact part number).

I show the final result and complete details of the EF-180C feedpoint in
my videotape product sold on my website:

Bill, N3RR wrote:
> I've noticed the exact same thing with my EF-515 & EF-420/240 antennas.
> It usually happens as a storm front is approaching.  It even causes a little
> static in my TV & stereo.  I haven't turned on the rig to see how bad the
> noise is then.
> I went out one night when a storm was approaching and I could actually see
> arcs at the element to boom clamps.  Looks like the charge is arcing across
> the PVC insulators of the F-12 antennas.
> Is the arcing going to hurt anything???  Is there anyway to stop it??  It 
> seems
> like the antennas would be nearly un-useable with the kind of noise this
> would generate.
>         73
>         --Lee - KT4ZX
> <snip>
> > ..........At various times,especially when there is lightning in
> > the area I can here a distinct clicking sound coming from the
> > tower.The sound is a intermitent-click,click and it speeds up and then
> > will quit if there is lightning in the imediate area.It then will
> > start up after a few minutes pass.Is this static electricity that is
> > building up on my tower and then discharging?Thank you.    John W9RPM
> >
> --
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