On 10/20/05 11:44 AM, "Bob Wolters" <bobw5xc@hal-pc.org> wrote:
> I have a 18HT, and would like to hear from all that have a "body of
> knowledge"
> on how to increase the robustness of this antenna to withstand a KW on
> 160M
> while still retaining the vertical characteristics (not using the add on
> trap/wire to
> make it an inverted L).
>
> It appears this requires making changes to and around the insulator in
> the middle.
> I'd like to hear about specific things that have been done to do this.
>
A few years ago I acquired a Hy-Tower from an estate sale. It had been
modified to permit full power on 160m while using an 80/160m loading coil at
the base (rather than the inverted-L add-on). To prevent arcing of the top
vertical tube to the uppermost tower section, the previous owner had cut out
the metal on the two horizontal plates and installed some clear insulating
plates. Over time these plates crystallized and cracked due to UV, but I'm
told they worked well when new before the bright Colorado sun got to them.
I have replaced those defective plates with some 3/8-inch UV-protected
plastic (Poly Hi Solidur) plates, drilled to the original bracket positions.
The mechanical strength is very good, as is the dielectric strength, and all
components go together per spec.
By the way, I had intended to install this antenna on my small city lot here
in Denver, but the city officials say I can't because I already have a tower
on the property. So if anyone needs the 18HT, it is available at a
reasonable price for pickup only -- I have no desire to pack and ship it.
The hardware includes a brand new set of base insulators and posts, as well
as some replacement insulators for the stubs that I made out of the same
plastic material as the plates -- much stronger than the original fiber
insulators.
Gus Hansen
KB0YH
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