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Re: [TowerTalk] Experimental high efficiency reduced size antennas

To: vhfplus@bmg50.com
Subject: Re: [TowerTalk] Experimental high efficiency reduced size antennas
From: Jim Lux <jimlux@earthlink.net>
Date: Wed, 02 Apr 2008 09:50:04 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
vhfplus@bmg50.com wrote:
> I want to put up a 65-foot base insulated vertical, likely using Telex
> T-15 tower (similar to Rohn 25 but a bit larger). I have a copy of W0UN's
> note about utilizing G-10 rod as insulators but would like additional
> information. Does anyone on the llist have personal experience with such a
> base insulator system?
> 
> I am aware that there are commercial insulators available but those are
> cost-prohibitive for my meager budget (the G-10 rod will be expensive
> enough for my wallet).

You don't necessarily need G10. You could use anything that is an
insulator and has the needed mechanical properties. Granted, acetal
copolymer, Delrin, isn't cheap either, but you could potentially use
something that isn't made with Glass or Epoxy (e.g. would linen
reinforced phenolic work?)

the glass composites have the advantage of good high temperature
performance, but in your antenna application, that's probably a
non-issue.  Likewise,  fire resistance.

There's also other forms of structural fiberglass that might be
interesting to consider.  You can get I-beam made of fiberglass, for
instance (Extren is one brand). Cost for fiberglass structural material
is comparable to aluminum, as is the strength (the stiffness is about half).

So, you could make a sort of triangular sandwich that sits beween the
bolts sticking up from the base and a copy of a usual baseplate bolted
to the top of the sandwich. One would need to do some engineering to
make sure that it won't fall over.





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