On 12/26/13 12:36 PM, Charlie Gallo wrote:
On 12/26/2013 Patrick Greenlee wrote:
Any thoughts on insulating a tower? I have some Rohn 25 that I want to use
to make a home brew version of a Hy-Gain Hy-Tower multi-band vertical. I am
considering two approaches:
1. Buy a plastic cutting board to cut up for material to home brew
insulators to be electrically between the tilt base and the tower proper. (I
have a friend with MS Mech Eng and 35 years hands on experience who will, if
asked, consult on this or help me design it.)
The issue with plastic cutting boards is that they are made from High Density Polyethylene (HDPE)
HDPE will "cold flow" (technically called Creep), and is known for "Poor weathering
resistance"
You may want to look at one of the "filled" versions, or some other filled
engineering grade plastics - or use something like PEEK, PES or even Phenolic
Definitely..
Get something that is designed as a structural material.
http://www.mcmaster.com/#fiberglass-hollow-rods/
You may find that it's easier to just buy the premade insulators than to
figure out how to fabricate something out of the raw materials.
To a first order, structural fiberglass is a lot like aluminum, in terms
of strength. It's a lot less stiff, though.
There are very nice structural, electrical insulators out there that
look like a lump of plastic with two threaded bolts sticking out of it.
The trick, as always, is knowing what breakdown voltage you need, and
designing for that.
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