Date: Sat, 14 Oct 2017 14:30:52 -0400
From: Dave Sublette <k4to@arrl.net>
To: towertalk@contesting.com
Subject: [TowerTalk] driven element center insulation
<I just put up a 40 meter rotary dipole using leftover Telrex elements. The
center of the element is 1.625? O.D with a section of 1.5? O.D. tubing inside.
I had a friend turn down an Oak piece to 1.375? and inserted it to join the two
halves. I coated the Oak with epoxy to bond the two halves together and to try
and keep moisture out of the wood. I split a piece of schedule 40 PVC pipe and
put it around each half, clamshell fashion, to insulate the driven element from
the U-bolts used to hold it to the mounting plate.
My next project will be to build two, two element Moxon yagis for 40 meters. I
would like to use a split driven element. Instead of Oak, I would like to find
some sort of high strength insulating material in tube form to go in the
center. It would also have to be 1.375? O.D. because I am using more of the
Telrex elements to build the Moxon.
What sort of material would you all recommend? Telrex literature says they
used phenolic insulation. I?m guess there is a better material available after
forty years. I am hoping (but not very hopeful) that I won?t need stays on the
elements if the center material is strong enough.
As always, I look forward to the resulting discussion that this great group
always supplies.
73,
Dave, K4TO
## max gain systems. https://www.mgs4u.com/fiberglass-tube-rod.htm scroll
down till u get to solid rod.
https://www.mgs4u.com/ecommerce/product/1-12-od-round-solid-rod/ This is the
biggest they make... 1.5 inch OD..and its solid fiberglass. Available in
2-4-8 ft lengths. 4 ft is easy to ship.
Get ur buddy to machine .005 from the 1.5 solid rod. Then its down to
1.490
Then it will slide in like a glove... problem solved.
Jim VE7RF
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