10" truss seems pretty low. I would probably double or triple that height.
You need to attach to one of your larger element sections, perhaps 1/3 of
the way out. I had some issues with eye bolts on my 40m elements in
Illinois and I had to swap them with forged eye bolts that could withstand
more lateral force. I did this myself on the tower by positioning the
antenna so that I could reach each eye bolt and swap it. This took all day,
so use a quality eye bolt. Phillystran works well for element trusses and
so does some ropes.
John KK9A
To: towertalk@contesting.com
Subject: [TowerTalk] Trussing of antenna elements
From: Bill Conwell <bill@conwellpdx.com>
Date: Thu, 21 Jan 2016 15:44:25 -0800
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
I am toying with the idea of rebuilding a surplus M2 40M3L into a WARC
antenna, with full-size elements on 30m (as well as other elements for 18m
and 12m).
Due to local wind and ice, I'd like to truss the 30m elements. The
original M2 antenna trussed the 40m elements with linear loading rods. The
central truss supports were a mere 10 inches above the centers of the
elements (I presume to keep the linear loading rods sort of horizontal).
With
the linear loading considerations gone, I could raise the truss points
higher than the present 10 inches. Is there a good reason to do so?
Relatedly, what's the preferred way to connect trussing cables (e.g.,
Phillystran) to the elements? Shall I drill vertically through the
elements and install stainless steel eyebolts at the connection points? Is
another Phillystran-attachment arrangement preferable?
(Is there a definitive reference work that addresses trussing of antenna
booms and elements?)
Tnx,
/Bill, K2PO
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