M2 has a kit for some of the later antennas to help with ice and wind
problems. Basically, it doubles the height of the
central element truss support and uses Phillystran as the truss support. The
linear loading rods are connected
at the midpoint of the central element truss support. I did it to my
4030M4L. It provides substantially more
support to the element and takes the load off the linear loading. A kit for
4 el was about 300USD as I recall.
The central support was about 1 inch square as I recall. The Phillystran
was the small variety. Attaching the
Phillystran to the element is probably easier with the newer antennas. Mine
is probably 15 year old so some
Lexan pieces were fabricated to facilitate the Phillystran connection to the
element.
73, Larry W6NWS
-----Original Message-----
From: Bill Conwell
Sent: Thursday, January 21, 2016 6:44 PM
To: towertalk@contesting.com
Subject: [TowerTalk] Trussing of antenna elements
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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