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Re: [TowerTalk] Trussing of antenna elements

To: Larry <w6nws@arrl.net>, towertalk@contesting.com
Subject: Re: [TowerTalk] Trussing of antenna elements
From: Grant Saviers <grants2@pacbell.net>
Date: Thu, 21 Jan 2016 17:37:14 -0800
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
If you have a copy of Leeson's Mechanical Design of Yagi.. he covers it in depth.

Attach the guy to the element where there is at least double thickness as in a overlap joint. If you triple wall then a vertical hole and eye screw (forged and galvanized best) can be used.

Phillystran is the guy material to use. At the inboard end use a Big Grip. Since you are going to adjust this antenna a Big Grip might work at the outboard end.

Otherwise you have to use cable clamps (which I strongly dislike on PS). I have also seen Nicopress sleeves used on PS on several antennas I purchased used. They were in good shape after 7 years and known icing that bent an element on Leeson's 110mph design (scratch built correctly) 40m Moxon. oops.

The center post needs to be strong and taller is better as that reduces stress levels all around. Think 3 to 4' above the boom.

Grant KZ1W


On 1/21/2016 16:28 PM, Larry wrote:
I forgot, but I think element trussing was discussed in ON4UN's Low Band DXing book and in Lawson's book. I am not at
place where I can check.

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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