[TowerTalk] tower specs/not wind loads

[ersmar@comcast.net]

Bob:

     Which model Trylon tower is riveted?  I own a T-500-64 (Trylon's Titan
design) and I built the thing myself with SS bolts and associated HW.  I
didn't want readers to think that ALL Trylons were riveted.  (Plus I'm
curious.)  Thanks.

73 de
Gene Smar  AD3F


----- Original Message -----
From: "Robert Chudek" <k0rc at citlink.net>
To: <TowerTalk at contesting.com>
Sent: Tuesday, January 24, 2006 1:46 PM
Subject: Re: [TowerTalk] tower specs/not wind loads


> I will confirm what Gene is saying about the BX towers who's cross members
are riveted, not welded. In my youthful radio career, I put up 104 ft of
HDBX tower. It was 4-way guyed at several levels. I installed a 6 foot
torque bar at the top guy point to help reduce the twisting movement in the
wind. Periodic inspection revealed rivets that had popped on this tower. As
these were discovered I would install 1/4-20 bolts in their place. This
tower survived 4 or 5 seasons with a 6-element 15m homebrew yagi on top. Oh,
the boom was 2" OD irrigation tubing and was 40' long. (Did I mention I did
this installation in my youthful radio career?)
>
> As an aside, our local radio community was fortunate to have a ham
operator (WA0MGY - sk) who was our source for inexpensive undisturbed earth
anchors. These were really slick... you auger an 8" hole at the proper angle
about 8 feet deep, drop the anchor into the hole, use a special tool to
expand the head of the anchor into undisturbed earth, and backfill the hole.
Later when I removed the tower, I simply unscrewed the above ground head of
the anchor and pulled the rod out. You would never know there had been an
anchor in that location. I wanted to install elevated guy posts but was
(fortunately) elmered away from this type of installation.
>
> Trylon towers are also riveted and I have found rivets that have popped on
these towers as well.
>
> I conclude these mechanical failures are a consequence of torsion forces
created by the long booms on the antennas we use today.
>
> 73 de Bob - K0RC
>
>
> * * * * * * * * * * * *
> Message: 1
> Date: Tue, 24 Jan 2006 14:27:12 +0000
> From: ersmar at comcast.net
> Subject: Re: [TowerTalk] tower specs/not wind loads
> To:
> Message-ID:
>
> Mike:
>
>      You're correct - the BX-series of antennas has a torque limit on
them.  This is because they are assembled with rivets, not welds, between
the cross pieces and between the cross pieces and the legs.  The rule of
thumb with these towers is that a ten-foot long boom would impart just about
the maximum safe wind-induced torque on the tower.  A longer boom might
twist the thing apart.
>
>      Caveat Amateur.
>
> 73 de
> Gene Smar  AD3F
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>
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