[TowerTalk] HBX tower rotational loading

[jamesnf@aol.com]

Guess I was lucky..........Had a HDBX48SAB (screw anchor base - no concrete) holding up a Hygain 204BA for a number of years with no issues.  It was a neat tower.  Because the sections nested, I was able to pick up the whole thing at AES Milwaukee and haul it home in the back of my F150 so no shipping charges.  With the screw anchor base, I needed no concrete to erect it.  And when I sold it, the new owner hauled everything away leaving only three small holes where the augers were screwed in.  I suppose it was a grossly under-engineered installation but it gave good service for a number of years and through many Chicago area storms.
 
Jim W9TM 
 
-----Original Message-----
From: Jim Jarvis <jimjarvis at comcast.net>
To: towertalk at contesting.com
Sent: Wed, 13 Apr 2005 13:28:19 -0400
Subject: [TowerTalk] HBX tower rotational loading



I've been reluctant to continue this guying thread...
but this really is slightly different...it's hbx/hbdx related:

chuck wrote:

Yes Dave, *I* was one of those idiots who attempted using an HDBX48 tower
to hold up a KT34XA and a 14 element 2 meter beam atop that!!
Unfortunately, I can no longer find any of the photos of that disaster of 7
years ago, it is still etched firmly in my memory!  DON'T DO IT!  I was
lucky..... nobody was killed or injured!  And yes, I even had mine
guyed!!

Dave wrote:

>I hope that everyone knows the BX series is only designed to hold a beam
>with a boom of NO longer than 10 feet.  Guyed or unguyed.
>
>There have been horror stories of those who tried longer beams such as the
>TH7 or KT34XA or even quads bigger than  3 elements.  Longer booms stress
>the bolts holding the top section so that the metal splits.
>I think some of this is recalled in the towertalk archives.

I will add:

I saw an hbdx48 come apart from torsional loading from a KT34A...a 16'
boom.  It was guyed at 48', and around 24'.  The top section torqued,
tore, crumpled, and crushed the second section down.  From the mid-point
down, the tower was bent, but not crushed.

And that ended thoughts of a small lpda with a 14' boom on that tower.
For the record, I don't think the guying hurt or caused the failure...
just that the tower wasn't very strong to begin with.

N2EA
jimjarvis at ieee.org


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