[TowerTalk] Re: bracketed LM-470?

[John Kozak]

I don't know the specifics of this particular tower, but I agree that a house mounting bracket is a bad idea on a free standing
tower. It is designed to support itself without restraints and that involves a certain amount of flex and movement. I have used
house brackets on a number of installations of free standing towers to comply with stupid zoning rules ( tower must be attached to
the house..), but after the inspector has come and signed it off, all the attachment bolts have mysteriously disappeared to allow
the tower to move the way it was designed. On some of todays flimsy houses, I have observed the wall actually flex in and out
several inches while the bracket was still attached. It's an interesting sight!

John Kozak N3AGG
----
From: rattmann <rattmann@cts.com>
To: Bob Duckworth <wb4mnf@atl.org>
Cc: towertalk@contesting.com
Date: Friday, August 22, 1997 2:08 PM
Subject: [TowerTalk] Re: bracketed LM-470?

Hi Bob,
Can't help you with your specific query re calcs/strength of LM-470 with a
house bracket.  But I feel compelled to mention to you that I believe this
is not a good idea.

Any bracketed tower couples a large amount of vibrational energy into the
house structure.  An engineer stated to me years ago that structural damage
could happen if the energy is coupled into primary beams in the wall or
ceiling, although it may take a few years!

Short of that, I can state that with a bracketed tower, there will be a
constant audio racket of varying amplitude, depending on the wind and what
you have on the tower.  In a big storm, the racket on that end of the house
can be incredible.  If it is a bedroom wall, your wife will move out!

The LM-470 is a great tower when used within its specifications.  If a
massive structure like that were ever to fail, do you really want it
connected to a wall of your house? That additional bracket would not prevent
the tower failure (I've never heard of a base section of an LM failing; a
higher section would bend first), but it sure as heck would guarantee you
would have to repair your wall if the whole thing did go over.

73, Glenn K6NA


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