[TowerTalk] Re: K8DX Tower Collapse--Conv. wisdom ain't so!

[Stephen Vinson]

> WARNING:  Don't delude yourself into believing ALL towers will
> fall within some smaller radius than their height.  Note that this
> scenario usually occurs with VERY  TALL towers which have
> MULTIPLE  guy points in each direction.
> 
> SHORTER  (AMATEUR)  TOWERS with a SINGLE anchor for
> each direction OFTEN fall straight out to their FULL height when
> there is an anchor failure.  I have personally  seen three such
> instances.  TWO, where the guys pulled through the cable clamps
> at the anchor, one (picture) where an equilizer plate main bolt failed
> (cheap counterfeit bolt), and one where the anchor bolt pulled through
> a telephone pole elevated support that was located too close to a
> garage roof and the pole had rotted out.   EVERY  ONE of those towers
> fell straight out to it's full height.
> 
> de  Tom  N4KG
> 

Tom is right.  I dare say all single guy point towers with one guy point
failure will fall straight out or nearly so.  Its the physics of the
tension on the guys and gravity.  This points out that NO tower should
totally depend on a single guy point.  If a single point of attachment
is used, then a second anchor should be installed a little farther out
and attached to the guy head.  If one fails the other will be there to
safety off the tower or cause a "controlled" destruction.  

On another light ... with all the discussion on lightning over the past
month or so.  Lightning does strike more than once in the same place ...
and grounding and PolyPhasers are worth their weight in gold.  The
PolyPhaser strike counter I have on the tower now reads "7" and no
damage inside my shack.  Can't say the antenna faired as well but a
small price to pay.  And I haven't ever finished my grounding plans.

Later ...

Steve
KD4WIW



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