Not necessarily a vibration causes a metal stress in aluminium or a failure
in a riveted joint.
Thousand of yagis elements are infact happily surviving and vibrating day
after day (likewise aircrafts, etc.).
While noise and wistling can be bothering and caps & rope can easily fix the
problem, when antenna pieces are found dropped down on the ground something
wrong had occurred. The mistake can be a design that underestimated
vibrations but also a wrongly performed installation or even a mistake in
the metal itself.
73,
Mauri I4JMY
----- Original Message -----
From: "Tom Rauch" <w8ji@contesting.com>
To: <towertalk@contesting.com>; <Jan.E.Holm@telia.se>
Sent: Wednesday, March 28, 2001 4:27 PM
Subject: Re: [TowerTalk] rope in elements
> Hi Jim,
>
> > An antenna that needs ropes in elements are poorly
> > constructed.
>
> I disagree with that. My Rohn 25G with open ends at the top (I use
> it as a vertical antenna and for supporting ropes, no yagi's) vibrates.
>
> I'm not worried about the vibration because it is steel. I did know of
> a fellow with an aluminum tower who lost the whole top 30 feet or
> so of the tower in a mild breeze, because it vibrated and cracked.
>
> As I look back, most of my tubing antennas vibrated. Some of
> them had end caps and vibrated, but rope always fixed it. I had that
> problem with Wilson yagis, and everything else.
>
> I don't think that means the antenna is a poor design...not when it
> is a problem so easily cured.
>
> 73, Tom W8JI
> W8JI@contesting.com
> --
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