Hi Gain Antennas were noted for this.. the 15 meter especially, you could see
the element resonate ( vibrate)
in a mild breeze / Rope dampening RTV ed was a must in all there designs,
Once that was used you never had the problem again.
Wayne W3EA
> Date: Wed, 4 May 2016 15:54:38 -0400
> From: john@kk9a.com
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] [Bulk] Re: Rotator Choice for Larger Yagi
>
> I had a couple of Hy-Gain monobanders and they also shed element tips.
> The 7/16 tips have a very thin wall, around .030 if I remember correctly
> and mate to a much larger swedged section creating a break point. There
> are much stronger element taper schedules in the ARRL antenna book.
>
> John KK9A
>
>
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] [Bulk] Re: [Bulk] Re: Rotator Choice for Larger
> Yagi
> From: Bob K6UJ <k6uj@pacbell.net>
> Date: Wed, 4 May 2016 11:44:33 -0700
> List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
> I remember the rope dampers Grant. I had the same issue and resolved it
> with the poly rope. I went out to my back yard and found element sections
> stuck in the ground like they were
> shot like an arrow.
>
> Bob
> K6UJ
>
> On 5/4/16 11:30 AM, Grant Saviers wrote:
> Which reminds me of the rope dampers in my prior TH7DX. Apparently, the
> elements w/o traps were falling off due to coupling of element mechanical
> resonances. HyGain/Telex came up with a clever fix by putting a 2 ft
> length of polypro rope into the tips of those elements to dampen the
> vibrations. A nasty property of aluminum is that it has no fatigue limit
> like steel. If a certain stress level is not exceeded, steel won't fail in
> fatigue. There is no such threshold in aluminum. A small stress over many
> cycles and aluminum will fatigue fracture.
>
> Grant KZ1W
>
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