To: | <towertalk@contesting.com> |
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Subject: | [TowerTalk] Force 12: rivets, hardware |
From: | steve@oakcom.com (Steve Maki) |
Date: | Thu, 20 Nov 1997 01:00:17 -0500 |
Joe E. Mesh wrote: > The solution to this light wind harmonic vibration is element dampening > with enclosed ropes? I have seen this done many times in old Telrex > installations I have disassembled. Typically owners installed jute > ropes inside the elements of the 20m antennas. I have always wondered > if this was actually valuable. The ropes themselves are universally > wet and heavy with water content. They tend to move over the years and > collect to one end of the element or the other thus greatly upsetting > the mechanical static balance of the structure. This has always > concerned me. I've been using small (1/4" or 3/8") poly rope in every element I install for years; it definitely works to STOP flutter, the major cause of element failure in otherwise sound mechanical designs. Telrex antennas were particularly bad for some reason. I secure the ropes at the element ends by either cutting them a couple of inches long, folding over (outside the element tip) and taping; or cutting to exact length, and drilling a small hole thru the element AND rope at the end, and fastening with a sheet metal screw or piece of wire. I've seen no evidence (extra sag) of abnormal weight caused by soaked ropes. If care is taken to ensure no direct water ingress near the element center, it doesn't seem likely that condensation could overcome normal drainage out the ends. -- Steve Maki K8LX steve@oakcom.com -- FAQ on WWW: http://www.contesting.com/towertalkfaq.html Submissions: towertalk@contesting.com Administrative requests: towertalk-REQUEST@contesting.com Problems: owner-towertalk@contesting.com Search: http://www.contesting.com/km9p/search |
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