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Re: [TowerTalk] [Bulk] Re: antenna choices for K4XS

To: towertalk@contesting.com
Subject: Re: [TowerTalk] [Bulk] Re: antenna choices for K4XS
From: Grant Saviers <grants2@pacbell.net>
Date: Mon, 13 Apr 2015 09:55:25 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
One hint for putting together many antennas with clamps so they stay together (whether stamped or hose clamps, e.g HyGain, CC, etc).

One poster said his TH7 fell apart. I've had two which survived 5 serious hurricanes between them without any problems. What I found was the clamp forces relax after the initial tightening. HyGain stamped element clamps or telescoping tube hose clamps, it makes no difference. So after the initial torque of the bolts, let the antenna stabilize for a few days. Best if it can be exposed to temperature cycling, e.g. hot day sun and cool nights. After several cycles go back and torque all clamps and fasteners, it is amazing how much they relax. (don't forget to lube stainless bolts or the torque is meaningless if they seize).

Of course, it's best to use a calibrated means of torque setting, but those aren't in many ham toolboxes for smaller than 1/4-20 fasteners.

One commercial product I was responsible for had required clamping forces near the yield points of the very high strength fasteners but the parts would still move in service. So we set up temp cycling ovens/coolers to cycle the assembly and then a final torque to the limit solved the relaxation problem.

http://www.mountztorque.com/learning-center/article/techniques-reduce-joint-relaxation-fastened-joints

Grant KZ1W



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