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Re: [TowerTalk] Orion 2800 Rotator Cable Replacement

Subject: Re: [TowerTalk] Orion 2800 Rotator Cable Replacement
From: Jim Brown <>
Date: Tue, 10 Dec 2019 16:27:43 -0800
List-post: <>
On 12/10/2019 2:41 PM, Bob Shohet, KQ2M wrote:
My non-engineering understanding of wires and stretch is that a given wire after being 
subject to variable strength forces over a given period of time, will stretch only so far 
before it breaks.  Assuming that that is conceptually correct, let’s say that we have 
two wires – Wire A and Wire B.  Wire A has been pre-stretched before being put up and 
is now compared against Wire B which has just been put up without being pre-stretched

Now we subject both wires to the same forces over the same period of time.  I would 
expect that going forward Wire A will not stretch as far as Wire B, but is more likely 
to break and break sooner under significant force than Wire B because it has already 
been pre-stretched.  Wouldn’t this be correct?

If this is not correct, can you please explain why?

It all depends on what you define as a significant force. I use 100# weights at ground level on the ropes on one end of my high (125 ft) dipoles to maintain tension and allow for "give" with tree sway. That's a LOT less than the pulling tension applied by W6GJB's pickup to stretch and break them.

Hard drawing copper strengthens it significantly; NEC requirements for wire antennas call for either CCS or hard drawn copper for strength (so they won't break and create a potential shock or fire hazard). The stretching we're doing is a first approximation of hard drawing.

73, Jim K9YC


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