This is too much of a stretch. Change the SUBJECT line if you are going to
hijack the topic!!
> On Dec 10, 2019, at 4:27 PM, Jim Brown <jim@audiosystemsgroup.com> wrote:
>
> 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
>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|