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Re: [TowerTalk] Philly installation

To: jimlux <jimlux@earthlink.net>
Subject: Re: [TowerTalk] Philly installation
From: "Roger (K8RI)" <K8RI-on-TowerTalk@tm.net>
Date: Tue, 01 Sep 2009 01:35:24 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>

jimlux wrote:
> bob finger wrote:
>   
>> Amen!!  .  Bending and twisting Rohn 25 trying to put enough tension on 
>> the guys can ruin a good day.  73 bob de w9ge
>>     

Actually you can install the 6600# Phillystran on 25G and properly 
tension it if if has the guy brackets in place and don't wrap the stuff 
around a tower leg. BUT  if you run the figures for say a 100-120 foot 
tower with three tier of guys, you will have some where between 3000 and 
4000 pounds of vertical load added.  What is the ultimate load

The angles in the following example are the included angle between the 
tower and guy lines. It assumes an angle for the top of 60 deg, 45 deg 
middle, and 30 deg for the bottom set.

The 6600# line properly tensioned gives 660sin(60)=571# download and 88# 
side load per line
at 45 degrees it gives 660sin(45)=446.69# download and 193.31 side load
and at 30 degrees 660sin(30)=330# down and 330 side load
This neglects the weight of the actual guys.  We end up with a total 
calculated down force from the guy lines of  1347.69 * 3 = 4043# plus 
the weight of the tower and accessories if I did the math right.

73

Roger (K8RI)



>> Cqtestk4xs@aol.com wrote:
>>
>>     
>>> You do not need the heavy duty stuff!!!!! DO NOT use it.  You  can not 
>>> tension it to the proper tension as it will be pulling way too hard on  the 
>>> Rohn 
>>> 25 tower. 
>>>
>>>       
>
>
> Nothing says you have to tension the cable to a particular fraction of 
> it's breaking strength. It's more a matter of the desired tension for 
> appropriate stability for the structure.  You could tension million 
> pound breaking strength cable to the same few hundred pounds as the the 
> regular non-EHS cable.
>
> Now, if the cable is particularly heavy (per unit length) compared to 
> the design cable, there are some issues, but I wouldn't think that's the 
> case here, comparing EHS and regular cables.
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