David--
That's all very good, and is a good synopsis, but-- it contain one big
mistake-- you used the word "Cosine".
Those who savvy "Cosine" need less help, but those to whom that is Greek
will get frightened off-- again.
Really- a Fine summary.-- Thanks.
Bill--W4BSG
----- Original Message -----
From: "K1TTT" <K1TTT@ARRL.NET>
To: "'Tower and HF antenna construction topics.'" <towertalk@contesting.com>
Sent: Friday, January 15, 2010 5:09 PM
Subject: Re: [TowerTalk] FW: Guy article in CQ
> Ah, but if you have asymmetric guys, which ones do you put the gauge on?
> Here are some things to consider.
>
> The key is that when the tower is vertical the horizontal force from all
> the
> guy wires HAS to be equal. If it weren't then the tower would be moving!
> So the objectives are 2 things... first, to have the tower vertical.
> Second, not to exceed manufacturer specs on tower or guy wire forces.
>
> If all the guy wires are the same it is obvious that you only have to
> measure the tension on one set of guy wires and the others have to be the
> same if the tower is vertical. But if the guy wires are at different
> angles
> to the tower the ones that are closer to the tower will have higher
> tension
> than the ones farther out(it goes as the cosine of the angle between the
> guy
> and the tower, or the sine of the angle from the ground to the guy wire).
> So as you pull a guy wire farther out from the tower the tension in it has
> to decrease to keep the tower vertical.
>
> Now the question is, which one do you measure? Personally I would
> recommend
> measuring the tension on the one that is anchored closest to the tower
> since
> this one would have the highest tension. This will result in lower than
> recommended tensions in the other guy wires which will make them look/feel
> loose. If the farther out ones are much farther out than the others there
> may be problems with movement in the wind because it will have more slack
> to
> be taken up. This is one of the reasons that rohn specifies limits on guy
> locations, if you go outside their limits you should have the design
> evaluated by an engineer... there may be other options, like changing the
> guy wire type, elevated anchors, using 4 anchors instead of 3, or other
> configurations to equalize the anchoring.
>
> David Robbins K1TTT
> e-mail: mailto:k1ttt@arrl.net
> web: http://www.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
>
>
>> -----Original Message-----
>> From: Roger (K8RI) [mailto:K8RI-on-TowerTalk@tm.net]
>> Sent: Friday, January 15, 2010 22:46
>> To: Tower and HF antenna construction topics.
>> Cc: 'N1MM'
>> Subject: Re: [TowerTalk] FW: Guy article in CQ
>>
>>
>>
>> Rex Lint wrote:
>> > Tom, et. al.,
>> >
>> > A couple of field days ago we put up a tower with one of the anchors
>> > reeeeaaaalll far away: they guys on this side were very long.
>> >
>> > When we tightened all the guys, the long ones were "looser" then the
>> others
>> >
>> I think someone was confusing the catenary (sag) with tension.
>> > - they sagged like crazy. But, we cranked away with the come-along,
>> > and
>> > finally the tower BENT OVER at the lower guy point.
>> >
>> >
>> That is because too much tension was put on the longer guys. With the
>> same tension the longer guys will have much greater sag in this case.
>> > Out take-away was, "Keep all sets of guys symmetric."
>> >
>> >
>> Although it is a good idea to keep guys symetrical this was not a case
>> of asymmetrical guys, but some one assuming the longer guys weren't
>> tight enough. In cases like this it should have been obvious that even
>> with the extra sag the effort to use the come along would have indicated
>> the guys were under plenty of tension. When ever pulling like that use
>> a tension gage.
>>
>> 73
>>
>> Roger (K8RI)
>> >
>> _______________________________________________
>>
>>
>>
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>
>
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