Dale,
Using 1/4 inch EHS rather than 3/16 inch EHS will not be a problem.
Initial guy tension is normally set at 10 percent of its published
breaking strength, with upper and lower limits of 15 and 8 percent.
Guy wire tension less than 8 percent places excessive wear on guy
attachment hardware as the guy slackens and tightens repeatedly during
wind events. There have been many documented cases of guy attachment
hardware failure as a result of excessive wear caused by inadequate
guy tension.
Guy tension is excess of 15 percent of breaking strength reduces the
useful load capacity of the tower by placing unnecessary vertical
loads on the tower.
73!
Frank
W3LPL
---- Original message ----
>Date: Tue, 24 Apr 2007 13:04:03 -0500
>From: "Dale Martin" <kg5u@hal-pc.org>
>Subject: Re: [TowerTalk] Tower guy wires / EHS size
>To: <K7LXC@aol.com>, <towertalk@contesting.com>
>
>
>
>I'm curious, Steve, where 1/4" EHS is used in place of recommended and
>spec'd 3/16" EHS, does one tension the 1/4" EHS to 400 lbs. as one would do
>with 3/16" or to whatever tension 1/4" is rated for?
>
>Looking from another aspect, is the 400 lbs. tension specified when using
>3/16" EHS on a Rohn 25g based on the tower type/heighth where 3/16" EHS
>conveniently has a stength of 4000 lbs and the 400 lbs tension is just right
>for the tower? Or should the tension be 10% of whatever guy wire size
>strength is being used...e.g., 670 lbs. based on 1/4" EHS strength of 6700
>lbs.?
>
>73
>Dale, kg5u
>
>
>>
>> In a message dated 4/23/2007 9:03:02 A.M. Pacific Daylight
>> Time, towertalk-request@contesting.com writes:
>>
>> > I am in the process of erecting a few towers at the new
>> QTH and have
>> > a guy
>> wire size question. Two of the towers will be Rohn 45 @
>> 100' and the third
>> will be Rohn 25 @ 100'. They will all have multiple yagis
>> at various heights on them, so not just a top mounted
>> antenna. The Rohn book indicates that each tower should be
>> guyed at three elevations and the bottom two guys should be
>> 3/16" EHS.
>>
>> > QUESTION: I have LOTS of 1/4" EHS and guy grips. Is the 3/16"
>> > mandatory
>> to
>> meet the specs (as in the 1/4" is too heavy) or - is the
>> 3/16" simply suggested (as in the 1/4" is not necessary but
>> acceptable)?
>>
>> While the LXC Prime Directive to "DO what the
>> manufacturer says" still applies, what you're proposing is a
>> little bit of over-engineering (which is not discouraged, BTW).
>>
>> The capacity of any tower is a function of its leg
>> strength. By using bigger guys you'll be putting more
>> compression on the legs but at the heights you mentioned,
>> it's not a big deal. 45G will go to 300' and 25G will go to
>> 200' so you're not overstressing anything.
>>
>> Cheers & GL!
>> Steve K7LXC
>> TOWER TECH -
>> Professional tower services for hams
>> Cell; 206-890-4188
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