[TowerTalk] Tower guy wires / EHS size

Don Havlicek n8de at thepoint.net
Wed Apr 25 15:18:17 EDT 2007



Frederick M. Mott wrote:

>I have a 155' of Rohn 45G at my qth with 4 sets of 1/4" EHS (with
>Insulators) torque to 590 lbs and there is no slack in the lines.  73's Fred
>  
>
No slack?  
If there is no catenary in the guy lines, please give us your method of 
defying the Law of Gravity!
Don
N8DE

>-----Original Message-----
>From: towertalk-bounces at contesting.com
>[mailto:towertalk-bounces at contesting.com] On Behalf Of Dale Martin
>Sent: Wednesday, April 25, 2007 11:24 AM
>To: towertalk at contesting.com
>Subject: Re: [TowerTalk] Tower guy wires / EHS size
>
> 
>Thanks, Frank. Good info. 
>
>I'm still curious, though.  Is there that much slack in 1/4" EHS tensioned
>to 400 lbs. -- 10% 3/16" strength?  Is it the weight of the cable
>introducing a sag that 400 lbs. tension cannot remove that wears away at the
>hardware?    
>73,
>Dale
>
>  
>
>>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 at hal-pc.org>
>>>Subject: Re: [TowerTalk] Tower guy wires / EHS size
>>>To: <K7LXC at aol.com>, <towertalk at 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 at 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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>>
>>    
>>
>
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