[TowerTalk] Guying a TX-472 bottom section

[SPWoo]

Hi Steve,

I need to guy the tower because I've exceeded the tower's design limit by a factor of 3.7.  If my two yagis were both mounted one foot above the thrust bearing I'll be below the limit.  However having one yagi at one foot above the bearing and another one seven feet above the bearing generate enough bending moment that exceeds the tower's limit in the retracted position (3,700lb-ft vs. 1,000lb ft. at 122mph wind speed).  I didn't do my homework before I put everything in.  Hindsight is always 20/20.  Getting a new tower is out of the question.  So I have two choices, do without my 40m yagi or guy the tower.  I read the UST FAQ document and it does say it's ok to guy the bottom section of the tower.  There are no details on how to do it.  I didn't go with a traditional guyed tower because I don't have enough space for one.  However I do have space to guy the bottom section of my retractable tower.  I get extreme winds here (>100mph once or
 twice a year, >70mph ten days a year).  UST did the calcs. for me at 122mph and they said the tower could handle 15.6 sq. ft. when retracted.  However my Skyhawk yagi is rated at 8.5sq. ft. which is too optimistic.  The true number is more like 12.2 sq. ft. projected.  8.5 sq. ft. is most likely an 'effective' windload for flat members.  The TH-11 is about the same size as my Skyhawk and it's rated at 12.5 sq. ft.  My F12 D240 is rated at 5.8 sq. ft. projected.  I'm unsure if the 5.8 figure is optimistic or not but that's what Mark at F12 told me.  So in a nut shell I don't want to lose my 40m yagi and that's why I'm looking into guying the tower.

 
Best Regards,
Jonathan Woo
(970) 646-1711


________________________________
 From: "K7LXC at aol.com" <K7LXC at aol.com>
To: towertalk at contesting.com; jj_2_woo at yahoo.com 
Sent: Sunday, October 7, 2012 4:06 PM
Subject: Re: [TowerTalk] Guying a TX-472 bottom section
 

>  I'm looking for someone who has guyed the bottom section 
of a TX-472.? I need a guy bracket and the Rohn standard bracket wouldn't fit.? 
I want to hear from those who has guyed the same or similar tower.? 
 
    And the purpose of this guying is...?  
 
    What does the factory say about guying the bottom 
section? I don't think they do. Unless there's some compelling reason to do so ( 
and I can't think of any), guying the bottom section is unnecessary. The tower 
is designed to be free-standing. If the factory doesn't say to do it, don't do 
it. 
 
    The LXC Prime Directive is to "DO what the 
manufacturer says." The opposite is also true - "DON'T do what they don't tell 
you."
 
Cheers,
Steve    K7LXC
TOWER TECH
UST Factory authorized installer