[TowerTalk] guying distance

[Bob Shohet, KQ2M]

My guys have been battle tested through two hurricanes and two direct hit tornadoes and countless ice and wind storms and violent T-storms and Macrobursts.  As far as I know, the wind gusts have not exceeded ~ 110 mph in any storm, but with the F1 tornado and Macrobust we also had swirling winds, so in terms of force and torque I don’t know what that equates to.  Likewise, what is the overall force of a 70 mph wind gust on antennas and guys with > 1/2” of radial ice?  

The guys are not equivalent in distance from the tower or their overall length, and their ASL heights relative to the tower base also vary.  

You do what you have to do in the hills of Connecticut, land of ledge and hardpan.   :-)

However, to reduce overall stresses in the system, both towers use a pier pin and a base plate that can swivel around it on the concrete base which is much larger than recommended.  The guys also connect go to guy anchors which are in 2 – 3 cu yds of concrete (the holes were MASSIVE).  That of course doesn’t change the angle but it does help to ensure that the guys won’t pull out in extreme wx events.   And the top two sets of guys on the 130’ Rohn 45 tower are star guys.    I believe that my big tower might not have survived without the star guys.

Thankfully the Hurricane wind gusts have not been Cat 3 or higher (although 110 mph is almost Cat 3)  and the Tornados have not been EF2 or higher.  I’m reasonably sure that my towers would not have survived that.  I’m hoping that I never have to find out!

73

Bob  KQ2M


From: Bill via TowerTalk 
Sent: Wednesday, December 05, 2018 12:27 PM
To: kq2m at kq2m.com ; towertalk at contesting.com ; grants2 at pacbell.net 
Subject: Re: [TowerTalk] guying distance

I too, have gone greater than 80% to allow the antennas on the rotating tower to clear the guy wires.  Currently the top guys on my tower are at 84 feet and are pulled out to around 100 feet. Realize though, that the tower is now pulling more sideways and less downward than before when it was at 84 feet.  I believe that taken to extremes this would eventually allow the tower to pull apart in heavy wind, especially if it was Rohn 25.  I have done the height equals guying distance on 200 footers and have had no issues.  However, they were never tested in a hurricane, so who knows?
Bill KH7XS/K4XS


-----Original Message-----
From: Bob Shohet, KQ2M <kq2m at kq2m.com>
To: cqtestk4xs <cqtestk4xs at aol.com>; towertalk <towertalk at contesting.com>; Grant Saviers <grants2 at pacbell.net>
Sent: Wed, Dec 5, 2018 4:54 pm
Subject: Re: [TowerTalk] guying distance

For various terrain and property line related reasons I have had to go shorter than and significantly longer than the 80% with specific legs of my two towers, as short as 65% and as long as 130%.  This also has an effect on the tensioning of the guy wires – and which needs to be taken into account. What is often not realized until after the fact is that if your intention is to stack multiple antennas and rotate them separately, either on sidemounts or ring rotors, using less than ~ 80% may compromise or eliminate your ability to stack and rotate the “in-between” antennas because they will likely get caught in the guy wires.  And, if there is not enough extra clearance, even if you can safely rotate under the guy wires on a calm day, on a day when it is windy or icy or both, you might not clear those same guy wires!  It is quite remarkable to see just how much those guy wires can move and bounce around in violent T-storm or worse! Depending on the band, length of the boom and elements, proposed height of the antenna, heights of the guy wire attachment points and proximity to the antenna, radius of antenna (mounted on the rotator) from the tower legs (especially if side-mounted) and other factors, 80% may not be enough either; but it will at least get you “in the ballpark” and give you some viable options. 73 Bob KQ2M  From: Grant Saviers Sent: Wednesday, December 05, 2018 11:17 AMTo: cqtestk4xs at aol.com ; towertalk at contesting.com Subject: Re: [TowerTalk] guying distance Except that a PE can change this with the proper analysis.  Also, a post 
plus deadman end is a way to geometrically shorten the 80%.  Look at 
commercial guyed towers and they often have a shorter guy anchor to base 
perecent (ie steeper guy angles).

Grant KZ1W

On 12/5/2018 7:42 AM, Bill via TowerTalk wrote:
> Rohn specifies 80% of the height for their towers..25, 45, 55, 65 all the same.
> Bill K4XS/KH7XS