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Re: [TowerTalk] guying a Rohn 25 tower

Subject: Re: [TowerTalk] guying a Rohn 25 tower
From: Jim Lux <>
Date: Sun, 09 Sep 2012 17:09:23 -0700
List-post: <">>
On 9/9/12 4:00 PM, wrote:
  I would like to put up 40-50 feet of 25. It would be  behind my single
story ranch house. One guy would go towards the rear. The other  2 would head
toward the front left and right. The easiest would be to guy to the  roof.
This tower will be for some vhf and uhf antennas. Your thoughts.

     I've seen roofs that have been pulled loose by  attached guy wires. You
can do it but I'd be very careful about the engineering.  A fellow
TowerTalkian, Tony, K1KP, wrote a QST article some years ago about this  topic. 
ahold of a copy of it and you'll be much wiser.

     Please note that 25G uses 3/16" EHS with a ultimate  breaking strength
of 4000#. Could your homebrew roof guy anchor take that kind  of stress? I
didn't think so.

     Obviously your proposed installation will be on the  small side so you
won't have much risk but I'd still be careful.

This falls in the "is it ok if it fails" category. Maybe you're willing to have the tower collapse, as long as it happens in a safe way. Maybe it's like folks putting up 40 feet of thin wall pipe to hold up a TV antenna, and guying it with 1/8" solid steel wire. The wire fails before the anchor pulls out of the roof. If you're not going to climb the tower (i.e. you'll rig pulleys at the top or bolt everything on and tilt it up assembled), it's not much different than the TV antenna scenario.

The thing to worry about would be that the r25 is heavier than the 2" push up mast, so when it comes down, it might break more stuff (like your roof or car)

Think of it as a field day installation? I'm sure more than one person on this list has pushed up 40 feet of Rohn 25 with something like rope guys to iffy T-stakes or Bull Pins hammered in the ground. Likewise, I'm sure all those people have had an exciting time when it came down unexpectedly, but hopefully with no damage to people or expensive things (bent yagi elements don't count).

The thing to watch out for is starting small, and then forgetting your original design compromises. A 3 element 6 meter Yagi to start, guys made of fence wire so it doesn't wiggle too much. Then, 5-6 years later, Oh, I'll just add another couple sections on (and the guys you DO have make it seem sturdy enough when you climb it) and throw a 40 meter Yagi on, oh, and a microwave dish, and a bigger 2m Yagi array for moonbounce with an Az El positioner, etc.


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