[TowerTalk] guying a Rohn 25 tower

[Jim Lux]

On 9/9/12 4:00 PM, K7LXC at aol.com 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. Get
> 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.