[TowerTalk] Rohn 45

[Jim Lux]

On 12/26/13 4:42 AM, Gregg Seidl wrote:
> Looks like I’ve got suggestions from weld the 45 to the 25 and this just isn’t going to work. For those who do not understand what a 24 foot box is,it is 4 antennas mounted on each corner of a 24 feet by 24 feet box. It is for EME. The way you end up with 28 feet of Rohn 45 is 2 ten foot sections and one flat-plate top section,I think those are 8 feet but they may be 7 feet. II ‘d have to go in the shed and measure it. I could guy it but it would not be guyed at the typical 70-80% of the towers’ height. The guys would get in the way of the bottom antennas.I could possibly guy the tower about 10 feet up and 10 feet out which isn’t spec but it would help a LOT. The 18 square feet I stated is close with all the H frame pipe there. The antennas are only 10 square feet but the pipes add about 8 more square feet plus the rotor face adds a little more too. I have a M2 2800 rotor to use for this project.
> I must say that my first thought was to remove the base and place the 45 in the hole and re-cement and that is what I still think I might do.
> Hopefully this will clear up what my intentions are with the 45.
>
>

One thing to think about is whether you care if it falls down in an 
extreme wind event.  You might be willing to take the risk, in exchange 
for getting your antennas on the air.

10 foot guys are one possibility. The other might be some sort of rigid 
guy.  If your "strut" is connecting 10 feet up, and maybe 5-10 feet out, 
then something like a suitable piece of pipe might be the way to go. 
Think in terms of compression to resist the tower moving as opposed to 
tension.  There's some standard equations to tell you what the buckling 
load of a pipe is: In general, you want large diameter, thin wall, but 
it won't be that huge. 3 story apartment buildings are supported on 4" 
steel pipe columns on 15-20 foot centers. Something like fence top rail 
might work.

If you do something like this, then the base of the bottom section isn't 
taking as much of the load. (In fact, you could weld up some sort of 3 
or 4 legged platform 10 feet off the ground, and bolt your sections to that.

Sounds like an interesting project, especially if you're somewhat 
failure tolerant.