Rohn 25G install plan?

[K1ZJH]

The base isn't doing much work, since as others noted the house bracket as taking the brunt of
the lateral stress. Do not skimp on how that bracket is attached to the frame!!!! And don't
exceed the free standing height above the bracket per the Rohn guidelines.
Getting a permit and having it inspected is good advice--but based on my experiences many
building inspectors will rubber stamp the approval since they don't have a clue what they are
looking at.

Pete

[W9GB]

Rohn 25G --- Product Page
http://www.rohnnet.com/rohn-25g-tower

Municipal and County/Parish governments are revising their permit process,
that require tower installation permits to address compliance with current TIA-222 standard.
Design Considerations Using The ANSI/TIA-222-Rev G Standard
http://www.rohnnet.com/resourcesmodu...48eced0c124b9/

The tower itself is in excellent shape, but the base shifted and she was a doing the Tower of Pisa act.

That would be due to an improper base installation ... Not deep enough (your local frost line).
http://en.wikipedia.org/wiki/Frost_line

The frost line (depth) for your geographic area will be KNOWN by any contractor who performs foundation work (footings, basements).

As I remember, it will be at least 5 feet below grade for your area !!

Rohn sells short base sections that are set into a hole, with concrete poured around them.
The SB25G is 3 feet long. The SB25G5 is 5 feet long. The SBH25G is a hinged three foot section.
Your local hole depth (frost line) determines which one you use !!
http://www.texastowers.com/rohn_25gsb.htm

[N5TGL]

I'd suggest a pinned base rather than embedding the 5' section. No worries about legs rusting out, and if you do, you can replace them. If the pier pin rusts out, you can remove it, and embed a new one in epoxy.

The base is actually doing a LOT of work. First, it's resisting the tower from sinking. Secondly, it's preventing wind loads from kicking the base out. With a bracket at 15', all the tower above that provides quite the lever against that base. I'd say it needs to be guyed at the very top too, but I'm sure someone will come in there with a story about their old uncle doodlebob who did it without guys and it was just fine. The question you have to ask is "do you mind 50' of tower coming down at a most inappropriate time?"

[WB2WIK]

I'd suggest a pinned base rather than embedding the 5' section. No worries about legs rusting out, and if you do, you can replace them. If the pier pin rusts out, you can remove it, and embed a new one in epoxy.

Except he said he has no room for guys. I can't imagine using a pier pin base without guys, that was never the intention. A house bracket alone won't do this job without an actual concrete foundation (not a pier pin). Well, it might work with two brackets spaced 20' apart and secured to something very solid; but as stated here a few times now, if a permit and inspections are required, and the inspector knows how to read, he probably wouldn't approve that as it's not recommended in any of the Rohn engineering documentation.

The base is actually doing a LOT of work. First, it's resisting the tower from sinking. Secondly, it's preventing wind loads from kicking the base out. With a bracket at 15', all the tower above that provides quite the lever against that base. I'd say it needs to be guyed at the very top too, but I'm sure someone will come in there with a story about their old uncle doodlebob who did it without guys and it was just fine. The question you have to ask is "do you mind 50' of tower coming down at a most inappropriate time?"

Yeah, I agree with you. I think 25G is good tower, and I've seen them unguyed at 50' stand up for 30-40 years holding simple antennas like a TV antenna or a ground plane; but not with a rotator and HF beam. The torsion requirements to turn and stop something with long elements like an HF beam, or even the long boom of a high-gain VHF beam, are just too much. Every time you STOP a beam with any long members (elements, or boom, or both), you're trying to twist the tower into a pretzel, and eventually that will happen.

[K1ZJH]

I'd suggest a pinned base rather than embedding the 5' section. No worries about legs rusting out, and if you do, you can replace them. If the pier pin rusts out, you can remove it, and embed a new one in epoxy.

The base is actually doing a LOT of work. First, it's resisting the tower from sinking. Secondly, it's preventing wind loads from kicking the base out. With a bracket at 15', all the tower above that provides quite the lever against that base. I'd say it needs to be guyed at the very top too, but I'm sure someone will come in there with a story about their old uncle doodlebob who did it without guys and it was just fine. The question you have to ask is "do you mind 50' of tower coming down at a most inappropriate time?"

I agree, I was careful to state that the bracket takes care of the lateral stress. My 64 Rohn
foldover is on a hinged base... with two sets of guys. The base is six cubic yards of concrete left
over from a HDBX tower that previously occupied the same spot.

Pete