In a message dated 96-12-06 07:32:44 EST, you write:
>Hello all,since we have been on the subject of tower loads maybe someone
>can help me out. I have a 70ft. rohn 20g tower with guys at the 45 ft level
>and a house bracket. the base is set down 5ft deep by 3 by 3 ft and filled
>with concrete.Just wondering how much antenna load i could put up and get by
>with. seems to me rohn stated 2 sq ft. I am not in a normal high wind area
>usually 45 mph is the max .
First of all, the lowest TIA-222 wind speed rating in the US is 70 MPH.
You're in one.
My Rohn catalogs go back to 1980 and Rohn 20G isn't listed anywhere. It
is another TV tower. It's very similar to 25G but lacks the diagonal bracing
that adds much torsional rigidity to the structure. I would be very cautious
with this tower since it should be considered to be less (half?) than 25G.
You're probably overloaded already since the Rohn spec calls for the top set
of guys to be 5 feet from the top of the tower, not the 25 that you have.
The two square feet you mentioned might be the real, albeit old, factory
rating but I can't confirm that. Sounds like VHF/UHF stuff on top of this
installation would be okay but an HF antenna would be pushing it without
addtional guying.
73, Steve K7LXC
TOWER TECH -- professional tower supplies and services for amateurs
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