Am embarking on construction of my first tower. I've studied the Rohn
catelog intently for the past 2 months.
Its to be a 50 ft. flattop. All parts of it will be new. Since i live
about 120 miles or so from the North Carolina coast, it may be subject to
110+ mph wind even though we are an 80 mph county. We had gusts here in Nash
County during hurricane Fran in '96 between 100 and 110 mph. Rohn rates the
windloading allowable for this tower at 8.3 sq. ft at 110 mph. I'm going to
use a Mosley TA-33 jr.which represents 4.3 sq. ft. of windloading. Its a 21#
tribander with a 14-15 ft. turning radius and a 12 ft. boom.The mast will be
4 ft. of 1.9" O.D. schedule 40 aluminum with a wall thickness of .145". TB3
thrust bearing, Yaesu 450 rotator,
5 ft. "short" section embedded in concrete(2 x 2 x 4 ft), guys(3/16" EHS) at
24 and 51 or 52 ft. Lower guys will attach to a GA25GD guy bracket, uppers i
assume will attach to the corners of the BAS25G Bearing/Accessory Shelf with
shackles. The guys will go to anchors in .5 c.y. of concrete poured in 3 x 3
x 3.5 ' deep holes. I've departed fron the specs. here in that Rohn wants
the holes 4 ft. deep but my anchors are (i think) GAR25 instead of the
modern day GAR30(they're 5-1/2 ft. long instead of 7 ft. long).They're
unused but i found them in the backroom at a local Motorola shop(from years
ago)and my friend(the owner)gave them to me. The concrete will be
re-enforced with over 40 ft. of 1/2 " rebar in each hole.
Equalizer plates ,turn buckles, wire clamps, thimbles, etc. are all Rohn
parts. Not going to use preforms as i have no experience there and trust the
regular method with 3 clamps and wrapping the dead end afterwards, even if
it is more work.
I'm going to use my new IIX ginpole kit with an 11 ft. section of the same
stuff i'll use for the mast.Also a "tower block", ONV safety belt w/climbing
lanyards, etc.Even new rope(braided, not twisted).
Any and all opinions as to whether i am overlooking something or need to
consider or reconsider something will be most welcome.
Now- My big question. When i laid it all out last weekend, my measurements
between the base and each guypoint was within 6 inches and same for guypoint
to guypoint. Is this within an acceptable range or do i need to adjust them
to tighter tolerances?(the yard is flat).
Thanks in advance es 73 de Roy Lincoln WA4DOU
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