We at the N6IJ contest station in Marina CA, have been
offered a dismantled broadcast tower for use at our contest
station. It is 7 ea., 20 ft. sections of heavy steel triangular
tower, 15" face width. The vertical are 1 - 5/8" steel tubing,
and the cross braces are only the horizontal type (no diagonals,
like Rohn) but heavy, 1/4" thick, 2 inches wide, and spaced
every 23". At the top and bottom of each section, there are
heavy, (3/8" thick) welded, triangular gusset plates/flanges at
the inside of each corner, and are drilled to accept 3/4"
assembly bolts. The base has a conical ceramic insulator, which
we may just choose to not use, and bury the first section in a
poured concrete base.
Our wish is to use this at the site, guyed, at the full height,
to mount a large Yagi Array. We have a KLM-Derived, dual band
Yagi, 3 element 40, 5 element 20 meter, with a 56 foot boom
for the top Yagi. Perhaps rotate the whole tower/perhaps using
a Tic-Ring Rotator for intermediate level yagis. We inherited from
the Ft. Ord military base large amounts of 5/16" ehs guy strand,
still on new spools, and 10 ft. guy anchors, with steel
expandable bottom fixtures. (Will these anchors with the expandable
fixtures (approx 12- 15" expanded diamater) be strong enough to anchor the
tower in compacted sand, or will we need to use concrete?)
The tower donor is a Crane company, (that took down the
tower) owned by a newly licensed ham, who will offer to use his 110 ft
crane to help assemble the tower. We are looking for expertise
in tower construction to advise us of pitfalls, safety issues, and
structural capabilities of this tower. We have large open areas
on the top of a hill, (guying is no problem, space wise) and
sandy soil. We will hire a PE to do the design calcs, (obviously)
but would like to have some idea of what this PE certification
will cost, not having done this before.
Any Help, Comments Suggestions?
If you are ever in the Monterey Peninsula area stop by the N6IJ
contest station site, or contact me ahead of time....Take the
12th St Entrance to old Fort Ord, off of Highway 1, and travel
East (abt 1.5 miles) until you see the antenna farm..
73, DX de Pat, AA6EG
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