I used a method that I haven't seen mentioned yet to ensure the base
section of my Rohn 45G tower was plumbed throughout the concrete pour and
set-up phase:
A foot of gravel in the bottom of the hole. Rebar placed, short-base
section with the first 10' section bolted to it placed, Ufer ground
connections made (optional, depending on your beliefs. . .).
I braced the 10' section of tower with three 10' 2x4's inserted from the
flat side of the tower and butting up against the vertical tower leg
opposite the flat side. The 2x4's extended to the ground at a (roughly) 45
degree angle. Stakes were pounded into the ground to brace the bottom ends
of the 2x4's. By using little wedges between the stakes and bottom ends of
the 2x4's I was able to tighten up the braces against the tower and plumb
the tower at the same time, checking with a 4' carpenters level. The level
I have just happens to have a groove in one side that enabled me to hold it
in place against the round tower leg; the four foot effective length gave
me a long "radius" to minimize inaccuracies in leveling the bubbles. . .
The tower didn't shift at all during the pour, and the base set up plumb
and true.
Besides making sure the tower base is plumb, it is very important with an
embedded-base, guyed tower to make sure the legs point exactly at the guy
anchors and the tower doesn't rotate in relation -- otherwise the guys will
torque the tower and twist it until it DOES line up when the guys are
tensioned.
FWIW,
Steve Zettel KJ7CH
near Libby, MT Where it has finally started to snow, just when I am trying to
get antennas and feedlines up on the tower!
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