Hard to imagine it wouldn't be easier to just put a 10ft tripod on the roof
top, but I realize that wasn't the question.
Not sure why you need the tilt base. Once up and tied off, a single person, a
lever & fulcrum could lift the tower up enough for someone on the ground to
bolt it to a fixed base. On my roof anchored 25G, I pounded 3 four foot pipes
in the ground and set the tower base legs in them. Didn't even bolt it;
where's it gonna go? After years it hasn't moved, though gotta make sure there
is proper drainage. I've seen similar installs where the legs rot out.
Tying ropes at the 50ft or 60ft top rather than at 25ft will make it easier to
pull up for sure, as would a pully attached to the roof. It won't flex that
much.
I agree that a better ground would be the rebar in the concrete, if it has
rebar, or use both ground rods and rebar (that's what I am specifying on my
current semi-ufer tower project) Wouldn't worry about the air gap. I would
worry about tying that ground system in with the building's ground system and
doing it well. If you have a separate ground from other things in the building
and they are at all in contact (for instance, through a radio power cord or
data cable) then the potential between grounds will be related to the
resistance of the earth between them, and the lowest resistance path might just
be your wall outlet or radio electronics or something you are holding in your
hand inside the building.
Lets say you have 5Kamps, with soil resistivity of 1 ohm per meter and just 1
meter between grounds... that's enough to scare me!
Marlon Wood
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