Hi all, and thanks for the multitudes of replies. (40+)
Many of you had some excellent ideas, and here is the short version for all
to see.
By far the best idea was as follows:
I don't know what they are called but there is a shackle that has
a spring clip and can be released by pulling on a line if there is
nothing pulling on the shackle. We use them on the boat.
Crane slacks off, you pull the line, the shackle opnes and the crane
is free. "Bob Duckworth" <wb4mnf@atl.org>
Numerous people said to preassemble the mast on the tower on the ground and
take the antennas up with the crane seperately.
Several people said to weld a large ring at the top of the mast to let the
crane's ball/hook grab onto.
Back in the "good old days", one of my crew would probably have ridden the
ball to the top with the antennas. They often rode the ball down with the
antenna we were removing.
name withheld :)
Using a sling:
attache one end to the ball, the other end about in the middle of your mast
pipe.. since the big antenna is below this point, the balance is also below
the attachment point... now after the mast pipe is lifted into place, you
can easily reach up a couple of feet above the tower and disconnect the strap!!
First Prize for ingenuity:
1. run a cable down thru the mast to a pin that can be pulled
out of a hole drilled in the mast after it is in place. just
be sure to use a heavy enough pin so it doesn't bend or break
during the lift. you may be able to make a plate with an eye
bolt that you could put on the bottom of the mast to hold the
cable, but remember that this has to fit thru the thrust bearing
and has to stay centered, if it shifts during the lift you may
not be able to get it thru the thrust bearing.
If I can't find one of the spring shackles easily, then it will be a tossup
between the welded ring at the top of the mast (have to see if crane company
will allow safety bar on the ball hook to be strapped off), or using a large
sling on the th-7 and a half hitch further up the mast. Just hope the 1/2
hitch doesn't get stuck :(
Thanks again all for the input, will keep everyone updated on progree.
73,
Scott
KA1CLX
P.S. The general consensus on the antenna spacing was minimum of 10' to
reduce interaction. Guess i'm going to a 15' mast now.
Only got one reply for the concrete fund! And he was broke! :)
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