John,
I doubt you will be able to lift the array. Hopefully the weight of
the array is not all on the rotor. If that is the case, I would take a
muffler or boom clamp the size of the mast and attach it securely right
above the thrust bearing. That should hold the mast stationary. However,
it will be able to rotate in the wind so you may need to do something
about that too. If all the weight is on the rotor, you will probably
have to use another clamp and come-along to take the weight off the
rotor first. Good luck.
Mike / W8DN
On 11/17/2014 9:11 PM, John McCormick via TowerTalk wrote:
It was bound to happen, although I wasn't expecting it so soon. I experienced a
rotor issue during the Sweepstakes contest last weekend when a visitor was
operating my station in a multi-operator effort. The Ham IV rotor is still
working, but the meter dial is stuck at southwest, even when the beam is
pointed in another direction. A ham buddy who is much more electrically savvy
helped me do some troubleshooting today and we are pretty convinced that the
potentiometer up in the rotor is not working properly. We also discovered that
the previous owner of the control box had removed the fuse that is supposed to
protect the potentiometer and metering circuitry.
The good news: I have a spare Ham IV rotor (purchased for this exact kind of
situation), so I can swap them out an make repairs to the one now up in the
tower. I also have a spare control box (we tried that as well today and it
produced the same southwest reading).
The bad news: I've never swapped out the rotor before and I don't have a gin
pole, something I plan to eventually acquire.
My question: What's the best procedure for swapping out the rotor? Will I be
able to lift up the mast and beam 18 inches and place it on a wooden brace in
the tower, while I make the swap, securing the base of the mast with some ropes
or wires to keep it from moving laterally? Am I foolish to even attempt this
without a gin pole, helping me lift the weight from the ground?
Some other specifics:
+ US Tower TX-455, with a KF7P work platform installed (cranks down to 22 feet,
but I don't have the tilt-over fixture at this point)
+ 5-element yagi (57 pounds)
+ WARC rotatable dipole (about 10 pounds)
+ 10-foot mast, 2-inch diameter (25 pounds)
+ one thrust bearing installed at top of tower
Thanks for any thoughts directly or through the list.
73s, John/N0FCD ( N0FCD@yahoo.com )
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