I would not assume that it is the bearing without climbing the tower. Since
you mentioned having two bearing plus I assume a bearing inside the rotator
you have a big potential for binding the mast. Not long ago I operated a
Caribbean station that had a similar issue and there was a tower bracket
that had fallen off and was jammed between the mast clamp and tower. You
could also have cables binding or even a bad rotator. I'm not sure what a
"truth table" is but if it is just measuring the motor resistance this will
not tell you that the motor and gearbox is working properly. If it does
happen to be a bearing there are split ones that can be installed around the
mast, K3EJJ makes nylon ones that match Rohn's TB3.
John KK9A
W7ZZ wrote:
Today, I tried to rotate my antennas in a clockwise direction. My Green
Heron control box for the Prosistel 61D gave me a ?no rotation? error
message. I verified by looking out the window that the antennas were not,
in fact, rotating. I then tried to rotate counterclockwise and the antennas
did turn, although it seemed that they turned more slowly than usual, but
that?s hard to tell for a small amount of rotation. I went back and forth
like this several times until the antennas had been rotated counterclockwise
about 90 degrees. They still would not rotate clockwise, and finally they
wouldn?t rotate counterclockwise either. I applied the ?truth table? to the
rotator and it seems to check out OK. The Green Heron checks out OK. I?m
thinking I have a stuck thrust bearing. I use two pillow type thrust
bearings supplied by the tower manufacturer (AN Wireless) and the tower has
been in the air for about 3 ½ years now. I lubed the bearings before
putting the tower up and once since then, probably about a year later.
Any other guesses as to what?s wrong?
If my guess is correct, any suggestions on what to do, since removing the
bearings would require me to remove a 2 element 40 meter beam, a 4 element
Steppir and the mast, not an easy task at the top of a 70 foot tower.
Suggestions appreciated.
73 Doug W7ZZ
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