[TowerTalk] Hindsight: Check your rotator bolts

[Barry Merrill]

In 2003, I (actually, I watched, while Bill, N5YA, 
and a 60 ton crane with 161 foot boom did the work)
installed a US Tower HDBX72 with a 24 foot mast,
and mounted a 2-el Cal AV 40 at the bottom and an
OB16-3 at the top, turned with an Orion RC2800
rotator, and have had zero problems and fantastic
results.

Yesterday, after a day of 50mph winds, I noticed
that the antennas were rotated about 45 degrees,
and then discovered I could not rotate them.

After Reading The Fine Manual and making the voltage
and resistance checks, which confirmed the motor
was fine, I called M2 support and received excellent
support, as Jeremy went thru the system and gave me 
additional diagnostics, in particular, to connect an
ohmmeter to the counter wires, toggle the rotator
control, and see if reed switch opened and closed, 
which it did, confirming the rotator electrics
were not the problem.

Looking at the rotator from the shack (from the West)
I had seen nothing obvious, but when I then looked from 
the North, I could now see that the rotator was no longer 
in the center of the tower; the rotator was now flush 
with the West side of the tower, and the mast was 2-3 
inches off vertical at its bottom!!!

Clearly, the bolts holding the rotator to the
tower plate had loosened.

When I called Jeremy back to thank him for the 
excellent diagnostics that eliminated elecrics
and to report what I had observed, he said that
this did, very rarely, happen, and that M2 now
offered a set of bolts that were pre-drilled for,
and were shipped with, safety wire, and he personally
packaged a set (only he and the Purchasing manager
were in the office, so he did it all!) and sent 
them via UPS early AM delivery (promised for 8:30am, 
the doorbell rang at 7:31am)!

On the tower this morning, with the new bolts in hand,
before the wind kicked up again, Bill discovered
that two bolts were gone, one was still in place,
but loose, and one had enlarged its hole in the
tower plate so that it was above and sitting on
the plate, cocking the rotator.  Fortunatly,
with ropes on the boom for horizontal pull, 
a jimmy bar in Bill's hand to lift, and a 
comealong strap around the rotator body, 
he was able to realign the rotator and its
holes, and the new bolts AND SAFETY WIREs were in
place with only about 2 hours tower time by Bill!

With hindsight, it is now intuitively obvious to
the casual observer (or more certainly, casually
obvious to the intuitive observer), that I should
have had the rotator bolts checked before
five years had elapsed.

And, now, with the awareness of the alternative
bolts and safety wires, even at $50.00 for the
package of six, I'd strongly recommend they
be purchased if you install the Orion, and
maybe for all rotators, and, periodically check
your bolts!

Photos of the original tower installation are
in the lower left corner at http://www.mxg.com,
and you can see the load on the Orion is most
definitely non-trivial.

73,

Barry, W5GN