Mark,
Last weekend I did a rotor swap for a friend, changing out a damaged Yaesu
G2800 for a Prosistel Big Boy PST-61. I faced the same problem with close to
300 pounds of mast and antenna that needed to be raised a few inches. The
rotor is 10 feet below the top of the tower (Rohn 45G). I rigged a large
pulley about 5 feet above the rotor using a pair of short chains to suspend
it inside the tower between 2 legs. Just above the rotor clamp, I used a
muffler clamp to pinch a threaded chain link to the mast. I used a
come-along chained to the outside of the tower, the cable going up from the
come-along on the outside of the tower, threading through the pulley to the
inside of the tower and down to the link held by the muffler clamp. It was
very easy to lift the mast and antennas. I also rigged a stabilizer bar (2
feet of 2 inch angle iron with a muffler clamp centered between the ends)
inserted between the tower legs with the clamp around the mast. Once I had
lifted the mast, I tightened the stabilizer bar clamp to limit the mast
rotation in the breezes. The top section of tower has a second rotor shelf
with thrust bearing to keep the mast vertical when not inserted in the
rotor. The stabilizer bar can also be used to keep the mast vertical by
attaching it to one leg and the tower bracing opposite that leg. The muffler
clamp then substitutes for the second thrust bearing. I've successfully used
that technique on towers without a second bearing. I can send you a jpeg
sketch (about 160K) illustrating how I rigged the tower. Please let me know
if you want me to send it.
73,
Mike, WA4BPJ
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of EL34GUY@aol.com
Sent: Saturday, April 15, 2006 12:19 AM
To: towertalk@contesting.com
Subject: [TowerTalk] rotor removal question
Hello Everyone,
I had a problem changing out my rotor today. Its a rd1800 rotor on a rohn
ssv tower. The 2inch mast has slid down farther on top of the rotor mount
and Im unable to remove the rotor now(cant slide it out to replace). Im
looking for advice on how to lift up the mast maybe an inch, considering
the rd1800 is still underneath the mast. The mast and antenna weigh about
200lbs and Im unable to lift it w/o some assistance. The only support I
have for the mast is the thrust bearing(should have put another plate or
support inbetween) on top of the tower. Im considering trying to attach
some clamp or bar metal to the mast and use a car jack or something to push
the mast back up to get the rotor out. Tower is 80ft and Id like to do it
right the first time. Any ideas on how to jack the mast back up?
Thankyou.
Mark
W0NCL
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