John, I've two beams (a TH7DXX and A3WS on my HG-70HD plus a 16 foot 2M
monopole). I lay the tower over till the reflector of the TH7DXX is just off
the ground. I supplement the layover fixture double pulley system by placing
a strong metal brace fixture under the tower at the appropriate point and
let most of the weight rest on it, then do any needed antenna repair using a
ladder. To do a rotator swap I extend only the inner section enough to reach
the rotator and then lift the mast out (with antennas) just enough to ensure
the rotator will pull out. With the inner sleeve and thrust bearing above
the rotator this is relatively easy. Replace the tower cables at the same
time when necessary or prudent.
Don W7WLL
-----Original Message-----
From: Jim Thomson
Sent: Tuesday, November 18, 2014 5:23 AM
To: Alan Swinger ; towertalk@contesting.com
Subject: Re: [TowerTalk] Rotor swap query
## How do you tilt the tower over..with a yagi on top ?
## Id just extend the tower as required, block it off at the bottom,
then climb it.
Jim VE7RF
-----Original Message-----
From: Alan Swinger
Sent: Tuesday, November 18, 2014 5:11 AM
To: Jim Thomson ; towertalk@contesting.com
Subject: Re: [TowerTalk] Rotor swap query
If your TX-455 nests like my TX-472 does, you will not likely be able to get
the rotator out without extending the tower to get access. This is easy when
the tower is tilted over (did it this summer), but a different matter with
it vertical and extended. Think about getting that Tilt-over fixture.
73, Alan K9MBQ
-----Original Message-----
From: Jim Thomson <jim.thom@telus.net>
Sent: Nov 18, 2014 12:22 AM
To: towertalk@contesting.com
Subject: [TowerTalk] Rotor swap query
Date: Tue, 18 Nov 2014 02:11:06 +0000 (UTC)
From: John McCormick via TowerTalk <towertalk@contesting.com>
To: "towertalk@contesting.com" <towertalk@contesting.com>
Subject: [TowerTalk] Rotor swap query
Content-Type: text/plain; charset=UTF-8
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 )
## Get the UST MRF....... aka mast raising fixture. I believe it will
work on all the ust towers. Then its safe and a snap..to raise the mast
up a ft to get the
rotor out. I would also temp install a heavy duty clamp around the
mast... so it sits on the top bearing. Then its perfectly safe to swap
rotors. If you do use a
gin pole, it doesn’t have to extend above the top of the tower very high. I
would use a cum-along between top of gin pole and mast..just above the top
bearing.
Either method will work, then its just a case of winching the mast + yagi
up 1 foot. Most ust towers have a locking pin to pin the mast..when doing
rotor swaps etc,
so the mast is not rotating..while doing the rotor swap. Make sure the
new rotor is 100% tested good..on the ground.
Jim VE7RF
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