Wow, this was a busy "tower work weekend". The temp were in the low 90's with high humidity, so we started early. First thing, I helped a friend take down his 48' Rohn 25 tower, in preparation for a move to his new home. Ken had already removed his antennas and dropped the guy cables (he had a Hazer on it!), so it came down fast. In less than 2 hours, it was laying on the ground and ready to haul away.
Before....
After, in under 2 hours!
I returned to my QTH and climbed to the top of the 90' section on my tower, relocating the gin pole from 80' to 90', in preparation for pulling up the next section. I've decided to put the top on it here, and stop the tower at 100'. There will be 15' of mast above that, with a 21' vertical antenna mounted on top of the mast...that'll put the tip top of my stuff at 136'. I'm already on a hilltop, located at 375' ASL, and the nearly identical setup has worked very well for me over the last 24 years.
Gin pole moved to 90' and extended to over 100', ready for the next section of tower...
I needed to do a bit of preparation and a few mods to the top section, to remedy problems I've had in the past. I cleaned the grease fitting on the thrust bearing and lubricated it well. It seemed to be dry, but then, it has been in the weather and in operation many years. The pinch bolts in the collar of the thrust bearing needed attention, as one had become loosened and fallen out somewhere along the years, shifting all of the vertical load directly onto the rotator.
Thrust bearing on the top...new allen screws installed for centering the mast in the bearing...
Mast guide plate, mid-section...
Next, the lower rotator shelf has always been a problem, requiring the rotator to be left slightly loose on the shelf due to an alignment issue. It was pre-drilled when I got it (don't remember where it came from), and I found it was off about 1/4"! Whew... I marked the plate and slotted it with my old manual mill to allow for perfect alignment when it is reinstalled.
Rotor shelf marked up to determine the error and corrections needed...
Rotor shelf clamped down on the table of my old manual mill...
Slotting the rotor bolt holes to allow for accurate alignment of rotor, once installed in the tower...
The rotator is an old Alliance HD-73, and has served me well all these years. It's had a rough life, being operated severely overloaded for turning load, as well as having supported a tremendous amount of weight. Rotation, lock to lock, was generally on the order of 80 seconds. It was welded together once by a lightning strike, and I literally broke it loose with a hammer and never removed it for service...about 19 years ago! Never-the-less, it has performed well. When the storm destroyed the tower back in April of 2016, it was stuck upside down in a tree for about a month, until we could get a crane to get it down. During that time it rained inside of the rotator, which certainly did it no good. I pulled it apart today, cleaned out all of the rust, wire brushed all of the moving parts and all 4 of the bearing races, cleaned and packed all of the 104 individual ball bearings, reassembled it, gave it a good cleaning and a coat of paint. A quick test found it working like new and ready for action.
I had to use the Dremel tool and a cut-off disk to deepen the slots of the screw heads, so they could be removed from the terminal strip where the rotor cable connects. Lots of rust...
Loads of rust on the terminal strip...
Corrosion on the bottom of the housing was so bad, it looked as if the bottom of the rotor has been hammered in... I cleaned it off with a wire brush, and it got a heavy coat of paint later...
Terminal strip cleaned with a small sanding wheel...
New screws installed in the terminal strip...
Rotor, after disassembly, internal cleaning and lubrication, and re-assembly...
I gave it a "road test", a fresh coat of paint, and she's ready for action!
That was all I could do today, and tomorrow is another work day. More work coming soon, the tower top will be headed up to the 100' point in a few days!
Dave WB4IUY
http://www.WB4IUY.net
