Antenna Party Time-Part2….
So in the first installment I described the cause for the recent rotor swap and the lead up to the actual day of tower work. After the very funny exchange between Dennis-K7DEH and myself, a couple different things happen. The most important is that Scott-N7SS solved problem number one that I’d been struggling with since planning this exercise. The Yaesu rotor requires this bolt to go through the mast clamps and the mast, which I’ve been calling the anti-slip bolt. (The anti-slip bolt is something unique to the Yaesu rotar, it is a 1/2 bolt which goes through the mast clamps and the mast. The idea is that instead of using lots of force to keep the mast from slipping in the rotor, they put a simple bolt through everything. (I’m not going to argue with the mechanics, because it seems to work)
So if I didn’t pull everything down from the tower, I would have to drill the hole for the anti-slip bolt while everything was still at the top of the tower. For those that have never been at the top of a tower, there are very few things which are ‘easily done’. In this case, I couldn’t figure out how I was going to ‘hold’ the mast and manage to drill while also drilling nice and level hole that was required. Then Scott pointed out that if we drop the mast back down onto a piece of wood laying across the rotor plate, the weight of everything would probably hold it in place. Duh! So given that nobody wanted to completely dismantle the entire antenna array to drill a simple hole, we went with plan B.
The first hour or so I was on the tower was spent removing the old dead rotor. This went pretty smoothly right up until I dropped it. Initially you would think I would have been upset or maybe a little surprised, but I really wasn’t. You see I have a long history of dropping rotors from the tops of towers when I remove them. Don’t quite know why, but I’ve done it enough times that nobody hangs around the bottom of the tower when I’m doing stuff like this. Which is another important safety tip, nobody should really ever be around the bottom of the tower when someone is climbing. Using a pulley clipped to the bottom of the tower for lift lines works really well and then the guy up top doesn’t have to be so freaked out when he drops something. (And all your helpers can be far away) I do have to point out that one of the funniest lines of the day came from Art-N7CC about the time the rotor dug itself into my yard. Art was quick to point out that I had probably “fixed” the rotor by dropping it. I haven’t spent the time to find out yet, but he is probably right. :-)
So with the old rotor out of the way, I loosen the thrust bearing and we lowered the mast onto a piece of 2×6 wedged in the tower. And just like Scott predicted, with the weight of the antennas kept the mast pretty much in place. I still had to put pressure against the back when drilling, but it worked. This is the point where you ask how I managed to drill the hole and get it in the right place while hanging from the top of the tower? Good question. The mast clamps on the Yaesu rotor are removable, so I removed them and used them as a template to mark where the holes went. This was probably one of the trickiest things I did all day, since I was juggling the two sides of the mast clamps, the mast itself and the magic marker. (The mast had to be a little “free”, so I could get the mast clamps under it)
With the mast drilled for the anti-slip bolt and the whole thing ready for re-assembly, I decided it was time to take a break. I had a couple muffler clamps with short pieces of rope tied to carabiner for holding the mast in places. I just clamped a couple to the mast below the thrust bearing and clipped them off to the tower after lowering the whole thing back down onto is piece of wood. It didn’t even twist when the wind came up. (The mast was lowered through the rotor plate as well)
I climbed down, drank several bottles of water and got the food out for lunch. Scott was nice enough to throw the brats on the BBQ while Art and I got the rest of lunch out. We had a nice meal under the deck (where it was cool) and prepared for round two. Dennis arrived just in time for lunch, so we had to take a little longer break so he could eat. (We were of course heart broke about this :-) Eventually it was time for me to climb back up the tower and finish the re-assembly.
Getting the new rotor attached was more annoying then difficult. For those that don’t know, there are four bolts which hold the rotor to the rotor shelf and they attach into the bottom of the rotor. The gotcha here is trying to get yourself into a position so you can actually see the holes to line things up, because your head isn’t going to fit inside the tower and the climbing harness isn’t really designed for lots of odd movements. Eventually I got two bolts started, so the last two were quick. With the bottom of the rotor attached, I just had to attach the mast clamps and the mast itself.
This was where the only real problem of the day happen. The mast clamps pretty much only attach one way with the anti-slip bolt is in place, which really only goes on the rotor main body one of two ways. (each 180 degrees opposite of the other) The only problem was with the everything put together, the antennas were no longer pointing north. (I had previous tried to set everything so that when assembled, the antenna would be pointing North)
I then realized that I needed to actually drill the anti-slip bolt hole in a specific place so the whole thing would be aligned correctly. Oops. This really isn’t a big deal, the Yaesu rotor control comes with a little dial replacement, which allows you to put “north” anywhere on the dial you want. I was only off about 90degrees, so I just adjusted things to work. I’m sure if I cared a little more, I could have fixed this with adjusting the controller, but I really didn’t care. The rotor turnes and I could easily look and see what direction the antennas were pointed.
Once we tested everything, I spent a couple minutes double checking things. I specifically climbed all the way to the top of the tower and made sure the mast was centered in the thrust bearing, I was worried this was part of the problem with the old rotor. I also double checked all the nuts, made sure everything was tight and climbed down. (I actually used this ‘red’ version of locktight on all the bolts per a recommendation from Art) There was about 30 minutes of clean up to finish, specifically taping up the rotor cable and several of the coax runs needed re-taped. (Some of them have been up there for more then five years now) But I decided they could survive for a couple days and I was tired.
Which brings up another really important tower lesson, don’t over do it. Plan things out so you can safely stop and take breaks. Be sure to don’t over do it, because that is when mistake will happen and chances are you won’t be in any condition to deal with it. Since most of the tower work in the northwest happens during the summer, it also means you need to take on lots of water and don’t forget the sunscreen.
I climbed back up the tower about two weeks later and ‘cleaned-up’ all the cables. Things are now ready for the winter and I now can point the beams again. I’m quite happy with the new rotor. Of course now I’m planning the next antenna project, any takers for invitations to my next antenna party?