Author Topic: Getting ready for new tower  (Read 1275 times)

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Offline k7rmj

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Getting ready for new tower
« on: February 11, 2017, 12:34:36 AM »
I think I mentioned that I got a new tripod tower for putting an HF beam on the roof. So, it is time to get that project moving along. The cable that goes between the rotor control box in the shack and the rotor on the tower has disappeared. I think those pesky gremlins ate it. I checked where it is supposed to be and it is not there so then I checked everywhere else and it wasn't there either.

A couple of days ago I started shopping around the internet. The cable is supposed to be 6-wire, 22 GA stranded cable. The Wireman is the only one who has it with a decent price. I'll probably only need about 75 feet of it but Wireman sells it for $0.59 per foot or in 100 ft spools. The per foot price for 75 ft was $42 and the 100 ft spool was $45 so I sent them an email and asked if they had it in stock and if not, how long will it take to get it here.

Here we are 3 days later and no response from them. Glad I didn't give them my credit card number. Oh well. Then I noticed that the Lowes hardware store had some control cable for sprinkler systems that was the right size wire but only had it in solid wire instead of stranded. Hmm, oh well, at only $25 for a 50 ft spool it was worth a try. At least I will be able to hook up the control box to the rotor and test out my rotor before I bolt it up inside the tower. So we went to Lowes Hardware this afternoon.

This evening I took the control box apart and cleaned it up. All the caps look new and none were the old paper or oil type so I figured it was worth a try so I put it back together and wired it up to the rotor. That went pretty well so I plugged it and turned it on with the rotor on the bench inside the shop here.

It lit up and like magic appeared to be working but the "Azmuth Indicator" meter went all the way over and pegged to the right side of the meter. Okay, I fiddled with the Calibrate knob and it would only go to about East. It wouldn't zero. hmmm.

Opened up the control box again and went after the Calibrate pot with some cleaner. Also, since I was into it anyhow I cleaned all the switch contacts while and guess what? It still didn't work.

I tried rotating it left, then right, then back and forth. No movement. So, I placed my hand on the rotor and tried the left and right control again and I can feel the motor trying to turn but it doesn't move.

I couldn't believe the rotor would be frozen because it worked well back in St Louis up until I took down the tower. I refurbished this rotor about 5 years ago when I put that tower up.

So my question is this. Would using 50 ft of 18 GA solid wire not work on this rotor for some reason? The manual does say to use stranded wire. I rechecked all the wire connections at the screw terminals and they are tight and no broken wires or shorts.

What do you think?

Any input is welcome.

73 DE K7RMJ  Frank

Offline The Radio Shop

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Re: Getting ready for new tower
« Reply #1 on: February 12, 2017, 07:40:18 AM »
I did not see a brand or model of the control and rotor you mentioned. That would help.  Rotors can stick with no use. Had one on a 100 foot tower that did that.  I would take the rotor apart and connect the wiring. And with the housing removed you can see what is going on. The motor turns various gears and if just one sticks it locks it up.

As far as the wire, it should be fine.
Buddy kc4umo

Offline k7rmj

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Re: Getting ready for new tower
« Reply #2 on: February 15, 2017, 12:10:39 AM »
Thanks for the comment Buddy. I took your advice and took the rotor apart on the bench. I fooled the Gremlins this tome though and took the rotor apart in a large tray. None of the little ball bearings were able to escape this time LOL.

The Rotor is an old Alliance HD-73 with the old CD control box. Your advice paid off. I cleaned the bearings and races again and re-greased them. It worked! The old rotor came to life.

I started testing again to get the calibration set. No dice this time. I could get it to indicate about 270 degrees rotation on the meter, but the rotor was actually doing about 400 degrees of rotation. It would not reliably center either. I suspect there is something wrong with the positioning potentiometer in the rotor unit. It measures the correct 75 ohms and the calibration pot in the control box in series with it measures the correct resistance but it just does not indicate correctly.

Oh well, the wife got me a new Yaesu G-450 rotator for Valentines day. I must have had a LOT of "Good Husband" points saved up LOL. The rotator will handle up to 10 sq ft of wind load so it is a good replacement for the old Alliance work horse. Now I can work on the Alliance unit whenever I get around to it LOL.

Regards and thanks again for the suggestions.

73 DE K7RMJ  Frank