HAM IV Problem

[VE1PEW]

I had been dealing with my Ham IV having an inaccurate readout on the control box for the winter months and finally decided to lower the tower and repair things. My guess was the resistor in the rotator. I figured that since I had everything lowered down and the rotor apart I would replace the bearings, the ring gear and the resistor all at the same time so that the rotor would be "freshened up" and hopefully last several years. The first thing I noticed when I took the rotor apart was that the resistor looked fine. no cracks or wear to be seen anywhere. In fact I would say it looked practically new. But, since I had it apart and had all the new parts I decided to swap everything as planned. After I put everything back together I noticed that the meter was still doing the same thing. All the movement on the needle is in about the first 1/4 turn cw of the rotor or the last 1/4 turn ccw. Which is why I originally thought the resistor was bad.

So, after looking at the rotor in disbelief for a few minutes I decided that I had assembled something incorrectly and that was the culprit. Being the stubborn person I am I disassembled and reassembled the rotor about 10 more times to make sure everything was indeed lined up. I even turned the rotor part turns to see if the resistor was where it should be when I took it apart and it always was.

When I had finally decided that I had indeed assembled the rotor correctly I checked the manual and did all the electrical tests on the rotor that it said to check and everything looked fine. So I concluded that the problem was in my control box. Not really very many parts in there so my first guess was the resistor that goes to the meter. It tested fine. I checked the other resistor and it was fine. I don't have a capacitance meter so I couldn't really check that. I am starting to think that maybe the variable resistor for the calibration circuit is bad. (This typing thing helps to come up with ideas).

Any other suggestions?

73,Paul
VE1PEW

[WB6MMV]

Paul:

I have also rebuilt a couple of my Ham IV's more that I would like. The easy way to troubleshoot it is to isolate the variables. I assume that if you did all the electrical tests on the unit and they passed, then verify that the electrical connections from the rotor to the shack are adequate (no broken wires, corrosion, etc.)

Next, does the brake work properly? Will the rotor turn properly? If all that is wrong is that the meter is not reading correctly, you should check the meter movement to verify that it is working properly. You can just feed it voltage to verify that it swings from end point to end point with voltage. Obviously the discrete meter components such as the resistors can easily be checked.

I am also assuming you read p.19 in the manual about improper meter readings and followed the tests they suggest. If not, try those first. I found that in one case the actual meter movement was defective and the meter would "hang" roughly 25% of the way. Hopefully its not a bad meter since they are a bit more expensive and the older style meters are really hard to find. I also found that the meter fuse (F1) needed to be removed and cleaned. Apparently I had corrosion on the contacts in the fuse holder which affected performance (I lived in an area with lots of salt fog). A good cleanout and things worked ok. I ended up replacing the entire fuse holder as insurance going forward.

Good luck with the troubleshooting.

Ken WB6MMV

[N6DCN]

All the movement on the needle is in about the first 1/4 turn cw of the rotor or the last 1/4 turn ccw.

This sounds like the rotor pot is not engaged in the rotor bell correctly.

[VE1PEW]

This sounds like the rotor pot is not engaged in the rotor bell correctly.

I thought that too but I took the thing apart and put it together a bunch of times and every time the pot was where it should have been, no matter where I stopped the rotor.

73,Paul
VE1PEW

[VE1PEW]

Paul:

I have also rebuilt a couple of my Ham IV's more that I would like. The easy way to troubleshoot it is to isolate the variables. I assume that if you did all the electrical tests on the unit and they passed, then verify that the electrical connections from the rotor to the shack are adequate (no broken wires, corrosion, etc.)

Next, does the brake work properly? Will the rotor turn properly? If all that is wrong is that the meter is not reading correctly, you should check the meter movement to verify that it is working properly. You can just feed it voltage to verify that it swings from end point to end point with voltage. Obviously the discrete meter components such as the resistors can easily be checked.

I am also assuming you read p.19 in the manual about improper meter readings and followed the tests they suggest. If not, try those first. I found that in one case the actual meter movement was defective and the meter would "hang" roughly 25% of the way. Hopefully its not a bad meter since they are a bit more expensive and the older style meters are really hard to find. I also found that the meter fuse (F1) needed to be removed and cleaned. Apparently I had corrosion on the contacts in the fuse holder which affected performance (I lived in an area with lots of salt fog). A good cleanout and things worked ok. I ended up replacing the entire fuse holder as insurance going forward.

Good luck with the troubleshooting.

Ken WB6MMV

I will try feeding the meter with voltage to see if it moves as you say. All the tests on the rotor were fine and everything works as it should except the meter on the control box.

73,Paul
VE1PEW

[WB2WIK]

Sticky meter movement?

I've used HAM-IVs for many years and have two of them currently and have never seen what you describe.

You could place an ordinary 500 Ohm linear taper pot across the control box terminals (for a few bucks) and check out to see if the meter itself has a problem.

[VE1PEW]

Sticky meter movement?

I've used HAM-IVs for many years and have two of them currently and have never seen what you describe.

You could place an ordinary 500 Ohm linear taper pot across the control box terminals (for a few bucks) and check out to see if the meter itself has a problem.

That's another good idea. I never thought of that.

73,Paul
VE1PEW

[KC4LNX]

I'll say this. The meter face is just a ohm meter reading the pot in the bell housing. I had a issue with mine not giving me a reading on the meter even thought the rotor was turning. it was on the ground at this tme. turns out a small piece of metal had bent in the rotor so that while the housing was turning, the pot and wiper arm were not. the bent metal didnt allow the wiper to engage with the bell housing and turn across the pot, so no reading on the meter ( ohm meter ) good luck

[WB6MMV]

Paul:
Upon checking further, I would agree with the conclusion that you probably didn't clock the directional pot correctly in the rotor. Since the meter is showing readings at both ends of the clock, the meter power supply and associated circuitry is probably just fine.

In case you have not seen the following website you will find his tutorial on repairing a HY-Gain rotor to have a very good section on how he clocked his directional pot before buttoning up his tailtwister. This was what I used and it worked fine for me. Hopefully if you have not see it, you can use it to get the pot set properly.

http://www.hayseed.net/~jpk5lad/Roto...air%20Menu.htm

Ken WB6MMV

[WA2OLZ]

Paul,

Try removing the meter from the circuit board and then put your DVM across the lands where the meter connects. Run the rotator end to end in both directions. T\Your DVM should track from zero to ~12.6V if all is good between the POT in the rotor and the meter. If the DVM reads true the meter itself is sick, I won't, just back up through the circuit