Friday, February 13, 2015

KOPEK AR1002 light duty VHF antenna rotator modification

Most of the Ham in Malaysia knows about this rotator and those who have and using it gets it from the neighbouring country, specially Indonesia. Initially, I am surprised that it is hard to get in Malaysia. Most of the ham who own this buy them from Jakarta.

 At first, you may have already know that I've made a heavy duty rotator using some industrial worm gear reduction gearbox and controlled using the open source arduino rotator controller by Radio Artisan, K3NG aka Anthony Good,

 I have not managed to get it installed due to my work commitments and it has been sitting inside the box. I was still thinking of the best way to mount it.

 I am fortunate that a senior ham pass me an old rotator, and at first it was without a controller. I didn't know how to make the motor turn. It has only 3 wire, CCW, COM, CW. I tried connecting it to a 25VAC transformer and the motor vibrate but not turning. But it's not jammed. It's a 4 pole AC motor! And I have no experience of how to wire it. Upon some reading and searching, I finally got the answer.

The 3 wire must be connected to the AC supply,in this case, it was 24-25VAC with a capacitor is connected across the CCW & CW terminal.The pin that is connected directly will act as a power, the other pin that is connected through the capacitor act as a direction. This is due to the changes of phase by the capacitor.

So, I decided to embark into another mission... give the rotator a new lease of life! this time with a far better and advance way. Arduino Antenna Rotator Controller!!

To use the Arduino controller, you have the choice of using potentiometer, digital compass or encoder as a direction feedback. The Kopek rotator mechanical assembly does not have a potentiometer as a direction feedback like what you will find in most modern rotator. It only has 3 wire for the motor as mentioned above. The direction is show by another mechanical assembly in the original controller.

If you own EST MTV7000 rotator, it is the same with KOPEK AR1002!!

I decided to add a 10 turn potentiometer inside the rotator  mechanical housing, but I am in big trouble.. There is no space to put in a standard size 10 turn potentiometer inside. Apart from that, a suitable location to tap the gear to turn the potentiometer shaft. Meaning, I must find an calculate so that, in 1 full turn of the rotator, my potentiometer shaft will turn less than 10 turn. I managed to get 8 turn of potentiometer for 1 full turn of the rotator. I have room for overlap provided the rotator mechanical assembly allows it! It has 7 degree overlap actually with a mechanical stop limit. NO limit switches inside ya!

I managed to find a small potentiometer from a surplus components supplier in China through Aliexpress. Took a chance and bought a unit. 

I cleaned and serviced the gear assembly. Added a few 0.1mm shims to prevent the gears from having too much gap. I also cleaned the old greased and re-greased the ball bearings.

Connected it to the controller and did the calibration procedure... tadaaaa!!!!!! IT WORKS!!!!

If you have a KOPEK AR1002 and have the balls to do the mods.. go ahead... I claim no responsibility to whatever issues you may encounter... do it at your own risk.. what risk?? never try never know yeah!

What's next?? To mount the rotator for good use.. when?? I'll let you know.. visit my blog regularly.. hehehe..

Thank you for reading my blog.

73, 9W2DTR

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