Hi folks,
Tony did a great job building his AZ-EL tracking system.
I have also done some work on this, building a lightweight system with a couple of motors from motorized car windows and discarded bicycle parts.
I have used an acetylene welder and manufactured a tool for forming helicoïdals out of 8mm diameter steel rods you can find in DIY shops. These helicoïdals drive the bicycle chainwheels. The AZ-EL booms are welded on the axes of the chainwheels.
The tracking sensors are microswitches moved by the teeth of the chainwheels. Zeroing the AZ-EL positioning is done by a second pair of microswitches sensing a 180 degrees semicircular rod epoxied to the chainwheels.
I have written the adhoc tracking software in Delphi. The electrical interface is a kit sold by a popular electronics editor (Elektuur). It uses an USB port.
This lightweight system is very rugged. Angular precision of AZ-EL positioning is limited to about 8 degrees, due to the chainwheel teeth sensing. This is sufficient for tracking the ISS with 145MHz crossed yagis.
73 Gaston - ON4WF
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At 03:50 11/09/2007, Tony VK5ZAI wrote: Hi Guys, Seems a lot of talk about rotators lately, have you thought about building up your own, I did this around 15 years ago and the system has never been switched off apart from twice when moving QTH and the occasional service, greasing etc. My present QTH is 300 yds from the Southern Ocean and we get some almighty winds in the winter but it keeps on going. It's driven by 2 windshield wiper motors and constructed of parts that can generally be scrounged from vehicle and machinery junk yards etc. You will require a small welder to put it together and access to a lathe but really there's no great precision required in it's construction. I've described it's construction on my web site listed below. hopefully it will be of interest to some of you.