I responded to Samudra Haque after a couple of preliminary Emails with this idea on lo-cost az/el rotors. I presented the idea at an AMSAT-DC meeting 3? years ago and showed a working kludge example. Somewhere in my archives I have the Powerpoint from then and I will dig it up if there is any interest, particularly from someone who wants to do some development!

The rotor scheme I described in my presentations is based on the DISEQC consumer antenna control protocol (seehttp://en.wikipedia.org/wiki/DiSEqC http://en.wikipedia.org/wiki/DiSEqC) pushed by EUTELSAT and found in nearly every backyard satellite dish system (see http://www.eutelsat.com/satellites/pdf/Diseqc/associated%20docs/position_app...). The DISEQC scheme superimposes DC (to run the rotors, switches, downconverters, etc) plus RF (typically 500-1500 MHz IF satellite downlinks) plus control (PWM 22 kHz tones) and it has an amazingly rich instruction set. Many BUD (Big Ugly Dish) receivers include DISEQC controllers for controlling antenna position, polarization, bandswitching, etc.

Most of the DISEQC rotors cover only 180 degrees and are very suitable for elevation with 1 degree precision (see http://www.sadoun.com/Sat/Products/PowerTech/Sadoun-DG380B_HH_Motor.htm) for example. Sadoun is a main suplier in USA.

However I have found one 540 degree DISEQC Azimuth rotor (http://www.solidsignal.com/pview.asp?p=rotr100&d=eagle-aspen-rotr100-one...) http://www.solidsignal.com/pview.asp?p=rotr100&d=eagle-aspen-rotr100-one-cable-antenna-rotator-%28rotr100%29 ).

Total cost for a pair of az/el rotors is < $200 but the antennas that could be controlled must be pretty small. My application was for a solar radio telescope using a couple of small DirectTV Ku-band dishes.

I'd LOVE to find someone who was interested in developing a microcontroller/interface for DISEQC az/el use. The coding should be pretty simple. Also someone needs to figure out a scheme to adapt the "crooked pipe" on the elevation rotor to couple to a real antenna. Let me know if you can find someone who is interested.

Also, if anyone is interested, you might want to browse the Sadoun & Solid Signal web sites where you will also find DISEQC controlled 75 ohm RF switches good for low power use well into the microwave spectrum.

73, de Tom K3IO (ex W3IWI)