[amsat-bb] inquiry about homebrew az-el systems

Samudra Haque samudra.haque at gmail.com
Sat Feb 23 15:59:35 PST 2013

Hi, about two years ago, I started a design for a robotics class project of
a AZ-EL rotator controller system, and a hardware package for the mechanism
for rotating an antenna in any direction subject to mechanical stops. The
system would have been able to handle regular and flip modes. I didn't do
anything more than calculations, and moved on to building a classroom
instructional robot then.

Lately, as I am setting up (K3GWU, the George Washington University Amateur
Radio Club and Research Station) I find that the price of az-el systems
such as G5500 + Yaesu AZ-EL rotors are expensive, and are not typically
available on an affordable basis on Ebay or eham.net etc. Well, of course,
expensive is a relative term, for a student hobby organization, it's a lot,
and I guess for small ham operators it is also moderately expensive.

This may be a frequently asked topic: does any one have experienced with
(tested) kit designs for AZ-EL rotors that can be made with parts from
 current suppliers ? I know there are a number of controller designs, but I
am interested to know if there are any options for suppliers of the
required gears/motors etc.

I have located several large AC motors / DC motors at my university
mechanical engineering workshop, but they are not all guaranteed the same
specs. I now realize if I do embark on a actual design process with my
model/simulation/hardware, it would be nice to build several of these all
at once to share the development cost over the production run, and ensure
those who want a cheap AZ-EL system can get one. Otherwise the production
cost of one heavy duty system is going to be quite high.

I hope some of you may have suggestions for me, both (+) and (-) or perhaps
(~) in nature. I thought amsat / amateur radio folks have a common need to
encourage homebrew activity to keep their brain cells in working condition?

I'm opening this question up to the national US audience, and welcome any
discussion on the challenges of making the ever-so-important
azimuth-elevation rotor. I've studied some of the alternatives: Alliance
U100 and Yaesu G-5500. I think we can do better in 2013. But ideally, to
allow the wide adoption of AMSAT ground stations, what price point would
the system have to be to make it worth building ?

73 de N3RDX
George Washington University

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