[amsat-bb] Home brewing El. Az. rotators
gaston.bertels at skynet.be
Wed Sep 12 01:21:11 PDT 2007
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.
Gaston - ON4WF
At 03:50 11/09/2007, Tony VK5ZAI wrote:
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.
Regards Tony. VK5ZAI
P.O.Box 470 Kingston SE
South Australia 5275
National ARISS Co-ordinator
and Satellite ground Station.
Web Site :-
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Gaston Bertels, ON4WF
Avenue Paul Hymans 117 B29
B-1200 Brussels, Belgium
Phone : +32.2.771.67.74
Fax : +32.2.771.49.89
E-mail : gaston.bertels at skynet.be
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