The antenna is a 6.1 m diameter reflector,
and has been meshed with 3 mm mesh hole size. The reflector is highly accurate,
and we hope it is good to 10 GHz. To report the position of both Azimuth and
Elevation, we are using US Digital encoders. We are using DC motors for both AZ
and EL. The DC motors get a PWM signal from the motor controller, so have full
speed control. The motor controller has an I²C bus, to receive commands as slow,
high speed, and STOP. Walter ON4BCB build an interface to drive the I²C bus of
the controller. Ones a command ( left, right up or down ) is received, the motor
controller will start moving from very slow to slow mode. When the slow mode is
on for more than 5 seconds, the interface drives the controller to high speed.
Ones a command is released, the stop command will be send to the controller, and
the DC motors will be "shortened", to get an electrical brake.
Since the antenna is mounted in the back yard, about 150 m
away from the house ( shack ), we needed to find a solution to install the
equipment next to the antenna tower.
I acquired an air conditioned and heated equipment
shelter, large enough to mount two 19" racks. One rack holds the power
amplifiers and the amplifier housekeeping, leaving the second rack to mount
antenna controllers, transverters etc. It will also leave some extra equipment
space for future projects.
The EME tower has been installed on April 19th, 2003 :
One tower leg folds down, so we can work on the antenna at
ground level. The antenna will be constructed at ground level, and the fold down
tower leg is being raised by an electrical winch. At the same time, by moving
the EL motor, the reflector will move away from the vertical tower sections. It
takes 2 minutes to move the antenna on or off the tower !

