ON7UN Amateur Radio
ON7UN EME
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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 IC bus, to receive commands as slow, high speed, and STOP. Walter ON4BCB build an interface to drive the IC 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 :

 eme_tower.jpg (115264 bytes)                              

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 ! 

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