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Page 17 of 21 www.alfaradio.ca AlfaSpid Rotator
Alfa Radio Ltd. 11211 - 154 St. Edmonton, Alberta, Canada T5M 1X8
Using the AlfaSpid Rotator with LONG Cable Distances
By VE6JY
Since the motor uses relatively low voltage DC, a combination of long
cable runs and/or thinner than required cable may reduce the voltage at the
motor to an unacceptably low value. It may turn in warm weather or light winds
but the power will not be available to rotate under more severe conditions.
While it is easy to say just use a heavier cable, this may be costly,
impractical or both. I have one tower that is over 1700 feet (approx 500 meters
away) and running large cable out there would be very expensive.
My solution is to use this rotator controller's output voltage to control
another set of relays that will feed a higher voltage DC to the motor. In the
above-mentioned example, I find a voltage between 60 to 80 volts gave suitable
performance. This is a pretty extreme case but it illustrates the versatility of this
design. The external DC supply voltage needed will vary depending on the DC
voltage rating of your motor, the cable size and length of the run. Typically 36 to
50 volts at 3-5 amps should be quite adequate. These DC motors are quite
tolerant on their voltage ratings.
Relay Board Schematic