Research Concepts RC2000A - Manual (Page 83)

RC2000A Dual Axis Antenna Controller Appendix F AC or Large DC Motors 83
Polarization Control
If the polarization is controlled with something other than a polarotor, an interface for a polarization
motor is necessary. If control for a polarization motor is needed, use the RC2000 with the RC2KPOL
option. For a single axis antenna this will mean that the elevation control capability of the RC2000 is
not used. The polarization control can use a scheme similar to that used for the azimuth and elevation
axis which employs relays and steering diodes. Note that the RC2KPOL option requires the use of a
potentiometer for position sensing.
Motor Control Interface Products
A number of products are available from RCI which implement the motor control scheme outlined
above.
The 2K90INT is a board level product which implements azimuth, elevation, and polarization control
circuits based on the method outlined in figure 1 above. The contact closures generated by the
2K90INT board are isolated from the antenna controller’s control outputs and can be used to activate
either contactors which control three phase AC motors or DC motors. When used with DC motor drive
modules, the 2K90INT board supports a latching relay that allows a single DC motor drive module to
power both the azimuth and elevation motors (not simultaneously). This allows for a lower cost
installation.
The RC2K90INT-1 and RC2K90INT-2 interface boxes use the 2K90INT circuit board described above
with a KBPB DC motor drive module manufactured by KB Electronics (phone: 954 346 4900) to power
either 90 or 180 volt DC azimuth and elevation motors. The interface boxes are housed in NEMA 4
enclosures suitable for outdoor mounting. The RC2K90INT-1 interface box uses the latching relay
feature described in the previous paragraph to allow a single KBPB DC motor drive module to control
both the azimuth and elevation axis. With the RC2K90INT-1 simultaneous azimuth and elevation
movement is not supported. The RC2K90INT-2 uses a pair of KBPB motor drive modules and supports
simultaneous azimuth and elevation movement. With both interface boxes, the only support for
polarization movement is a pair form C relay contact closures activated by steering diodes. These
outputs can be used with a DC power supply to control a rotating feed powered by a DC motor if the
drive output of the RC2KPOL daughterboard is not suitable for direct interface with the polarization
motor.
A heater option is available for the RC2K90INT-1 and RC2K90INT-2 interface boxes that allows
operation at temperatures to -45 C.
Position Sensor Interface
The RC1000A and RC2000 antenna controllers require the use of single-phase pulse type sensors to
determine the position of the antenna. A pulse type sensor produces a rectangular shaped waveform
as the antenna moves about the axis associated with the sensor. A quadrature pulse type sensor
produces 2 rectangular waveforms, one being 90 degrees out of phase with the other. With a
quadrature type pulse sensor it is possible to determine which way the antenna is moving. The
RC1000A and RC2000 antenna controllers are not compatible with quadrature pulse sensors. Please
see figure 2.
Research Concepts, Inc. • 5420 Martindale Road • Shawnee, Kansas • 66218-9680 • USA www.researchconcepts.com