RESEARCH CONCEPTS RC2000A DUAL AXIS Instructions Manual page 26

26 RC2000A Dual Axis Antenna Controller
4. When the feed has been centered in its range of travel, connect the ohm meter between the wiper
and one of the other terminals of the pot. Rotate the shaft of the pot until the resistance readfrom
the ohm meter is one half of the value of the pot's total resistance (obtained in step (1)).
5. Tighten the allen screw and verify that the pot is properly centered by performing the procedure
above entitled "Verifying Pot Center Position".
Replacement Potentiometer
The biggest problem encountered when using potentiometers in an outdoor application is moisture.
When moisture gets past the shaft seal on the pot, it will cause inaccurate readings and can eventually
lead to failure. The Contelec model PD2205, 5K ohm, 5 turn device has excellent environmental
characteristics. It is available from Novotechnik, Marlborough, MA, (508) 485-2244.
When replacing a pot on an existing feed (controlled via either the RC2KPOL or RC2KHPP options), the
resistance value of the potentiometer is not that important. It is necessary that the replacement pot
have either the same number of turns or a greater number of turns than the original pot. If the
replacement pot has a greater number of turns, there will be somewhat less resolution available in the
measurement of polarization position. When a potentiometer is replaced, the sensed polarization
positions which correspond to the satellite's horizontal and vertical positions will change.
Configuring the Controller for Optional Feed Drives
Use the following procedure to configure the RC2000A for use with a 5-40V DC polarization motor.
1. Connect the polarization/sensor assembly as shown in figure 3.4. Note that shielded cable is
required for the sensor and that the shield MUST be connected to the GROUND terminal (1) at the
back of the controller and MUST NOT be connected to anything at the antenna. Research
Concepts, Inc. can supply cable for installation. RCI part number CBL-2_16-3_22A contains 2 16
gauge conductors for carrying the motor drive current and a shielded triple with a drain wire in a
single UV resistant-direct burial jacket. Contact RCI for details.
2. If using software version < v2.6x :The CONFIG mode item Rotating Feed Present? must be set to
YES (1). Activate CONFIG mode and use the SCROLL DOWN key to bring up the Rotating Feed
Present? item and key in a 1 followed by the ENTER key. (If the Rotating Feed Present? item is not
accessible in CONFIG mode, the Expert Access Flag has been reset. If this occurs, set the Expert
Access Flag (1) as described in section 2.5.)
If using software v2.6x or later: At the Pol Control? CONFIG mode prompt, the user can specify
either None, One Port, Two Port, or Polarotor. The following paragraphs describe the various
possible responses to the Pol Control? CONFIG mode prompt.
•
If the user enters None at the Pol Control? prompt the controller assumes that a polarization
control device is not present in the system. Polarization jog commands are ignored and the
user is not prompted to specify polarization values in SETUP mode.
•
One Port refers to a single port rotating feed powered by a DC motor that employs a
potentiomter for position feedback. This type of feed can only receive a single signal (and only
has one LNB). When a single port feed is looking at a satellite that transmits both horizontally
and vertically polarized signals, the controller has to 'remember' both a horizontal and vertical
position for each satellite. Accordingly, the user is prompted for horizontal and vertical
polarization positions in SETUP mode. If this option is specified the RC2KPOL polarization
control daughterboard must be installed in the controller. Setting the Pol Control? CONFIG
mode item to One Port results in controller operation identical to that of older versions of the
software with the Rotating Feed Present CONFIG mode item set to Yes.
•
A two port feed can receive horizontally and vertically polarized signals simultaneously. Like a
one port feed, a two port feed is powered by a DC motor, employs a potentiometer for position
feedback, and requires that the RC2KPOL daughterboard be installed in the controller. In
SETUP mode, when a single band (either C or Ku) satellite is specified the user is only
prompted to specify a single polarization. When the feed is adjusted to that position it can
receive horizontally and vertically polarized signals simultaneously. In SETUP mode, when a
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