Sea Tel 9797A-27, Installation And Operation Manual

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9797A-27 C-Band TXRX Maintenance and Troubleshooting
7-7
J 1 0 1 0 Ref + LV
K 1 0 1 1 Ref + LV + CL
L 1 1 0 0 Ref + AZ
M 1 1 0 1 Ref + AZ + CL
N 1 1 1 0 Ref + AZ + LV
O 1 1 1 1 Ref + AZ + LV + CL
7.4. Maintenance
7.4.1. Balancing the Antenna
The antenna and equipment frame are balanced at the factory however, after disassembly for shipping or
maintenance, balance adjustment may be necessary. Balancing must be done with the power supply
turned OFF. No belt removal is required to balance the antenna pedestal. Balancing is accomplished by
adding or removing balance trim weights at strategic locations to keep the antenna from falling
forward/backward or side to side. The antenna system is not pendulous so 'balanced' is defined as the
antenna remaining at rest when left in any position. The antenna should be balanced within one or two
ounces at the typical trim weight location of 2 feet from the axis of rotation.
The recommend balancing order is Elevation Axis with the antenna pointed at the horizon (referred to as
front to back balance). Elevation Axis with the antenna pointed at zenith (referred to as top to bottom
balance). Then Cross Level axis at any elevation position (referred to as side to side balance). The
balance about azimuth axis is accomplished by accurately positioning the cross level beam in the azimuth
stabilization assembly. This adjustment is done at the factory using special alignment tools. Do NOT
attempt to adjust the cross level beam position in the field without the proper test fixtures.
7.4.2. 24 VDC Polang Alignment
1
Select the POL TYPE parameter under the MODE/SETUP display and change the POL type
setting to 9 (8+1). Press ANTENNA key 3 times to select the POL display. Rotate the feed using
the UP and DOWN keys so that the feed is in the CENTER of its range and the ports are aligned
Horizontal and Vertical (Align the metal patches horizontally and vertically on an HCDC feed with
the Ku band LNB at 2 o'clock). This is the Center Reference position.
2
Verify the POL display reads 120 +/-10. Adjust the potentiometer on the feed if necessary to
bring this reading into spec (2.5v for xx96/xx97 systems). Note the display reading as the
Center Reference value.
3
Rotate the feed CW 90 degrees viewed looking towards the satellite (CCW looking into the dish)
by pressing the UP key. The display reading must have INCREASED. Record the change in
the POL display reading from the Center Reference value. The change must be 60 or 90. If it
is any other value, there is a problem with the Polang potentiometer scale settings and should
be corrected for proper operation.
4
Rotate the feed CCW 180 degrees or as far as it will travel, viewed looking towards the satellite
(CW looking into the dish). If the feed allows full 180-degree rotation, the POL display will show
60 or 90 counts below the center reference value. Enter this value as the POL OFFSET
parameter and the value recorded in step 3 as the POL SCALE parameter under the
MODE/SETUP window.
NOTE : If the feed does not allow a full 180 degree rotation to the CCW position, (CW looking into