AvL Technologies 1278K User manual

AvL TECHNOLOGIES
Operation and Maintenance Manual
MODEL 1278K Mobile VSAT Antenna System
Contents Subject to Change
Rev 0, February 2006
900-017-001-A
©Copyright 2006
No part of this document may be photocopied or otherwise
reproduced without the prior permission in writing of
AvL Technologies, Inc.. Such written permission must
also be obtained before any part of this document is stored
in an electronic system of whatever nature

Model 1278K Mobile VSAT Antenna System 2 Operation and Maintenance Manual
TABLE OF CONTENTS
SECTION 1 - OVERVIEW PAGE
1.1 Technical Description 2
1.2 Specifications 3
SECTION 2 - INSTALLATION AND SETUP
2.1 General 5
2.2 Installation to Vehicle 5
2.3 Controller Operating Instructions 6
SECTION 3 - AZIMUTH POSITIONING SYSTEM
3.1 Azimuth Bearing 9
3.2 Azimuth Gear Box 9
3.3 Azimuth Motor 9
3.4 Azimuth AvL Cable Drive 10
3.5 Azimuth Position Feedback 11
3.6 Azimuth Stow Switch 11
SECTION 4 - ELEVATION POSITIONING SYSTEM
4.1 Elevation Pivot Assembly 12
4.2 Elevation Gear Box 12
4.3 Elevation Motor 12
4.4 Elevation AvL Cable Drive 12
4.5 Elevation Position Feedback 13
4.6 Elevation Stow Switch 13
SECTION 5 - POLARIZATION POSITIONING SYSTEM
5.1 General 14
5.2 Feed 14
5.3 Polarization Drive 14
5.4 Polarization Position Potentiometer 14
5.5 Polarization Limits 15
5.6 Feed Assembly 15
SECTION 6 - ANNUAL INSPECTION AND MAINTENANCE
6.1 General 16
6.2 Annual Inspection 16
6.3 Replacement Parts List 17
SECTION 7 - INTERFACE DRAWING 18
TracStar Controller Operating Instructions Accompanying Disk

Model 1278K Mobile VSAT Antenna System 3 Operation and Maintenance Manual
SECTION 1 — OVERVIEW
TECHNICAL DESCRIPTION
The Model 1278K Mobile VSAT Antenna System is a three axis positioner featuring the simple,
rugged AvL cable drive system which produces very low backlash, high-stiffness and high-reliability
when driven by a low backlash, gear box with DC motors. All drive components are high-strength
steel, housed in lubricated-for-life housings, which results in the most reliable, no maintenance, stiff
system with the minimum of weight. The polarization drive rotates the feed assembly +/95° with
lightweight gear motor. A 20 lb. (9kg) HPA may be located on the feed boom.
AvL CABLE DRIVE SYSTEM
The patented AvL cable drive sytem utilizes highly reliable aircraft control cables in a redundant
configuration to achieve a zero backlash, light-weight, very stiff drive system. It achieves this high-
tech performance using low-tech components by wrapping the cable around the drive capstan
several times before wrapping the larger drive drum. The method used to wrap the capstan results in
a minimum free length of cable. The load in the cable on the main drum is exponentially reduced as it
is wrapped around the drum. Therefore, the total elongation of the cable when under load is
minimized. The AvL Cable Drive system results in stiffness of up to 10 times that of comparable gear
or
harmonic drive systems. The cables are pretensioned and spring loaded at the main drum
attachment point which eliminates backlash at installation and from any cable stretch in the future.
SECONDARY DRIVE SYSTEM
The Az and El AvL cable drive systems are driven by a low backlash worm gear set with a 40:1 ratio.
The factory low backlash of the worm gear set is reduced further by the AvL cable drive ratio resulting
in a lash of only .06 dB seen by the RF system. The gear sets are housed in a sealed housing which
allows the gear set to be continuously lubricated in synthetic oil which maximizes gear efficiency and
minimizes wear.
MOTOR DRIVES
Lightweight, reliable, DC motors with integral gearbox are used for the az, el and pol drives. These
motors were selected because they provide the best torque-to-weight ratio as well as allowing dual
speed operation for slewing and peaking. These motors produce constant torque over the speed
range with no cogging at low speeds, which ensures smooth operation when peaking antenna. The
24V DC design provides current limiting torque control and will allow vehicle battery operation if
necessary.
RF WAVEGUIDE
The positioner is designed so that the up-link BUC can be installed on the feed boom.
CONTROLLER
The TracStar Systems controller is manufactured by TracStar Systems, Inc. an antenna and controller
manufacturer. Complete operating instructions can be found in the TracStar Controller Operating
Instructions included on the accompanying disk.
CONSTRUCTION
Except for the drive components and bearings, all metal components are aluminum or stainless-steel.

Model 1278K Mobile VSAT Antenna System 4 Operation and Maintenance Manual
Model 1278K MOBILE VSAT
1.2M MOTORIZED VEHICULAR MOUNT
Reflector 1.2 Meter
Optics Offset, Prime Focus, .8 f//d
Drive System Patented AvL Cable Drive Positioner
Mount Geometry Elevation over Azimuth
Polarization Rotation of Feed
Electrical RF Receive Transmit
Frequency Range 10.95-12.75 Ghz 13.75-14.5 Ghz
Gain (Midband) 42.0 dBi 43.2 dBi
VSWR 1.30:1 1.30:1
Beamwidth (degrees)
-3 dB 1.4 1.2
-10 dB 2.5 2.1
First Sidelobe Level (Typical) -19 dB -22 dB
Radiation Pattern Compliance FCC §25.209, ITU-R S.528.5
Antenna Noise Temperature 30° K at 30° Elevation
Polarization Linear Orthogonal Standard, Optional Co-pol
Power Handling Capability 40 Watts
Cross Pol Isolation
On-Axis (minimum) 35 dB 35 dB
Off-Axis (within 1 dB BW) 26 dB 28 dB
Off-Axis (peak) 22 dB 25 dB
Feed Port Isolation - TX to Rx 75 dB
Satellite System Compliance FCC and PanAmSat Worldwide
Controllers
Optional Upgrades
Auto-acquisition One-button acquisition of selected satellite including
peaking and optimization of cross pol (certified for auto-
commissioning on most satellite services)
Size Single Rack Unit for Auto-acquisition
Input Power 110/240 VAC, 1 ph, 50/60 Hz, 6/3A peak, 1A continuous
Reflector Options
Reflector Back Cover
Mechanical
Az/El Drive System Patented AvL Cable Drive System
Polarization Drive System Stainless Steel Chain Drive
Reflector Material Glass Reinforced Plastics
Travel
Azimuth 400°
Elevation True elevation readout from calibrated inclinometer
Mechanical 0° to 90° of reflector boresight
Electrical Standard limits at 5° to 65° (CE Approval) or 5° to 90°
Polarization ±95°
Speed
Slewing/Deploying 2°/second
Peaking 0.2°/second

Model 1278K Mobile VSAT Antenna System 5 Operation and Maintenance Manual
Motors 24V DC Variable Speed, Constant Torque
RF Interface
BUC Mounting Feed Boom
Waveguide Grove Flexible Waveguide From Feed
Coax 2-RG59 run from feed to base plus 25 ft. (8 m)
Electrical Interface 25 ft. (8 m) Cable with Connectors for Controller
Manual Drive Handcrank on Az and El Axii
Weight 115 to 125 lbs. (52 to 57 kg) depending on options selected
Stowed Dimensions 74 L x 49 W x 17 H inches (188 L x 125 W x 43 H cm)
Environmental
Wind
Survival
Deployed 65 mph (121 kmph)
Stowed 80 mph (161 kmph)
Operational 45 mph ( 72 kmph)
Pointing Loss in Wind
20 mph (32 kmph) 0.5 dB Typical
30 Gusting to 45 mph (48 to 72 kmph) 1.0 dB Typical
Temperature
Operational ±5° to 125°F (-15° to 52° C)
Survival -40° to 140°F (-40° to 60° C)

Model 1278K Mobile VSAT Antenna System 6 Operation and Maintenance Manual
SECTION 2 — INSTALLATION AND SET-UP Model 1278K K Mobile VSAT
2.1 GENERAL
The AvL Model 1278K Mobile VSAT positioner has been fully
tested with the TracStar Systems controller prior to shipment.
All position feedback, limit sensing, limit switches and motor
speeds have been calibrated or set. The positioner needs only
to be deployed and the coax and control cables connected to
the controller.
1. Model 1278K Mobile VSAT shown in stowed position.
(Figure 2. 1)
2. Connecting the coax cable first, make the appropriate electrical connections. (Figure 2.2.)
3. Press “+” on TracStar hand-held controller and hold for 3
seconds until unit begins deploying.
Figure 2. 3 shows the unit fully deployed.
2.2 INSTALLATION TO VEHICLE
The 1278K Mobile VSAT positioner is attached to a base plate and rail assembly, that can be mounted to
a variety of different vehicle configurations. Angle clips are furnished with positioner unit to allow unit to
be mounted to vehicle rack system provided by customer. ( See Interface drawing.)
Figure 2.1
Figure 2.2
Figure 2.3

Model 1278K Mobile VSAT Antenna System 7 Operation and Maintenance Manual
2.3 CONTROLLER OPERATING INSTRUCTIONS
The TracStar Systems controller applies advanced motor control capability in a cost effective controller.
The controller is configured to require only two commands – Deploy and Stow. When the controller
receives the Deploy command the antenna is raised to a preset elevation angle where it scans in
azimuth until approximate southern direction is determined. It then pauses to collect GPS information of
latitude and longitude. It quickly calculates az, el and pol angles to North Star satellite. It scans in
anticipated direction of North Star satellite until it is found. This usually takes less than one minute. It
verifies it has found the North Star satellite, and then peaks up on signal. Once the North Star satellite is
determined the satellite of service az, el and pol angles are calculated from North Star satellite including
accommodating for any tilt in the vehicle. The controller then precisely commands the antenna to the
satellite of service.
1.1 To activate system, turn on power to the TracStar Systems In-Door Unit (IDB)
1.2 The display should read “Ready”. Press the + key to begin a satellite acquisition. To Stow the
antenna, press and hold the “-“ key for 3 seconds. There will be a 3 second delay before the
antenna begins to stow to ensure that transmit is disabled.
1.3 If at any time, either during an acquisition (Display reads “Run”), while locked or during a stowing
operation (Display reads “Stow”), the user may stop the motion by pressing the Start/Stop, + or –
key.
Controller Quick Start Guide
Deploy:
1. From the READY screen, press “+”.
2. The antenna will move to the deploy position.
3. If the reflector is removable, the controller will display COMPASS DISH ERROR.
4. Install the reflector, feed and cables as required, and press “+” again.
Auto-Acquisition: The antenna will now begin the acquisition cycle. The antenna will step through the
following sequence:
Determine direction of south
Get GPS data
Locate reference satellite
Peak on reference satellite
Locate data satellite
Peak on data satellite
When complete, the display will indicate “LOCK ON xxx” where ‘xxx’ is the longitude of the data satellite.
Stow:
1. From the READY screen, press “-”.
2. The antenna will move to the reflector removal position and display REMOVE REFLECTOR.
3. Remove the reflector and feed as required, and press “-” again.
4. The antenna will move to the stow position.

Model 1278K Mobile VSAT Antenna System 8 Operation and Maintenance Manual
Change Polarization:
Setting the POLARITY (horizontal or vertical downlink):
1. From the READY screen, press “÷” three times to move to the POLARITY screen.
2. The blinking cursor will be over “HorzDN” or “VertDN”.
2.1 Press “+” to change the downlink polarity from H to V.
2.2 Press “ENTER” to save the value.
Changing the REF Satellite: (In case of blockage of pre-programmed REF satellite)
1. From the READY screen, press “÷” once to move to the “REF satellite screen”.
2. The blinking cursor will be over the primary REF satellite’s Xd longitude.
3. Press “+” to scroll through the list of REF satellites.
4. Press “ENTER” to save the newly selected REF satellite. (Blinking cursor moves to the secondary
REF satellite’s Yd longitude.)
5. Press “+” to scroll through the list of REF satellites.
6. Press “ENTER” to save the second newly selected REF satellite.
Jogging the Antenna:
1. From the READY screen, press “MAIN” once to reach the USER SETUP screen.
2. From the USER SETUP screen press “÷” once to move to JOG.
3. Press “ENTER” to move the cursor to the speed item FAST or SLOW.
4. Press “+” to change from FAST to SLOW as desired.
5. Press “ENTER” to move the cursor to the desired axis (A is AZ, E is elevation, P is pol).
6. Press START/STOP button to activate the motors. (The “jog” displayed in the upper left will change
to upper case.)
7. Press “+” or “-“ to move the axis one unit. (One unit in FAST is 1.0 degrees and one unit in SLOW
is 0.2 degrees.)
8. Press and hold “+” or “-“ to move the axis continuously. (“+” moves AZ clockwise as view from the
top, EL up and POL clockwise as viewed from behind the reflector.)
9. The index displayed next to each axis counts up or down 1 unit each time the “+” or “-“ is pressed.
If the index reaches 99 or –99, the axis will not move any further. Press START/STOP button twice
to reset the index.
Note: The controller will automatically acquire the either Satellite A or Satellite B depending upon which is
selected in step 2 above.
THE FOLLOWING FUNCTIONS ( * ) REQUIRE A CHANGE IN PASSWORD (CODE 13) IN THE TracStar
Systems CONTROLLER:
1. From the READY screen, press “MAIN” twice to get TECH SET UP screen.
2. Press the “+” button until it reads 13 and then press “ENTER” to save the code.
3. Press “MAIN” once to get back to the READY screen.

Model 1278K Mobile VSAT Antenna System 9 Operation and Maintenance Manual
* Changing the DATA satellite *:
1. From the READY screen, press “ ÷” twice to move to the “DATA satellite” screen.
2. The blinking cursor will be over “SatA/SatB”.
2.1 Press “+” to change the DATA satellite from A to B.
3. Press “ENTER” to move the blinking cursor to “Satellite A”.
3.1 Press “+” or “-“ to change the longitude value for DATA satellite A.
3.2 Press “ENTER” to save the value.
4. Press “ENTER” to move the blinking cursor to “Satellite B.
4.1 Press “+” or “-“ to change the longitude value for DATA satellite B.
4.2 Press “ENTER” to save the value.
* Manual GPS Entry (This can be used if the automatic GPS system fails):
1. From the READY screen, press “MAIN” four times to reach the GPS screen.
2. The blinking cursor will be over NORMAL.
3. Press “+” to change to MAN.
4. Press “ENTER” to save the value.
5. Press “+” until the desired latitude is displayed.
6. Press “ENTER” to save the value and move to the LONG item.
7. Press “+” until the desired longitude is displayed.
8. Press “ENTER” to save the value.
* Manual Compass Entry (This can be used if the automatic compass system fails):
1. From the READY screen, press “MAIN” five times to reach the “COMPASS” screen.
2. The blinking cursor will be over “NORMAL”.
3. Press “+” to change to MAN.
4. Press “ENTER” to save the value.
5. Either jog the AZ or physically move the entire antenna to point approximately south.
6. Press “”MAIN”” to return to the READY screen.
Complete operating instructions will be found in the TES75 and TES960 controller manual.

Model 1278K Mobile VSAT Antenna System 10 Operation and Maintenance Manual
SECTION 3 - AZIMUTH POSITIONING SYSTEM
3,1 AZIMUTH BEARING
The azimuth platform sits on top of a ball bearing platform with a dynamic and static moment capacity of
over four times the worst-case wind load specification. It is surrounded by double seal to protect the
bearing platform, which is permanently lubricated. This rests on the azimuth drum and the azimuth cables
wrap around the drum and capstan.
Because of the excess capacity, low rpm, and low number of cycles compared to the bearings B10 design
life, no wear is expected. No maintenance should be required over the life of the positioner.
3.2 AZIMUTH GEAR BOX
The azimuth gearbox is a low backlash worm gear box. The
worm gear drive isolates any backlash in the motor drive from
the system. In addition, since it is a 40:1 ratio it will not back
drive, eliminating any need for a brake on the drive train. (Fig.
3.1)
The motor drives the input worm via a quill/female hole and
square key. The worm shaft is extended with a hex shape
installed for the hand crank. The azimuth capstan is secured to
the output shaft with a square key knurl plus permanent
locktite to eliminate any backlash between the capstan and
gearbox.
The low backlash is achieved by selective fit of the worm and worm gear. The nominal backlash for the
gearbox is 30’ which is reduced by the AvL cable drive to less than 4’of the beam of the antenna. The
gearbox contains synthetic oil filled half way to the level plugs. Because of the design capacity of the
gearbox, low rpm and limited cycles experienced by the system, no maintenance is required.
3.3 AZIMUTH MOTOR
The azimuth drive motor is a 24 DC motor with integral 30:1 spur gear train. An optical encoder is mounted
to other end of motor output shaft to provide real time positional information to TracStar Systems
controller.
The motor armature rotates at up to 3000 rpm causing a high frequency noise that will vary depending of
the loading condition of the motor.
The maximum output speed is 100 rpm. The output shaft is "D" shaped with a special adapter with a slot
for a square key.
Since the low backlash worm gear drive isolates the backlash from the motor, any backlash between the
shaft adapter, square key or motor gear train will not be seen by the reflector bore sight. The motor is
mounted to an adapter plate that is bolted to gearbox with (4) screws.
No maintenance of the azimuth motor is required.
Figure 3.1

Model 1278K Mobile VSAT Antenna System 11 Operation and Maintenance Manual
Figure 3.2
3.4 AZIMUTH AvL CABLE DRIVE
The patented azimuth AvL cable drive produces a drive
system with zero backlash high stiffness, no wear, no
lubrication, and maximum reliability. The system
consists of three 5/64 7x19 stainless steel aircraft
control cables reverse wrapped twice around the
grooved capstan (Figure 3.2) and once around the
drum, with solid connections on one end and high force
Belleville springs on the other end. One cable has the
capacity to withstand a 80mph wind load. The
additional cables are used to provided increased
stiffness and drive redundancy. If a cable becomes
damaged during usage, cut off cable and continue
to use positioner. Replace cable when time
permits at your maintenance facility.
The cables are sized to last the life of the
positioner. No replacement from wear is expected. The springs package at one end will
automatically compensate for any elongation of the cable.
Cable position should be checked as per periodic maintenance schedule in Section 7. If cables have
drifted, manually move cables using blunt instrument on azimuth drum until correct position is obtained.
(Figure 3.2)
At installation, the Belleville springs are collapsed until no “air” is seen
between the springs. (Figure 3.3) You should check this condition yearly
to account for the slow settling of the cable strands. Use 3/8 box-end
wrench to tighten the nut. Be sure not to over tighten.
Figure 3.3

Model 1278K Mobile VSAT Antenna System 12 Operation and Maintenance Manual
3.5 AZIMUTH POSITION FEEDBACK
The azimuth position feedback is produced by a 10 turn, 1K-ohm potentiometer driven by the output shaft
of the worm gear box. (Fig 3.1) Since the AvL cable drive has no backlash, the position feedback is as
accurate (1%) as the resolution (.3°) and accuracy of the potentiometer and the backlash between the
potentiometer and the azimuth capstan. The potentiometer is sealed and rated for IP 65 environment -
wind, rain, dust, etc. In addition, a optical encoder mounted to output shaft on motor and provides
redundant feedback on azimuth position. Since the AvL cable drive has no backlash, the position feedback
is as accurate as the resolution and accuracy of the potentiometer, encoder and the backlash between the
potentiometer and the output shaft of the worm gear box.
The potentiometer is mounted on a bracket that straddles the az gear box. The azimuth potentiometer is
slotted and driven with a cross pin in the az capstan. The potentiometer is mechanically centered at the
travel position (5 turns from either end) when az platform is in the az stow position. This is accomplished
by loosening the 1/2” nut, which secures the potentiometer to the bracket. The controller may also
electrically zero the potentiometer. The limits are controlled by using inputs from the potentiometer and
optical encoder together and are set in and controlled by the TracStar Systems controller.
The AvL has the mechanical capability of ±400º or ±200º from stow position.
3.6 AZIMUTH STOW SWITCH
The TracStar System controller uses the az potentiometer voltage
to determine limits. Therefore, the AvL positioner is equipped with
only an azimuth stow position switch. Limit switch
mounting holes are provided if needed for other brand controllers.
The azimuth stow switch is mounted on the azimuth platform
accessible from under az/el cover. (Fig 3.4) The switch is fixed
relative to the mounting surface and is actuated by magnet located
on the azimuth bearing clamp ring.
Since the controller drives to 0° az after sensing the stow switch,
the az stow position can be varied by either changing the zero
position of the az potentiometer or zero voltage of the controller.
Rotation Direction Convention : + is clockwise (CW) viewed from above mount. - is counter clockwise
(CCW) viewed from above mount.
NOMINAL AZIMUTH LIMITS
Model 1278K Mobile VSAT (With 400° AZ ) +210° / -190°
Notes:
1) The limits should be set after the potentiometer has been centered as described above. If the
potentiometer is moved from this position, the limits should be reset.
2) The az angle displayed by the controller is affected by several parameters in the controller. (These
include az Scale Factor, az Reference Position).
3) While setting the limits, watch the az capstan to make sure it does not run into the spring block at the
end of the cables.
4) The angles at the limits in the chart shown above are for nominal values of these parameters, and the
values actually displayed by the controller at the limits may vary.
Figure 3.4

Model 1278K Mobile VSAT Antenna System 13 Operation and Maintenance Manual
SECTION 4 — ELEVATION POSITIONING SYSTEM
4.1 ELEVATION PIVOT ASSEMBLY
The elevation pivot assembly consists of two elevation drum assemblies pivoting between two clevis blades
assemblies. The drum shafts pivot in hi-tech plastic bushings. No maintenance is required. If squeaking
noise is heard, simply spray silicone lubricant with “straw” nozzle down between the drum side and clevis
plate on to the pivot shaft.
4.2 ELEVATION GEAR BOX
The elevation gearbox is a low backlash (30’) worm gear box. The worm gear drive isolates any backlash
in the motor drive from the system. In addition, since it is a 40:1 ratio it will not back drive, eliminating any
need for a brake on the drive train.
The motor drives the input worm via a quill/female hole and square key. The worm shaft is extended with a
hex shape adapter for the hand crank. The dual elevation capstans are driven with a square key and
clamped to the gearbox shaft to eliminate backlash.
The gearbox contains synthetic oil filled half way to the level plugs. Because of the design capacity of the
gearbox, low rpm and limited cycles, no maintenance is required.
4.3 ELEVATION MOTOR
The elevation drive motor is a 24V DC motor with integral 32:1
spur gear train. The motor armature rotates at up to 3300 rpm
causing a high frequency noise that will vary depending of the
loading condition of the motor. (Fig. 4.1) An optical encoder is
mounted to other end of motor output shaft to provide real time
positional information to TracStar Systems controller.
The maximum output speed is 104 rpm. The output shaft is a
standard keyed shaft. The output torque capacity of the motor is
rated for the operational wind load.
Since the low backlash worm gear drive, isolates the backlash
from the motor, any backlash between the square key and motor
gear train will not be seen by the reflector bore sight. No
maintenance of elevation motor is required.
4.4 ELEVATION AvL CABLE DRIVE
The patented elevation AvL cable drive produces a zero backlash, high stiffness, no wear, no lubrication,
and drive system with maximum reliability. The system consists of 12 1/16, 7x19 stainless steel aircraft
control cables reverse wrapped three times around the capstan with solid connections on one end and
high force, Belleville springs on the other end. Eight cables have the capacity to withstand a 75 mph wind
load. The additional cables are used to provided increased stiffness and drive redundancy. If a cable
becomes damaged during usage, cut off cable and continue to use positioner. Replace cable
when time permits at your maintenance facility.
The cables are sized to last the life of the positioner. The springs will automatically compensate for any
elongation of the cable.
Figure 4.1

Model 1278K Mobile VSAT Antenna System 14 Operation and Maintenance Manual
Figure 4.2
The position should be checked per the periodic maintenance schedule in Section 6. If the cables have
drifted, manually move cables using blunt instrument on elevation drums until correct position is obtained.
At installation the Belleville springs are collapsed until no "air" is seen between the springs. You should
check this condition yearly to account for the slow settling of the cable strands. Use pliers to hold stud
and 1/4 box end wrench to tighten nut. Be sure not to over tighten. Tighten until springs are almost
fully collapsed.
4.5 ELEVATION POSITION FEEDBACK
The elevation position feedback is produced by an electronic inclinometer and encoder mounted on output
shaft of motor. Since the AvL cable drive has no backlash, the position feedback is as accurate as the
resolution and accuracy of the clinometer and encoder. The clinometer has a resolution of 0.1 degrees
with and accuracy/linearity of 1% in the 0-45º range and monotonic in the 45-90º range. The clinometer is
rated for an outdoor environment. The encoder also provides precise feedback on units position during
operation. The limits are controlled by using inputs from the potentiometer and optical encoder together
and are set in and controlled by the TracStar Systems controller.
The clinometer mounted in the pol motor box, which provides
additional weather protection. (Fig 4.2)
4.6 ELEVATION STOW SWITCH
The elevation stow, the east elevation pivot assemblies under
the drum. (Fig 4.1) The switch is fixed to pivot wall and are
actuated by a cam profile machined into the drum side plates.
The elevation stow switch is adjusted by using needle nose
pliers and bending the limit switch lever as needed.

Model 1278K Mobile VSAT Antenna System 15 Operation and Maintenance Manual
SECTION 5— FEED AND POLARIZATION POSITIONING SYSTEM
5.1 GENERAL
The Feed assembly consists of feed boom, upper and lower feed brackets, feed housing, RF components
and polarization drive housing. The pivot connection at the end of the feed is made with brash bushings. A
piece of 18" flex wave-guide is used at the end of the wave-guide tube to the OMT and connects to the
BUC. The chain drive assembly and 12V DC motor rotate the feed/OMT. Position feedback is from a 10-
turn potentiometer.
5.2 FEED
The feed assembly consists of an inclinometer, feed horn and OMT with male pivot bushings. The male
bushings pivot in delrin female bushings at each end of the OMT. These bushings are mounted to
mounting plate. The pol drive sprocket attaches to the OMT and the wave-guide attaches to other end
with M6 screws at the rear flange of the OMT. The feed/polarization drive is mounted underneath pol
mounting plate in feed box with gear on outside and driving pol sprocket to rotate feed.
5.3 POLARIZATION DRIVE
The feed/polarization drive is mounted underneath pol mounting plate in the pol drive box with a drive
sprocket mating to the motor shaft, which extends through the feed drive box. The polarization drive
motor) is a 12 VDC gear motor. Small gear is attached to the end of the motor shaft, that drives small gear
to drive the position potentiometer. The controller travel limits are +/- 95 degrees for a 2 port. See
TracStar Systems Controller Manual section 3.3).
If the chain becomes loose, re-tighten wire at chain joint. No maintenance of the polarization
motor/assembly is required.
The polarization drive is replaced by a complete unit including the motor, motor sprocket /gear, chain,
elevation inclinometer, potentiometer and gear, and drive sprocket.
5.4 POLARIZATION POSITION POTENTIOMETER
The polarization feedback is produced by a 10 turn, 1K-ohm potentiometer driven by the motor gear, and
mounted in the feed box and shaft extends outside the box. The resolution and accuracy is 0.3 degrees.
The potentiometer is rated for IP 65 environment, wind, rain, and dust, etc. The potentiometer is
mechanically set at the one-half travel position, ( 5 turns from either end) and will read approximately
500ohms at 0 degrees pol (stow). The potentiometer may be set using the controller the voltage reading
pol stow will read 2.5V at 0 degrees. See TracStar Systems Controller Operating Instructions included on
the accompanying disk.

Model 1278K Mobile VSAT Antenna System 16 Operation and Maintenance Manual
5.5 POLARIZATION LIMITS
TracStar Systems Controller uses the polarization potentiometer voltage to determine limits. The
controller drives to 0° pol when it stows. The AvL positioner has the mechanical capability of +/-92.5
degrees per section 3.3 of the TracStar Systems Controller Manual. If the Controller Fails to terminate
power to the motor and the system is driven to a hard limit stop, the DC motor will stall. To correct, reset
the pol jam error in the controller.
5.6 FEED ASSEMBLY
The feed assembly consists of the feed, the polarization drive, and the polarization potentiometer. The
elevation inclinometer is also mounted on the inside of feed motor drive box.
The feed assembly is installed as a complete unit and secured to lower feed bracket. (Fig. 5.1) The feed
horn is mechanically positioned with a template within 1/8" of the theoretical focal point of the reflector.
This positioning assures the RF System provides the gain and FCC compliance as stated in the
specifications.
Figure 5.1

Model 1278K Mobile VSAT Antenna System 17 Operation and Maintenance Manual
SECTION 6 — MAINTENANCE
6.1 GENERAL
The AvL Model 1278K Mobile VSAT is designed such that any wear should never degrade performance
below specifications and essentially no maintenance will ever be required. However, since it is impossible
to ascertain or test for all possible environments, the following check up is recommended each year. If any
problems are observed, refer to the appropriate section.
6.2 ANNUAL INSPECTION
AZIMUTH
• Check for unusual noise in azimuth bearing and azimuth gearbox, and azimuth motor.
• Run in azimuth and check for unusual noise in azimuth motor.
• Check position of azimuth drive cables on capstan at 0°az
• Check drive cables for damage.
• Run both az limits and observe cable tracking.
• Check for excessive backlash in gearbox.
• Inspect cable terminations.
• Inspect az potentiometer
.
ELEVATION
• Hand crank in elevation - the unit should hand crank easily.
• Unit should hand crank with approximately 50-75 in-lbs. torque.
• Check for unusual noise in elevation pivot bearings and elevation gearbox.
• Run in elevation and check for unusual noise in elevation motor. (Run to limits)
• Check position and tracking of elevation drive cables.
• Check drive cables for damage.
• Check oil level in gearbox.
• Remove backing structure covers and inspect cable terminations. Tighten springs if more than
.010 gap exists between spring sets. Tighten with an open-end 7/16” wrench and using Visegrip
pliers holding stud.
• Inspect elevation limit switches.
POLARIZATION
• Run in polarization and check for unusual noise in polarization gearing or motor.
• Inspect polarization potentiometer.
• Inspect wave-guide for any damage, dents, or cracks.

Model 1278K Mobile VSAT Antenna System 18 Operation and Maintenance Manual
6.3 SPARE / REPLACEMENT PARTS
Since no maintenance is required, only electrical parts are recommended as spares. These parts
will not fail from activity, but may fail from environmental exposure.
Description Manufacture Manufacture Part No.
Limit Switch (Long Arm) Omron D2VW-5L2-1HS
Potentiometer, 1k, 10T ETI MW20B-2982-1K
Clinometers Lucas 02111-002-000
Optional
WR75 Super flex 18" Microtech MTES75-502-N-18B
Elevation Motor Globe 455A888
Azimuth Motor Globe 455A889
Polarization Motor Globe 415A886

Model 1278K Mobile VSAT Antenna System 19 Operation and Maintenance Manual
SECTION 7 - INTERFACE DRAWING

Model 1278K Mobile VSAT Antenna System 20 Operation and Maintenance Manual
SECTION 7 - INTERFACE DRAWING