Sea Tel 4012 Quick Start Manual Download Page 2

Field Service Procedure – Replacement Pol Pot Kit, 4012 

 

Page

 

1

 

of

 

16

 

 

Document No 

136829 Rev A

 

Copyright © Sea Tel, Inc 2012 - The information contained in this document is proprietary to Sea 
Tel, Inc.  This document may not be reproduced or distributed in any form without prior written 

consent of Sea Tel, Inc.  

 

 

1.

 

Brief

 

Summary:

   

Troubleshooting

 

document

 

for

 

diagnosing

 

a

 

fault

 

with

 

and

 

replacing

 

the

 

pol

 

pot

 

on

 

the

 

4012

 

antenna.

   

2.

 

Checklist:

   

 

 

Verify

 

Range

 

of

 

Motion

  

 

Verify

 

Pot

 

Feedback

  

 

Measure

 

Resistance

  

3.

 

Theory

 

of

 

Operation:

   

A

 

polang

 

potentiometer

 

is

 

used

 

to

 

provide

 

a

 

feedback

 

reference

 

for

 

the

 

position

 

of

 

the

 

feed

 

assembly

 

for

 

linear

 

polarization.

 

The

 

pot

 

acts

 

as

 

a

 

potential

 

divider

 

giving

 

an

 

output

 

voltage

 

which

 

varies

 

from

 

0VDC

 

to

 

5VDC

 

throughout

 

the

 

feed

 

assembly’s

 

270

 

degree

 

range

 

of

 

motion.

 

The

 

4012

 

antenna

 

has

 

a

 

phase

 

card

 

installed

 

in

 

the

 

feed

 

horn

 

which

 

will

 

reflect

 

the

 

signal

 

meaning

 

for

 

each

 

0.5

 

degree

 

of

 

physical

 

rotation

 

of

 

the

 

feed

 

the

 

change

 

in

 

signal

 

will

 

be

 

1.0

 

degree

 

meaning

 

that

 

the

 

feed

 

assembly

 

of

 

the

 

4012

 

antenna

 

only

 

has

 

to

 

physically

 

drive

 

135

 

degrees

 

to

 

view

 

the

 

full

 

270

 

degrees

 

of

 

rotation.

     

The

 

ICU

 

converts

 

the

 

voltage

 

output

 

from

 

the

 

pot

 

into

 

the

 

numerical

 

value

 

to

 

align

 

the

 

feed

 

in

 

the

 

required

 

position

 

based

 

on

 

the

 

vessels

 

GPS

 

location

 

and

 

the

 

look

 

angle

 

to

 

the

 

required

 

satellite.

 

A

 

failure

 

with

 

the

 

pot

 

will

 

cause

 

it

 

to

 

output

 

an

 

incorrect

 

voltage

 

will

 

result

 

in

 

the

 

feed

 

assembly

 

not

 

being

 

aligned

 

correctly

 

causing

 

bad

 

cross

 

pol

 

isolation.

 

One

 

indication

 

that

 

there

 

is

 

a

 

fault

 

with

 

the

 

feed

 

alignment

 

of

 

the

 

system

 

is

 

that

 

the

 

target

 

light

 

will

 

be

 

permanently

 

illuminated

 

on

 

the

 

MXP

 

and

 

that

 

the

 

antenna

 

won’t

 

target

 

correctly.

 

It

 

will

 

sit

 

8

 

degrees

 

above

 

(or

 

8

 

degrees

 

below

 

at

 

high

 

elevation

 

look

 

angles)

 

the

 

satellites

 

elevation

 

look

 

angle.

 

As

 

part

 

of

 

the

 

antennas

 

targeting

 

procedure

 

the

 

system

 

will

 

target

 

8

 

degrees

 

above

 

(or

 

8

 

degrees

 

below

 

at

 

high

 

elevation

 

look

 

angles)

 

the

 

satellite,

 

calculate

 

the

 

auto

 

threshold

 

setting

 

based

 

on

 

the

 

noise

 

floor

 

level

 

and

 

then

 

align

 

the

 

feed

 

for

 

the

 

correct

 

reception

 

position

 

based

 

on

 

the

 

vessels

 

GPS

 

location

 

and

 

the

 

lookup

 

table.

 

If

 

the

 

system

 

is

 

unable

 

to

 

drive

 

the

 

pol

 

motor

 

to

 

obtain

 

the

 

correct

 

feedback,

 

or

 

if

 

the

 

pot

 

has

 

failed

 

and

 

won’t

 

give

 

the

 

correct

 

feedback,

 

the

 

antenna

 

can’t

 

complete

 

the

 

target

 

process

 

and

 

the

 

antenna

 

will

 

stay

 

in

 

this

 

position.

 

Setting

 

the

 

pol

 

setting

 

to

 

manual

 

will

 

make

 

the

 

antenna

 

target

 

by

 

removing

 

the

 

automatic

 

function

 

from

 

the

 

targeting

 

process;

 

however

 

the

 

miss

 

alignment

 

of

 

the

 

feed

 

will

 

cause

 

bad

 

cross

 

pol

 

isolation.

      

 

 

Summary of Contents for 4012

Page 1: ......

Page 2: ...nto the numerical value to align the feed in the required position based on the vessels GPS location and the look angle to the required satellite A failure with the pot will cause it to output an incorrect voltage will result in the feed assembly not being aligned correctly causing bad cross pol isolation One indication that there is a fault with the feed alignment of the system is that the target...

Page 3: ...hroughout its range This will also verify if the pol motor is driving correctly Log into the MXP and from the configuration menu select the Reflector page from the configuration section and verify the polang drive option is set to Automatic Now select the Position Antenna screen from the tools window and configure the satellite settings as follows Longitude Enter the longitudinal value of your cur...

Page 4: ...s issued the function of the 24VDC polang motor should be verified as per section 7 of this document 5 Verify the Feed Assemblies Range of Motion To verify if the 4012 antennas polarity function is calibrated correctly refer to section 3 of this document Once verified that the pot is calibrated the next step will be to verify that the system has the full range of motion 135 degrees of physical rot...

Page 5: ...shown above 3 Now enter into the value 00 0 into the linear window of the polang target option and press the enter key on the keyboard The feed horn should rotate 45 0 degrees counter clockwise when viewed from the front of the reflector so that the alignment marks of the phase card in the feed horn are aligned diagonally in a north east position as shown above 4 Now enter into the value 90 0 into...

Page 6: ...se card in the feed horn are aligned diagonally in a north west position as shown above 6 If the system completes all of the above tests than the polang assembly is operating correctly Set the antenna back into automatic polang mode by entering into the Reflector screen under the configuration options and set the polang drive mode to Automatic and click the save button The antenna will now automat...

Page 7: ...op Now measure the resistance between the slider and the CCW contact grey cable pin 2 on the IDC connector and the red cable pin 3 on the IDC connector The feedback should be approximately 5k ohms Now slowly rotate the shaft of the pot counter clockwise the reading should count down sequentially After one and a half turns the pot will be in the center of its range giving a resistance of approximat...

Page 8: ...replacing If no voltage is present verify the connections of the reflector harness by measuring pin to pin as per the below diagram If the harness connections are good then the ICU main PCB isn t outputting the voltage to drive the motor and needs replacing As long as the pol range is within the pot limits the ICU will issue the voltage to drive the motor based on the antenna targeting a change in...

Page 9: ...242 8 2 Procedure Procedure for replacing the pol pot Sea Tel kit part number 136741 pol pot part number 115425 6 Caution Power down the pedestal before following this procedure 1 Using a 2 5mm Allen wrench remove the four screws securing the feed horn to the front of the reflector and remove the feed horn Save the hardware for futures use 2 Disconnect the military spec connector from its socket t...

Page 10: ...any form without prior written consent of Sea Tel Inc 4 Snip the cable tie securing the RF cage harness to the mounting plate 5 Disconnect the pol pot pol motor and optical switch IDC connections from the termination block on the 6 Disconnect the orange coax cable from the X Pol LNB 7 Disconnect the yellow coax cable from the Co Pol LNB mounted on the underside of the RF cage 8 Snip the cable tie ...

Page 11: ...de of the RF cage 10 Disconnect the TX IF coax cable from the BUC 11 Unwind the harness from around the RF cage and set it over the cross level beam to allow removal of the RF cage from the rear of the reflector 12 Using a 17mm wrench remove the four mounting nuts and washers securing the RF cage from the back of the reflector Save the hardware for future use 13 Support the weight of the RF cage w...

Page 12: ... 4mm Allen wrench remove the 5 screws securing the bracket to the RF cage Save the hardware for future use Note The four 3mm screws do not need to be removed to gain access to the pol pot 16 Remove the bracket along with the Co Pol LNB as a complete assembly to allow access to the pol pot assembly 17 Using a 3mm Allen wrench loosed the pol motor screws enough to allow the backlash gear to be disen...

Page 13: ...e feed motor pot gears 23 Connect your multi meter and measure the resistance across the red and grey wire connections in the IDC connector Using needle point probes or wires inserted into the IDC connector pins 24 Set the multi meter to Ohms Resistance function 25 The picture to the right is the view looking down on the assembly You will rotate the feed throat by hand as needed to align the 2 ali...

Page 14: ... aligned If correct this completes calibration of the assembly 32 Route the pot wires throught the RF cage where they will not be pinched when re installing the side bracket and install the harnesses back into the wrap removed is step 18 33 Flip the RF cage over to expose the pol motor backlash gear 34 Use a small flat blade screwdriver to hold the bottom half of the backlash gear steady while rot...

Page 15: ...stalling the RF cage ensure that it is oriented correctly so that the alignment pin on the left side of the reflector will locate into the hole on the back of the RF cage In this orientation the X Pol LNB will be on the right of the RF cage 39 Using the hardware removed in step 12 secure the RF cage to the rear of the reflector using a 17mm wrench Apply Loctite 242 to the threads 40 Route the harn...

Page 16: ...nd connect it to the BUC 46 Sit the upper bracket on top of the RF cage and reconnect the IDC connectors with the 4 pin sensor connector on the left the 5 pin pot connector in the center and the 2 pin motor connector on the right as shown in the image on the right 47 Secure the pot motor and sensor harness to the underside of the upper bracket using a cable tie 48 Using the hardware removed in ste...

Page 17: ...e 242 to the threads Note The feed horn has alignment pins located in it to so it can only be installed with the phase card in the correct orientation Verify these are in the correct position when installing 51 Access the configuration reflector page to adjust the linear offset value by the amount of change in skew Example The amount of change in skew was 2 degrees so you need to add that amount t...

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