ATX Larcan MXD5U Operating manual

MXD5U AMPLIFIER
TECHNICAL SERVICE MANUAL
LARCAN INC.
228 AMBASSADOR DRIVE
MISSISSAUGA, ONTARIO
CANADA L5T 2J2
PHONE: [phone]
FAX: [phone]
EMAIL: [email protected]m
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16 April, 2009

MXD5U OPERATIONS AND MAINTENANCE
CONTENTS
1AMPLIFIER ......................................................................................................................................................................1
2CONTROLLER.................................................................................................................................................................2
2.1 CONTROL BOARD ASSEMBLY AND JUMPER SETTINGS ..................................................................................................2
2.2 REMOTE CONTROLS AND THE MXD5U FRONT PANEL ON/OFF BUTTON....................................................................4
2.3 EXTERNAL REMOTE CONTROL CONNECTIONS..............................................................................................................6
2.3.1 Remote Command Inputs.....................................................................................................................................6
2.3.2 Remote Telemetry Outputs...................................................................................................................................6
2.3.3 Remote Status Outputs.........................................................................................................................................7
2.3.4 External1 Interlock ..............................................................................................................................................7
2.4 EXTERNAL TRANSMITTER INTERLOCK .........................................................................................................................8
3AMPLIFIER INSTALLATION AND STARTUP..........................................................................................................9
3.1 BEFORE APPLYING AC TO THE UNIT ............................................................................................................................9
3.2 APPLYING AC TO THE UNIT..........................................................................................................................................9
3.3 BEFORE TURNING THE AMPLIFIER ON .........................................................................................................................9
3.4 AMPLIFIER ON SEQUENCE..........................................................................................................................................10
3.4.1 Turning ON the Amplifier.................................................................................................................................10
4TEST AND TROUBLESHOOTING .............................................................................................................................11
4.1 BENCH TEST PROCEDURES .........................................................................................................................................11
4.1.1 Front-End Module Bench Test Procedure.........................................................................................................11
4.1.2 IPA1 Bench Test Procedure...............................................................................................................................11
4.1.3 Pallet 21B1751 Bench Test Procedure..............................................................................................................11
4.2 BASIC TROUBLESHOOTING TECHNIQUES ....................................................................................................................12
4.2.1 Amplifier Completely OFF.................................................................................................................................12
4.2.2 No RF Output.....................................................................................................................................................12
4.2.3 Output Reduced to 25%.....................................................................................................................................12
5MAINTENANCE.............................................................................................................................................................13
5.1 DAILY.........................................................................................................................................................................13
5.2 MONTHLY...................................................................................................................................................................13
5.3 SEMI-ANNUALLY AND ANNUALLY.............................................................................................................................13
5.4 TRANSMITTER COOLING SYSTEM ...............................................................................................................................13
6TEST EQUIPMENT SETUP..........................................................................................................................................14
7SPECIFICATIONS .........................................................................................................................................................15
7.1 ELECTRICAL ...............................................................................................................................................................15
7.2 ENVIRONMENTAL .......................................................................................................................................................15
7.3 COOLING ....................................................................................................................................................................15
7.4 DIMENSIONS...............................................................................................................................................................15
7.5 SHIPPING WEIGHT ......................................................................................................................................................15
FIGURES
FIGURE 1MXD5U AMPLIFIER HEATSINK ASSEMBLY..................................................................................................................1
FIGURE 2CONTROLLER BOARD....................................................................................................................................................2
FIGURE 3FRONT PANEL ...............................................................................................................................................................2
FIGURE 4REMOTE COMMAND INPUTS..........................................................................................................................................6
FIGURE 5REMOTE TELEMETRY OUTPUTS ....................................................................................................................................6
FIGURE 6REMOTE STATUS OUTPUTS ...........................................................................................................................................7
FIGURE 7REAR PANEL SHOWING INTERLOCK TERMINAL BOARD................................................................................................9
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FIGURE 8TEST EQUIPMENT SETUP.............................................................................................................................................14
FIGURE 9-FRONT END AMPLIFIER,MXD5U.............................................................................................................................16
FIGURE 10 -IPA ASSEMBLY,MXD5U.......................................................................................................................................17
FIGURE 11 -AMPLIFIER PALLET,MXD5U.................................................................................................................................18
FIGURE 12 MXD5U CONTROL BOARD ASSEMBLY ....................................................................................................................19
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MXD5U OPERATIONS AND MAINTENANCE
1 AMPLIFIER
The RF section of the MXD5U Amplifier consists of a heatsink assembly that includes three cascaded broadband
amplifier modules and a directional coupler. Figure 1 shows the layout of this assembly.
Figure 1 MXD5U Amplifier Heatsink Assembly
Also mounted on the heatsink is a thermal switch that protects the amplifier from over temperature conditions.
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2 CONTROLLER
The control board (Assembly 31C1971) is a single-circuit assembly that provides all of the control functions
required for the transmitter on a single circuit board. This board can be configured for a number of different
transmitter types, power levels, transmission standards and options.
Figure 2 Controller Board
The control board provides local front panel interface via ON/OFF and RESET buttons. The board implements
controls/status/telemetry for remote control through a rear panel connector that will interface to a typical remote
control systems (such as Moseley or Gentner). An RS232 serial port is also provided to allow the operator to
access the transmitter through an external computer (with the appropriate software). The control board has RF
detectors for forward and reflected power and all the circuitry to support AGC/VSWR/Cutback functions. Circuitry
to control and monitor the +28V power supply is also included on this board.
Figure 3 Front Panel
2.1 CONTROL BOARD ASSEMBLY AND JUMPER SETTINGS
Figure 9 shows the assembly diagram for the control board (Part No 31C1897A2) that performs all the control,
monitoring, RF detection and communication functions.
There are a number of jumpers on this board that are factory set and should not be altered in the field without
consulting Larcan Technical Services first. Changing the jumper settings may result in improper operation of the
transmitter.
The factory jumper settings are given here in the case that either a jumper is dislodged during shipping or has
been removed for any other reason.
Note: This circuit board is used for a number of transmitter models and a number of components and jumpers are
not installed or used for this transmitter model. We will only detail the jumpers that are used in the MXD5U.
E1 BDM Enable
Allows connection of the BDM program cable to the board
Setting = NORM for all MXD5U transmitters
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E2 Not used in the MXD5U transmitter
Setting = no jumper installed
E3 Not used in the MXD5U transmitter
Setting = no jumper installed
E4 Not installed in this assembly
E5 Front Panel ON/OFF button Mode
This jumper determines the function of the Front Panel ON/OFF button
If E5 is in the ‘INT’ position, Remote ON/OFF Controls are disabled, Local Controls Only
If E5 is in the ‘EXT’ position, Remote ON/OFF Controls are enabled, Local OFF Control Only
More detail on this function is given in Section XX of this manual
Setting = EXT for all MXD5U transmitters
E6 Transmitter Switching Interlock
This may have either a two pin header or may be permanently jumpered with bus wire
If there is a two pin header, then it requires a shorting jumper
If this is not shorted, then the transmitter will not turn ON.
Setting = Jumper installed
E7 Not used in the MXD5U transmitter
Setting = no jumper installed
E8 Not installed in this assembly
E9 Not installed in this assembly
E10 Not installed in this assembly
E11 Forward Power Sample Gain
Sets either High or Low gain from the DC sample received from the RF coupler
Set to obtain a voltage between 4.5 and 8V at TP2 for full power RF output
Can be either in the HI or LO position depending on channel and RF coupler
Typical Setting = LO for most MXD5U transmitters
E12 Not installed in this assembly
E13 Not installed in this assembly
E14 Not installed in this assembly
E15 Reflected Power Sample Gain
Sets either High or Low gain from the DC sample received from the RF coupler
Set to obtain a voltage between 4.5 and 8.0V at TP4 for 10% reflected power
Can be either in the HI or LO position depending on channel and RF coupler
Typical Setting = HI for most MXD5U transmitters
E16 AGC Disable
This jumper disables the AGC circuitry
DO not install this jumper. It is meant for factory setup
Setting = not Installed for all MXD5U transmitters
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E18 Direct Vswr Relay reset from the Remote Reset Command
This jumper allows the Remote Reset Command to directly clear the VSWR trip relay
Setting = Installed for all MXD5U transmitters
E19 Forward Power Detection Type
Setting = PK for all MXD5U transmitters
2.2 POWER CALIBRATION,AGC AND CUTBACK SETUP
HIGH VOLTAGE
RISK OF EXPOSURE TO VOLTAGES UP TO 260VAC
Use particular caution near the power supply’s transformer terminals.
The following setup is for the overall assembly of the MXD5U transmitter. It assumes that all individual
components in the assembly have been tested and biased, including the Control Board, the Amplifier Boards and
the Directional Coupler.
Note that the tests below are factory specific and therefore do not include the use of an Output Mask Filter. If one
is available, it can be inserted and setup performed as described in the procedure, with the following exceptions.
-perform power calibration at the filter output calibrating to a 5W level
-installation and alterations of test loads are done at the filter output, not transmitter RF Output.
PLEASE NOTE SAFETY WARNING ABOVE.
Connect a jumper wire across the terminals of the INT’K (External Interlock) terminal block at the rear panel. This
is temporary and must be removed when tests are completed.
Confirm Amplifier Bias
Terminate RF Out with 50R (min 20W rating). Apply no rf drive.
Turn ON Amplifier at front panel. Check for 28VDC at Amplifiers.
Check Amplifier Bias Currents: Front End Amplifier: 0.2-0.3A, IPA:1A, Amplifier Pallet: 1.0A
Power Calibration
Set R105 completely CCW. Ensure J8 is connected.
Remove all Control board jumpers except;
-E7 and E8 IN
-E2 to RS232
Monitor TP1. Adjust R39 for 0.02VDC.
Apply signal to get full power + filter losses at output. Approx 6W.
Check out-of-band shoulder levels at 6W for the broadcast channel before proceeding.
Set E5 to get 4-8V at TP1. Monitor TP2; adjust R46 for 4.00V.
Adjust R79 for 100% meter reading.
Increase Power to get 110%. Remove E7 and set R73 to get 4.0V on TP3. Meter should again read 100%.
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Turn OFF Amplifier.
VSWR Trip
With Amplifier OFF, install a short length of cable at the RF output, if one is not already there. Add an N-type Tee
connector on the output of the cable. Connect a 50R load on each of the two female connections on the Tee. This
results in a 10dB Return Loss for VSWR setup.
Ensure E8 is installed. Remove J8 temporarily to prevent cutback.
Turn on the Amplifier.
Monitor the Reflected Detect port on the Directional Coupler. Note a voltage in the range of 0.4 to 0.9V.
Remove RF input. Measure TP3 and set R54 (offset) for 0.02VDC.
Apply RF again. Set E6 to get TP3 between 4 and 8VDC.
Monitor TP4. Set R60 for 4.4V.
Install J8 and set R105 (cutback) clockwise to where VSWR condition (LED DS9) clears; Forward power is
between 25% and 40%.
Turn off Transmitter, Connect good load to RF Output again. Turn on Transmitter and check front panel sense
output. Rf Level should be 24-26dB down from the transmitter output level; about 12-14dBm.
Shut off Transmitter. Remove the jumper wire from the INT’K (External Interlock) terminal block at the rear panel.
Performance Checks
Total DC Current Consumption at 6W output: 3.3 to 4.0A.
Shoulder levels: 37dB WRT Barts Head at 6W output, full UHF band.
Restore EXT INTL’K at rear panel as required for end use.
2.3 REMOTE CONTROLS AND THE MXD5U FRONT PANEL ON/OFF BUTTON
The Front Panel ON/OFF button on the transmitter can function in two distinct modes which depends on the
position of jumper E5 on the 31C1897 control board located inside the transmitter chassis. E5 that can be placed
in either of two positions, one labeled ‘INT’ and the other position EXT.
When the jumper E5 is in position INT, then the transmitter will ignore any ON or OFF remote controls. This
remote controls can either come from the serial communication program or from the external remote control
connector on the rear of the transmitter chassis. Please note that only the ON and OFF remote controls are
disabled and the AGC raise/lower and Vswr reset commands will still be operational. In this mode the transmitter
can only be turned ON or OFF via the front panel button. This is mostly for maintenance purposes when the
technician is working on the transmitter and doesn’t want anyone to remotely turn it ON or OFF.
When jumper E5 is in the EXT position then remote controls are enabled, this is the normal factory setting as
shipped. Even when E5 is in the ‘EXT’ position, the front panel button will still shut the transmitter OFF if it is
placed in the OFF position but when the front panel button is pressed in then the remote ON/OFF controls are
enabled. The transmitter records the last known requested ON/OFF state from the remote control and will cause
the transmitter to enter into that state. If the operator last issued a remote OFF command then the remote state of
the transmitter would be OFF and if the operator last issued an ON command then the remote state of the
transmitter would be OFF. This is done to insure that when remote control is enabled and an AC power failure
occurs, then upon restoration of AC power the transmitter will return to the ON/OFF state is was in prior to the AC
power failure. This is necessary since the remote ON/OFF commands are momentary closures and are not
present all the time.
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2.4
2.4.1
EXTERNAL REMOTE CONTROL CONNECTIONS
External remote controls are intended to interfacing to a third party remote control vendor such as Moseley or
Gentner if such systems are installed or available at the transmitter site. These external controls function in
parallel with the serial remote commands implemented with the Larcan supplied remote control program.
These remote signals are available on the 15-pin D-connector labeled Telemetry on the rear panel of the MXD5U
transmitter. The remote controls can be broken down into four categories, control inputs, status outputs,
telemetry outputs and interlock as follows:
Remote Command Inputs
There are only three remote commands available to the operator, these being TX ON, TX OFF and VSWR Reset.
In the table of remote signals, all remote commands have an RC_prefix.
All remote controls are active low, opto-isolated inputs configured as shown at left, all of which require a GROUND
for assertion and the activator to be able to sink 15mA or more for at least 200ms to accomplish reliable keying.
Each of these is current-limited by an individual resistor. A ground reference pin is provided at pin 12 to ease the
interface task since all these remote commands are active low and require a short to ground.
Figure 4 Remote Command Inputs
2.4.2 Remote Telemetry Outputs
There are only four remote telemetries available to the operator, these being RF forward power, RF reflected power,
AGC voltage and Cutback voltage. In the table of remote signals, all remote commands have a RT_ prefix.
The only further note on the telemetry outputs concern the AGC and Cutback telemetry levels. These levels are
normally sent to the PreAmp attenuator and range from 0V to about 10V. The circuit that generates these
telemetries for the remote interface only has a range of 0V to 5V and so the values of these two telemetries are
actually half of their true value. That is an AGC telemetry reading of 2.3V actually represents an AGC voltage
level to the PreAmp attenuator of 4.6V.
All telemetry outputs of the transmitter are designed to operate between zero and +5V, referenced to ground.
Where possible and practical, factory calibration is standardised on 100% normal power or 100% normal voltage as
applicable, and adjusted to deliver +4V to the appropriate telemetry output. All come from op-amps that can supply
only a few mA. A ground reference pin is provided at pin 12 to ease the interface task since all these remote
commands are active low and require a short to ground.
Figure 5 Remote Telemetry Outputs
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MXD5U OPERATIONS AND MAINTENANCE
2.4.3 Remote Status Outputs
There are only two remote statuses available to the operator, these being transmitter ON and an Error status. In the
table of remote signals, all remote status have a RS_ prefix.
The transmitter ON status is a relay contact that with one side of the contact connected to ground. When the
transmitter is in the ON state, this relay closes providing a path to ground to the RS_TXON signal. Thus when this
status sinks current to ground, it indicates that the transmitter is ON.
The transmitter Error status is also an active low current sink to ground, but is implemented with the output transistor
of an opto-isolator as shown in the diagram below. When the transistor sinks current to ground, it indicates that there
is some fault condition with the transmitter. This fault is an indication to the operator that there is some problem with
the transmitter (such as a VSWR trip, Interlock open or Power supply problem) that needs some attention. A ground
reference pin is provided at pin 12 to ease the interface task since all these remote commands are active low and
require a short to ground.
The Error status is a current sinking open collector output that comes directly from the NPN transistor outputs of the
opto-isolator devices. The available output sink current is dependent on the opto-isolator transfer ratio. Generally,
one can expect at least 20mA of sinking current for each output listed here. Because these are open collector, they
can be connected to maximum 30 VDC output. The active (true) condition whether high or low will depend on the
specific status output.
Figure 6 Remote Status Outputs
2.4.4 External1 Interlock
There is a pair of terminals on the D-connector that is used for an external interlock to interface to any site alarms or
shutdown conditions. These pins would expect a dry contact that is closed when there is no error condition. This
External #1 interlock is in parallel with the two pin terminal block on the rear of the transmitter chassis. The
transmitter applied its own +12V to one side of this interlock (the Ext1+ line) and will sense this +12V on the other
interlock side (the Ext1- line).
REMOTE SIGNAL PIN# DESCRIPTION
RC_TXON 1 Control, Transmitter ON
RC_VSWRRst 2 Control, VSWR Reset
RS_TXON 3 Status, Transmitter ON
Spare [Unused] 4
RT_FwdPwr 5 Telemetry, Forward Power
Spare [Unused] 6
RT_CutBack 7 Telemetry, Cutback Voltage (1/2 Scale)
Ext1- 8 External Interlock, Normally Open
RC_TXOFF 9 Control, Transmitter OFF
Spare [Unused] 10
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