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AMPLIFIER CONTROLLER BOARD REV.5

PUB12-030 Rev. 1 Feb 14, 2013 12-030-i Amplifier Controller Board Rev.5

CONTENTS

1 INTRODUCTION ..................................................................................................................................................... 1

2 GENERAL OPERATIONS ...................................................................................................................................... 2

2.1 CONNECTOR AND SIGNAL DEFINITIONS ........................................................................................................................ 2

2.1.1 J1 BDM (Background Debug Mode) Connection ................................................................................................ 2

2.1.2 J2 Remote RS232 Connection .............................................................................................................................. 2

2.1.3 J3 Front Panel LCD and Touchpad ..................................................................................................................... 2

2.1.4 E20, E22 +50 Volt DC Power Supply .................................................................................................................. 2

2.1.5 J5 +50 Volt DC Power Supply Sensing (External) .............................................................................................. 2

2.1.6 J6 Remote Interface ............................................................................................................................................. 2

2.1.7 J7 – Not implemented ........................................................................................................................................... 3

2.1.8 J8 Fan Interface ................................................................................................................................................... 3

2.1.9 J9 External Controls ............................................................................................................................................ 3

2.1.10 J10 AGC Control ................................................................................................................................................. 3

2.1.11 J11 Not implemented ............................................................................................................................................ 3

2.1.12 J12 Forward RF Sample ...................................................................................................................................... 3

2.1.13 J13 Reflected RF Sample ..................................................................................................................................... 3

2.1.14 J14 Front Panel LCD Power ............................................................................................................................... 3

2.1.15 U25 RJ45 Ethernet Interface ............................................................................................................................... 3

2.2 JUMPER OPTIONS .......................................................................................................................................................... 4

2.2.1 Jumper E1–Serial Receive Data Select ................................................................................................................ 4

2.2.2 Jumper E2–Remote Control Reset ....................................................................................................................... 4

2.2.3 Jumper E3–Spare Line Configuration ................................................................................................................. 4

2.2.4 Jumper E4–External or Internal Power Supply Current Sensing ........................................................................ 4

2.2.5 Jumper E5–Front Panel ON/OFF Control Switch (System/Manual) .................................................................. 4

2.2.6 Jumper E6– Fan DC Power Select ...................................................................................................................... 4

2.2.7 Jumper E7–Manual Remote ON/OFF Control .................................................................................................... 5

2.2.8 Jumper E8–Power Supply Fan Interlock Bypass ................................................................................................. 5

2.2.9 Jumper E9–Forward RF Detector Color Burst Trap ........................................................................................... 5

2.2.10 Jumper E10–Forward RF Detector Sound Carrier Trap / DVB Filter ................................................................ 5

2.2.11 Jumper E11–Forward RF Detector Final Gain Control ..................................................................................... 5

2.2.12 Jumper E12– Reflected RF Detector Color Burst Trap ....................................................................................... 5

2.2.13 Jumper E13–Reflected RF Detector Sound Carrier Trap / DVB Filter ............................................................... 5

2.2.14 Jumper E14–Reflected RF Detector Final Gain Control ..................................................................................... 6

2.2.15 Jumper E15–Remote Manual Vswr Reset ............................................................................................................ 6

2.2.16 Jumper E16–AGC Disable Control ..................................................................................................................... 6

2.2.17 Jumper E17–VSWR Disable Control ................................................................................................................... 6

2.2.18 Jumper E23– P/S ON Status Polarity .................................................................................................................. 6

2.2.19 Jumper E24– P/S ON Command Polarity ............................................................................................................ 6

2.3 RF DETECTOR OPERATION ........................................................................................................................................... 7

2.4 AGC, VSWR AND CUTBACK OPERATION .................................................................................................................... 7

2.5 INTERLOCKS ................................................................................................................................................................. 8

2.5.1 Hard Interlocks .................................................................................................................................................... 8

2.5.2 Soft Interlocks ...................................................................................................................................................... 9

2.6 EXTERNAL SIGNALS AND REMOTE CONTROL ............................................................................................................... 9

2.6.1 External #1 Interlock ......................................................................................................................................... 10

2.6.2 Remote Interface (Individual) ............................................................................................................................ 10

2.6.3 Serial RS232 Interface ....................................................................................................................................... 10

2.6.4 Serial Ethernet Interface .................................................................................................................................... 10

2.6.5 External DC Power Supply ................................................................................................................................ 10

3 SETUP PROCEDURES .......................................................................................................................................... 11

3.1 RF DETECTOR ............................................................................................................................................................ 11

3.1.1 Test Equipment Required ................................................................................................................................... 11

Summary of content (34 pages)

PAGE 1
AMPLIFIER CONTROLLER BOARD REV.5 CONTENTS 1 INTRODUCTION ..................................................................................................................................................... 1 2 GENERAL OPERATIONS ...................................................................................................................................... 2 2.1 CONNECTOR AND SIGNAL DEFINITIONS ........................................................................................................
PAGE 2
AMPLIFIER CONTROLLER BOARD REV.5 3.1.2 Jumper Installation ............................................................................................................................................ 11 3.1.3 Verify OpAmp Offsets ........................................................................................................................................ 12 3.1.4 Verify Output Power Level ..............................................................................................................
PAGE 3
AMPLIFIER CONTROLLER BOARD REV.5 1 INTRODUCTION This manual describes revision 5.0 or higher of the circuit board. The MXi amplifier control board (Assembly 31C1897) is a single-circuit assembly that provides all of the amplifier control functions required for the MXi series of transmitters on a single circuit board. This board can be configured for a number of different transmitter types, power levels, transmission standards and options.
PAGE 4
AMPLIFIER CONTROLLER BOARD REV.5 2 GENERAL OPERATIONS 2.1 CONNECTOR AND SIGNAL DEFINITIONS The connectors on the MXi control board are all shown in Figure 8, which is sheet #3 of the Schematic. The individual signals that are associated with each pin of the connector are also given. A brief description of each of the connectors on the board follows. 2.1.1 J1 BDM (Background Debug Mode) Connection This is used by the software developer to debug the software programmed into the HCS08 CPU.
PAGE 5
AMPLIFIER CONTROLLER BOARD REV.5 connect to an external device or be used as a simple remote ON/OFF. When this board is used in an MXi802 or MXi1002 the controls are disabled but the status and telemetries are still available. 2.1.7 J7 – Not implemented This connector was removed on revision 4 of the circuit board assembly 2.1.8 J8 Fan Interface This uses a special connector mounted on the bottom of the MXi amplifier controller board to connect to the fan assembly.
PAGE 6
AMPLIFIER CONTROLLER BOARD REV.5 2.2 JUMPER OPTIONS 2.2.1 Jumper E1–Serial Receive Data Select This jumper determines the source of serial received data into the HCS08 microcontroller. This will determine the source of remote control commands. When placed in the ‘RS232’ position, the board will respond to remote commands from the RS232 connections at J2. When placed in the ‘INET’ position, the board will respond to remote commands from the U25 Ethernet connections.
PAGE 7
AMPLIFIER CONTROLLER BOARD REV.5 2.2.7 Jumper E7–Manual Remote ON/OFF Control This jumper would be installed to allow the operator to manually turn the amplifier ON or OFF via a remote command that would directly control the ON/OFF relay and bypass the HCS08 microcontroller. For this mode to work properly, the front panel ON/OFF switch should be left in the OFF position. In normal operation, this jumper is not installed. 2.2.
PAGE 8
AMPLIFIER CONTROLLER BOARD REV.5 When the transmitter is used to broadcast a digital DVB signal or similar standard with high peak to average ratios, a jumper is installed in the lower two pins (marked as DVB) to enable a filter that removes the high peaks from the detected signal and allow for a measurement of the average power of the RF signal. For other digital transmitters with lower peak to average ratios (specifically ATSC), there would be no jumper installed in E13 2.2.
PAGE 9
AMPLIFIER CONTROLLER BOARD REV.5 2.3 RF DETECTOR OPERATION The RF Detector circuitry is show in Figure 9. This circuitry can be used for internally diplexed analog transmitters or for digital transmitters. RF Power levels are sampled by a directional coupler located on the RF amplifier heatsink and the resulting RF samples are detected and appropriately processed to provide DC outputs corresponding to the amplitude of the desired parameter of the input signal.
PAGE 10
AMPLIFIER CONTROLLER BOARD REV.5 The AGC circuit then compares this reference voltage to the actual voltage that is produced from the forward power RF detector. If there is a difference, this is amplified by a high gain OpAmp and this error voltage is fed out to connector J10. An external cable connects J10 to the attenuator on the RF preamp mounted on the heatsink. This will lower the drive to the amplifiers until the transmitter power level agrees with the AGC reference voltage.
PAGE 11
AMPLIFIER CONTROLLER BOARD REV.5 2.5.2 Soft Interlocks There are parameters that the CPU monitors and if they indicate an error condition, the CPU will issue and OFF command to the ON/OFF relay and set the appropriate error flag. Note: if the Local or Remote ON/OFF commands are jumpered to the Override state, the CPU will be unable to shut off the amplifier via K2. For this reason it is recommended that the ON/OFF controls are left jumpered in the normal positions unless an emergency condition exists.
PAGE 12
AMPLIFIER CONTROLLER BOARD REV.5 2.6.1 External #1 Interlock The interlock that is available on the rear panel is the External #1. This is a single dry contact that is provided to shut down the RF amplifier in the case of some external problems (such as a bad RF load). It has two possible connection points that are logically in parallel so that only one needs to be connected. One point is from pins 1 and 2 of J9 on the MXi board.
PAGE 13
AMPLIFIER CONTROLLER BOARD REV.5 3 SETUP PROCEDURES The following sections detail the various set up procedures for the MXi transmitter system. These procedures should only be done by qualified personnel. If the calibrations and setups are done improperly, it can result in the transmitter being prone to damage. The transmitter is normally set up in the factory for the particular operating power required when first installed.
PAGE 14
AMPLIFIER CONTROLLER BOARD REV.5 For ATSC Digital service, the above four jumpers would not be installed. If the desired transmitter output power is the same as what the transmitter was originally set up for at the factory, there should be no need to change the gain jumpers on the RF detectors.
PAGE 15
AMPLIFIER CONTROLLER BOARD REV.5 3.2 CUTBACK PROTECTION Before the operator attempts to set up the cutback circuitry, the forward and reflected power levels must be properly set up to calibrated levels as described in Section 3.1. To set up the cutback level, a power sample must be fed into the reflected power connector of the MXi board that is –16dB down from the forward power sample level.
PAGE 16
AMPLIFIER CONTROLLER BOARD REV.5 7. Reconnect the cable from the monitor port to the reflected power sample at J13. 8. Remove the jumper from E17 and the transmitter should trip three times and lock out on the fourth trip. 9. The setup is now complete: remove the monitor cable from J13 and attach the output coupler back to J13. 10. Clear the VSWR lockout and trip condition by either pressing the front panel reset button or issuing a remote reset command. 3.
PAGE 17
AMPLIFIER CONTROLLER BOARD REV.5 4 REMOTE CONTROL CONNECTIONS MXi TRANSMITTER On the rear of the transmitter Chassis, the remote control connections are available on a 15-pin male D-shell connector J6. This includes all of the remote controls, status and telemetries available to the operator. These remote signals are routed from the MXi Control board via a 15-wire ribbon cable from connector J6 of the MXi Control board.
PAGE 18
AMPLIFIER CONTROLLER BOARD REV.5 TX D-Connector PC Board Connector Designation Description Pin 5 J6 Pin 9 RT_FWD Forward RF power level Pin 13 J6 Pin 10 RT_RFL Reflected RF power level Pin 15 J6 Pin 12 RT_AGC AGC voltage (1/2 scale) Pin 7 J6 Pin 13 RT_CUTB Cutback voltage (1/2 scale) Pin 12 J6 Pin 8 Ground Ground Reference Remote Controls 4.3 REMOTE CONTROLS The Transmitter MODE must be in REMOTE for any of these remote controls to be operational.
PAGE 19
AMPLIFIER CONTROLLER BOARD REV.5 TX D-Connector PC Board Connector Designation Description Pin 1 J6 Pin 1 RC_TX_On Turns Transmitter ON Pin 9 J6 Pin 2 RC_TX_Off Turns Transmitter OFF Pin 2 J6 Pin 3 RC_Reset Resets VSWR Trip Pin 12 J6 Pin 8 Ground Ground Reference Pin 15 J6 Pin 14 EXT1+ Secondary Ext1 Intk Pin 8 J6 Pin 15 EXT1– Secondary Ext1 Intk Remote Control 4.3.
PAGE 20
AMPLIFIER CONTROLLER BOARD REV.5 4.3.3 RC_RESET Remote RESET Control The remote reset command can have four different possible operations depending on which jumpers are selected in the MXi board. If both jumpers E15 and E2 are removed (this is the normal mode), the reset command is fed only to the CPU chip, which then issues a VSWR reset, only if the MXi system is in Remote Mode.
PAGE 21
AMPLIFIER CONTROLLER BOARD REV.5 5 CIRCUIT DESCRIPTIONS 5.1 MC68HC9S08 MICROPROCESSOR The Motorola MC68HC9S08GT microprocessor (often referred to as the CPU or HCS08) performs all of the control interface and communications in the MXi transmitter system. It is a 44-pin surface mount PLCC type device that is permanently soldered to the circuit board and is not field serviceable or easily replaced without special surface mount tooling.
PAGE 22
AMPLIFIER CONTROLLER BOARD REV.
PAGE 23
AMPLIFIER CONTROLLER BOARD REV.5 5.2 POWER SUPPLY VOLTAGE AND CURRENT MONITORING For the following description, refer to Figure 7 (Sheet #2 of the Schematic) in the upper section of the drawing for the power supply monitoring circuitry. In the case of a MXi802 or MXi1002 the first section describing the onboard current sensor is for reference only since sensing is done in the power supply chassis.
PAGE 24
AMPLIFIER CONTROLLER BOARD REV.5 When K1 is energized, both poles of the relay will close and cause the transmitter to generate RF power. One pole of K1 (consisting of pins 4, 6 and 8) will generate the Power Supply ON command and also provide the CPU a status input of whether relay K1 is activated or not. A +12V arming signal is fed into the Common pin of the contact and if the relay is energized, this +12V signal is fed to the Normally Open contact and routed to the +50V power supply.
PAGE 25
AMPLIFIER CONTROLLER BOARD REV.5 The VSWR trip circuit provides protection to the RF amplifier in the presence of a persistent and high level reflected power condition. The VSWR system is set to trip at a reflected power level of –10dB down from the forward power. OpAmp U17 compares the reflected power voltage with the forward power voltage. When the RF detector setup is done, the reflected power voltage is set for 4.0V when it is at a level of –10dB lower that the full rated forward power.
PAGE 26
AMPLIFIER CONTROLLER BOARD REV.5 Transistor Q2 serves as a buffer and Q1 serves as another buffer. Following is filter FL2, which removes the aural carrier. An alternate Inductor/Capacitor trap consisting of L2, C44 and C26 is also provided. Jumper E10 is a three position jumper that can select this filter. The second position of E13 allows a filtering capacitor to be place in the circuit to eliminate the high peaks in broadcast signals such as DVB which have high Peak to Average ratios.
PAGE 27
AMPLIFIER CONTROLLER BOARD REV.5 The gain of the amplifier stage at U14D can be adjusted by selecting one of the three available feedback resistors R79 (6.2K ohms) or R82 (24K ohms) or R148 (20K ohms) using jumper E14. When the lowest gain is desired, E14 is placed in the LO position selecting R79 in parallel with R148. When the middle gain is desired, E14 is placed in the MID position selecting R82 in parallel with R148.
PAGE 28
Figure 5 MXi Controller Board Assembly Diagram 31C1897A1
PAGE 29
Figure 6 MXi Controller Board Schematic 31C1897S1 sht1
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Figure 7 MXi Controller Board Schematic 31C1897S2 sht2
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Figure 8 MXi Controller Board Schematic 31C1897S3 sht3
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Figure 9 MXi Controller Board Schematic 31C1897S4 sht4
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Figure 10 MXi Controller Board Schematic 31C1897S5 sht5
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AMPLIFIER CONTROLLER BOARD REV.5 NOTES PUB12-030 Rev 1 Feb 14, 2013 Amplifier Controller Board Rev.