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Axcera DT325B Instruction Manual

350 watt digital vhf low band transmitter
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INSTRUCTION MANUAL
DT325B
350 Watt Digital VHF
Low Band Transmitter
AXCERA, LLC
103 FREEDOM DRIVE P.O. BOX 525 LAWRENCE, PA 15055-0525 USA
(724) 873-8100 • FAX (724) 873-8105
www.axcera.com • info@axcera.com

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  • Page 1 INSTRUCTION MANUAL DT325B 350 Watt Digital VHF Low Band Transmitter AXCERA, LLC 103 FREEDOM DRIVE P.O. BOX 525 LAWRENCE, PA 15055-0525 USA (724) 873-8100 • FAX (724) 873-8105 www.axcera.com • info@axcera.com...

  • Page 2: Table Of Contents

    1.2 Assembly Designation Numbers ..............1-1 1.3 Safety ....................1-2 1.4 Contact Information................1-2 1.5 Material Return Procedure ..............1-2 1.6 Warranty for Axcera Products – Limited One-Year Warranty.......1-3 CHAPTER 2 SYSTEM DESCRIPTION 2.1 System Overview ..................2-1 2.2 Exciter Driver Chassis Assembly Description..........2-1 2.2.1 Control & Monitoring Power Supply Module Assembly.......2-2 2.2.2 Upconverter and Downconverter Module.........2-2...

  • Page 3: Section Page

    Amplifier LCD Display ................5-5 5.6.1 Forward Power Calibration.............5-5 5.6.2 Reflected Power Calibration ............5-5 APPENDICES APPENDIX A DT325B w/AXCITER SYSTEM DRAWINGS APPENDIX B DRIVER/AMPLIFIER CHASSIS ASSEMBLY DRAWINGS APPENDIX C VHF LOW BAND AMPLIFIER TRAY DRAWINGS DT325B, Rev. 0 September 12, 2008...
  • Page 4 Driver/Amplifier Chassis Assembly Front View ........2-1 Rear view Driver/Amplifier Chassis Assembly ........2-9 1 kW Minimum Ventilation Configuration...........3-4 Front and Rear view Driver/Amplifier Chassis Assembly......3-4 AC Input Box Assembly..............3-5 Rear view Driver/Amplifier Chassis Assembly ........3-6 Axciter Upconverter/Downconverter Main Screen.......5-4 DT325B, Rev. 0...
  • Page 5 Table of Contents LIST OF TABLES Table Page DT325B Assemblies and Trays ............2-1 Controller/Power Supply Front Panel Display ........2-2 Controller/Power Supply Front Panel Status Indicators .......2-2 Controller/Power Supply Front Panel Control Adjustments ....2-2 VHF Amplifier Front Panel Tray Control Adjustments ......2-4 VHF Amplifier Tray Sample..............2-4...

  • Page 6: Chapter 1 Introduction

    1.3 Safety and boards in the system. These designations are referenced in the text of The DT325B transmitters manufactured this manual and shown on the block by Axcera are designed to be easy to use DT325B, Rev. 0...

  • Page 7: Contact Information

    The RMA# can be obtained from any Axcera field service engineer by calling Replacement Parts – When the Axcera Field Service Department at 1- replacement parts are used, be sure that 724-873-8100. This procedure applies to DT325B, Rev. 0...

  • Page 8: Warranty For Axcera Products - Limited One-Year Warranty

    Warranties are valid only when and if The RMA# is intended to be used for the (a) Axcera receives prompt written return of the unit to Axcera. In addition, notice of breach within the period of all shipping material should be retained warranty, (b) the defective product is for the return of the unit to Axcera.
  • Page 9 NEVER OPERATE THE TRANSMITTER SYSTEM WITHOUT A PROPERLY MATCHED RF ENERGY ABSORBING LOAD ATTACHED. KEEP PERSONNEL AWAY FROM OPEN WAVEGUIDES AND ANTENNAS. NEVER LOOK INTO AN OPEN WAVEGUIDE OR ANTENNA. MONITOR ALL PARTS OF THE RF SYSTEM FOR RADIATION LEAKAGE AT REGULAR INTERVALS. DT325B, Rev. 0...
  • Page 10 Treat SKIN BLISTERED OR FLESH CHARRED: Apply victim for shock and take to hospital. ice cold water to burned area to prevent burn from going deeper into skin tissue. DT325B, Rev. 0...
  • Page 11 1 NANOWATT - 60 - 90 0.0000000001 100 PICOWATTS - 70 -100 0.00000000001 10 PICOWATTS - 80 -110 0.000000000001 1 PICOWATT - 90 -120 TEMPERATURE CONVERSION °F = 32 + [(9/5) °C] °C = [(5/9) (°F - 32)] DT325B, Rev. 0...
  • Page 12 FREQ. BAND 1000 - 2000 MHz 2000 - 4000 MHz 4000 - 8000 MHz 8000 - 12000 MHz 12 - 18 GHz 18 - 27 GHz 27 - 40 GHz 40 - 75 GHz 75 - 110 GHz DT325B, Rev. 0...
  • Page 13 350-Watt VHF LB Digital Transmitter Chapter 1, Introduction RETURN LOSS VS. VSWR 1.001 1.01 VSWR DT325B, Rev. 0...
  • Page 14 Motion Pictures Expert Group Direct Current Output Digital to analog Phase Locked Loop Decibel Printed circuit board Decibel referenced to 1 milliwatt Quadrature Amplitude Modulation dBmV Decibel referenced to 1 millivolt Decibel referenced to 1 watt Forward Error Correction DT325B, Rev. 0...

  • Page 15: System Overview

    1304363 2.1 System Overview 2.2: Exciter Driver Chassis Assembly, LXB, 220 VAC (1310206; Appendix C) The DT325B is a complete VHF low band solid-state digital television transmitter The chassis assembly is factory set for that operates at a nominal average operation using 220 VAC.
  • Page 16 8-VSB IF signal centered at upconverter, and also the transmitter, 44 MHz. that is -6 dBm in level, is cabled that connects to the power amplifier to J68 on the rear panel of the module. The gain controlled output of the DT325B, Rev. 0...

  • Page 17: Adaptive Equalization Circuits

    When a nonlinear adaptive equalizer is in an Amplifier Array. The output of the being calculated, the transmitter sample is phase shifter is cabled to the taken before the channel mask filter, so filter/amplifier board. The gain of the tray DT325B, Rev. 0...
  • Page 18 Adjusts the gain of the RF output when the amplifier control Gain board is in the AGC mode. Table 2-6: VHF Amplifier Tray Sample SAMPLE DESCRIPTION Forward power sample of the tray from the AGC control RF Front Panel Sample board. DT325B, Rev. 0...
  • Page 19 Reads the current of (A3-A3) the low band amplifier board (idling current=1.8 amps and operating current=12-13 amps, black picture) Reads the current of (A2-A1) the low band amplifier board (idling current=3 amps and operating current=3 amps, black picture) DT325B, Rev. 0...

  • Page 20: Control And Status

    RF output power, because of a fault red. Also, the +32 VDC stage of the condition that causes the firmware to Power Supply in the Control & Monitoring DT325B, Rev. 0...
  • Page 21 The transmitter controller is designed to operate on UHF frequencies. The exact output frequency of the transmitter can be set to one of the standard UHF frequencies, or to a custom frequency using the software channel set-up menu DT325B, Rev. 0...

  • Page 22: Maintenance

    After removal of the failed cooling of the components. This could module, slide the replacement module in lead to a thermal shutdown or the place and make certain it connects to the backplane board. If the replacement DT325B, Rev. 0...

  • Page 23: Customer Remote Connections

    “source” pin of Interlock TB30-3 an FET so that the transmitter interlock can be daisy Isolated Return chained with other transmitters. This signal does not directly interface to the microcontroller. DT325B, Rev. 0...
  • Page 24 (Connects to triple peak detector board.) Analog System Reflect Input - 0 to 1.00 V- This is the input of the “System TB31-13 Power Reflected Power ” indicating the transmitter's reflected output power. The scale factor is 25 % / 0.80V. DT325B, Rev. 0 2-10...
  • Page 25 TB30-5 to TB30-15, which is ground, needs to be connected to TB30. This jumper provides the RF System Interlock, which allows the transmitter to go to operate. Without the jumper, the transmitter will remain Muted. DT325B, Rev. 0 2-11...

  • Page 26: Chapter 3 Installation And Setup Procedures

    This is rarely attainable in the real need to be taken into account before the world. However, the closer the DT325B can be installed. For example, if environment is to this design, the greater the installation is completed during cool the operating capacity of the transmitter.
  • Page 27 Cooling air is of 300 feet per minute through the drawn in at the front of all filter. This is not a conservative transmitters and in the front and DT325B, Rev. 0...
  • Page 28 (see Figure 3-1). System elevation. The free air delivery interlocking and thermostat settings method must not be used. should be reviewed with Axcera. As with Regular maintenance of the filters, any equipment installation, it is always if used, can not be good practice to consult the overemphasized.

  • Page 29: Unpacking And Installation Of The Cabinet And Trays

    The trays are damage should be directed to the carrier. mounted in the cabinet using Chassis Inform Axcera as to the extent of any Trak cabinet slides. The slides are on the damage as soon as possible.

  • Page 30: Input And Output Connections To The Transmitter

    (A16) pre-filter coupler connects to J1, on the K2 relay. Check The main AC input circuit to the DT325B that the forward power sample, post- is a 30-amp, 220-VAC line, using AWG 6 filtering, of the output of the transmitter...
  • Page 31 SCADA (Input / Loop-Thru) CAT5 RJ-45 SCADA (Input / Loop-Thru) CAT5 RJ-45 System RS-485 Serial CAT5 1GHz Input (From Axciter) Downconverter RF Input (From K2 Relay) TB30 Termination Remote Control & Monitoring TB31 Termination Remote Control & Monitoring DT325B, Rev. 0...

  • Page 32: Setup And Operation Procedures

    If the % Reflected Power is very high, above 10%, a problem may exist with the output coaxial lines and they will need to be checked. A center bullet missing from the coax lines or loose bolts is a probable cause. Repair DT325B, Rev. 0...

  • Page 33: Front Panel Lcd Screen For Driver/Amplifier Chassis Assembly

    NOTE: The following screens are typical FAULT - This illuminates Red when a of an operating Exciter but may be fault has occurred in the transmitter. different from the screens in your system. DT325B, Rev. 0...
  • Page 34 Main Screen. The Model Number, Code Version Number and Firmware Number for your system are displayed on this screen. Make note of these two numbers when conferring with Axcera on software problems. Table 3-4: Menu 10 - Main Screen: This is the default main screen of the transmitter.
  • Page 35 Current values for all installed devices are shown. If a module is not installed, only a "MODULE NOT PRESENT" message will be displayed. The first screen displayed is Menu 30-1, Table 3-10, the System Details Screen. DT325B, Rev. 0 3-10...
  • Page 36 Pushing the ↓ Down Arrow, after scrolling through all of the detail screens, will put you back to Menu 30, Table 3-9. Push the ESC button to exit the Transmitter Device Parameter Screens to Menu 12, Table 3-6, the Transmitter Device Parameter Access Screen. DT325B, Rev. 0 3-11...
  • Page 37 Table 3-13: Menu 40-1 - Transmitter Set-up: Power Control Screen This screen of the transmitter is the first of several that allows access to transmitter set- up parameters. When + is selected, the Power will increase. When - is selected, the Power will decrease. DT325B, Rev. 0 3-12...
  • Page 38 Table 3-18: Menu 40-9 - Transmitter Set-up: System Reflected Power Calibration This screen is used to adjust the calibration of the system's reflected power. Again a calibration value symbol is used for this screen as on the previous screens. DT325B, Rev. 0 3-13...
  • Page 39 The same previous screens will be displayed by the back up exciter if it is switched to become the On Air Exciter. This completes the description of the menu screens for the Driver/Amplifier Chassis Assembly and the Setup and Operation Procedures for the DT325B. DT325B, Rev. 0 3-14...

  • Page 40: Chapter 4 Circuit Descriptions

    F2 fuse. The AC line #2 input after the operational, the Green LED DS5, F2 fuse is split with one line connected mounted on the board, will be lit back to Jack J1 at Pin 5, which becomes DT325B, Rev. 0...

  • Page 41: Schematic Sheet 4

    When the microcontroller, operation. When the contacts of SW1 U1, is held in reset, low on pin 20, by are closed, transmitter operation is either the programming port or the selected and the power monitoring lines DT325B, Rev. 0...

  • Page 42: Schematic Sheet 5

    Serial data, serial clock and serial pot read and write control. enables are supplied by the microprocessor to the dual serial RB1 is the connector to a Rabbit potentiometer ICs. Serial data to the Semiconductor RCM4300. This Ethernet DT325B, Rev. 0...

  • Page 43: Lcd W/Switches Board

    (A3) System Controller Board. the LED, the transistor and the current When a switch is closed, it connects a limiting resistors in the collector to the logic low to the system controller board DT325B, Rev. 0...

  • Page 44: Switching Power Supply Assembly

    Filter/amplifier board (mounted in A1-A2 1198-1606 [A1] an RF enclosure assembly) VHF low band amplifier board A2-A1 (mounted in [A2] an RF enclosure 1198-1605 assembly) Overdrive protection board A2-A2 (mounted in [A2] an RF enclosure 1198-1601 assembly) DT325B, Rev. 0...

  • Page 45: Vdc Switching Power Supply

    The output at J2 of the Phase Shifter Q1 to about +16.5 dBm; this signal is Board is directed to J7 the input jack on connected to the output of the board at (A1-A2) on the filter/amplifier board. DT325B, Rev. 0...
  • Page 46 R11, The RF signal inputs to the Output which is set to +.4 VDC as measured at Amplifier Boards, +33.3 dBm, are TP1. The set output of U1D is connected amplified to +51.3 dBm outputs at J2, DT325B, Rev. 0...
  • Page 47 IC U3A and related components which connected to U8 a +5 VDC Regulator IC, comprise the AGC circuit. This level is which supplies the +5 VDC needed for combined with the AGC reference inputs operation of the front panel mounted DT325B, Rev. 0...
  • Page 48 AGC Control Board and located on the rear of the Tray, are also the +12 VDC is connected through shorted. The Enable is generated by the the Current Metering Board, by the exciter/driver chassis assembly when the DT325B, Rev. 0...

  • Page 49: External Boards

    Cutback, located on the front panel, operational amplifier U1D and then remains lit until the Reflected level drops connected to RF I/P 1 power adjust pot below 20%. R14, which adjusts the gain of U2D. The DT325B, Rev. 0 4-10...

  • Page 50: Isolation Relay Board

    On Air Driver/Amplifier Chassis Assembly is switched to Standby. The +12 VDC needed for the operation of This completes the circuit description of Op Amps U1 and U2 enters the board at the boards that make up the DT325B. DT325B, Rev. 0 4-11...

  • Page 51: Chapter 5 Detailed Alignment Procedures

    Downconverter, (2) Blank panel, (3) replacement module. The failed module Blank Panel, (4) Axciter Upconverter, (5) can then be sent back to Axcera for Controller/Power Supply and (6) Blank repair. Contact Axcera Customer Service panel.

  • Page 52: Filter/Amplifier Board

    E = 250 mV. dBm input an output of +51.3 dBm is typical. 5.3.4 (A2-A1) VHF Low Band Amplifier Board (1198-1605; Appendix D) This board has 20 dB of gain and is biased for 3 Amps of Idling Current, no DT325B, Rev. 0...
  • Page 53 AGC Control Board until through the Axciter Modulator. DS4 the Red VSWR Cutback LED mounted on the front panel lights. This See Figure 5-1 for an example of the sets up the VSWR Cutback Circuitry. Axciter Upconverter/Downconverter DT325B, Rev. 0...
  • Page 54 1.7 Volts. Place the Transmitter into AGC by pushing the 3 of the key board entry on the Axciter Upconverter Screen. This will place the Transmitter AGC into Auto. Figure 5-1: Axciter Upconverter/Downconverter Main Screen DT325B, Rev. 0...

  • Page 55: Upconverter/Downconverter Adjustment

    Reflected Powers Using the Driver/AmplifierChassis This completes the set up and adjustment of the DT325B transmitter. NOTE: Do not adjust R38 on (A4) the If a problem occurred during alignment, Triple Peak Detector Board (1159713). contact Axcera field service at 1-724- It is factory set for .7 to .8 VDC typical...
  • Page 56 APPENDIX A DT325B SYSTEM SPECIFICATIONS...
  • Page 57 These low power VHF DTV transmitters and translators deliver high quality and per- formance in a compact and economical package - perfect for broadcasters wishing to get a DTV signal on the air quickly. The time-proven Axcera DT1C modulator or optional DT2B adaptive modulator, generates the ATSC-compliant 8VSB IF signal, which feeds the companion upconverter.
  • Page 58 2 Available with 700 W Filter Option Specifications published here are current as of the date of publication of this document. Because we are continuously improving our products, Axcera reserves the right to change specifications without prior notice. At any time, you may verify product specifications by contacting our office.
  • Page 59 APPENDIX B SYSTEM DRAWINGS...
  • Page 60 350-Watt Digital VHF LB Transmitter Appendix B, System Drawings DT325B DT325B Transmitter w/Axciter Interconnect........... 1311143 Triple Peak Detector Board Schematic ..................1160522 DT325B, Rev. 0...
  • Page 61 APPENDIX C EXCITER/DRIVER CHASSIS ASSEMBLY DRAWINGS...
  • Page 62 Axciter Manual. Exciter Control/Power Supply Assembly, LXB, 220 VAC Block Diagram ..................1310189 Interconnect..................1310190 Power Protection Board Schematic ..................1302839 LCD w/Switches Board Schematic ..................1307978 System Controller Board, LXB Schematic ..................1310090 DT325B, Rev. 0...
  • Page 63 APPENDIX D VHF LOW BAND AMPLIFIER TRAY DRAWINGS...
  • Page 64 VHF Filter/Amplifier Board Schematic ..................1198-3606 3 Way Splitter Board Schematic ..................1198-3608 3 Way Combiner Board, CH Schematic ..................1198-3626 VHF Low Band Low Pass Filter Board Schematic ..................1198-3628 Current Metering Board Schematic ..................1304366 DT325B, Rev. 0...
  • Page 65 350-Watt Digital VHF LB Transmitter Appendix D, VHF LB Amplifier Tray Drawings AGC Control Board Schematic ..................1306481 400 Watt VHF Amplifier Assembly (1304348) Delta RF Data Sheet ................P400-VHF-L DT325B, Rev. 0...

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