OUS835-3UHF television transmitter

ADC-835-3 Type Acceptance Report Users Manual June 20005-1 5. USER’S MANUAL The user’s manual for the ADC-835-3 system is provided as separate files.

3-kW UHF Transmitter Chapter 1, Introduction 835-3, Rev. 01-1 Chapter 1 Introduction This manual explains the installation, setup, alignment, and maintenance procedures for the 835-3 3-kW UHF transmitter. It is important that you read all of the instructions, especially the safety information in this chapter, before you begin to install or operate the unit. 1.1 Manual Overview This instruction manual is divided into four chapters and supporting appendices. Chapter 1, Introduction, contains information on the assembly numbering system used in the manual, safety, maintenance, return procedures, and warranties. The second chapter describes the transmitter. Chapter 3 explains how to unpack, install, setup, and operate the transmitter. Chapter 4, Detailed Alignment Procedures, provides information on adjusting the system to achieve peak operation of the assemblies. The appendices contain assembly and subassembly drawings and parts list. 1.2 Assembly Designation Procedure ADC has assigned assembly numbers, such as Ax (x=1,2,3...), to all assemblies, trays, and boards that are referenced in the text of this manual and shown on the block diagrams and interconnect drawings provided in the appendices. These supporting documents are arranged in increasing numerical order in the appendices. Section titles in the text for assembly or tray descriptions or alignment procedures also indicate the associated drawing(s) and the relevant appendix that contains the drawing. Sections describing vendor-supplied items, such as meters and power supplies, do not contain this information. 1.3 Safety The UHF transmitters manufactured by the Broadcast Systems Division of ADC are designed to be easy to use and repair while providing protection from electrical and mechanical hazards. Listed throughout the manual are notes, cautions, and warnings concerning possible safety hazards that may be encountered while operating or servicing the transmitter. Please review these warnings and familiarize yourself with the operation and servicing procedures before working on the transmitter. Read All Instructions – All of the operating and safety instructions should be read and understood before operating this equipment. Retain Manuals – The manuals for the transmitter should be retained at the transmitter site for future reference. We provide two sets of manuals for this purpose; one set can be left at the office while one set can be kept at the site. Heed all Notes, Warnings, and Cautions – All of the notes, warnings, and cautions listed in this safety section and throughout the manual must be followed. Follow Instructions – All of the operating and use instructions for the transmitter should be followed. 3-kW UHF Transmitter Chapter 1, Introduction 835-3, Rev. 01-2 Cleaning – Unplug or otherwise disconnect all power from the equipment before cleaning. Do not use liquid or aerosol cleaners. Use a damp cloth for cleaning. Ventilation – Openings in the cabinets and tray front panels are provided for ventilation. To ensure reliable operation of the transmitter, and to protect the unit from overheating, these openings must not be blocked. Servicing – Do not attempt to service this product yourself until becoming familiar with the equipment. If in doubt, refer all servicing questions to qualified ADC service personnel. Replacement Parts – When replacement parts are used, be sure that the parts have the same functional and performance characteristics as the original part. Unauthorized substitutions may result in fire, electric shock, or other hazards. Please contact the ADC Technical Service Department if you have any questions regarding service or replacement parts. 1.4 Maintenance The 835-3 is designed with components that require little or no periodic maintenance except for the routine cleaning of the fans and the front panels of the trays. The amount of time between cleanings depends on the conditions within the transmitter room. While the electronics have been designed to function even if covered with dust, a heavy buildup of dust, dirt, or insects will affect the cooling of the components. This could lead to a thermal shutdown or premature failure of the affected trays. When the front panels of the trays become dust covered, the top covers should be removed and any accumulated foreign material should be removed. A vacuum cleaner, utilizing a small wand-type attachment, is an excellent way to suction out the dirt. Alcohol and other cleaning agents should not be used unless you are certain that the solvents will not damage components or the silk-screened markings on the trays and boards. Water- based cleaners can be used, but do not saturate the components. The fans and heatsinks should be cleaned of all dust or dirt to permit the free flow of air for cooling purposes. It is recommended that the operating parameters of the transmitter be recorded from the meters on the trays and the system metering control panel at least once a month. It is suggested that this data be retained in a rugged folder or envelope. Photocopies of the log sheet should be made to allow you to make continued data entries. 1.5 Material Return Procedure To insure the efficient handling of equipment or components that have been returned for repair, ADC requests that each returned item be accompanied by a Material Return Authorization Number (MRA#). An MRA# can be obtained from any ADC Field Service Engineer by contacting the ADC Field Service Department, Broadcast Systems Division, at (724) 941-1500 or by fax at (724) 941-4603. This procedure applies to all items sent to the Field Service Department regardless of whether the item was originally manufactured by ADC. Note: To prevent damage to the product during shipping, ADC supplies a shipping container to the customer at no cost. 3-kW UHF Transmitter Chapter 1, Introduction 835-3, Rev. 01-3 When equipment is sent to the field on loan, an MRA# is included with the unit. The MRA# is intended to be used when the…

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3-kW UHF Transmitter Chapter 2, System Description 835-3, Rev. 02-4 Chapter 2 System Description The 834-3 is a complete 3-kW UHF solid-state, internally diplexed television transmitter that operates at a nominal visual output power of 3000 watts peak of sync and average aural output power of 300 watts, at an A/V ratio of 10 dB. 2.1 System Overview The 835-3 is made up of two cabinets: a UHF exciter cabinet (the left cabinet) and an amplifier array cabinet (the right cabinet). This 835-3 (1176-1527) is comprised of (A1) a UHF exciter assembly (1227-1200), (A2) an amplifier array assembly (1245-1700), (A9) a bandpass filter (2005-1064), (A10) an output trap filter assembly, and (A11) an output coupler assembly (1020-1002). The left cabinet contains (A1) the UHF exciter assembly (1227-1200) for the 3-kW transmitter, mounted at the top of the cabinet. The (A2) 3-kW amplifier array assembly (1176-1528) contains (A9-A1) an 8-way splitter (ZFSC-8-43), (A9-A2) an ALC splitter board (1181-1002), six (A1 through A6) 600-watt amplifier trays (1227-1300), (A7) a 6-way combiner, (A12) a reject load assembly (1278-1312), (A10) an AC distribution panel (1245-1300), and (A11) an interface panel. Switch S2 is an Automatic/Manual switch that controls the operation of the transmitter by the presence of the video input signal. When the switch is in Automatic, the green LED DS3 is lit and, if the video input signal to the transmitter is lost, the transmitter will automatically switch to Standby. When the video input signal returns, the transmitter will automatically switch back to Operate. In Manual, the amber LED DS4 is lit and the operation of the transmitter is controlled by the front panel switches. During normal operation of the transmitter, switch S2 should be in the Automatic position. The front panel of the UHF exciter also has LEDs that indicate an overtemperature fault, (red LED DS6), an ALC fault, (red LED DS8), a video fault (loss) (red LED DS9), and a VSWR cutback (amber LED DS7). The (A1) UHF exciter (1227-1200) takes the baseband audio and video inputs and produces a diplexed, modulated, and on-channel frequency visual + aural RF output. The RF output of the UHF exciter at J15 is connected to (A2) the 3-kW amplifier assembly (1245-1700), where it is split six ways in (A9-A1) the 8-way power splitter assembly (ZFSC-8-43). The outputs of the splitter feed the six (A1, A2, A3, A4, A5, and A6) 600-watt amplifier trays (1227-1300) that amplify the RF signals to approximately 600 watts each. A forward power sample from the 4-way combiner board inside the 600-watt amplifier tray is connected to the dual peak detector board. This board provides a peak-detected forward sample to the amplifier control board that supplies the sample to the front panel meter of the 600-watt amplifier tray. Before exiting each 600-watt amplifier tray, the RF is fed through a circulator for protection of the tray from high VSWR conditions. The reject port of the circulator provides a reject sample to the 4-way combiner board that supplies the reflected sample to the dual peak detector board. The peak-detected reflected sample connects to the amplifier control board that provides the sample to the front panel meter of the tray. The outputs of the six 600-watt amplifier trays are then 3-kW UHF Transmitter Chapter 2, System Description 835-3, Rev. 02-4 combined in (A7) a 6-way combiner that provides approximately 3400 watts peak of sync output. The combined output of the amplifier assembly is connected to (A9) a bandpass filter, (A10) an output trap filter, and then to (A11) the output coupler assembly (1020-1002). The bandpass filter and trap filter are tuned to provide high out- of-band rejection of unwanted products. The output of the trap filter is cabled to (A11) an output coupler assembly that provides two forward and one reflected power samples to the visual/aural metering board in the UHF exciter. The two forward samples are processed to provide peak-detected Visual and aural power output samples to the transmitter control board. The reflected power sample is also peak detected and wired to the transmitter control board. The transmitter control board connects the visual, aural, and reflected power output samples to the front panel meter for monitoring. 2.2 Transmitter Operation The 835-3 transmitter needs two AC inputs of 220 VAC: one to the exciter cabinet at 80 amps and one to the amplifier assembly cabinet at 100 amps. In the exciter cabinet, the 220-VAC input connects to the AC input assembly in the upper, right rear of the cabinet. The assembly contains terminal block TB1 that connects to the 220 VAC. The 220 VAC is wired from the AC input assembly to the TB1 in the AC distribution panel (1247-1100). The AC distribution panel contains six circuit breakers that supply the AC to the two UHF exciter trays, one for the 3-kW transmitter and one for the 1-kW transmitter. The input AC is connected to CB1, the main AC circuit breaker (80 amps) that distributes the 220 VAC to TB2. TB2 has three metal-oxide varistors (MOVs), mounted to the terminal block: one connected from each leg of the input AC to ground and one across the two legs. The input AC is wired from TB2 through five circuit breakers (CB2, CB3, CB4, CB5, and CB6) to the exciters and the rest of the 1-kW transmitter. CB2 (10 amps) supplies the AC voltage to the IEC outlet strip (A2-A1) into which the UHF exciter for the 3-kW transmitter and the UHF exciter for the 1-kW transmitter are connected. A circuit breaker mounted on the rear of each UHF exciter tray can be switched on and off to control the AC to that individual UHF exciter Tray. CB3 (20 amps) supplies AC through J5 to (A6) the 600-watt amplifier tray. CB4 (20 amps) supplies AC through J6 to (A7) the 600-watt amplifier tray. When the UHF exciter circuit breaker is switched on, +12 VDC from the bottom UHF exciter tray is supplied to the two 600-watt amplifier trays in the 1-kW transmitter and +12 VDC fro…

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3-kW UHF Transmitter Chapter 3, Installation and Setup Procedures 835-3, Rev. 0 3-1 Chapter 3 Installation and Setup Procedures There are special considerations that need to be taken into account before the 835-3 can be installed. For example, if the installation is completed during cool weather, a heat-related problem may not surface for many months, suddenly appearing during the heat of summer. This section provides planning information for the installation and set up of the transmitter. 3.1 Site Considerations The 835-3 transmitter requires two main AC input lines, a 3-phase 208/240 VAC, 60 Hz input of at least 100 amp rating that connects to the amplifier cabinet assembly and a single-phase 208/240 VAC, 60 Hz input of at least 40 amp rating that connects to the exciter/driver assembly. Make sure that the proposed site has the necessary voltage requirements. The 835-3 is designed and built to provide long life with a minimum of maintenance. The environment in which it is placed is important and certain precautions must be taken. The three greatest dangers to the transmitter are heat, dirt, and moisture. Heat is usually the greatest problem, followed by dirt, and then moisture. Over-temperature can cause heat-related problems such as thermal runaway and component failure. Each amplifier tray in the transmitter contains a thermal interlock protection circuit that will shut down that tray until the temperature drops to an acceptable level. A suitable environment for the transmitter can enhance the overall performance and reliability of the transmitter and maximize revenues by minimizing down time. A properly designed facility will have an adequate supply of cool, clean air, free of airborne particulates of any kind, and no excessive humidity. An ideal environment will require temperature in the range of 40° F to 70° F throughout the year, reasonably low humidity, and a dust-free room. It should be noted that this is rarely if ever attainable in the real world. However, the closer the environment is to this design, the greater the operating capacity of the transmitter. The fans and blowers designed and built into the transmitter will remove the heat from within the trays, but additional means are required for removing this heat from the building. To achieve this, a few considerations should be taken into account. The first step is to determine the amount of heat to be removed. There are generally three sources of heat that must be considered. The first and most obvious is the heat from the transmitter itself. This can be determined by subtracting the average power to the antenna (2100 watts) from the AC input power (10,000 watts). This number in watts (15,900) is then multiplied by 3.41, which gives 54,200, the BTUs to be removed every hour. 12,000 BTUs per hour equals one ton, so a 5-ton air conditioner will cool a 3-kW transmitter that is vented into the room. If the air exhaust will be vented externally, a 1-ton air conditioner will be needed to properly cool the transmitter. The second source of heat is other equipment in the same room. This number is calculated in the same way as the equation for BTUs. The third source of heat is equally obvious but not as simple to calculate. This is the heat coming through the walls, roof, and windows on a hot summer day. Unless the underside is exposed, the floor is usually not a problem. Determining this number is usually best left up to a qualified HVAC technician. There are far too many variables to even estimate this number without detailed drawings of the site showing all construction details. The sum of these three 3-kW UHF Transmitter Chapter 3, Installation and Setup Procedures 835-3, Rev. 0 3-2 sources is the total amount of heat that must be removed. There may be other sources of heat, such as personnel, and all should be taken into account. Now that the amount of heat that must be removed is known, the next step is to determine how to accomplish this. The options are air conditioning, ventilation, or a combination of the two. Air conditioning is always the preferred method and is the only way to create anything close to an ideal environment. Ventilation will work if the ambient air temperature is below 100° F, or about 38° C, and the humidity is be kept at a reasonable level. In addition, the air stream must be adequately filtered to ensure that no airborne particulates of any kind will be carried into the transmitter. The combination of air conditioning for summer and ventilation during the cooler months is acceptable when the proper cooling cannot be obtained through the use of ventilation alone and using air conditioning throughout the year is not feasible. Caution: The operation of air conditioning and ventilation simultaneously is not recommended. This can cause condensation in transmitters. For tube type transmitters, this can be especially serious if the condensation forms in the tube cavity and creates damaging arcs. The following precautions should be observed when using air conditioning systems: 1. Air conditioners have an ARI nominal cooling capacity rating. In selecting an air conditioner, do not assume that this number can be equated to the requirements of the site. Make certain that the contractor uses the actual conditions that are to be maintained at the site in determining the size of the air conditioning unit. With the desired conditioned room temperature under 80° F, the unit must be derated, possibly by a substantial amount. 2. Do not have the air conditioner blowing directly onto the transmitter. Condensation may occur on, or worse in, the transmitter under certain conditions. 3. Do not isolate the front of the transmitter from the back with the thought of air conditioning only the front of the unit. Cooling air is drawn in at the front of all transmitters and in the front and back of others. Any attempt to isolate the front from the rear will adversely affect the cooling air flow. 4. Interlocking the transmitter wi…

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3-kW UHF Transmitter Chapter 4, Detailed Alignment Procedures 835-3, Rev. 04-1 Chapter 4 Detailed Alignment Procedures Before beginning the alignment procedures, make sure that the RF output at J2 of (A11) the output coupler assembly of the transmitter is terminated into a dummy load of at least 3000 watts. While performing the alignment, refer to the test data sheet for the transmitter and compare the final readings from the factory with the readings on each of the trays. The readings should be very similar. If one of the readings is off by a significant degree, the problem is likely to be in that tray. Switch on the UHF exciter tray circuit breaker on the AC distribution panel in the UHF exciter cabinet and the circuit breaker on the rear of the UHF exciter tray for the 3-kW transmitter. Also switch on the main and the individual amplifier circuit breakers on the AC distribution panel in the amplifier array cabinet. 4.1 (A1) UHF Exciter Tray (1227-1200; Appendix A) The (A1) UHF exciter tray has been factory tuned and should need no alignment to achieve normal operation. Apply the baseband video and audio inputs of the test signals, as needed, to the A/V input and remote interface panel on the rear of the transmitter. 4.1.1 (Optional) (A6) Delay Equalizer Board (1227-1204; Appendix B) This board may not be present in the tray. This board has been factory tuned and should not be re-tuned without the proper equipment. To align this board: • Connect a sinX/X test signal into jack J1-2 on the delay equalizer board. • Monitor the video output of the board at video sample jack J2 with a video measuring set VM700 adjusted to measure group delay. • Tune the four stages of the board using the variable inductors (L1-L4) and potentiometers (R7, R12, R17, and R22) until the signal attains the FCC group delay curve. The stages are arranged in order of increasing frequency. Adjust R29, if needed, for the desired video gain. 4.1.2 (A7) IF Carrier Oven Oscillator Board (1191-1404; Appendix B) While monitoring J3 with a spectrum analyzer, observe the 45.75 MHz visual IF (+5 dBm). Connect a frequency counter to J3 and adjust C17 for 45.750000 MHz. Connect a frequency counter to J1 and check for 50 kHz; this is the aural phase lock loop reference. 4.1.3 (A5) Clamp/Modulator Board (1227-1208; Appendix B) Determine if jumper W1 on jack J3 is present. Jumper W1 terminates the video input into 75 ohms. Remove jumper W1 if video loop-through is required on the rear chassis jacks J1 and J2. 3-kW UHF Transmitter Chapter 4, Detailed Alignment Procedures 835-3, Rev. 04-2 Set the controls R28, the white clip; R31, the sync clip; and R43, the sync stretch, to their fully counter-clockwise (CCW) position. Note: On Revision 6 or later boards, controls R43, sync stretch cut-in, and R176, sync stretch magnitude, should be set fully CCW. Place jumper W5 on jack J11 to the clamp disable position (towards the top of the board) and jumper W2 on jack J4 to the AGC disable (out) position. Connect a 5-step staircase video test signal to the input of the transmitter. Monitor TP5 (on Revision 1 or later boards) with an oscilloscope. Adjust R15, the video gain pot, for 1 Vpk-pk. Alternately, pin 2 on video sample jack J7 can be monitored for 1 Vpk-pk when terminated into 75 ohms (2 Vpk-pk when unterminated). Change the video input test signal to a multiburst test pattern. While monitoring TP5 or video sample jack J7, pin 2, adjust C8 and R35 for a flat-frequency response. Change the input video test signal back to the 5-step staircase. Decrease the amplitude of the input video test signal (the 5-step staircase) to 0.5 Vpk- pk. (Double terminating the input will accomplish the required level reduction or R15 can be adjusted as needed.) Monitor pin 2 of IC U8B (or TP6 on Revision 1 or later boards) with an oscilloscope. Adjust R76, the sync separator, to obtain a steady waveform as shown in Figure 4-1. Figure 4-1. Steady Waveform Obtained When R76 is Adjusted Monitor pin 9 of IC U9 with an oscilloscope. The waveform shown in Figure 4-2 should be observed. Figure 4-2. Waveform Observed When Pin 9 of IC U9 is Monitored 3-kW UHF Transmitter Chapter 4, Detailed Alignment Procedures 835-3, Rev. 04-3 Monitor pin 13 of IC U6 (or TP7 on Revision 1 or later boards) with an oscilloscope. The waveform shown in Figure 4-3 should be observed. Figure 4-3. Waveform Observed When Pin 13 of IC U6 is Monitored Restore the input video level to 1 Vpk-pk. Monitor TP5 (on Revision 1 or later boards) or pin 2 of J7 (terminated into 75 ohms) with an oscilloscope. Adjust pot R105, manual bias, for a blanking level of -0.8 VDC. The waveform shown in Figure 4-4 should be observed. Move jumper W5 on J11 to the clamp enable position (towards the bottom of the board). Adjust pot R95, clamp bias, for a blanking level of -0.8 VDC. Again, the waveform in Figure 4-4 should be observed. Figure 4-4. Waveform Observed When An Adjustment is Made for a Blanking Level of –0.8 VDC Note: The waveform in Figure 4-4 represents the theoretical level for proper modulation depth. The second step below explains how to set the modulation depth by the use of a television demodulator or a zero-spanned spectrum analyzer tuned to the visual IF frequency. Connect the oscilloscope to the lead of L4 that is closest to C32 and adjust the color notch subcarrier trap, C32, until the 3.58-MHz color burst is nulled. Check the ratio of sync to video (0.286 volts of sync for a 1 Vpk-pk total video signal). If necessary, adjust R43, the sync stretch cut-in (on Revision 6 or later boards, also adjust R176, the sync stretch magnitude) for the proper sync ratio. Re-adjust R15, the video gain pot, as described above, to maintain a 1 Vpk-pk video signal. To construct the test setup for the adjustment of the depth of modulation and ICPM at IF: • Remove the cable on J18 and connect the double sideband 45.75-MHz visual IF signal from J18 to a 10-dB splitter/coupler. Connect the coupled port of the 3-kW…

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3-kW UHF Transmitter Appendix A, Assembly Drawings List 835-3, Rev. 0A-1 System – 835-3: 3-kW Transmitter Interconnect ............................................. 1176-8527 3-kW Amplifier Array Interconnect ........................................ 1176-8528 Transmitter Interconnect ...................................................... 1247-8000 AC Distribution Panel, Exciter Cabinet ............................................. 1247-1100 Interconnect ....................................................................... 1247-8100 UHF Exciter ................................................................................... 1227-1200 Block Diagram .................................................................... 1227-3200 Control Locations ................................................................ 1227-7200 Interconnect ....................................................................... 1227-8200 3-kW Amplifier Array Assembly: Interconnect ....................................................................... 1176-8528 AC Distribution Assembly, Amplifier Array Assembly ......................... 1245-1300 Interconnect ....................................................................... 1245-8300 600-Watt UHF Amplifier Tray (six in the amplifier array assembly) .... 1227-1300 Block Diagram .................................................................... 1227-3300 Control Locations ................................................................ 1227-7300 Interconnect ....................................................................... 1227-8300

3-kW UHF Transmitter Appendix B, Subassembly Drawing List 835-3, Rev. 0B-1 UHF Filter ................................................................................................. 1007-1101 Schematic ...................................................................................... 1007-3101 (Optional) FSK Identifier Board .................................................................. 1016-1107 Schematic ...................................................................................... 1016-3107 Channel Oscillator Board, Dual Oven .......................................................... 1145-1201 Schematic ...................................................................................... 1145-3201 (Optional) VCXO Board, Dual Oven ............................................................ 1145-1204 Schematic ...................................................................................... 1145-3204 AGC Splitter Board .................................................................................... 1181-1002 Schematic ...................................................................................... 1181-3002 IF Carrier Oven Oscillator Board, 45.75 MHz ............................................... 1191-1404 Schematic ...................................................................................... 1191-3404 x8 Multiplier Board .................................................................................... 1227-1002 Schematic ...................................................................................... 1227-3002 Visual/Aural Metering Board ...................................................................... 1227-1202 Schematic ...................................................................................... 1227-3202 +12V(4A)/-12V(1A) Power Supply Board .................................................... 1227-1203 Schematic ...................................................................................... 1227-3203 (Optional) Delay Equalizer Board ............................................................... 1227-1204 Schematic ...................................................................................... 1227-3204 Aural IF Synthesizer Board ........................................................................ 1227-1205 Schematic ...................................................................................... 1227-3205 ALC Board ................................................................................................ 1227-1207 Schematic ...................................................................................... 1227-3207 Clamp/Modulator Board ............................................................................. 1227-1208 Schematic ...................................................................................... 1227-3208 Transmitter Control Board ......................................................................... 1227-1209 Schematic ...................................................................................... 1227-3209 UHF Upconverter Board ............................................................................. 1227-1237 Schematic ...................................................................................... 1227-3237 IF Phase Corrector Board ........................................................................... 1227-1250 Schematic ...................................................................................... 1227-3250 Dual Stage Amplifier Board, Class AB ......................................................... 1227-1301 Schematic ...................................................................................... 1227-3301 1-Watt Amplifier Board .............................................................................. 1227-1303 Schematic ...................................................................................... 1227-3303 3-kW UHF Transmitter Appendix B, Subassembly Drawing List 835-3, Rev. 0B-2 Dual Stage Amplifier Board, Class A ........................................................... 1227-1305 Schematic ...................................................................................... 1227-33…

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