UBS Axcera 840A 10,000-watt UHF solid state television transmitter User Manual Chapter 3

UBS-Axcera 10,000-watt UHF solid state television transmitter Chapter 3

Chapter 3

10-kW UHF Transmitter with Chapter 3, Installation and Feedforward Drive Setup Procedures840A, Rev. 0 3-1Chapter 3Installation and Setup ProceduresThere are special considerations thatneed to be taken into account before the840A can be installed. For example, if theinstallation is completed during coolweather, a heat-related problem may notsurface for many months, suddenlyappearing during the heat of summer.This section provides planninginformation for the installation and set upof the transmitter.3.1 Site ConsiderationsThe 840A transmitter requires two mainAC input lines, a 3-phase 208/240 VAC,60 Hz input of at least 100 amp ratingthat connects to the high-voltage powersupply assembly and a single-phase208/240 VAC, 60 Hz input of at least 40amp rating that connects to theexciter/driver assembly. Make sure thatthe proposed site has the necessaryvoltage requirements.The cabinets should be positioned withconsideration given for adequate airintake and exhaust. In addition,installation planning should take intoaccount the amount of space required forthe opening of the front of the meteringcontrol panel on the 10-kW amplifier; theopening of the rear doors on the 10-kWamplifier and exciter/driver cabinets;access to the trays, including slidingthem out for testing; the main AC hook-up to the high-voltage power supplyassembly; and the installation of theoutput transmission line, including thetrap filters and the directional coupler.The 10-kW amplifier cabinet contains atube cavity air exhaust stack that is a10.5-inch chimney mounted on the roofof the cabinet. Forced air flows thoughthis chimney from the blower assemblythat cools the tube mounted in the cavityassembly (1,100 CFM at 30° C rise).The 10-kW amplifier cabinet also has twoexhaust fans, rated at 240 CFM, mountedin the top cover assembly of the cabinet.Air intake for the tube cavity blowerassembly is through the large filtermounted on the bottom rear of thecabinet.The high-voltage power supply cabinethas two exhaust fans, each rated at 550CFM, mounted in the top cover assemblyof the cabinet. Air intake for the cabinetis through the two filters mounted oneach side of the cabinet.The 840A is designed and built to providelong life with a minimum of maintenance.The environment in which it is placed isimportant and certain precautions mustbe taken. The three greatest dangers tothe transmitter are heat, dirt, andmoisture. Heat is usually the greatestproblem, followed by dirt, and thenmoisture. Over-temperature can causeheat-related problems such as thermalrunaway and component failure. Eachamplifier tray in the transmitter containsa thermal interlock protection circuit thatwill shut down that tray until thetemperature drops to an acceptable level.A suitable environment for thetransmitter can enhance the overallperformance and reliability of thetransmitter and maximize revenues byminimizing down time. A properlydesigned facility will have an adequatesupply of cool, clean air, free of airborneparticulates of any kind, and noexcessive humidity. An ideal environmentwill require temperature in the range of40° F to 70° F throughout the year,reasonably low humidity, and a dust-freeroom. It should be noted that this israrely if ever attainable in the real world.However, the closer the environment isto this design, the greater the operatingcapacity of the transmitter.
10-kW UHF Transmitter with Chapter 3, Installation and Feedforward Drive Setup Procedures840A, Rev. 0 3-2The fans and blowers designed and builtinto the transmitter will remove the heatfrom within the trays, but additionalmeans are required for removing thisheat from the building. To achieve this, afew considerations should be taken intoaccount. The first step is to determinethe amount of heat to be removed. Thereare generally three sources of heat thatmust be considered. The first and mostobvious is the heat from the transmitteritself. This can be determined bysubtracting the average power to theantenna (6950 watts) from the AC inputpower (25,000 watts). This number inwatts (18,050) is then multiplied by3.41, which gives 61,550, the BTUs to beremoved every hour. 12,000 BTUs perhour equals one ton, so a 6-ton airconditioner will cool a 10-kW transmitterthat is vented into the room. If the airexhaust will be vented externally, a 1.5-ton air conditioner will be needed toproperly cool the transmitter.The second source of heat is otherequipment in the same room. Thisnumber is calculated in the same way asthe equation for BTUs. The third sourceof heat is equally obvious but not assimple to calculate. This is the heatcoming through the walls, roof, andwindows on a hot summer day. Unlessthe underside is exposed, the floor isusually not a problem. Determining thisnumber is usually best left up to aqualified HVAC technician. There are fartoo many variables to even estimate thisnumber without detailed drawings of thesite showing all construction details. Thesum of these three sources is the totalamount of heat that must be removed.There may be other sources of heat, suchas personnel, and all should be taken intoaccount.Now that the amount of heat that mustbe removed is known, the next step is todetermine how to accomplish this. Theoptions are air conditioning, ventilation,or a combination of the two. Airconditioning is always the preferredmethod and is the only way to createanything close to an ideal environment.Ventilation will work if the ambient airtemperature is below 100° F, or about38° C, and the humidity is be kept at areasonable level. In addition, the airstream must be adequately filtered toensure that no airborne particulates ofany kind will be carried into thetransmitter. The combination of airconditioning for summer and ventilationduring the cooler months is acceptablewhen the proper cooling cannot beobtained through the use of ventilationalone and using air conditioningthroughout the year is not feasible.Caution: The operation of airconditioning and ventilationsimultaneously is not recommended.This can cause condensation intransmitters. For tube typetransmitters, this can be especiallyserious if the condensation forms inthe tube cavity and createsdamaging arcs.The following precautions should beobserved when using air conditioningsystems:1. Air conditioners have an ARInominal cooling capacity rating. Inselecting an air conditioner, do notassume that this number can beequated to the requirements ofthe site. Make certain that thecontractor uses the actualconditions that are to bemaintained at the site indetermining the size of the airconditioning unit. With the desiredconditioned room temperatureunder 80° F, the unit must bederated, possibly by a substantialamount.2. Do not have the air conditionerblowing directly onto thetransmitter. Condensation mayoccur on, or worse in, the
10-kW UHF Transmitter with Chapter 3, Installation and Feedforward Drive Setup Procedures840A, Rev. 0 3-3transmitter under certainconditions.3. Do not isolate the front of thetransmitter from the back with thethought of air conditioning onlythe front of the unit. Cooling air isdrawn in at the front of alltransmitters and in the front andback of others. Any attempt toisolate the front from the rear willadversely affect the cooling airflow.4. Interlocking the transmitter withthe air conditioner isrecommended to keep thetransmitter from operating withoutthe necessary cooling.5. The periodic cleaning of all filtersis a must.When using ventilation alone, thefollowing general statements apply:1. The blower and its filters shouldbe on the inlet. This will pressurizethe room and prevent dirt fromentering the transmitter.2. The inlet and outlet vents shouldbe on the same side of thebuilding, preferably the leewardside. As a result, the pressuredifferential created by wind will beminimized. Only the outlet ventshould be released through theroof.3. The inlet and outlet vents shouldbe screened with 1/8" hardwarecloth (preferred) or galvanizedhardware cloth (acceptable).4. Cooling air should enter the roomas low as practical but in no casehigher than four feet above thefloor. The inlet must be locatedwhere dirt, leaves, snow, etc., willnot be carried in with the coolingair.5. The exhaust should be located ashigh as possible. Some ducting isusually required to insure thecomplete flushing of heated airwith no stagnant areas.6. The filter area must be adequateto insure a maximum air velocityof 300 feet per minute through thefilter. This is not a conservativenumber but a never-exceednumber. In a dusty or remotelocation, this number should bereduced to 150 CFM.7. The inlet and outlet(s) must haveautomatic dampers that close anytime the ventilation blower is off.8. In those cases in whichtransmitters are regularly off for aportion of each day, atemperature-differential sensorthat controls a small heater mustbe installed. This sensor willmonitor inside and outsidetemperatures simultaneously. Ifthe inside temperature falls towithin 5° F of the outsidetemperature, the heater will comeon. This will prevent condensationwhen the ventilation blower comeson and should be used even in thesummer.9. A controlled-air bypass systemmust be installed to prevent thetemperature in the room fromfalling below 40° F when thetransmitter is operating.10. The blower should have twospeeds, which are thermostaticallycontrolled, and interlocked withthe transmitter.11. The blower on high speed must becapable of moving the requiredvolume of air into a half inch ofwater pressure at the requiredelevation. The free air deliverymethod must not be used.
10-kW UHF Transmitter with Chapter 3, Installation and Feedforward Drive Setup Procedures840A, Rev. 0 3-412. Regular maintenance of the filters,if used, can not beoveremphasized.13. Tube transmitters should not relyon the internal blower to exhaustcooling air at elevations above4000 feet. For external venting,the air vent on the cabinet topmust be increased to an 8"diameter for a 1 kW transmitterand to 15" for a 10-kWtransmitter. An equivalentrectangular duct may be used but,in all cases, the outlet must beincreased in area by 50% throughthe outlet screen.14. It is recommended that a site planbe submitted to ADC forcomments before installationcommences.To calculate the blower requirements,filter size, and exhaust size if the totalload is known in watts, 2000 CFM into1/2" of water will be required for each5000 watts. If the load is known in BTUs,2000 CFM into 1/2" of water will berequired for each 17,000 BTUs. The inletfilter must be a minimum of sevensquare feet, larger for dusty and remotelocations, for each 5000 watts or 17,000BTUs. The outlet for the exhaust must beat least four square feet at the exhaustscreen for each 5000 watts or 17,000BTUs.The information presented in this sectionis intended to serve only as a generalguide and may need to be modified forunusually severe conditions. Acombination of air conditioning andventilation should not be difficult todesign (see Figure 3-1). Systeminterlocking and thermostat settingsshould be reviewed with ADC. As withany equipment installation, it is alwaysgood practice to consult themanufacturer when questions arise. ADCcan be contacted at (724) 941-1500.Figure 3-1. 1 kW Minimum Ventilation Configuration
10-kW UHF Transmitter with Chapter 3, Installation and Feedforward Drive Setup Procedures840A, Rev. 0 3-53.2 Unpacking the Cabinets andTraysNote: Air conditioning and anyrelated heat-exhaust ducts should bein place before continuing with theinstallation of the transmitter.Thoroughly inspect the cabinets and allother materials upon their arrival. ADCcertifies that upon leaving our facility theequipment was undamaged and in properworking order. The shipping containersshould be inspected for obvious damagethat indicates rough handling. Check fordents and scratches or broken switches,meters, or connectors. Any claimsagainst in-transit damage should bedirected to the carrier. Inform ADC as tothe extent of any damage as soon aspossible.Remove the exciter/amplifier cabinet withtrays, the 10-kW amplifier cabinet, thehigh-voltage power supply cabinet,conduit pieces, directional couplers,output trap filter, all of the hard line andcoaxial cables, as well as any installationmaterial, from the crates and boxes.Remove the straps that hold theexciter/amplifier cabinet to the shippingskid and slide the cabinet from the skid.Remove the plastic wrap and foamprotection from around the cabinet. Donot remove any labeling or tags from anycables or connectors, as these areidentification markers which make re-assembly of the transmitter much easier.Remove the two L-brackets, mounted onthe front panel rails, that held the traysin place during shipment. The trays aremounted in the cabinet using ChassisTrak cabinet slides (see Figure 3-2).Open the rear door and inspect theinterior for packing material. Carefullyremove any packing material that isfound. Slowly slide each tray in and outto verify that they do not rub againsteach other and have no restrictions tofree movement. Adjustments may benecessary and are accomplished byloosening the front cabinet slidemounting bolts and moving the tray upor down as needed. Inspect the trays forany loose hardware or connectors andtighten where needed.Figure 3-2. Chassis Trak Cabinet SlidesRemove the straps that hold the 10-kWamplifier cabinet to the shipping skid andslide the cabinet from the skid. Removethe plastic wrap and foam protectionfrom around the cabinet. Do not removeany labeling or tags from any cables or
10-kW UHF Transmitter with Chapter 3, Installation and Feedforward Drive Setup Procedures840A, Rev. 0 3-6connectors, as these are identificationmarkers that make assembly of thetransmitter much. Open the meteringcontrol panel and the rear door of the 10-kW amplifier. Inspect the interior for anypacking material and carefully removeany that is found.Remove the straps that hold the high-voltage power supply cabinet to theshipping skid and slide the cabinet fromthe skid. Remove the plastic wrap andfoam protection from around the cabinet.Do not remove any labeling or tags fromany cables or connectors, as these areidentification markers that makeassembly of the high-voltage powersupply and its connection to the 10-kWamplifier cabinet much easier.3.3 Installation of the Cabinets andTraysThe cabinets should be positioned withthe exciter/amplifier cabinet to the left ofthe 10-kW amplifier cabinet when theoperator is facing the front of thecabinets. The high-voltage power supplycabinet should be placed at the rear ofthe 10-kW amplifier cabinet.Note: Refer to the specific floor planor the racking plan for the site forinformation on cabinet placement.The cabinets should be mounted,using bolts, to the floor of the site.Caution: If the exciter/driver cabinetis not mounted to the floor, theentire cabinet may tip over if thetrays are all pulled out at the sametime. Ground each of the cabinetstogether by connecting a groundstrap between each of them andthen connecting the strap to ground.Locate the 1/2" heliax cable labeled from(A11-J2) of the exciter/driver cabinet to(A2-A1-J1) the RF input jack of the tubecavity assembly in the 10-kW amplifierassembly cabinet. Connect one end ofthe 1/2 " heliax to the output at the topof the exciter/driver cabinet and theother end through the top of theamplifier cabinet to the bottom of thetube cavity.3.4 Output Trap Filter, OutputCoupler, and Transmission LineInstallationThe specific floor plan and interconnectdrawings for the transmitter site shouldbe consulted as the transmitter andtransmission lines are assembled. Thesedrawings provide the "A" numbers andlocation designations of the differentlength transmission lines, the output trapfilter, the output coupler assembly, andthe proper connections between thecabinets. Each transmission line sectionis labeled in its shipping container as toits respective location in the 10-kWassembly.The installation of the 3-1/8" EIAtransmission line begins at the output ofthe 10-kW tube cavity assembly andproceeds through (A2-A2) an outputdirectional coupler, mounted in thecabinet, to the outside of the cabinet.The 3-1/8" hard line connects to theinput of the output trap filter. The outputat J2 of the output trap filter connects tothe input of the next trap filter, toanother directional coupler, and then tothe connection for the antenna.To connect the harnesses between thecabinets, reference the systeminterconnect drawing for the transmitter.Connect the harnesses to the properterminations as shown in the drawing.3.5 Installation of the High-VoltagePower Supply AssemblyWhile performing the followinginstallation procedure, refer to the high-voltage power supply interconnectdrawing (1293-8100) for the properconnections.The location drawing for this assembly isrepresentative of a typical 10-kW high-voltage power supply assembly, with
10-kW UHF Transmitter with Chapter 3, Installation and Feedforward Drive Setup Procedures840A, Rev. 0 3-7208/240 VAC 3-phase input service. Theprimary and secondary terminals of thetransformer are clearly labeled for thereconnection of the wires.The 10-kW high-voltage power supplyconsists of three main assemblies, eachof which are packed separately forshipment: (1) the cabinet enclosure,which has components mounted to itssides and top; (2) the high-voltagetransformer, which, because of its weight(approximately 300 lbs), is shipped in aseparate crate; and (3) the dolly-mounted tray, which contains the high-voltage choke and filter capacitors. Whenreassembled, these three assembliesbecome the high-voltage power supply.To reassemble the high-voltage powersupply, first locate the three assembliesthat make up the high-voltage powersupply assembly. Set the high-voltagetransformer (A1) in the proper location(according to the floor plan drawing).Because of its weight, the transformerwill sit directly on the floor and be held inplace by the mounting brackets. Find thedolly-tray assembly and roll it into placeto the left of the transformer. Thetransformer and the dolly tray are thenenclosed by sliding the high-voltagecabinet assembly over them. Make surethat the transformer or the tray does nothit the high-voltage rectifier boards,mounted on the back of the cabinet, orthe contactor on the side of the cabinet.Reconnect the primary and secondaryterminals of the high-voltage transformerand the wires to the 5-henry choke andthe four 5 mF capacitors. All nine wiresthat are marked with an "X" in the high-voltage power supply assembly drawingare to be reconnected. The wires arelabeled to show where they are to beconnected.The primary connections are three 6-AWG wires, two of which originate at thestep-start contactor (K3) and one at thehigh-voltage contactor (K1). They shouldbe reconnected to the three 240-VACprimary connections of the high-voltagetransformer. There are additional tapslocated on the high-voltage transformerto accommodate different line voltageinputs. The taps that are used are chosenat the site in order to attain a platevoltage output of 5500 volts. The wirelengths will allow only one way ofconnecting the wires. The secondaryconnections are three, red high-voltagewires. They are connected to the E1connections of the three high-voltagerectifier boards (A5, A6, and A7). Thesethree red wires connect to the secondaryterminals of the high-voltage transformerlabeled 2.6 kV. The wire lengths willallow only one way of connecting thewires. After completion of the abovesteps, the high-voltage transformer isreconnected.The dolly tray has five reconnections thatneed to be made: two to the 5-henrychoke, one to the 5 mF capacitors, andtwo ground cables. The connection to the5 mF capacitors is made to the E3terminals of the high-voltage rectifierboards. The black high-voltage wire isreconnected to terminal #2 of the (A8)capacitor, as labeled. The black wireshould be jumpered to terminal #2 of theother three capacitors.There are two reconnections that mustbe made to the (A16) 5-henry choke. Theone red wire is from the 10Ω/30-wattresistor (R19) mounted on the backpanel; this wire must be connected to theterminal of the choke with no other wiresconnected to it. The other terminal of thechoke will have a red wire connected to itthat originates at the #1 terminal of (A8)the 5 mF capacitor. The red wire that isconnected to the junction of the10Ω/300-watt resistor (R2) and meteringresistor (R5) is reconnected to terminal#2 of the choke. The two ground cablesneed to be reconnected to the groundstud, on the side of the high-voltagecabinet, labeled GND. One of the cablesis for (A21) the grounding rod assemblyand the other is the ground connection to
10-kW UHF Transmitter with Chapter 3, Installation and Feedforward Drive Setup Procedures840A, Rev. 0 3-8the dolly tray. Reconnect both of thesecables.The high-voltage power supply is nowfully reassembled and ready for the mainAC hookup.3.6 Installation of the High-VoltagePower Supply to the 10-kW InterfaceControl CablesWhile performing the followinginstallation procedure, refer to theinterconnect drawing (1094338) for the10-kW transmitter.The high-voltage interface control cablesare inside the 3/4" conduit that runs fromthe 10-kW amplifier cabinet to the high-voltage power supply. To reinstall thesecables, connect the conduit between thehigh-voltage power supply and the 10-kW amplifier cabinet, using the floor plandrawing as a reference. Connect thethree alpha wires and the three otherwires to the proper terminals of TB2 onthe roof of the high-voltage power supplyassembly and on the other end to (A10-J2) of (A10) the remote control andcabinet interface assembly in the 10-kWamplifier cabinet.3.7 Installation of the High-VoltageWire HarnessThe anode (plate) voltage cables connectthe high-voltage output of the high-voltage power supply to the anodevoltage connector of the tube cavity inthe 10-kW amplifier cabinet. The twowires are labeled, wrapped, and storedinside of the 10-kW amplifier cabinet forshipment. The installation of the 1"conduit between the high-voltage powersupply assembly and the 10-kW amplifiercabinet must be performed first. Locatethe 1" conduit labeled for the high-voltage power supply. Using the floorplan drawing as a guide, connect theconduit between the high-voltage powersupply and the 10-kW amplifier cabinet.Now feed the red and the black high-voltage wires through the conduit fromthe connected side at (A8-S11-E and F)the high-voltage interlock switch of the10-kW amplifier to the high-voltagepower supply assembly. After the twowires are fed through the conduit,connect the black ground wire to thechassis ground bolt labeled High-VoltagePower Supply RTN on the high-voltagepower supply. Solder the red plate(anode) wire to the fuse holder, terminal#2 (F1-2), in the high-voltage powersupply cabinet.3.8 AC Interface HarnessThe AC interface harness provides ACvoltage from the high-voltage powersupply assembly to the 10-kW amplifiercabinet. To hook up the AC interfaceharness, locate the 1-1/2" conduitlabeled High-Voltage Power Supply. Thesix, AWG-14 wires of the harness willalready be inside the conduit. Mount theconduit onto the high-voltage powersupply assembly and the 10-kW amplifiercabinet according to the top view of the10-kW transmitter and the floor plandrawing. Four of the wires inside of thehigh-voltage power supply assemblyconnect to TB6 on the side of the cabinetaccording to the labeling on the wires.Two of the wires inside of the high-voltage power supply assembly connectto TB4 on the side of the cabinetaccording to the labeling on the wires.This completes the connections inside ofthe high-voltage power supply assembly.To connect the harness to the 10-kWamplifier cabinet, the six wires areconnected to the terminal block, TB1.These wires should be connectedaccording to the labeling of the wires andthe terminal block.
10-kW UHF Transmitter with Chapter 3, Installation and Feedforward Drive Setup Procedures840A, Rev. 0 3-93.9 Main AC ConnectionsCaution: Check that all circuitbreakers are off (Down) beforemaking the main AC connections.The AC feeds for the 840A 10-kWtransmitter consist of two main circuitsas described in Table 3-1.Table 3-1. 840A Main CircuitsCABINET ASSEMBLY CIRCUIT WIRE SIZEExciter/Driver Assembly 40 amp, 208/240 VAC AWG 6, 1-1/4" ConduitHigh-Voltage PowerSupply/10 kW 100 amp, 208/240 VAC AWG 2, 2" ConduitThe AC is connected to (A1) theexciter/amplifier assembly through anopening in the roof assembly of thecabinet. A 1-1/4" conduit should be usedfor running the AC line to the cabinet.The single-phase AC is connected toterminal block TB1 of (A2) the ACdistribution assembly directly under theopening. The single-phase 208/240 VACis connected to terminals 1A, 2A, and 4A.The neutral is connected to terminal 2Aand the safety ground is connected toterminal 3A.Note: In 240 VAC, connect the highleg (L1) TO TB1-1A.The 3-phase AC input to the high-voltagepower supply cabinet is connected to the100-amp main AC breaker (CB1) on theinside, top right of the cabinet. A 2"conduit should be used for running theAC line to the cabinet. The AC isconnected to CB1 according to the localwiring codes. Connect L1 to CB1-2, L2 toCB1-4, and L3 to CB1-6 with the safetyground connected to the ground studnear the circuit breaker.Note: In 240 VAC, connect the highleg (L1) to CB1-2.Refer to section 3.5 of this manual forinformation on the three-phaseconnections and see Appendix A for theinterconnection drawings for the high-voltage power supply assembly.After the cabinets and the transmissionlines have been installed, and during thetest and setup procedure, the systemshould first be connected to a 10-kW testload and not the antenna. Thetransmitter should be operated in thismode until testing and setup arecompleted. After the initial turn-on andsetup procedures are completed, theoutput of the transmitter can beconnected to the antenna for normaloperation.3.10 Installation of the Tube into the10-kW Tube Cavity AssemblyTo install the TH610 tube into the 10-kWtube socket assembly, first remove thecover to the chimney. Raise the chimneyuntil it reaches the top and then turn it tolock it in place. This will allow access tothe top cover of the tube cavity. Theupper anode section can then beremoved by loosening the two 6-mm hexbolts on the top of the assembly andpulling up the upper anode section. Oncethe section is removed, inspect thesocket assembly by looking down insidethe assembly. Check closely around thefinger stock for any foreign material thatmay have fallen into this area duringinstallation.Remove the TH610 tube from theshipping box and carefully place the tube,with the small end (filament) down, intothe socket assembly. Using the tubepuller that has been supplied with thetube, seat the tube into the socket
10-kW UHF Transmitter with Chapter 3, Installation and Feedforward Drive Setup Procedures840A, Rev. 0 3-10assembly by putting a firm, evendownward pressure onto the top of thetube. The tube puller should be mountedonto the right, front corner of the tubecavity assembly.Caution: Do not turn or twist thetube while seating it. This willdamage the finger stock.Snugly replace the upper anodeassembly. After the cover is seated, the6-mm hex bolts must be tightened tohold it in place.3.11 Initial Turn-On ProcedureNote: Make sure that all of theinstallation procedures describedearlier in this chapter have beencompleted before proceeding withthe initial turn-on of the transmitter.Caution: Check that all of the circuitbreakers on the exciter/amplifierassembly, the 10-kW amplifier, andthe high-voltage power supplycabinets are off.Check that the combined RF output ofthe (A18) coupler assembly is terminatedinto a dummy load with a rating of atleast 10,000 watts. If the individualassemblies are tested one at a time,check that the visual + aural RF output ofthe 10-kW amplifier assembly or the250-watt amplifier trays in theexciter/amplifier assembly areterminated into appropriate dummyloads.3.11.1 Exciter/Amplifier AssemblyInitial Turn-On ProcedureFor the initial turn-on of theexciter/amplifier assembly, the 10-kWamplifier does not need to be enabled,but the Driver Mode Select switch on themetering control panel of the 10-kWamplifier must be in the Test position.For the normal operation of thetransmitter, the switch must be in theNormal position.Note: In order to proceed, the outputof the exciter/amplifier cabinet atthe top of the cabinet must beterminated into a 500-watt load.Switch on the main AC, exciter, switcher(if used), precise frequency tray (ifused), 3-watt amplifier, and 250-wattamplifier circuit breakers on the ACdistribution panel of the exciter/amplifierassembly. Switch on the on/off AC circuitbreaker on the AC distribution panel inthe rear of the cabinet.Switch on the circuit breaker on the rearof the 250-watt amplifier trays. Thecircuit breakers should light to indicatethat the AC is present to that tray. Movethe Operate/Standby switch on the UHFexciter front panel to Operate andobserve the front panel power supplymeter readings for the 250-watt amplifiertrays; a typical reading is ≈+27 VDC.Return the Operate/Standby switch toStandby.3.11.2 10-kW Amplifier and High-Voltage Power Supply AssemblyInitial Turn-On ProcedureCaution: Check that all of the circuitbreakers associated with the high-voltage power supply and the 10-kWamplifier are switched off beforeinstalling the tube.3.11.2.1 10-kW Amplifier Initial Turn-OnProcedureThe 10-kW transmitter is equipped with avideo presence detector that is part ofthe transmitter control system. Checkthat switch S6, the Mode Select(Auto/Manual) on the metering controlpanel of the 10-kW amplifier, is in theManual position for normal operation ofthe transmitter. When the switch is in theAuto position, the transmitter will notoperate unless the video input is presentto the exciter(s). This method can be
10-kW UHF Transmitter with Chapter 3, Installation and Feedforward Drive Setup Procedures840A, Rev. 0 3-11used for the automatic turn-on and shutdown of the transmitter (translatorcontrol mode).The initial turn-on of the 10-kW amplifierassembly should begin by first applyingAC power to each cabinet, in sequence,beginning with the high-voltage powersupply and then the 10-kW amplifier. Thehigh voltage that operates the 10-kWamplifier is supplied by the separatehigh-voltage power supply assembly.Note: Verify that the front cover ofthe high-voltage power supply is inplace before continuing. If it is not inplace, an interlock switch will keepthe high-voltage power supply fromoperating.Table 3-2 shows the initial switchpositions for the 10-kW transmitter.Table 3-2. Initial Switch Positions for the 10-kW TransmitterCABINET PANEL OR TRAYMODE/POSITION SWITCH/BREAKERExciter/Amplifier AC Distribution Panel On On/OffExciter/Amplifier AC Distribution Panel On Exciter AC On/OffExciter/Amplifier AC Distribution Panel On Amp(s) AC On/OffExciter/Amplifier Exciter(s) On AC On/OffExciter/Amplifier Precise Frequency Tray AC On/OffExciter/Amplifier Exciter(s) Standby Operate/StandbyHigh-Voltage Power Supply Side Panel On Main AC On/OffHigh-Voltage Power Supply Side Panel On High Voltage On/OffHigh-Voltage Power Supply Side Panel On 10-kW Cabinet AC On/OffHigh-Voltage Power Supply Side Panel On Blower AC On/Off10-kW Amplifier AC Control Assembly On Control On/Off10-kW Amplifier AC Control Assembly On Filament On/Off10-kW Amplifier AC Control Assembly On Bias On/Off10-kW Amplifier AC Control Assembly On Screen On/Off10-kW Amplifier Metering Control PanelManual Mode Select Auto/Manual10-kW Amplifier Metering Control PanelManual High Voltage Enable/Disable10-kW Amplifier Metering Control PanelNormal Driver Mode Normal/Test10-kW Amplifier Metering Control PanelStandby Operate/StandbyThe system control logic and statusindications for the exciter/amplifier andthe 10-kW amplifier assemblies will nowbe operational.Note: The filament of the tuberequires ten minutes of black heat(1.5 volts) before any Operatecommands will occur.Switch the Operate/Standby switch onthe metering control panel of the 10-kWamplifier assembly to Operate. Verifythat the Blower, Filament, and Bias OnCommand LEDs are illuminated on thefront panel, indicating that the commandto have these components begin theiroperations has been initiated. The BlowerStatus LED should be lit when the bloweris on and the Filament Operating StatusLEDs should be lit after a three-minuteramp-up cycle for the filament voltage.After the filament has been on forapproximately three minutes, the Bias On
10-kW UHF Transmitter with Chapter 3, Installation and Feedforward Drive Setup Procedures840A, Rev. 0 3-12Operating Status LED will light, indicatingthat bias is present at the tube. Open thehinged door of the metering control paneland verify that the status of the LEDindicators on the control logic board(1137-1402) is as shown in Table 3-3.Table 3-3. Status of the LED Indicators Mounted on the Control Logic BoardLED FUNCTION GREEN LEDDS1 Operate IlluminatedDS2 Interlock IlluminatedDS3 Air Flow IlluminatedDS4 Filament IlluminatedDS5 Filament UV IlluminatedDS6 Bias IlluminatedDS7 Interlock IlluminatedDS8 HV ExtinguishedDS9 Interlock (Not used) IlluminatedDS10 RF ExtinguishedWhen the filament circuit breaker on thefront panel is activated, the filamentcontrol board requests an output fromthe power supply of +1.5 VDC. After tenminutes of valid operation at thisreduced, or float, voltage thetransmitter can be placed in Operate.Once the Operate switch has beenenabled at the front panel, the powersupply controller gradually increases thefilament operating voltage. After threeminutes, the filament voltage shouldread +5.2 VDC. Switch the voltagemeter on the metering control panel ofthe 10-kW amplifier to the FilamentVoltage position and verify that thefilament voltage has a reading of +5.2VDC.Turn the Voltage Metering switch to theBias Voltage position and verify a readingof approximately -80 VDC.The 10-kW amplifier is now ready for thehigh voltage to be applied.3.11.2.2 High-Voltage Power SupplyInitial Turn-On ProcedureVerify that the high-voltageEnable/Disable switch on the meteringcontrol panel is disabled. Move theVoltage Metering switch to the PlateVoltage position. While observing theplate voltage metering, move the High-Voltage Enable/Disable switch on themetering control panel to the Enableposition. The plate voltage readingshould take two steps and beapproximately 5200 VDC.Move the Voltage Metering switch to theScreen Voltage position. Switch thescreen voltage AC circuit breaker on theAC control assembly to the On position.The screen voltage reading should beapproximately 500 VDC.All of the power supply voltages for the10-kW amplifier should be present at thistime and the following front panelcommand status LEDs should beilluminated: Blower, Filament, Bias, HighVoltage, Screen, and RF Request.
10-kW UHF Transmitter with Chapter 3, Installation and Feedforward Drive Setup Procedures840A, Rev. 0 3-13The following front panel operating statusLEDs should also be illuminated: Blower,Filament, Bias, High Voltage, and Screen.The RF Present will remain off until theexciter/amplifier assembly is enabled.Move the Operate/Standby switch to theStandby position and observe the offcycle of the 10-kW amplifier. The frontpanel command status LED sequenceshould occur as shown in Table 3-4.Table 3-4. Command Status LED Sequence for the 10-kW Amplifier Off CycleLED (GREEN) STATUSRF Request Removed ExtinguishedScreen V Removed ExtinguishedHV Removed ExtinguishedBias V Removed ExtinguishedFilament V Removed ExtinguishedA delay in the off cycle will maintain aBlower On command, for coolingpurposes, for approximately threeminutes after the ramp-down of thefilament voltage. The blower will remainon while the filament is on black heat.Switch on the 10-kW amplifier once moreby moving the Operate/Standby switch toOperate. This time, as the 10-kWamplifier cycles on, check the staticcurrents of the grid, plate, and screen toverify that they are within 10% of thoserecorded on the Test Data Sheet. Turnthe Current Metering switch on the 10-kW metering control panel to thePlate I (Current) position and verify areading of approximately 1.5 amps. Thenswitch to the Screen I position and verifya reading of approximately 5 mA. Turnthe Current Metering switch on the 10-kW metering control panel to the ControlGrid I position and verify a reading ofapproximately 2 mA. The Meter Reverseswitch must be in the Up position. Thenormal position for the switch is in theDown position.The system requires the presence offilament voltage for a three-minute rampup (after 10 minutes of black heat)before the bias voltage, the platevoltage, and the screen voltage areapplied to produce an RF Requestcommand.After completing the initial turn-onprocedure for the 10-kW amplifier, thetransmitter can be operated by using the10-kW Operate/Standby switch on themetering control panel of the 10-kWamplifier assembly.This completes the initial turn-onprocedures for the 840A UHF transmitter.Proceed to the setup and operatingprocedures to attain normal operation ofthe transmitter.3.12 Setup and OperationProceduresInitially, the transmitter should be turnedon with the RF output at J2 of the (A18)coupler assembly terminated into adummy load of at least 10,000 watts. If aload is not available, check that theoutput of the coupler assembly at J2 isconnected to the antenna.Connect the baseband balanced audioinput to the terminal block (TB1) on(A12) the remote interface assembly(1293-1204) at the rear of the excitercabinet. If composite audio, stereo, isused instead of balanced audio, connectthe composite audio input to the BNCjack (J6). Connect the baseband videoinput to the BNC jack (J2) that is also on(A12) the remote interface assembly.Switch on the main AC circuit breaker onthe AC distribution panel assembly
10-kW UHF Transmitter with Chapter 3, Installation and Feedforward Drive Setup Procedures840A, Rev. 0 3-14mounted toward the rear of the singleUHF exciter/amplifier cabinet. Also switchon the circuit breakers for the 250-wattamplifier trays.Turn the Operate/Standby switch on theexciter to Standby and the Auto/Manualswitch on the UHF exciter to Auto.Normal operation of the transmitter iswith the switch in Automatic. Automaticoperation of the exciter uses the videoinput to the exciter as anOperate/Standby switch. In Auto, if thevideo input is lost, the exciter willautomatically revert the transmitter toStandby and, when the video signal isrestored, return the transmitter toOperate.Move the Operate/Standby switch on theexciter front panel and the meteringcontrol panel on the amplifier assemblyto Operate and enable the high voltage.After allowing a warm-up period ofseveral minutes, verify that the frontpanel meter on the amplifier assemblymetering panel, with the switch in theVisual Output Power position, is reading100%. If necessary, with the switch inthe Visual Output Power position, adjustthe Power Raise/Lower switch on thefront panel of the amplifier assemblymetering control panel to attain 100%output on the front panel meter.As the output power level is beingobserved, check the meter readings onthe 10-kW metering panel in the %Reflected Power position. If the %Reflected Power for the readings is high,above 10%, a problem exists with theoutput coaxial lines for the system andneeds to be checked and corrected. Acenter bullet missing from the 3-1/8"rigid coax lines, or loose bolts on theconnections, can cause this problem.Observe the % Exciter Power reading ofthe meter on the exciter; it should be thesame as on the Test Data Sheet for thetransmitter.The gain control on the front panel of theexciter tray was adjusted at the factoryto attain 100% output of the transmitterand should not need to be readjusted.Refer to the Test Data Sheet for thetransmitter and compare the finalreadings from the factory on the TestData Sheet with the readings on the trayafter the setup. They should be verysimilar. If a reading is significantlydifferent, refer to the power adjustmentprocedure for the exciter tray in Chapter5, Detailed Alignment Procedures, of thismanual before trying to make anyadjustments.If a dummy load is connected to thetransmitter, switch the transmitter toStandby and switch off the main ACcircuit breakers found on the ACdistribution panels in each cabinet.Remove the dummy load and make all ofthe connections needed to connect thetransmitter to the antenna. Switch on themain AC circuit breakers and move theOperate/Standby switch to Operate. Tunethe exciter power adjust pot to attain a100% combined output.If the transmitter is already connected tothe antenna, check that the combinedoutput is 100%. If needed, tune thepower adjust pot on the 3-watt tray for areading of 100% in the Visual Outputposition.This completes the transmitter setup andoperation procedures for the 840A 10-kWUHF transmitter. The transmitter cannow be operated normally. For normaloperation, the exciter should be inOperate and the Auto/Manual switchshould be in Auto.If a problem occurred during the setupand operation procedures, refer toChapter 4, Detailed AlignmentProcedures, of this manual for moreinformation.

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