UBS Axcera 420A Low Power Television User Manual Chapter 3

UBS-Axcera Low Power Television Chapter 3

Chapter 3

100 Watt High Band VHF Transmitter Chapter 3, Installation and Setup Procedures420A, Rev. 0 3-1Chapter 3Installation and Setup ProceduresThere are special considerations thatneed to be taken into account before the420A transmitter can be installed. Forexample, if the installation is completedduring cool weather, a heat-relatedproblem may not surface for manymonths, suddenly appearing during theheat of summer. This section providesinformation that will assist in planning forthe installation and set up of thetransmitter.3.1 Site ConsiderationsThe transmitter requires an AC input lineof 115 or 230 VAC with a rating of 10amps. Make sure that the proposed sitefor the transmitter has the voltagerequirements that are needed.The 420A 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. Overtemperature 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 its overallperformance and reliability and maximizerevenues by minimizing down time. Aproperly designed facility will have anadequate supply of cool, clean air, free ofairborne particulates of any kind, andwithout excessive humidity. An idealenvironment requires temperatures inthe range of 40° F to 70° F throughoutthe year, reasonably low humidity, and adust-free room. It should be noted thatthis is rarely if ever attainable in the realworld. However, the closer yourenvironment is to this design, the greaterthe operating capacity of the transmitter.Although the fans and blowers designedand built into the transmitter will removethe heat from within the cabinet,additional means are required forremoving heat from the building. Toachieve this, a few considerations shouldbe taken into account. The first step is todetermine the amount of heat to beremoved. There are generally threesources of heat that must be considered.The first and most obvious is the heatfrom the 100-watt transmitter itself. Thiscan be determined by subtracting theaverage power to the antenna (69.5watts) from the input power (750 watts).This number in watts (680.5) is thenmultiplied by 3.41, which gives 2320, theBTUs to be removed every hour.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. The
100 Watt High Band VHF Transmitter Chapter 3, Installation and Setup Procedures420A, Rev. 0 3-2options 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 kept at areasonable level. In addition, the airmust be adequately filtered to ensurethat no airborne particulates of any kindwill be carried into the transmitter. Acombination of air conditioning forsummer and ventilation during the coolermonths is acceptable when the propercooling cannot be obtained through theuse of ventilation alone and using airconditioning throughout the year is notfeasible.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 regarding 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 unit.With the desired conditioned roomtemperature under 80° F, the unitmust be derated, possibly by asubstantial amount.2. Do not have the air conditionerblowing directly onto thetransmitter. Under certainconditions, condensation mayoccur on, or worse in, thetransmitter.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 of the transmitterfrom the rear of the unit 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, with attendant filters,should be on the inlet, therebypressurizing the room andpreventing the ingress of dirt.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 ventmay be released through the roof.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.
100 Watt High Band VHF Transmitter Chapter 3, Installation and Setup Procedures420A, Rev. 0 3-35. 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 applies even in thesummer.9. A controlled-air bypass systemmust be installed to prevent thetemperature in the room fromfalling below 40° F duringtransmitter operation.10. The blower should have twospeeds that are thermostaticallycontrolled and interlocked with thetransmitter.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.12. Regular maintenance, cleaning,and/or replacement of the filterscan not be overemphasized.13. It is recommended that a site planbe submitted to ADCTelecommunications for commentbefore installation commences.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 ADCTelecommunications. As with anyequipment installation, it is always goodpractice to consult the manufacturerwhen questions arise. ADCTelecommunications can be contacted at(724) 941-1500.
100 Watt High Band VHF Transmitter Chapter 3, Installation and Setup Procedures420A, Rev. 0 3-4Figure 3-1. 1 kW Minimum Ventilation Configuration3.2 Unpacking the Cabinets andTraysNote: Air conditioning and anyrelated heat exhaust ducts should bein place before continuing with theinstallation of the transmitter.Thoroughly inspect the cabinet (ifprovided), 100-watt tray, and all othershipped material upon their arrival. ADCTelecommunications certifies that uponleaving our facility the equipment wasundamaged and in proper working order.The shipping containers should beinspected for obvious damage that isindicative of rough handling. Check fordents and scratches or broken switches,meters, or connectors. Any claimsagainst in-transit damage should bedirected to the carrier. Inform ADCTelecommunications as to the extent ofany damage as soon as possible.Remove the cabinet (if provided) and the100-watt tray, as well as any installationmaterials that make up the 420A, fromthe crates and boxes. Remove the strapsthat hold the cabinet to the shipping skidand slide the cabinet from the skid.Remove the plastic wrap and foamprotection from around the cabinet. Donot remove any labeling or tags from thecabinet as well as any cables orconnectors. These are identificationmarkers which make reassembly of thetransmitter much easier.
100 Watt High Band VHF Transmitter Chapter 3, Installation and Setup Procedures420A, Rev. 0 3-53.3 Installation of the Trays NotSupplied With a CabinetThe trays are to be mounted in astandard 19" cabinet using Chassis Trakcabinet slides (see Figure 3-2). The siderails are pre-mounted on the sides of thetrays. Install the tray slides found in theinstallation materials into the left andright side of a standard 19" cabinet, asshown in Figure 3-3. Check that the trayslides are mounted in line with eachother. Secure the slides by connectingthem to the front and rear mounting barsby using the No. 10 bolts and bar nutsthat have been provided. Insert thetray(s) onto the tray slides and slide thetray(s) into the cabinet. Slowly slide eachtray in and out to verify that they do notrub against each other and have norestrictions to free movement.Adjustments to the position of the traysmay be necessary. This can beaccomplished by loosening the cabinetslide mounting bolts that hold the front ofthe slide to the mounting frame of thecabinet and moving the tray up or downas needed to correct for the rubbing.Retighten the bolts after making anyadjustments. If multiple transmitters arepurchased, refer to the tray layoutdrawing for that specific system for theproper position of each tray.Figure 3-2. Chassis Trak Cabinet Slides
100 Watt High Band VHF Transmitter Chapter 3, Installation and Setup Procedures420A, Rev. 0 3-6Figure 3-3. Cabinet Mounting DiagramConnect the baseband video input to J2on the rear of the tray.Note: J2 is a loop-through connectedto J1. It can be used as a basebandvideo source if the jumper W1 on J3of the sync tip clamp/modulatorboard is removed.Connect the baseband balanced audio tothe terminal block (TB1) or connect thecomposite audio (stereo) to the BNC jack(J13).NOTE: J13 is a loop-throughconnected to J3. It can be used as acomposite audio source if the jumperW4 on J12 of the aural IFsynthesizer board is removed.Connect the transmission line of theantenna to the bandpass filter assemblyoutput A2-A2-J2.If the remote power raise/lower kit(1227-1039) is purchased, the externalpower raise/lower control connects tojack (J10), a 25-position, "D"-typeconnector, on the rear of the tray. Otherremote control functions also connect toJ10 and J11 of the transmitter. Theremote power raise/lower switchconnects to the J10 jack at J10-11 powerraise, J10-13 power raise/lower return,and J10-12 power lower.Connect the AC line cord into jack (J14)on the rear of the tray. Connect the otherend of the AC line cord into an AC outletcapable of supplying at least 10 amps ofcurrent.Note: If the incoming AC requires areconfiguration, see Chapter 2,System Description, for informationon the AC input.This completes the unpacking andinstallation procedures for the 420A.Refer to the system setup and operationprocedures which follow before applyingpower to the transmitter.
100 Watt High Band VHF Transmitter Chapter 3, Installation and Setup Procedures420A, Rev. 0 3-73.4 Setup and Operation ProceduresInitially, the transmitter should be turnedon with the RF output at the bandpassfilter asssembly terminated into adummy load with a rating of at least 100watts. If a load is not available, checkthat the output is connected to theantenna.Connect the baseband video or the(optional) 4.5 MHz composite input to J2on the rear of the tray.Note: J2 is a loop-through connectedto J1. It can be used as a basebandvideo source if the jumper W1 on J3of the sync tip clamp\modulatorboard is removed.Connect the baseband audio, if it isbalanced audio, to the terminal block(TB1) or connect the composite audio(stereo) to the BNC jack (J13).Note: J13 is a loop-throughconnected to J3. It can be used as acomposite audio source if the jumperW4 on J12 of the aural IFsynthesizer board is removed.Note: To operate using the basebandvideo input with the (optional) 4.5MHz composite input kit, thebaseband select must be present atJ18-6 and 7 on the rear of the tray.To operate using the 4.5 MHzcomposite input, the baseband selectmust be removed from J18-6 and 7on the rear of the tray.Switch on the AC circuit breaker CB1 onthe rear of the tray. Switch theOperate/Standby switch to Standby andthe Auto/Manual switch to Manual.Normal operation of the transmitter is inAutomatic and the video input to thetransmitter is used as anOperate/Standby switch. In Auto, if theinput video is lost, the transmitter willautomatically revert to Standby. Whenthe video signal is restored, thetransmitter will automatically return toOperate.Move the Operate/Standby switch,located on the front of the tray, toOperate.Note: If the transmitter does notswitch to Operate when theOperate/Standby switch is switchedto Operate, check that the externalinterlock plug, with a jumper frompins 23 to 24, system interlock, isconnected to jack (J11) on the rearof the tray.Observe the % Visual Power reading onthe front panel meter; it should read100%. If needed, set the power adjustpot located on the front panel. As you arechecking the power level, also check themeter reading in the % Reflected Powerposition. If the % Reflected Power is veryhigh, above 20%, a problem with theoutput coaxial line is present and needsto be checked. Return theOperate/Standby switch to Standby.If a dummy load is connected to thetransmitter, switch off the on/off ACcircuit breaker on the rear of the 100-watt tray. Remove the dummy load andmake all connections needed to connectthe transmitter to the antenna. Switchthe AC circuit breaker on and theOperate/Standby switch to Operate.Adjust the output power front paneladjustment to attain 100% output.Return the Operate/Standby switch toStandby.This completes the setup and operationprocedures for the 420A transmitter.If a problem occurred during the setupand operation procedures, refer toChapter 4, Detailed AlignmentProcedures, of this manual for moreinformation concerning specific trays.

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