UBS Axcera 835-3 UHF television transmitter User Manual

UBS-Axcera UHF television transmitter Users manual for equipment

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Chapter 3

3-kW UHF Transmitter Chapter 3, Installation and Setup Procedures835-3, Rev. 0 3-1Chapter 3Installation and Setup ProceduresThere are special considerations that need to be taken into account before the 835-3can be installed. For example, if the installation is completed during cool weather, aheat-related problem may not surface for many months, suddenly appearing during theheat of summer. This section provides planning information for the installation and setup of the transmitter.3.1 Site ConsiderationsThe 835-3 transmitter requires two main AC input lines, a 3-phase 208/240 VAC, 60 Hzinput of at least 100 amp rating that connects to the amplifier cabinet assembly and asingle-phase 208/240 VAC, 60 Hz input of at least 40 amp rating that connects to theexciter/driver assembly. Make sure that the proposed site has the necessary voltagerequirements.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 betaken. The three greatest dangers to the transmitter are heat, dirt, and moisture. Heatis usually the greatest problem, followed by dirt, and then moisture. Over-temperaturecan cause heat-related problems such as thermal runaway and component failure. Eachamplifier tray in the transmitter contains a thermal interlock protection circuit that willshut down that tray until the temperature drops to an acceptable level.A suitable environment for the transmitter can enhance the overall performance andreliability of the transmitter and maximize revenues by minimizing down time. Aproperly designed facility will have an adequate supply of cool, clean air, free ofairborne particulates of any kind, and no excessive humidity. An ideal environment willrequire temperature in the range of 40° F to 70° F throughout the year, reasonably lowhumidity, and a dust-free room. It should be noted that this is rarely if ever attainablein the real world. However, the closer the environment is to this design, the greater theoperating capacity of the transmitter.The fans and blowers designed and built into the transmitter will remove the heat fromwithin the trays, but additional means are required for removing this heat from thebuilding. To achieve this, a few considerations should be taken into account. The firststep is to determine the amount of heat to be removed. There are generally threesources of heat that must be considered. The first and most obvious is the heat from thetransmitter itself. This can be determined by subtracting the average power to theantenna (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 everyhour. 12,000 BTUs per hour equals one ton, so a 5-ton air conditioner will cool a 3-kWtransmitter that is vented into the room. If the air exhaust will be vented externally, a1-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 iscalculated in the same way as the equation for BTUs. The third source of heat is equallyobvious 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 usuallynot a problem. Determining this number is usually best left up to a qualified HVACtechnician. There are far too many variables to even estimate this number withoutdetailed drawings of the site showing all construction details. The sum of these three
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Document ID108439
Application IDNGywfngW/saIIG3C96KN8w==
Document DescriptionChapter 3
Short Term ConfidentialNo
Permanent ConfidentialNo
SupercedeNo
Document TypeUser Manual
Display FormatMicrosoft Word - pdf
Filesize3.65kB (45569 bits)
Date Submitted2000-07-10 00:00:00
Date Available2000-08-16 00:00:00
Creation Date2000-07-10 11:39:06
Producing SoftwareAcrobat Distiller 4.0 for Windows
Document Lastmod2000-07-10 11:39:08
Document TitleChapter 3
FCC ID Filing: OUS835-3

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