Harris Platinum Series Technical Manual

Harris Platinum Series Technical Manual Manual pdf 13 page image

SECTION IINTRODUCTION1.1 IntroductionThis section contains a general description of Platinum Seriestelevision transmitters, their control systems, signal paths, andsystem specifications.1.2 General DescriptionPlatinum Series transmitters employ rugged field effect tran-sistors (FETs), parallel amplifier modules, multiple power sup-plies, and a high-resolution flat display screen for metering.The control and monitor system includes storage of up to 32 faultevents with time, date, and description. VSWR foldback auto-matically reduces power during high VSWR operation, such asthat encountered with antenna icing.Available options include dual exciters and an automatic exciterswitcher, redundant drive chains, and 20% aural power on somemodels.Each transmitter consists of a control cabinet and one or moreamplifier cabinets. Transmitters from 1-10 kW have a singleamplifier cabinet containing the aural path, the visual drive chain,and the visual final. 20 kW transmitters have two amplifiercabinets like those used in the 10 kW transmitter.15 kW transmitters have two amplifier cabinets: one for the auralpath and visual drive chain, and one for the visual final. 30 kWtransmitters have one cabinet for aural path and visual drivechain, and two 15 kW visual final cabinets. 45 kW units have twoaural path/visual drive chain cabinets and three 15 kW visualfinals. Finally, 60 kW transmitters have six cabinets, doublingthe 30 kW architecture.In transmitters with multiple visual amplifier cabinets, outboardhybrids are used to combine the outputs of the visual finals.Optional notch or hybrid diplexers are available for all modelsto combine aural and visual signals to permit using a commonantenna system.1.2.1 AC Power DistributionRefer to AC Power Distribution drawing for the following dis-cussion. Each cabinet has its own AC power source. Controlcabinet breaker CB-1, located behind the control panel left of thecontroller boards, protects the wiring in the control cabinet (seeFigure 1-1). A phase monitor guards against low voltage, loss ofone phase, and reversal of the phase sequencing. Line voltagesamples are provided for the system monitor. All logic supplies,exciter power and fan in the control cabinet are controlled byCB-1.Each amplifier cabinet’s AC power is fed through CB-1 to thelogic supply (see Figure 1-3). AC Contactor K-1 feeds the 50 voltsupplies and fan breaker CB-2 (see Figure 1-4). Aux relay K-2activates the AC contactor through commands from the slavecontroller.1.2.2 Transmitter Control SystemSee Figure 1-5. The control system for the transmitter consistsof a main controller mounted in the control cabinet, plus individ-ual slave controllers mounted in each amplifier cabinet. Datafrom the system is interfaced through the monitor board to thedisplay controller, and shown on the front panel flat displayscreen as bar graphs and numerical readings.Transmitter ON/OFF, LOCAL/REMOTE, and powerRAISE/LOWER switches are located on the control cabinet, tothe right of the display panel.1.2.3 Display PanelThe monitor system samples each cabinet and gathers all of thestatus and analog data for the display. The Monitor board inter-faces the main and slave controller information to the displaycontroller. The display is menu-driven, with “soft keys” belowthe display panel for accessing and maneuvering through thevarious pages of information.A HELP key below and to the right of the display panel providesa short description of the page of information being viewed, toassist non-technical personnel in interpreting the data.1.2.4 Fault IndicatorsFault lamps are located below the display and switches. Eachlight, when illuminated, indicates a problem in one of the follow-ing areas: exciter, VSWR fault, VSWR foldback, power supply,controller, air, door, failsafe, phase loss, module, monitor, visualdrive fault, aural drive fault, and external interlock.1.2.5 Main ControllerThe transmitter main control unit provides a central point forcontrol and monitoring the entire system. The main controllerinterfaces with the slave controller(s) for the amplifier cabinets’ON/OFF commands, and with the exciter for powerRAISE/LOWER commands.Peak detectors collect aural and visual RF samples and send themto the main controller for power metering. The main controlleralso directs VSWR foldback action.The main controller has a battery backup to restore the transmit-ter to its previous operating condition after a temporary ACpower failure. A power down timer will automatically turn thetransmitter off if the power is not restored within approximatelytwo hours.Remote status and analog outputs are provided by the maincontroller to a series of D connectors in the rear of the controlcabinet.1.2.6 Slave ControllersThe slave controllers are mounted in the upper left-hand slot ofeach amplifier cabinet. Each is responsible for controlling andmonitoring its PA cabinet. The controllers interface the cabinetto the main controller and monitor in the control cabinet.888-2365-001 1-1WARNING: Disconnect primary power prior to servicing.