Tait TB8100 Installation And Operation Manual

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Tait TB8100 Installation And Operation Manual Manual pdf 49 page image

TB8100 Installation and Operation Manual Functional Description 49© Tait Electronics Limited June 20054.4 Power DistributionThis section details how the input power feed is distributed throughout thebase station system to power its various sub-systems. The high level blockdiagrams in Figure 4.5 on page 50 show the power distribution paths insingle and dual base station systems, while Figure 4.9 on page 67 providesmore detailed information on a typical single base station system. Also referto “Circuit Description” on page 15 for more detailed circuit descriptionsof the individual sub-systems that make up the BSS.The TB8100 can receive input power from either the AC or DC input.Internal seamless switching between the AC or DC input ensures there areno power interruptions should a changeover occur between the two inputs.The base station will default to the AC input if both AC and DC inputs areprovided.The AC converter has a series switch which isolates the mains input fromthe converter. The DC input, however, has much higher current ratings,and supports an on/off switch on the converter only.The outputs from both the AC and DC high power converters are addedtogether and fed to the PA via the PA1 and PA2 outputs. The auxiliaryoutput is also tapped off this summed output.When a DC module is fitted, a high efficiency standby card can be used topower up the receiver circuitry. If required, the high power but lowefficiency converters can then be disabled, saving considerable power duringperiods of no channel activity, by using the standby card to power the recitermore efficiently.Base stations fitted with a 12V PA do not require a PMU. In this case theDC input is connected directly to the PA, where it is fed to the internalboost regulator board. This board provides a 12VDC output for the reciterand a 28VDC output for the PA circuit boards.The reciter input power feed is distributed to all internal reciter boards.Local regulation ensures that noise and common mode interface signals arekept to a minimum between sub-assemblies. Various power supplies in thereciter further power and isolate critical sub-sections.The reciter also powers the control panel, via a backpower protection diode.The system control bus is used to route power to the control panel, thuswhenever a reciter is powered, and plugged into the control bus, if a controlpanel is connected there will always be a reciter present to drive the controlbus functions.