Specifications

Section-4 Theory
November 11, 2013
4‐30
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4.8.1 RFBlockDiagram
AschematicorientatedblockdiagramoftheMaxiva16ModuletransmitterisshowninFigure4‐18onpage4‐31.
Theexciterswitcher(locatedintheTCUassembly)selectsoneexciterforontheair,theotheroneisconnectedtoa
load.Followingtheexciterswitcherisathreewa ysplitter,whichprovidesRFdriveforuptothreePAcabinets.From
thethreewaysplitter,theRFgoesto
thepredriverassembly.
Note
The IPA and PA modules are the same if the transmitter cabinet has more than 8 PA modules. A modified
IPA module is used in systems that have less than 8 PA modules. Refer to
1.2.7 on page 1-9 for more infor-
mation on modified IPA modules.The predriver assembly features an RF splitter and two predriver mod-
ules. It therefore has one input and three outputs. The predriver assembly is discussed in greater detail
4.6.2 on page 4-18, and its block diagram is shown in Figure 4-11, on page -20.
ThetwoRFoutputsignalsfromthepredriverareappliedtotheIPAbackplane,wheretheydrivetwoIPAmodules.
ThetwoIPAoutputareappliedtotheRFdriveswitch,wheretheoutputfromoneIPAdrivesthePAmodulesandthe
otherissenttoatestload.
TheontheairIPAoutputdrivesatwowa ysplitter,witheachofitsoutputsdrivinganeightwaysplitter.Eachof
these16RFoutputsareusedtodrivethe16PAmodules.
ThePAmodulesareinsertedintomatingconnectorsonbackplanemodules.Eachbackplanemodulewillholdfour
PAmodules,therefore,fourPAbackplanesarerequiredtohousethe16PAmodules.
ThePA(andIPA)backplanesareinterfaceswhichsupplyeachPA(orIPA)modulewiththefollowing:
• ThreephaseACpowertofeedtheeightACtoDCconverterswithineachPAmodule.Theseconverterssupply
theDCpowertothefourPApalletswithineachPAmodule.
• RFdrive.
• Controlandmonitoringsignals.
• Sync,requiredforanalogTV transmittersonly.
TheoutputsfromthePAmodulesarecombinedasfollows:
• PASlots1through8arecombinedin8‐WaycombinerA13.
• PASlots11through18arecombinedin8‐WaycombinerA12.
• Theoutputsofthetwo8‐Waycombinersarejoinedin2‐WaycombinerA14.