Sharp SD-AT1000W Dokumentacja Pobierz pdf (Strona 21)

Maxiva UAX

October 17, 2013

1‐7

888‐2693‐004 WARNING:Disconnectprimarypower priortoservicing.

TheLPUusesRTAC™(RealTimeAdaptiveCorrection)toperformpre‐correctionsfornon‐lineardistortionsoccurring

inthetransmitterRFpoweramplifiersandforlineardistortionsoccurringinthehighpowermaskfilter.Lowpower

RFsamplesfromvariousstagesofthetransmitterarerequiredbytheRTACcircuitstodet

erminetheproper

precorrectioncurvestoapply.

TheLP

UmodulatorsectionRFoutputcanbesettoanyUHFchannelandmaybeadjustedtoanylevelupto100mW

averagepowerwhenoperatedinthedigitalmodeandupto200mWpeakofsyncintheanalogmode.TheRFpower

leveladjustmentfortheentiretransmittersyste

misviaavariablegaincontrolcircuitlocatedintheupconverter

portionoftheLPUmodulatorsection.

1.5.1.3 LPUAmplifierSection

ThelowlevelRFsignalfromtheLPUmodulatorsectionispassedviaanexternalcoaxialjumperontherearpanelto

theLPUamplifiersectioninthelowerhalfoftheLPUchassis.

LPUa

mplifiersectionsareavailableintwoconfigurations.Oneconfigurationcontainsasinglepowersupply(PS)and

poweramplifier(PA)module.ThedualPALPU isusedtodrivepoweramplifierblocks(PABs)orasastandalone

transmitterwithoutputpowerofupto100W(digitalmodulation).

LPUPAmodule

shaveoneRFamplifierpalletthatoperateseitherinseries(10Wmoduleonly)orparalleltoprovide

enoughgaintoboosttheoutputsignaltoapproximately10W‐100Wdependingonconfiguration.

TheRFa

mplifierpalletsoperateon50VDCsuppliedbythePSmodules.

Therea

rpaneloftheLPU amplifiercanremovedtoallowamplifiersection50Vfanreplacementwithoutremoving

theLPUchassisfromtheequipmentrack.TheLPUtopcovermustberemovedtochangethetwo12Vfansmounted

inthefrontpartoftheunit.

1.5.2 PowerAmplifierBlock(PAB)

Figure 1-5 PAB (Power Amplifier Block)

1 2 ... 16 17 18 19 20 21 22 23 24 25 26 ... 291 292

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Sharp SD-AT1000W Dokumentacja Strona 21