Specifications

Section-5 Maintenance
October 17, 2013
5‐16
Copyright©2013,HarrisBroadcast
WARNING:Disconnectprimarypower priortoservicing. 888‐2693‐004
5.5.1.1 TroubleshootingPrecorrection
IftheRTACmodearesettoADAPT,buttheAttemptscounterdoesnotincrementwithinthirtyseconds,thereisa
problemwiththefeedbacksamples.
Checkthesignallev
elsatthePREandPOST‐FILTERinputsonthebackoftheLPU.Theyshouldbebetween‐10dBm
and+5dBm(optimumis‐5dBmattheinputsonthebackoftheLPU).
ChecktheRT
AClevelsontheLPUSTATUS>RTACGUIscreen.Thebarmetersshouldbegreenandthelevelshould
bejustbelowtheblack100%line.
Checktha
ttheExciterHomescreenshowsONintheup perleftcorneroftheGUIscreen.IftheexciterisOFFor
MUTE,thecorrectionscannotbecalculated.
5.5.2 StoringPrecorrection
FollowthisproceduretostorethecalculatedRTACcorrectionvaluestoLPUmemory.
STEP 1
GototheRTAC‐StoredCorrectionsetsScreen,Figure5‐8onpage5‐16.
Figure 5-8 RTAC Stored Correction Sets Screen
STEP 2
Enteranameofuptosixteencharactersforthedesiredset.
STEP 3 PresstheSAVEbuttontostorethecorrectiontomemory.
Note
The correction currently being applied will be stored, overwriting any values previously stored in mem-
ory.
STEP 4
Endofprocedure.
5.5.3 RTACSetupandOperationinCombinedSystems
HarristelevisiontransmissionsystemsuselinearRTAC(RealTimeAdaptiveCorrection)tocompensatefordistortions
producedbytheoutput maskfilter.Single transmittersystemsuseaforwardpowersample,takenfr omadirectional
couplerafterthemaskfilterthatissentbacktotheexciterviacoaxialcable.Thesample(‐5dB
mlevelisnominalfor
M2Xexciters,LPUs,andCCD‐LPUs)isusedtoproducepre‐correctionwhichisappliedtotheexciteroutput.Thus,
theexciteroutputispre‐distortedtocompensateforthedistortionsproducedintheoutputmaskfilter.Single
transmittersystemsnormallyoperatewithRTACcorrectionssettoAdap
tmode.Preandpost‐filterRTACsample
levelsshouldbewithin1dBofeachother.
Multipletr
ansmitters(atdifferentchannels)canbecombinedintoacommonantennausingacombinersystemas
showninthesamplesketchbelow.