Specifications

Section-5 Maintenance
October 17, 2013
5‐14
Copyright©2013,HarrisBroadcast
WARNING:Disconnectprimarypower priortoservicing. 888‐2693‐004
Caution
PAB POWER METERS ARE CALIBRATED AT TIME OF FACTORY FINAL TEST.
DO NOT ALTER POWER METER CALIBRATIONS UNLESS POWER
READINGS ARE CLEARLY IN ERROR. CONSULT FACTORY TEST DATA
SHIPPED WITH TRANSMITTER, PAYING PARTICULAR ATTENTION TO LPU
OUTPUT AND PA MODULE CURRENTS, TO DETERMINE IF METERING MIS-
CALIBRATION IS A POSSIBILITY TO BE INVESTIGATED.
STEP 1 Connectaveragepowermetertoaprecisiondirectionalcouplertemporarily
installedatthePABoutput.Thecoupleroutputshouldbeattachedtoa1kW
load.Ifthedirectionalcouplerwassuppliedwithtransmitter,consultthe
stickersnexttosampleportsforcouplingvaluein‐dB.Ifnocouplingfigureis
ava
ilable,measurethecouplingvaluewithnetworkanalyzer.
Note
Do not forget to include loss of hook-up cables in measurement!
STEP 2 UsetheLCDcontrolbuttonsontheLPUtoselect SETUP>XMTRPOWER
SETTINGS>P OWERCALandthenPABLK#FORWARD.
STEP 3 RaisepowerandcalibrateatthefirstdBmlevel.SelectSaveandthenraise
powertotheseconddBmlevelperinstructionsonthescreen.
STEP 4 Uponcompletionofthefinalcalibrationprocedurethemenuwillprompt
youtoselect“Save”(orcontinue)toexittheprocedure.
STEP 5 ProceedtoPABreflectedcalibrationifrequired,orreconfiguresystemto
resumenormaloperation.
5.4.8 CalibratingPABReflectedPower
STEP 1 ConnectacalibratedcouplertothePABoutputandconnecta1kWloadto
thecoupleroutput.Thisproceduremustbeusedtocalibrateeachpower
amplifierblockinthesystem.
STEP 2 UsetheLCDcontrolbuttonsontheLPUtoselect SETUP>XMTRPOWER
SETTINGS>P OWERCALIBRATION.
STEP 3 UsethecursorkeystoselectPA1REFLECTEDorPA2REFLECTED,etc.
STEP 4 Withthecouplerinthesystem(asabove)measurethepowerattheforward
couplerport(don’tusemeteroffsetforthis).Theactualpoweroutofthe
couplerwillbeusedasareference.
STEP 5 Forthefirstpowerlevelrequestedinthereflectedcalibrationroutineyou
willturnupPABpoweroutputuntila‐16.5dBmpowerlevelatthecoupler
portisachievedfora500WPAB.Fora250WPABthelevelshouldbe‐
22.5dBm
STEP 6 Whenthe‐16.5or‐22.5dBmlevelisachieveddisconnectthepowermeter
andconnectashortSMAcablefromthecouplerporttotheREFIN
connectoronthebackofthePABbeingcalibrated.
STEP 7 PressSA VE.Thiswillmovethecalibrationroutinetothenextstepandask
youforanewdBmlevel.
STEP 8 Connectthepowermetertotheforwardcouplerportandthistimeincrease
theoutputpoweruntilyouread+3.5dBmonthemeterfora500WPABor‐
2.5dBmfora250WPAB.Whenthatlevelisattaineddisconnectthepower
meterandconnectashortSMAcablefromthec
ouplerporttotheREFIN
connectoronthebackofthePABbeingcalibrated.
STEP 9 SelectSave(orcontinue)toexitthereflectedcalibrationprocedure.
STEP 10 RestorethePABtoitsinitialstate.RepeattheprocedureforthenextPABto
becalibrated.