Sharp SD-AT1000W Especificaciones descargar pdf (Pagina 190)

Section-5 Maintenance

October 17, 2013

5‐10

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

RecallfromtheforwardpowercalprocedurethattheLPUFWDsampleinputisalsoapproximately0dBmatfull

systemoutputpower.ThiswasbydesigntoallowtheFWDsampletobeusedasaconvenientsignalsourcefor

reflectedcalibration.

Inge

neral,thecalibrationisperformedbyconnectingapowermetertotheforwardcouplerusedinthesystem

forwardcali brationandthenraisingthesystemoutputtofullpower.Therequiredlevelwillbeindicatedonthe

calibrationscreen:itisthesameasthehighcalibrationpointinthefo

rwardcalibration(e.g.61dBmina1.0kW

digitalsystem)asindicatedonthemeter.TheuserwillthenremovetheRFLDsampleinputcablefromtheactive

LPUandconnecttheFWDsampleinitsplace‐‐througha20dBpadforthelowpointanddirectlyforthehighpoin

t

‐‐thusprovidingthedesired‐20dBmand0dBmlevels,respectively.

5.4.4 SystemReflectedCalibrationProcedure

STEP 1 ZeroandcalibrateyourRMSpowermeter,followingthemanufacturer’s

proceduresforyours pecificmodel.

STEP 2 Locatethesystemforwardcalibrationsample,whichshouldhavebeen

measuredandlabeledatthefactorywiththecouplingfactorforyour

frequencyofoperation.Thiswilleitherbeaforwardportonthepre‐filter

directionalcouplerwhichisleftavailableforthispurposeinastandalone

(i.e.non‐ra

cked)configuration,orthefrontbulkheadPREFILTERforward

powersampleinarackedconfiguration.Ifthecouplingfactorisinquestion,

orifthefrequencyhaschanged,theapplicableforwardcouplerportshould

besweptwithanetworkanalyzertodeterminethecorrectcouplingfactor

tobeused.Remembertoincludeth

elossintheroutingcablesinthis

networkanalyzermeasurementwhencharacterizingthebulkhead

measurementpoint.

STEP 3 Oncethecouplingvalueisdetermined,enterthisvalueasanoffsetinyour

powermeter,setthemeter’sdisplaytoreadindBm(3digitsissufficient,i.e.

xx.xdBm),andconnectthemeter’ssensortothisport.

Note

Please ensure that the sample level present at this point (max system output, in dBm, minus the coupling

factor) does not exceed the maximum input range of your particular power sensor.

STEP 4 Enterthereflectedpowercalibrationmenu,eitherfromthefrontpanel

(SETUP>XMTRPOWERSETTINGS>POWERCAL>REFLECTED)orfromthe

WebGUI.See’SystemCali bration’(leftside)Figure5‐3onpage5‐6.

STEP 5 UsetheapplicableRaise/Lowerbuttons(dependingonwhetheryouare

calibratingfromthefrontpanelorWebGUI)toadjustthetransmitter

outputpoweruntilthepowermeterindicatesthevaluerequestedonthe

calibrationscreen.Thiswillbethefullsystemoutputpowervalue,thesame

asthehighcalibrationpo

intintheforwardcalibrationprocedure,(e.g.

61dBmina1kWdigitalsystem).Onceastablereadinghasbeenobtainedon

thepowermeter,proceedtothelowpointcalibration.

STEP 6 Lowpointcalibration:RemovetheFWDandRFLDsamplecablesfromthe

activeLPU(thecablesarelabeledFWDandRFLDontheirrespectiveheat

shrinktubinglabels).Ifdesired,useapowermetertomeasurethelevel

presentontheFWDsamplecableandverifythatitisapproximately0dBm.

ConnecttheFWDsampleca

ble,througha20dBattenuatorpad,totheREF

PWRinput.PresstheSavebuttontostorethevalueinmemoryandproceed

tothehighpointcalibration.RefertoFigure5‐6.

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