Specifications

Section-5 Maintenance
October 17, 2013
5‐32
Copyright©2013,HarrisBroadcast
WARNING:Disconnectprimarypower priortoservicing. 888‐2693‐004
STEP 10 PressLPUOFFbutton.
STEP 11 OnthefrontscreenselectSETUP>SYSTEMSETTINGS>MODELNO.andthen
usetheupordownarrowstochangethemodelno.tothepreviousvalue.
STEP 12 Removecouplerandsettransmitterbacktonormaloperatingcondition.
STEP 13 Endofprocedure.
5.6.6 CalibratingPABPower
PABpowerlevelscanbefoundintheLPULCDbynavigatingtoSTATUS>PAB#>FWDPWRorREFPWR.Theselevels
canalsobeseenonthewebbrowserbynavigatingtotheEXCITERHOME>XMT RHOME>POWERAMPSscreen.If
thePABpowerlevelsdisplayeddono
tagreewiththemeasuredlevels,thencalibrationisneeded.
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
EXCITER GAIN SETTINGS AND PA MODULE CURRENTS, TO DETERMINE IF
METERING MIS-CALIBRATION IS A POSSIBILITY TO BE INVESTIGATED.
STEP 1 ConnectacalibratedcouplertothePABoutputandconnecta625wattload
(minimumsizefora500WPAB)tothecoupleroutput.Thisproceduremust
beusedtocalibrateeachpoweramplifierblockinthesystem.
STEP 2 OnfrontscreenselectSETUP>XMTRPOWERSETTINGS>POWER
CALIBRATION.
STEP 3 UsetheUPcursorkeytoselectPA1REFLECTED,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andthenpressSA VE.
STEP 9 RestorethePABtoitsinitialstate.
STEP 10 SelectCONTINUEtoexitthereflectedcalibrationprocedure.
STEP 11 Repeatsteps1‐10forthenextPABtobecalibrated.
Note
An alternate to the PAB reflected power calibration is possible if a signal generator is available on site.
The generator can be connected directly to the REF IN connector on the PAB rear and simply apply (on
frequency) the two signal levels noted above to that port to calibrate the reflected levels. That simplifies
the reflected calibration procedure by eliminating the need for a directional coupler.
STEP 12 Proce dur ecomplete.