Sharp SD-AT1000W Dokumentacja Pobierz pdf (Strona 199)

Maxiva UAX

October 17, 2013

5‐19

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

5.6 AnalogPowerCalibrations

Analogpowercalibrationdiffersfromdigitalpowercalibration.Usethefollowinginformationwhencalibratinga

transmitteroperatinginanalogmode(NTSC/PAL/SECAMtelevision).

Equipmentnee

ded:

• HPEPM‐seriesPowerMeterand8482HPowerSensor,orAgilentE4418BandType“N”toSMAadapter(or

equivalent).MetershouldbecapableofdisplayingmeasuredvaluesinWattsorindBm.

• Precisiondi rectional couplers(precisionmeaningthecouplingratioshavebeenaccuratelymeasuredforthe

operatingfrequencies).

• Videosignalsource.TektronixTG700orequivalent.

• Blackpicturewithzerosetup

• TektronixVM700Tmeasurementsystemorequivalent

• Spectrumanalyzer(tomeasureintermodulationproducts).HP8150orequivalentwithanalogmode.

TheUA

Xtransmitterhasbeencalibratedatthefactory .Fieldcalibrationcanbeperformedanytimeitisneeded.

PowercalibrationshouldberequiredonlyifaUDC(updownconverterinLPU),PAB,LPU,directionalcoupler,or

samplecableisreplaced.

Caution

POWER CALIBRATIONS SHOULD ONLY BE DONE WHILE OPERATING THE

TRANSMITTER INTO A KNOWN GOOD LOAD SUCH AS A STATION TEST

LOAD. BE CERTAIN THAT THE LOAD IS A CONFIRMED 50 OHMS AND HAS

THE CAPABILITY TO HANDLE THE POWER THAT WILL BE GENERATED BY

THE TRANSMITTER.

Forwardcalibrationmustbeperformedfirstandisfollowedbyreflectedcalibration.Afterselectingthecalibration

type,presstheStartCalsoftkeytobeginthecalibrationprocess(seeFigure5‐10onrigh

tbelow).

Figure 5-10 System Calibration options

System Calibration started

Powerc

alibrationsinclude:

• Forward‐Powerattheoutputofthetransmitteramplifyingstages,beforethebandpassfilter(BPF).

• Reflected‐Poweratthe outputofthetransmitteramplifyingstagesandbeforethebandpassfilter(BPF).

• UDCOut‐PoweratoutputofLPUmodulatorstage(SMAconnectoronupperrearofLPU)

• LPUForward‐Powerattheoutput(typeN)oftheLPUamplifiersection

• PAB#Forward‐Powerattheoutputofindividualpoweramplifierblocks

• PAB#Reflected‐Powerattheoutputofindividualpoweramplifierblocks

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Sharp SD-AT1000W Dokumentacja Strona 199