Tektronix 494AP service manual Preliminarypreparation, MAX 10DB/ 2ODB

PerformanceCheckProcedure- 4g4Ll4g4ApServlceVol. 1

PRELIMINARYPREPARATION

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lnitial Power-Up

Duringinitial power-up cycle, the instrumenttype, instrumentoperating system processor firmwarever_

d.The operating functions and modes should initial- ize to th€ following state:

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sion, and the front panel processorfirmwareversions are displayedon the crt for approximatelytwo seconds. The ReplacementParts List in the Serviie manual,lists the ROMsused for each version. The servicemanual also lists the firmwareoperatingnotes associatedwith eachfirmwareversion.

lf the microcomputerdetectsa hardwarefailure.a failurereportwill come on screenand remainfor about

2 seconds. A status messagewill then appear and

remainfor the duration of the failure. press <Blue_

SHIFT> MAX HOLD to bring eror messagesto the

screen.

a. Connectthe spectrumanalyzerpowercord to an

appropriatepower source (refer to power Sourceand

Power Requirementsin Section g, Installation). Set

Readout

REFLEVEL CENTERFRECIUENCY MARKERFREQUENCY sPAN/DrV

VERTDISPLAY RF ATTEN FREORANGE REFOSC RESOLUTIONBANDWIDTH TRIGGERING

AUTORESOLN DIGITALSTORAGE MINNOISE

All otherpushbuttons

On

ODBM 0.90GHZ 0.00GHz

MAX 10DB/ 2ODB

0-1.8a t-ub 3MHZ

FREERUN On

V I E W A & V I E W B o n On

lnactiveor off

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TIME/DIVto AUTOand switchpOWERon.

b. WhenPOWERis sivitchedoR,the pOWERindi-

cator(a greenLED)shouldcomeon.

c. The microprocessorrunsa memoryand UOt€st.

lf no processorsystemproblemsare found,the power-

up programwill completein approximately10 seconds,

and the instrumentwilt be readyto operite. After the

power-uproutine,the crt will initiatizeas shownin Fig-

ure4-'l.

e.Set the MIN RF ATTENdB controtto 0 (NORM) and th€ PEAK/AVERAGEcontrolfullycounterclockwise.

set the TlMEiDlv controlto AuTo, REFLEVELto read -20DBM,and adjust th€ INTENSITYcontrol for the desiredbrightness.Notethat the RF ATTENreadoutis now 0DB.

f.Apply the CAL OUT signal to the RF INPUT througha 50O cableand a N-TO-BNCadapter.

g, A dot markerwill appearin the upperportionof the screen in the MAX frequencymode. This marker indicatesthe locationon the displayto whichthe spec- trum analyzerfrequencyis tuned, With a frequency

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readoutof 0.00GH2,the markerwill be in the upperleft portion of the screen. Rotate the CENTER/MARKER FREQUENCYcontrol and note that the dot marker moves across the display. Notice that the oENTER FREOUENCYreadout (top line) remains at 0.90GH2, and that the MARKERFREOUENCYreadout(second line) changesaccordingto the positionof the marker (dot).

h.Harmonicsof the 100MHz calibratorsignalwill be displayedas shownin Figure4-2. To select100 MHz centerfrequency,pressthe pushbuttonsequence of <Blue-SHIFT>FREO'100MHz.

i.To changethe SPAN/DIVto 100 MHz,pressthe pushbuttonsequenceof <Blue-SHIFT>SPAN/DIV100 MHz. The dot markeris now horizontallycentered,and the 100MHzcalibratorsignalis at centerscreen.

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Figure4-1. Grt disptayat initialpower-up.

aGHz

btntEnNeL UNLOCK:Most lrequencymeasurementswill not be accurateunlil afterthis readouthas changedto lNT.

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