Tektronix 494AP service manual O a o o o o, Date 6/1190, Product494N494Ap, ServiceVot.1

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Tektfgnl;.	MANUAL CHANGB INFORMATION
Date: 6/1190	ChangeReference:CA59A(revised)
Product:494N494Ap
	ManualPartNo.070-5560-00	productGrOup:2E
ServiceVot.1

The followlngis a revisionof change Reference:c2ls90 datectslztgo. ln section 4 - PERFORMANCEcHEcK pRocEDIJRE changeas foilows:

Replacestep5 wlth the fottowlng.

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5. CheckCenterFrequencyStabitity

[Driftis50Hzlminorlesswith1stLOlocked(SPAN/DtV <200kHz for band1 and bands5 through12, and SPAN/DlVs100kHzforbands2through

+)lftert hour

ol warmuptimein a stableambienttemperature].

a.ApplytheCatibralorsignalrotheRF tNpUT.

b.SettheSpectrumAnalyzercontrolsas{ollows:

CENTERFREOUENCY	100MHz
SPAN/DIV	50Hz
RESOLUTION	100Hz
BANDWIDTH
REFLEVEL	-20 dBm
MINRFATTENdB	0
VERTICAL	2 dB/DIV
DISPLAY
TRIGGERING	FREERUN
VIEWAandVIEWB	On
TIME/DIV	AUTO

c.Aclivatethe End Of Sweep(EOS)correctionby selecting<blue-SHIFT>WIDEVIDEOFtLTERrhen"3=EOS

CORRECTIONMODETOGGLE.

d.Tunerhe CENTERFREOUENCYro establisha referenceat the intersectionof two graticulelines and activateSAVEA. SeeFigure4-4.

g.check thatthe totaldriftover 60 secondsis within+1 divisionof the referencesignal.

h.DeactiveEOSconectionby selecting<blue-SHIFT> WIDE VIDEOFILTERthen B-EOS CORRECTTONMODE TOGGLE'

l. Enable FrequencyConeclions by selecting<blue-

SHIFT>PULSESTRETCHERthe.6=D

n selecring TSABLE/

ENABLEFREOUENCYCORRECTIONS'.

F€Hc€ffi		ffiREffi
uilEntna,	tw	IM(EN Ff,€q,€Td		SPAW
-20ogr	*	t6,@rrE			frl
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					Drift
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		tl		f			t;
SHIFT>PULSE				,+,-,"1,		t l
STRETCHERrhenseleciing"6=DSABLE/					I
ENABLEFREOUENCY		20&	ODB	G-lr			tmta
CORRECTIONS".			*
		GF		reo	E	vD@	&Jm
f. Observe		O3RAY	Alm	asG	G	fLE	WA
thedriftofthedisplayed
the relerence	signalinrelationto
for 60secondsSee.	Figure4_4.	Figure4-4. Centerfrequenry drift wilh 1st LO locked.