Tektronix 494AP service manual OTi#i, O o a, Frequencyrange

Adlustment Procedure- 494A/494ApServlceVot. 1

PRESEIECTONOR]YEREOARD

TtrsooMAN FRATE

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NETARK	DIGITA	OOTB	SPECTRTI AilALYZERlrl'DERTEST
GilERffOR	VOLTreTER GEilERATOR
		SOURCE	OMGEilERATOR
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Figure5-21. PreselectorDriveradiustmentlietup.

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b. Setth€ test equipmentas follows:

TimeMarkGenerator .l0 ns

CombGenerator On

c.Connectthe DVM betweenthe center tap of the MANUALPEAK potentiometerand ground. Adjust the control for 0 V indication. lf index on the knob is not alignedwith the mark on the front panel,loosen knob and positionthe markso it is aligned.

d.Set the SpectrumAnalyzercontrolsas follows:

FREQUENCYRANGE	1.7-5.5 GHz
FREQSPAN/DV	20 MHz
AUTORESOLN	On
REFLEVEL	_30 dBm

E.SEt thE CENTERFREQUENCYtO CENIETthE

2.1GHz markEr. Center the Input Ofiset adjustment R1031 (Figure 5-221,then center the 2.1GHz marker with the CENTER FREQUENCY control. Ground TP1069witha jumperstrap.

f.Adjustthe PreselectorOffsetRl064 for maximum responseof the 2.1 GHz signal. Removethe grounding strap.

s.Peak the 2.1 GHz signalwith the -829MHz lF OfisetR1049(Figure5-22).

h, Remove the Time Mark Generatorfrom the comb Generator. change the REF LEVELto 0 dBm. set FREQUENCYto 5.5 GHz, and centerthe 5.5 GHz combmarkeron screen.

i.Peak the 5.5 GHz signal with the Preselector Sense,R1065adjustment.

j.Due to interactionbetweenR1049and R1065, repeatpartsg throughi.

k.changethe FREQRANGEto 5.4-18.0 (Band4). S€t REF LEVEL and RESOLUTIONBANDWIDTHto obsgrvethe 6 GHz marker. Set the MANUALPEAK controlto peakthe 6 GHzsignal.

l.Set FREOUENCYto 9 GHz and observe th€ 9 GHz marker on screen. Peakthis responsewith the X3 GainRl052 adjustment.

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5-22

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