Tektronix 494AP service manual Ot o, AdfustrnentProcedure- 4g4A/4g4ApServtceVol

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Figure 5-23. Test equipmentsetup for bandlevelingadiustmenl

1tt.Adjust Band Levetinglor CoaxialBands (Bands 1-5)

(R2031,R3034,R3090,R9019andR3022ontheVRInpul trom VR #1 #2 Motherboard)

The mean valueof the frequencyresponse for each band is set to a -20dBm refer- enceat 100MHz.

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a.PerformFrequencyResponseCheckof bands1 through5 as describedin the performanceChecksec- tion and note th€ frequencyat the mean level (average level betweentwo extremes)for each band.

b.Performadiustmentstep 11 (presettingthe Vari-

able ResolutionGain and Baseline Leveling)prior to proceedingwith this step.

c.Remove and install the Variable Resolution moduleon an extender.

d.Connecttest equipmentas shownin Figure5-23.Set the SpectrumAnalyzercontrolsas follows:

FREQUENCYRANGE 1.7-5.5 GHz

FREQSPAN/DV 10 MHz

AUTTORESOLN on

REFLEVEL-20 dBm

MIN RF ATTEN OdB

VERTCALDTSPLAY 2 dB/Drv

VIEWA andVIEWB on

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Figure5-24. Bandlevelingadiustmentandgaindiodeloca- tion3.

e. Apply a calibrated-20dBm signal,whose fre-

quencyis the same as that notedfor the meanlevelin part 'a",

to the RF INPUT. Set the FREQUENCYto the input signal and reduc€ the FREQ SPANIDIV to 500kHz.

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5-24

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