Tektronix 494AP service manual O a a, TrME/DtV, Testsettings

PerformanceCheckprocedure_ 4g4Ll4g4ApServlceVol. 1

Tabte4-5

	OTO 30 dB RF ATTENUATOR
SpectrumAnalyzer		TESTSETTINGS
	MIN RF ATTEN dB	ExternalAttenuator	PowerMeter	PowerMeter
ReferenceLevel
	Setting		dB(Rel)
-30 dBm	0 d B			dBm
		20 dB	0 dB:Ref	--15	dBm
-20 ctBm
	1 0 d B	20 dB	+ 1 0 d B	:-5	dBm
-20 dBm	1 0d B
		1 0 d B	0 dB-Ref	- - l A ;
-10 dB,"
	20 dB	1 0d B	+10 dB	=-5	dBm
-10 clBm
	20 dB	0 d B	0 dB-Ref	:-15	dBm
-0 dBm	30 dB
		0 d B	+ 1 0 d B	:-5	dBm

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o. Check that the differencebetweenthe SAVEA andVEWB_disptays tessthanO.SdB up to 1.gGHz, lessthan1.5dB from .t.gGHzto 1g GHz,andtessthan 3.0 dB from 18 GHZ to 21 GHz. Make a note of the level difference between the SAVEA and VIEWB displays.

p. To check the next 10 dB step,resetthe genera_ !o^rlor a 0 dB power meter reading,and replacethe 20 dB attenuatorwith a 10 dB attenuitor.

_- _e.I"peat parts m througho, exceptthat the next MfN RF AfiEN dB settingwitt Ue20 and rhe reference levelwillbe -10dB flabte 4-5).

. r. lepeat,the procedurefor the third 10 dB step as a guidefor setupinformationfor

lfing__T19le-4-5th€ thirdMINRF ATTENdB setting.

PART II

a.The 30-60dB range is checkedin the same fashionas the 0-30 dB range using differentpower levelsbecauseof the outputlevellimititionof the signal generator.

b.Connectthe test equiprnentas shownin Figure

4-14.Setth€ SpectrumAnalyzercontrolsas follows:

CENTERFREQUENCY			Test Frequency
sPAN/DtV			200 kHz
RESOLUTIONBANDWIDTH			100kHz
REF LEVEL			-25 dBm
MIN RF ATTEN dB			30
MIN NOISE			On
VERTICALDISPLAY			2 dB/Dtv
NARROWVIDEO FILTER			On
TrME/DtV			AUTO
PEAK/AVERAGE			FullyClockwise
VIEWA	and
		VIEWB	On

c. Set the powermetercontrolsas follows:

ModeWatts

RangeHold Out

PowerReference Out

d.Disconnectthe power s€nsor from th€ power divider, and connectit to the 1 mW/S0MHz reference output port through an appropriateadapter. Be sure that the 50 MHz referenceis turnedoff.

e.On the powermeter,pressSensorZeroandwait for the zero light to turn off. Repeat until a zero is attained.

f.On the powermeter,set the S0MHz referenceon and set the Cal Factorswitch to the S0MHz reference. Set the powermeterCatAdj for a 1.000mWreading.

g. Turn off the 50 MHz referenceon the power meter, and reconnectthe power sensor to the power divider.

h. Resetthe powermetercontrolsas follows:

CalFactor Testfrequency

Mode dBm

RangeHold Out

i. Set the generatorcontrolsfor a maximumpower meter reading,then reduce the generatoroutput tevel untilthe meterreads't dB lessthanthe maximum.

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j. Tune the CENTERFREQUENCyconrrotto bring the signalto centerscreen. The REFLEVELmayhave to be variedslightlyto obtaina convenienton-screen display.

k. Usethe SpectrumAnalyzer'sAMPLCALcontrol to positionthe signalpeakat a convenientgraticuleline, then activatesAvE A.

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