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4. Check Center Frequency Accuracy

. This is a two part procedure;part I checkscenter frequencyaccuracywith the 1st LO unlocked,part ll checksaccuracywith the l st LO phaselockecl.A front panel CAL should be done before performingthis check.

Part - lst LO not phase Locked Accuracywith the .lst LO unlockedis :r {(20%of the Span/Div or ResolutionBandwidth, whicheveris g.relter)+ (CF x ReferenceFrequencyEror) + 15N kHz).

PerformanceCheck procedure - 4g4ful4g4ApServlce Vol. .l

f.Checkthat the disptayedsignatis within

-0.271

divisions(5T kHz)of center screen.

S.Continuecheckingfrequenciesas indicatedin Table4-2 as per the foilowingexample:

CheckCenterFrequencyAccuracyat 19.5GHz

Fundamentalindicated by frequency counter : 499.99831MHz.

DeternineCenterFrequencyto the nearestkHz: Fundamentalx 37 (from Table 4-2) 0.499998GHz x 37 - 18.a99926GHz

Use Data Entry keypad to s€t CENTER FRE_ QUENCYto 18.499926eHz.

Check that the disptayed signat is within 0.424 divi_ sions (89 kHz) of center screen.

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The 1st LO is not phase_locked

in Fre_ quency Span/Divsettings >200 kHz. For Span/Divsettings (200t<Hz, the 1st LO may be unlocked by first going to an unlockedSpan/DivsettinganOOisa6lingtre- quency corrections (Btue-SHtFT0 dB), then spanningdown to a Span/Divsetting (200 kHz.

QuantityN is the 1st LO harmonicnumber used for the first conversion.press HELp and BAND(down)for the valueof N.

The frequencycountermust be clockedby an externalreferencestandard.

a.Use a FrequencyCounterwith a prescalerto measurethe fundamentaloutputfrequencyof the Comb Generator(Comb Generatorsource output excluding the CombGeneratorModule).

b.Makea noteof,themeasuredfrequency,whichis approximately500 MHz. This is the fundamentalfre- quency referred to in Tabte4-2, and will be used to determineeachcenterfrequencychecked.

c.Connectthe test equipmentas shownin Figure

4-3.

d.Set the SpectrumAnalyzercontrolsas follows:

REFLEVEL -10 dB

SPAN/DIV210k:Hz

AUTORESOLN On

VERTCALDTSPLAY 10 dB/DtV

MINRF ATTENdB O

PEAK/AVERAGE FuilyCtockwise

TIME/DIVAUTO

e.use the Data Entry keypadto set the CENTER FREQUENCYto the fundarnentaltrequencynoted ,n part b {roundedoff to the nearestkHz).

lf a particularcheck shouldfail, measure the fundamentalfrequencyand recheck.

Part ll - lst LO Phase Locked

Accuracywith 1st LO tocked(SPAN/DIV<200kHz for band 1 and bands 5 through 12, and SPAN/DV<10OkHz for bands 2 through 4) is +(20% of the Span/Divor ResotutionBandwiOth,

whichever is greater) + (CF x ReferenceFrequencyEror) + (2N+ 25)Hz.

a.Apptythe cAL ouT signatto the RF tNpuT.

b.Set the SpectrumAnalyzercontrolsas follows:

CENTERFREQUENCY 100MHz

REFLEVEL	-20 dBm
MINRFATTENdB	O
SPAN/DIV	50 Hz
TME/DV	AUTO
VERTCALDTSPLAY	2 dB/DtV
AUTORESOLN	On
TRIGGERING	FREERUN

c. Resetthe REFERENCELEVELto bringthe top of the signalbelowthe dot marker.

d. Check 'l center frequencyaccuracyby 00 MHz

measuringthe deviationof the 100MHzsignalfromthe dot marker. Error must not exceed *.(20T" of the Span/Oiv)+ (25+ 2N)or r,g7 Hz (*9.7 minordivision). The factor (CF x 10-7)is canceledwhenthe CAL OUT signalis used.

e.Repeatthis procedureto check the centerfre- quencyaccuracyto 1.8 GHz in 100MHz increments. Reset the BEF LEVEL as nec€ssaryto observethe comb of 100 MHz markersat the upper end of the range.

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