Tektronix 494A O o a o o a o o o o o o o o o o o o o o o o o o o o a, Performancecheckprocedure

PerformanceCheck Procedure- 4g4Ll4g4ApServlceVot..l

PERFORMANCECHECKPROCEDURE

o o o o o o

1.Check 10 MHz Reference Oscillator Accuracy (Agingrate <1 x 10-7)

The 10 MHz ReferenceOscillatoraccuracyis not a performancerequirement;however,it must be checked so the centerfrequencyaccuracycan be verified. Since the calibrator is locked to the 10 MHz oscillator this procedureverifiesaccuracyby countingthe frequency of the calibratorsignal.

a.Connectthe CAL OUT signal to the frequency counter. (Counterswith a frequencyrange above 200 MHz may requirea 150 MHz low passfilterto €nsurea stabletriggeron the 100MHz CALOUTsignat).

The TektronixDC 509 must.bemodifiedto accept an external oscillator reference. Refer to the TMS00ffM5000Series Rear InterfaceData Book, part No. 070-2099_04 for modificationinstructions.

b.Connectthe frequencystandardto th€ External FrequencyStandardInputof th€ frequencycounter.

c.Checkthat the frequencyof the GAL OUT signat is 100MHz*10 Hz .

d.Disconnectthe counterfrom the CAL OUT con_ nector.

2.CheckCounterAccuracy

[CFx gslslsnceFrequencyError+ (10+ 2N)Hz+ l LSD

a.SettheSpectrumAnalyzercontrolsas follows:

CENTERFREOUENCY 500MHz

sPAN/DrV2AkHz

AUTO RESOLN	On
REF LEVEL	-30 dBm
VERTICALDISPLAY	10dB/Dlv
TrME/DrV	AUTO
TRIGGERING	FREERUN

b.Applythe CAL OUTsignatto the RF lNpUT,and centerthe 500MHz markercalibratorharmonic.

c.Press <Blue-SHtFT> COUNT RESOLNand enter1 Hz via the DataEntrykeypad.

d.Press COUNT and note that the error over several counts does not exceed .lSHz. The factor (CFx ReferenceFrequencyError)is canceledwhenthe CALOUTsignalis used.

e.ResetSPAN/DIVto 500 kHz.

f.Press <Blue-SHIFT> COUNT RESOLNand enter1 kHz for a counterresolutionof 1 kHz.

g.Press COUNT and note that the error over severalcountsdoesnot exceed1 kHz.

h.Resetthe sPAN/Dlvto 200 kHz and repeatpart

g.

i.SEt thE CENTERFREOUENCYtO 1.8GHZ Or

1.7GHzand repeatthe counteraccuracycheckfor this end of the band.

3.Check Counter Sensitivity

(At least 20 dB above the averagenoise level at center screen and no more than 60 dB down from the refer€ncelevel)

a.Applythe CALOUTsignalto the RF INPUTviaa

1dB and a 10 dB step attenuator.Set bothattenuators for 0 dB attenuation.

b.Set the SpectrumAnalyzercontrolsas follows:

CENTERFREOUENCY	100MHz
sPAN/DrV	1 MHz
RESOLUTIONBANDWIDTH 1 MHz
REFLEVEL	0 dBm
NARROWVIDEOFILTER	On
VERTICALDISPLAY	10dB/Drv
TrME/DtV	AUTO
TRIGGERING	FREERUN

c, Set the 1 dB and 10 dB attenuators such that the signal amplitude is approximately 20 dB above the noise floor.

d. Press <Blue-SHIFT> COUNT RESOLN and enter 1 Hz via the Data Entry keypad.

e. Press COUNT and note that the counter is count- ing the signal with the accuracy noted in performance check step 2.

f. Reset SPAN/DIVanclRESOLUTIONBANDWIDTH to 100 Hz, REF LEVEL to -30dBm, and activate WIDE VIDEO FILTER.

g, Reset the 1 dB and 10 dB attenuatorssuch that the signal amplitude is approximatety60 dB down from the referencelevel.

h. Press COUNT and note that the counteris count- ing the signal with the accuracy noted in performance check step 2.

o o o o a o o a o o o o o o o o o o o o o o o o o o o o a

O O

o o o o

4-6

o o o