Tektronix 494AP service manual PerformanceCheckprocedure- 4g4Al4g4ApServiceVol.1

PerformanceCheckprocedure- 4g4Al4g4ApServiceVol.1

SpectrumAnalyeerUnderTest

Figure4-18.Test equipmentsetuplor checklngharmonicdistortion.

d.Monitorthe 10 MHz lF outputon the rear panel with a test sp€ctrum analyzerthrough a 1 dB step attenuator.Set this step attenuatorfor 0 clBof attenua- tion.

e.Set the test spectrumanalyzercontrols as tol-

lows:

CenterFrequency	10 MHz
Frequency	i MHz
Span/Div
Resolution	Auto
Ref Levet	_20 dBm
VerticalDisptay	2 dB/Div
Time/Div	Auto

f.Usethe test spectrumanalyzerCenterFrequency controlto cent€rthe 10 MHz signalon the test spec- trumanalyzer.

g.ActivatezERo spAN and set the CENTERFRE- OUENCYcontrolto maximizethe 10 MHz signalon the test spectrumanalyzerdisplay.

h.Resetthe test spectrumanalyzerreferEncelevel for a fourdivisionexcursionof the signal.

i.Increasethe input signal level to the Spectrum Analyzerby switchingout 1 dB of attenuationbetween the signalgeneratorand the RF INPUT. Add 1 dB of attenuationbetweenthe 10 MHz lF outputandthe test spectrumanalyzer.

j.Checkthat the 10 MHz lF outputlevelon the test spectrumanalyzerdisplayremainsconstantas 1 dB of attenuationis removedfrom the generatoroutput path andinsertedin the 10 MHzlF outputpath.

k.Continueto increasethe inputsignallevelto the RF INPUT by 1 dB incrementswhile increasingthe attenuationbetweenthe 10 MHz lF output and the test spectrumanalyzeruntilthe signalamplitudeon the test analyzerdecreases1 dB (0.5division).Thisis the 1 dB compressionpoint.

4-30