Troubleshooting
Troubleshooting Harmonic Spurious
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Troubleshooting Harmonic Spurious
Harmonics are multiples of the output frequency. The second harmonic is two times the output frequency at
an x dBc down. If the harmonic falls beyond the frequency range of the signal generator, the harmonic is not
specified or measured.
To measure harmonics that fall within the signal generator frequency range, set the signal generator and
spectrum analyzer to the harmonic frequency and set the signal generator to a specified power level. Measure
the output signals peak power level on the spectrum analyzer. This peak power level is the reference level for
the harmonic measurement. Turn on Marker Delta, set the signal generator to the fundamental frequency,
and measure the power level of the fundamental frequency. The dBc value is the difference between the
fundamental peak power level and the harmonic frequency power level.
20 GHz Models
Harmonic problems with a fundamental frequency between 500 kHz and 3.2 GHz.
1. Set the signal generator as follows:
• Frequency - set to harmonic frequency to be measured
• Amplitude +10 dBm
• ALC Off
• Amplitude Power Search (softkey)
2. Remove the cable on A30 Modulation Filter J3 (W27). Connect the spectrum analyzer to the cable.
3. Set the spectrum analyzer to the harmonic frequency, then press peak search and marker delta.
4. Set the signal generator to the fundamental frequency of the harmonic.
5. Using the delta marker, read the harmonic power level on the spectrum analyzer. Compare the spectrum
analyzer reading to the specifications in Table1-40.
6. If the harmonics do not meet specifications, replace the A8 Output.
7. If harmonic meet specifications reconnect the cable to the A30 Modulation Filter J3 and remove the cable
going to A30 Modulation Filter J2 (W31). Connect the spectrum analyzer to the A30 Modulation Filter J2.
8. Set the signal generator and spectrum analyzer to the harmonic frequency, then on the spectrum analyzer,
press marker peak search and then delta marker.
9. Set the signal generator to the fundamental frequency of the harmonic.
10.Using the delta marker, read the harmonic power level on the spectrum analyzer. Harmonic level should
be ≤-55 dBc.
11.If the harmonic level is >-55 dBc, replace the A30 Modulation Filter.
Table 1-40
Harmonic Specifications
<-30 dBc 1 MHz to 2 GHz
-55 dBc 2 GHz to 3.2 GHz
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