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Troubleshooting
Troubleshooting Harmonic Spurious
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 Table1-22.
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.
Table 1-22
Harmonic Specifications
< –30 dBc 1 MHz to 2 GHz
–55 dBc 2 GHz to 3.2 GHz
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