Fluke 5500A, Service Manual

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5500A
Service Manual
6-116
3. You need to adjust the wave until the spur disappears. To do this, slowly rotate R44
(shown in the diagram) counterclockwise until the spur just disappears. As you
adjust it, the spur will move down the waveform, towards the right. As soon as the
spur is gone, stop rotating R44. If you rotate it too far, the spur will reappear.
Once you have turned R44 to the point at which the spur just disappears, the signal is
balanced between the VCOs and you have completed the adjustment.
R44
om037f.eps
Figure 6-31. Adjusting the Leveled Sine Wave Balance
6-149. Adjusting the Leveled Sine Wave Harmonics
The following procedure adjusts the harmonics for the leveled sine wave function.
Note
This procedure should only be used for adjusting the leveled sine wave
harmonics. Do not use this procedure as a verification test. The
specifications in this procedure are not valid for verification.
1. Set the Spectrum Analyzer to the parameters listed below.
Spectrum Analyzer Setup
Start Frequency 50 MHz
Stop Frequency 500 MHz
Resolution Bandwidth 3 MHz
Video Bandwidth 3 kHz
Reference Level 20 dBm
2. Use your Spectrum Analyzer’s Peak Search function to find the desired reference
signal. The Analyzer should show the fundamental, and second and third harmonics.
The harmonics need to be adjusted so that the second harmonic is at 40 dBc and
third harmonic should typically be at 50 dBc as shown in Figure 6-32.
3. To adjust the harmonics, adjust R8, as shown in Figure 6-32 until the peaks of the
second and third harmonic are at the correct dB level. You may find that you can
place the second harmonic at 40 dBc but the third harmonic is not at 50 dBc. If this