Fluke 5500A, Service Manual

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5500A
Service Manual
6-62
6-79. 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 6-16.
3. To adjust the harmonics, adjust R8, as shown in Figure 6-16 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
is the case, continue adjusting R8. The second harmonic will fluctuate, but there is a
point at which both harmonics will be at the correct decibel level.
R8
40 dBc
50 dBc
2nd harmonic
3rd harmonic
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Figure 6-16. Adjusting the Leveled Sine Wave Harmonics
6-80. Adjusting the Aberrations for the Edge Function
Adjustments need to be made after repair to the edge function to adjust the edge
aberrations.