Fluke 5500A, Service Manual

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5500A
Service Manual
6-112
6-137. Equipment Required
The following equipment is necessary for performing the hardware adjustments
described in this section. The models listed are recommended for providing accurate
results.
•
Standard adjustment tool for adjusting the pots and trimmer caps
•
Extender Card (pn 661865, 5800A-7006K, Extender Kit )
•
Oscilloscope Mainframe and Sampling Head (Tektronix 11801 with SD-22/26 or
Tektronix TDS 820 with 8 GHz bandwidth)
•
10 dB Attenuator (Weinschel 9-10 (SMA), or Weinschel 18W-10, or equivalent)
•
Cable provided with SC300
•
Spectrum Analyzer (Hewlett-Packard 8590A)
6-138. Adjusting the Leveled Sine Wave Function
There is one adjustment procedure that needs to be made for the leveled sine wave
function. The procedure adjusts the harmonics.
6-139. Equipment Setup
This procedure uses the spectrum analyzer. Before you begin this procedure, verify that
the Calibrator Mainframe is in leveled sine wave mode (the Levsine menu is displayed),
and program it to output 5.5 V p-p @ 50 MHz. Press
O
to activate the output.
Refer to Figure 6-24 for setup connections and connect the Calibrator Mainframe to the
Spectrum Analyzer. Adjust the Spectrum Analyzer so that it displays one peak across its
horizontal centerline. The far right of the peak is fixed at the far right of the centerline,
as shown below.
6-140. Adjusting the Leveled Sine Wave Harmonics
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.
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
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 -34 dBc and third
harmonic should typically be greater than or equal to -39 dBc as shown in Figure 6-29.
To adjust the harmonics, adjust R8, as shown in Figure 6-29 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 -34 dBc but the third harmonic is less than -39 dBc. If this is the
case, continue adjusting R8 until the third harmonic is at –39dBc and the second