Fluke 5500A, Service Manual

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SC300 Option
SC300 Hardware Adjustments for the A4 Board
6
6-115
6-144. SC300 Hardware Adjustments for the A4 Board
Hardware adjustments must be made to the leveled sine and edge functions each time the
SC300 is repaired. In addition to the adjustment procedures, this section provides lists of
the required equipment and some recommendations on models that have the capabilities
required by these procedures. Equivalent models can be substituted if necessary.
6-145. 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
•
Oscilloscope Mainframe and Sampling Head (Tektronix 11801B with SD-22)
•
Delay Cable, 60 ns
•
Spectrum Analyzer (Hewlett Packard 8590A)
6-146. Adjusting the Leveled Sine Wave Function
There are two adjustment procedures that need to be made for the leveled sine wave
function. The first procedure adjusts the balance out of the LO VCO so that the signal is
balanced between the two VCOs. The second procedure adjusts the harmonics.
6-147. 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 5.5V p-p @ 110 MHz. Press
O
to activate the output.
Connect the Calibrator Mainframe to the Spectrum Analyzer. Adjust the Spectrum
Analyzer so that it displays one peak across its horizontal center line. The far right of the
peak is fixed at the far right of the center line, as shown below.
6-148. Adjusting the Leveled Sine Wave VCO Balance
Once you have completed the setup described above, perform the following procedure to
adjust the VCO balance for the leveled sine wave function.
1. Program the Calibrator Mainframe for an output of 5.5V @ 110 MHz.
2. Set the Spectrum Analyzer to the parameters listed below.
Spectrum Analyzer Setup
Start Frequency 110 MHz
Stop Frequency 113 MHz
Resolution Bandwidth 30 kHz
Video Bandwidth 3 kHz
Reference Level 20 dBm
The Spectrum Analyzer will display a spur in the waveform approximately 1 MHz
away from the carrier frequency. Refer to Figure 6-31 to identify the spur.