Tektronix P6248, Руководство по обслуживанию

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Appendix A: Alternate Verification Procedures
P6248 1.7 GHz Differential Probe Service Manual
41
CMRR (Common-Mode Rejection Ratio)
1.
Normalize the setup as follows:
a. Connect the equipment as shown in Figure 18.
18-inch BNC cable
Spectrum analyzer
1103
CH 1
input CH 1
output
18-inch BNC cable
Frequency synthesizer
Figure 18: Normalizing the setup
b. Set the synthesizer to 1 MHz and 10 dBm.
c. Adjust the spectrum analyzer input attenuator to accept the high level of
10 dBm.
d. Set the reference level to 10 dBm, the center frequency to 1 MHz, and
the vertical scale to 10 dB/div.
e. Adjust the span to 10 kHz and the resolution bandwidth to auto.
f.
Record the level displayed on the spectrum analyzer.
2. Remove the BNC cable from the 1103 input, and insert the adapter and
probe as shown in Figure 19. Use the CM pins of the BNC to probe tip
adapter.
NOTE
. CMRR performance is influenced by cable dress. When making CMRR
measurements, keep the probe cable away from ground planes and objects. Do
not allow kinks, loops or other deformities in the probe cable, and maintain a
maximum distance between the probe head and the probe control box.