Tektronix P6248, Service Manual

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Performance Verification
P6248 1.7 GHz Differential Probe Service Manual
15
Network analyzer
1103
CH 1
input CH 1
output
P6248
Female N-to-male
BNC adapter
Female N-to-male
BNC adapter
BNC-to-probe-tip adapter
CM pair for CMRR test
DM pair for bandwidth test
Port 1 Port 2
Figure 8: Setup for CMRR test
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.
4. Set the reference value of the network analyzer to 0 dBm.
5. Connect the probe input to the CM pins on the BNC-to-probe-tip adapter.
Polarity is unimportant.
6. Set the probe for
÷
1 attenuation.
7. Position the 0 dBm reference near the top of the screen.
8. The network analyzer plot is common-mode feedthrough, the reciprocal of
common-mode rejection ratio. CMRR can be read by inverting the sign of
the magnitude, (that is, -- 46 dBm common-mode feedthrough equals
+ 46 dBm CMRR).
9. Measure the feedthrough magnitude at 1 MHz, 100 MHz, 500 MHz, and
1 GHz. Analyzers with marker capability can do this directly by setting the
marker intercepts at 1, 100, 500, and 1 GHz. If necessary, turn on the
network analyzer Average mode with 16 averages to stabilize the reading.