Testing Performance 6
Keysight Infiniium MXR-Series Real-Time Oscilloscopes User's Guide 67
Input Impedance Test
This test checks the input impedance of the vertical inputs. A four-wire
measurement is used to accurately measure the 50 Ω and 1 MΩ inputs.
Specifications •1MΩ ±1%
•50Ω ±3.5%
Equipment
Required
Procedure
1 Set up the multimeter to make a four-wire resistance measurement.
2 Assemble the test cables:
a Use the two BNC-to-banana adapters to connect one end of each BNC
cable to the four-wire resistance connections on the multimeter.
b Connect the free ends of the cables to the BNC tee as shown here.
3 Connect the male end of the BNC tee to the channel 1 input of the
oscilloscope.
4 Click Control > Factory Default to set the oscilloscope to default conditions.
5 Open the Channel dialog box for channel 1 (Setup > Channel 1...). Set the scale to
5 mV/div and set the channel input impedance to 50 Ω. Verify a resistance
reading of 50 Ω ±1.75 Ω.
6 Record the readings in the "Input Impedance Test" table of the "Performance
Test Record" on page 89.
7 Repeat step 5 and step 6 for the remaining 50 Ω vertical scale settings in
Table 5.
Description Critical specifications Recommended model
or part number
Digital Multimeter Measure resistance (4-wire) at better than
±0.1% accuracy
34411A, 3458A, or
34465A
Cables (2) BNC 10503A
Adapter BNC Tee (m)(f)(f) 1250-0781
Adapters (2) BNC (f) to dual banana (m) 1251-2277
To DMM 4-wire
inputs
To oscilloscope
channel input
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