Chapter 3: Testing Performance
To test input resistance
42
To test input resistance
This test checks the input resistance of the vertical inputs. A four-wire measurement
is used to accurately measure the 50 Ω and 1 MΩ inputs.
Specification: 1 MΩ ±1% and 50 Ω ±1.5%
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.
See Figure 3- 2.
Figure 3-2
Input Resistance Equipment Setup
3 Connect the male end of the BNC tee to the channel 1 input of the oscilloscope.
4 Press Default Setup to set the oscilloscope to default conditions.
5 Press the Input key for Channel 1 to select 1 MΩ, then 50 Ω, and verify resistance
readings of 1 MΩ ±10 kΩ and 50 Ω ±0.75 Ω respectively.
6 Record the readings in the Performance Test Record.
7 Repeat steps 3 through 6 on the remaining channels, and on the external trigger
of the oscilloscope.
Equipment Critical Specifications Recommended Model/Part
Digital Multimeter Measure resistance (4-wire) at better than
±0.1% accuracy
Keysight 34401A
Cables (2) BNC Keysight 10503A
Adapter BNC Tee (m)(f)(f) Keysight 1250-0781
Adapters (2) BNC (f) to dual banana (m) Keysight 1251-2277
To ohmmeter 4-
wire inputs
To oscilloscope
channel input
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