To Test Input Resistance; Procedure - Agilent Technologies 54835A Service Manual

Chapter 3: Testing Performance

To test input resistance

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-M Ω inputs.
Specification: 1 M Ω ± 1% and 50 Ω ± 1.5%
Equipment Required
Equipment
Digital Multimeter
Cables (2)
Adapter
Adapters (2)

Procedure

Set up the multimeter to make a four-wire resistance measurement.
1
Assemble the test cables.
2
a Use the two BNC-to-banana adapters to connect one end of each BNC cable to the four-
b Connect the free ends of the cables to the BNC tee.
Figure 3-3
To oscilloscope
channel input
Input Resistance Equipment Setup
Connect the male end of the BNC tee to the channel 1 input of the oscilloscope.
3
Press Default Setup to set the oscilloscope to default conditions.
4
Press the Input key for Channel 1 to select 1 M Ω , then 50 Ω , and verify resistance
5
readings of 1 M Ω ± 10 k Ω and 50 Ω ± 0.75 Ω respectively.
Record the readings in the Performance Test Record.
6
Repeat steps 3 through 6 on the remaining channels.
7
3–6
Critical Specifications
Measure resistance (4-wire) at better than
0.25% accuracy
BNC
BNC Tee (m)(f)(f)
BNC (f) to dual banana (m)
wire resistance connections on the multimeter.
See figure 3-3.
Recommended Model/Part
Agilent 34401A
Agilent 10503A
Agilent 1250-0781
Agilent 1251-2277
To ohmmeter
4-wire inputs