Input Impedance Test - Keysight Infiniium S Series Service Manual

3
Testing Performance

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
•
•
Equipment Required
Description
Digital Multimeter
Cables (2)
Adapter
Adapters (2)
Procedure
1
2
To oscilloscope
channel input
3
4
5
22
1 MΩ ±1%
50 Ω ±3.5%
Critical specifications
Measure resistance (4-wire) at better than ±0.1%
accuracy
BNC
BNC Tee (m)(f)(f)
BNC (f) to dual banana (m)
Set up the multimeter to make a four-wire resistance measurement.
Assemble the test cables:
Use the two BNC-to-banana adapters to connect one end of each BNC
a
cable to the four-wire resistance connections on the multimeter.
Connect the free ends of the cables to the BNC tee as shown here.
b
Connect the male end of the BNC tee to the channel 1 input of the
oscilloscope.
Click Control > Factory Default to set the oscilloscope to default conditions.
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
±1.75 Ω.
reading of 50
Ω
Recommended model or
part number
34411A or 3458A
10503A
1250-0781
1251-2277
To DMM 4-wire
inputs
S-Series Oscilloscopes Service Guide