Agilent Technologies 54641A, Service Manual, Page: 31 / 124

2- 7
Preparing the Oscilloscope for Use
To connect the oscilloscope analog probes
To connect the oscilloscope analog probes
The analog input impedance of these oscilloscopes is selectable either 50
Ω
or
1 M
Ω
. The 50
Ω
mode matches 50
Ω
cables commonly used in making high
frequency measurements. This impedance matching gives you the most
accurate measurements since reflections are minimized along the signal path.
The 1 M
Ω
mode is for use with probes and for general purpose measurements.
The higher impedance minimizes the loading effect of the oscilloscope on the
circuit under test.
C A U T I O N
Do not exceed 5 Vrms in 50
Ω
mode. Input protection is enabled in 50
Ω
mode
and the 50
Ω
load will disconnect if greater than 5 Vrms is detected. However
the inputs could still be damaged, depending on the time constant of the signal.
C A U T I O N
The 50
Ω
input protection mode only functions when the oscilloscope is
powered on.
1 Connect the Agilent 10073C 1.5-meter, 10:1 oscilloscope probe to the
analog channel 1 or 2 BNC connector input on the oscilloscope.
Maximum input voltage for analog inputs in 1 M
Ω
impedance mode:
CAT I 300 Vrms, 400 Vpk
CAT II 100 Vrms, 400 Vpk
with 10073C 10:1 probe: CAT I 500 Vpk, CAT II 400 Vpk
2 Connect the retractable hook tip on the probe tip to the circuit point of
interest. Be sure to connect the probe ground lead to a ground point on
the circuit.
The probe ground lead is connected to the oscilloscope chassis and the ground
wire in the power cord. If you need to connect the ground lead to a point in the
circuit that cannot be grounded to power ground, consider using a differential
probe.
service.book Page 7 Wednesday, August 28, 2002 3:25 PM