4.13-2 Section 4: Using the Model 9500B — Overload Pulse Function
Final Width = 215mm
Descriptions assume 9500B/1100
4.13.6.1 Introduction
The test procedure consists of inputting a single
pulse as specified in the oscilloscope
manufacturer's overload protection test, and
checking that the protection reacts to open-
circuit the 50Ω input termination.
The form of input overload indication will
vary between oscilloscopes.
4.13.6.2 Interconnections
a. Use an active head to connect from the
required 9500B signal output channel to
the UUT input channel.
b. If a UUT trigger is required, use an active
head (or trigger cable) to connect from the
required 9500B channel output to the UUT
Trigger input.
4.13.6.3 9500B and UUT Scope
Setup
The following procedures assume that the
9500B instrument is in Manual Mode. It is also
assumed that the user will be familiar with the
methods of editing screen values. In the case
of difficulty, re-read the paragraphs earlier in
this Section 4.
1. Preparation
Ensure that both instruments are powered ON
and warmed up.
2. UUT 'Scope
Select the required function for overload pulse
protection test.
3. 9500B
Ensure that the 9500B is in Overload Pulse
Function with Output OFF. If in any other
function, press the 'Aux' key on the right of the
'OSCILLOSCOPE CALIBRATOR' panel,
then the
soft key on the right of the
screen.
4.13.5.4 Value Editing
Overload Protection
Different oscilloscope manufacturers have
different ways of defining the overload which
will activate their protection system.
For example, into 50Ω, the two specifications
±
20V for 200ms and 1.6J at a power of 8W are
equivalent.
Normally, where voltage and time are specified,
the voltage will be set and the energy adjusted
to achieve the specified time.
The 9500B can output single pulses whose two
adjustable constituents are Amplitude and Pulse
Energy. The limits on these parameters are:
Amplitude ±5V to ±20V
Pulse Energy 1.6J to 50J
For a fixed Pulse Amplitude the power into
50Ω will remain constant, regardless of pulse
duration. Adjusting the Pulse Energy operates
on the pulse duration at fixed amplitude.
Controlling these two parameters can adapt to
all specifications between the above limits.
Maximum and minimum power values into
50Ω are:
Power 0.5W to 8W
Amplitude ±5V to ±20V
Maximum and minimum pulse durations, with
corresponding parameters, are:
Duration 200ms to 100s
Amplitude ±20V to 5V
Pulse Energy 1.6J to 50J
Power 8W to 0.5W
4.13.6.4 Sequence of Operations
Refer to the table or list of UUT Oscilloscope
Overload Test points in the UUT Oscilloscope
Manufacturer's Test Guide.
Follow the sequence of test stages as directed
by the guide, and carry out the following
operations (1) to (5) at each stage.
1. 9500B
a. Use the front panel controls to set the
9500B Output to the required Overload
Pulse and polarity for the UUT 'Scope test
point.
b. If the scope requires a repetitive trigger,
press the 'AUTO TRIG' soft key at the
bottom right corner of the screen.
2. UUT 'Scope
a. Select the correct channel for the test point.
b. Select the correct range for the test point.
c. If required, adjust the sweep speed and
trigger level for a stable display.
3. 9500B
a. Set Output ON.
b. Press the 'TRIG PULSE' screen key once;
observe and note the UUT scope response.
c. If required, repeat pressing the 'TRIG
PULSE' screen key as detailed in the UUT
Oscilloscope Manufacturer's Test Guide;
observe and note the UUT scope responses.
4. UUT Response
Record the UUT 'Scope response at the test
point as detailed in the UUT Oscilloscope
Manufacturer's Test Guide. If required, reset
the scope protection circuit.
5. 9500B Set Output OFF.
4.13.5.5 Overload Pulse Editing
The 'Digit' and 'Direct' editing processes follow
the same general rules as for editing DC/
Square described in paras 4.4.
4.13.6 Using the 9500B to Test the Overload Response of a UUT
Oscilloscope
4.13.5 Overload Pulse
Operation (Contd.)
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