Keithley 2303, User Manual

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Long Integration Measurements 4-7
General notes
• Make sure the voltage and current settings are appropriate for detecting pulses.
• If a pulse timeout occurs (no pulses detected), current will not be measured (i.e. ----A)
and the “NO PULSE” message will be displayed. Pulses are not detected with the output
off. With the output on, pulses will not be detected if the trigger level is too low or too
high. Perform the “Determining correct trigger level” procedure to find an appropriate
trigger level.
• While the “NO PULSE” message is displayed, the instrument continues to search for a
pulse. The search can be terminated by pressing any front panel key. The “NOT TRIG”
message replaces the “NO PULSE” message. To restart the search, press any arrow key
while displaying long integration readings. The timeout or pulse detection will need to
elapse before the display changes.
• To stop taking long integration readings, press any front panel key. As long as the
instrument remains in the long integration display state, the measurement process can be
resumed by pressing an arrow key. While readings are not being taken, the bottom line
displays the last valid long integration reading, or dashes if no pulse detected before
being stopped.
Determining correct trigger level (long integration)
1. If using Model 2303-PJ, make sure it is on the same current range (5A or 500mA) that
is being used for long integration measurements (step 1 of the “pulse current measure-
ment procedure”).
2. After selecting the appropriate voltage and current values, turn on the output.
3. Select the long integration display type. If the trigger level is too low or too high, the
“NO PULSE” message will be displayed. If long integration measurements are instead
being displayed, the trigger level is valid. You can skip the rest of this procedure.
4. Go into the menu, select LONG INTEGRATION, and then TRIGGER LEVEL.
5. Adjust the trigger level and press ENTER. The unit starts looking for the pulse. If the
trigger level is still too low or too high, the “LONG INT TRIG NOT DETECTED” mes-
sage will be displayed briefly. Note that it may take as long as the timeout value for the
message to appear.
6. If the message appeared, repeat step 5 until a valid trigger level is found.
7. Use the MENU key to back out of the menu structure and display long integration cur-
rent measurements.