HP 4278A - Page 30

15. Press the 'AVG RATE' softkey. The averaging rate is displayed in the AVG : field
(second line from the top of the LCD). Each time you press the 'UP' softkey, the
averaging rate doubles (to a maximum averaging rate of 256), and inversely so by
pressing the 'DOWN' softkey. Set the averaging rate to 1. Press the 'return' softkey.
16. Press the 'DELAY (ms)=' softkey. This allows you to set the delay time from the
input of a trigger to the start of a measurement. The Input Line displays the set
delay time, and the delay time is also displayed in the DELAY : field (third line from
the top of the LCD). For this example, leave the delay time set to ©ms as it is now.
Press the 'return' softkey.
17. Press the NEXT key to display the second page of softkey labels (2/4).
18. Press the 'TRIG MODE' softkey, then press the 'MAN TRIG' softkey to set the manual
trigger mode. The selected trigger mode is displayed in the TRIG : field (fourth line
from the bottom of the LCD).
19. Press the TRIGGER key. Note that a single measurement is performed each time
you press the TRIGGER key. Press the 'return' softkey.
20. Press the 'CABLE LENGTH' softkey. Confirm that Om is selected (default setting)
and is displayed in the CABLE : field (fourth line from the bottom of the LCD). Press
the 'return' softkey.
Compensating for Test Fixtures
21. Press the 'COMPEN' softkey.
22. With the fixture's terminals open (nothing connected), press the 'OPEN COMPEN'
softkey, and observe the display. The message "Open offset compen. completed"
will be displayed on the Message Line (the bottom line of the LCD), and the open
admittance data will be displayed on the Monitor Line (second line from the bottom).
23. Press the TRIGGER key and confirm that the measurement result is the same (or
almost the same) as the open admittance data.
24. Press the 'OPEN ON' softkey, then press the TRIGGER key. The measurement result
is compensated for, in accordance with the open admittance data, and is close to
zero in value. Press the NEXT key.
25. Connect a shorting bar to the test fixture as shown in Figure 2-4.
NOTE
The recommended shorting bar is described in the operation note for each test
fixture.
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