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PERFORMANCE TEST
4.3.25
Horizontal deflection; VARiable mode accuracy MAIN TB.
The horizontal MAIN TB deflection coefficients can be varied in steps such as
done in 4.3.24. A range of much finer steps can also be selected. Here, the
accuracy of this range is checked.
Test equipment:
Fluke 5500A mode: marker (Alternative time marker generator TG 501).
Test set-up:
Settings/procedure:
1
-
Apply a 5 us time marker signal to input CH1.
2
-
Press the AUTOSET key.
3
-
Use a 50
Ω
termination. For instruments with switchable 50
Ω
input
impedance it is recommended to make use of this feature.
4
-
Press the TRIGGER menu key.
5
-
Select level-pp ’off’ and trigger coupling ’dc’ from the TRIGGER MAIN TB
menu.
6
-
Adjust the TRIGGER LEVEL control for a correctly triggered display.
7
-
Set the MAIN TB TIME/DIV to 5.00 us.
8
-
Select the MTB VARiable mode by pressing both MAIN TB TIME/DIV keys
at a time: the message; ’VARIABLE TIMEBASE’ is displayed briefly.
9
-
Press the ’ns’ key and adjust the readout to 2.50 us.
Requirements:
-
Verify that the horizontal distance between the time markers equals 2 divisions.
-
Use the X POS control to align the marker pulses with the graticule.
-
Now check (across the central 8 divisions) if the timebase accuracy is
±
2.8%:
make use of the deflection error facility of the time marker generator to check this.