Horizontal Deflection; Variable Mode Accuracy Main Tb - Fluke Autoranging CombiScope PM3370B Reference Manual

4 - 30
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 50Ω termination. For instruments with switchable 50Ω 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.
PERFORMANCE TEST