Fluke 91 Series II User Manual page 138

ScopeMeter Test Tool Tutorial
C. MAKING AN AC-COUPLED MEASUREMENT
To select an AC-coupled measurement:
10. Press .
11. Press to open the Meter mode Submenu.
12. Press (MORE METER).
13. Use to highlight ADD MAIN READING, and
press to open the list box.
14. Use to highlight Vrms AC (no DC), and press
to select.
15. Press to close the window.
Comparing the AC trace of Figure 8-6 with the DC trace of
Figure 8-5, you see that the waveform is now centered
vertically about the middle of the screen and slopes
between the switching edges. The slopes appear because
the waveform is AC coupled where higher frequency
waveforms (>50 Hz without probe or >5 Hz with a 10:1
probe) can be measured accurately.
Figure 8-6 Vrms AC Display in Meter Mode
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