Fluke PM3370B user manual Vertical Invert

HOW TO USE THE INSTRUMENT 4 - 19

VERTICAL INVERT

The INVERT function in Channel 2 can be used to make it easier to do out-of- phase signal comparisons. The most common use of the INVERT function is to obtain the display or make the acquisition of the voltage difference between two channels. This is done by displaying or capturing the sum of Ch1 and Ch2 as follows. (This is referred to as the differential mode.)

-Using two probes, connect the Probe Adjust signal to Ch1 and Ch2.

-Press AUTOSET.

-Both Ch1 and Ch2 are now displayed.

-Adjust POS and AMPL to get a display as illustrated on the left below.

-Press the CH1+CH2 key.

-Press the INV key of channel 2.

Since channel 2 is inverted before it is added to channel 1, the result will be CH1- CH2. This is indicated as ’1-2’ on the screen. The signals on both inputs are the same, resulting in a straight line at ground level.

(If the line is not straight, this may be an indication that the probes are not correctly adjusted. When one of the probes is not properly adjusted, the input signals at the input connectors of the oscilloscope will be unequal. The difference of the two input signals shows up in the differential mode).

CH1+CH2

1-
2-
CH1	200mV	1+2
CH2	200mV	CHP MTB 200μs	ch1

INV

1-
2-
CH1	200mV	1-	2	200μs
CH2↓	200mV	CHP MTB			ch1

ST5969