Fluke PM3370B user manual AC Input Coupling

GETTING STARTED 3 - 9

Step 3 You can change the amplitude of the signal in a 1, 2, 5 sequence by pressing one of the AMPL keys. Note that the bottom of the screen shows the AMPL/DIV setting of CH1.

CH1 100mV

CH1 500mV

ST6681

Step 4 Press the ON button of CH2 and observe that a second trace is now visible. The position and amplitude of this channel can be adjusted similar to the adjustment of CH1. The channel settings are also displayed in the bottom of the screen.

Press the ON key of CH2 once again to turn this channel off.

Step 5 Press the AC DC/GND key of CH1 so that a ’⊥’ sign is displayed in the bottom text line. This interrupts the input signal and connects the input to the ground. In this case, only the ’base’ line is visible.

Press the AC DC/GND key once again for ac input coupling; the bottom text line now displays ’~’.

In most cases, dc input coupling is used to show ac as well as dc components of the signal. However, in some cases where a small ac signal is superimposed on a large dc voltage, ac input coupling must be used. Then only the ac component is visible on the screen. The text line shows a ’=’ or ’~’ sign to indicate dc or ac coupling. Because the calibration signal is a square wave with a low level of 0V and a high level of +600 mV, the screen shows either of the following two displays:

AC INPUT COUPLING DC INPUT COUPLING

ZERO	1			ZERO	1
LEVEL				LEVEL
	CH1 200mV	MTB 200μs	CH1		CH1	200mV	MTB 200μs	CH1
								ST6682