Ac Voltage Measurements; Dbm/Dbv Ac Measurements - Extech Instruments GX900 User Manual

AC VOLTAGE MEASUREMENTS
WARNING: Risk of Electrocution. The probe tips may not be long enough to contact the live parts inside
some 240V outlets for appliances because the contacts are recessed deep in the outlets. As a result, the
reading may show 0 volts when the outlet actually has voltage on it. Make sure the probe tips are touching
the metal contacts inside the outlet before assuming that no voltage is present.
CAUTION: Do not measure AC voltages if a motor on the circuit is being switched ON or OFF. Large voltage
surges may occur that can damage the meter.
1. Set the function switch to the V~ position.
2. Insert the black test lead banana plug into the negative
COM jack. Insert red test lead banana plug into the
positive V jack.
3. Touch the black test probe tip to the neutral side of the
circuit. Touch the red test probe tip to the "hot" side of
the circuit.
4. Read the voltage in the display.
dBm/dBV AC MEASUREMENTS
The meter is capable of displaying AC voltage as a dB value;
relative to 1 milli‐watt (dBm), relative to 1V (dBV), or to a
custom reference value.
1. Set the function switch to the V~ position
2. Press the F1 key (MENU) on the LCD and then
navigate to the dBm/dBV field using the arrow keys
and then press OK.
3. Navigate to the menu item labeled dBm and then
press OK.
4. Insert the black test lead banana plug into the
negative COM jack. Insert red test lead banana plug into the positive V jack.
5. Touch the black test probe tip to the neutral side of the circuit. Touch the red test
probe tip to the "hot" side of the circuit.
6. Read the dBm in the primary display area and read the Voltage in the secondary
display area.
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Extech Instruments
GX900-EU-EN V1.6 4/14