dBm Measurements in AC Volts Functions
The ac volts functions allow you to display readings as deviations in dB (decibels) above or below an established level. Set up dB measurements with the following procedure:
- Make an ac volt measurement to be used as a reference point.
- Press
to select dB. The dBm value appears in the primary display and the ac volts reading appears in the secondary display.
- Press again to turn dB off.
Normally, dB is measured as dBm, which is a measure of decibels relative to 1 milliwatt. The meter assumes a resistance of 600Ω in making this calculation. This resistance can be set for any value for 50Ω, 75Ω，93Ω, 100Ω, 150Ω, 300Ω, 600Ω, 800Ω, 1200Ω, 2400Ω, using the meter’s setup capabilities to change the resistance.
Note
If dBm is displayed, check that thereference resistance value closely matches the impedance of the system being measured.
dB is calculated with the following formula:
dBm=20xlog10(Vx/Vr),
For dBm, Vr is the voltage across the reference resistance at 1mW. For example, Vr would be 0.7746V with a 600Ω reference resistance.
Measuring AC Voltage
- Set the rotary switch to
position, and "AC" "V" will be on display.
- Insert the black lead into "COM" terminal, and the red lead to into the "Ω
V" terminal.
- Connect the leads to the testing power.
- Read the measuring results from the screen.
- Press
to display the frequency and duty cycle ratio of the tested signals.
Warning
- Do not apply more than DC 1000V or AC 750 rms voltage; the meter will possible be damaged though the value could be displayed.
- Indicator “
” is on display for safety note when 30VAC and/or dc voltage present at the input terminals
- The meter beeps constantly if the input voltage is more than AC 750V rms, which is over the meter’s range.
Measuring DC Voltage
- Set the rotary switch to
position, and "DC", "V" will be on display.
- Insert the black lead into "COM" terminal, and the red lead to into the "ΩV" terminal.
- Connect the leads to the tested power.
- Read the measuring results from the screen.
Warning
- Do not apply more than DC 1000V or AC 750rms voltage; the meter will possible be damaged though the value could be displayed.
- Indicator "" is on display for safety note when 30V ac and/or dc voltage present at the input terminals
- The meter beeps constantly if the input voltage is more than AC 750V rms, which is over the meter’s range.
Measuring DC mV Voltage
- Set the rotary switch to
position, and "DC" "mV" will be on display.
- Insert the black lead into "COM" terminal, and the red lead to into the "ΩV" terminal.
- Connect the leads to the tested power.
- Read the measuring results from the screen.
Measuring Current
Warning
- Never attempt an in-circuit current measurement where the open-circuit potential to earth is greater than 1000V. You may damage the meter or be injured if the fuse blows during such a measurement.
- You must open the circuit under test, then place the meter in series with the circuit.
Caution
To avoid possible damage to the meter or to the equipment under test, check the meter’s fuses before measuring current. Use the proper terminals, function, and range for your measurement. Never place the probes across (in parallel with) any circuit or component when the leads are plugged into the current terminal.
- Insert the black lead into the COM terminal. Insert the red lead in an input appropriate for the measurement range as shown in Table
- When using A jack, set the rotary switch on
position; When using mA μA jack, set the rotary switch on 
position if the current is less than 4000μA and 
position if the current is more than 4000μA.
- The meter is preset to direct current, and the screen shows "DC"; Press blue push button（）once to select alternating current measurement and the screen shows "AC".
- Open the circuit path to be tested. Touch the red probe to the more positive side of the break; touch the black probe to the more negative side of the break. Reversing the leads will produce a negative reading, but will not damage the meter.
- Turn on power to the circuit, and read the measuring results from the screen.
- Press to toggle between the frequency and duty cycle ratio of the signals under test.
- Turn off power to the circuit and discharge all high voltage capacitors. Remove the meter and restore the circuit to normal operation.
| Rotary Switch | Input | Ranges |
|---|
| A | 4.000…10.00A |
| mA | 40.00…400.0mA |
| μA | 400.00…4000μA |
Notice
- Start measuring from the high range if the current can’t be evaluated.
- For safety, the measuring time should be limited within 15s, while the interval should be more than 10 min when measuring high current. If the input current is more than 10.00A, then the inner beeper sounds constantly indicating the value surpass the range.
DC Current Mesurement
AC Current Mesurement
Measuring Capacitance
Warning
To avoid possible damage to the meter or to the equipment under test, disconnect circuit power and discharge all high-voltage capacitors before measuring capacitance. Use the dc voltage function to confirm that the capacitor is discharged.
The meter’s capacitance ranges are 50.00nF, 500.0nF, 5.000μF, 50.00μF, 100.0μF.
To test capacitance, proceed as follows:
- Set the rotary switch to position to select capacitance measurement.
- Insert the black lead into "COM" terminal, and the red lead to into the "ΩV" terminal.
- Connect the leads to the tested capacitance.
- Read the measuring results from the screen.
Caution
- OL appears on the display if the tested capacitance is open or the value surpasses the maxim range.
- If the tested capacitance is polar capacitance, then connect the red lead with the positive point and the black lead with the negative point.
- High capacitance test needs more time, and 30s is necessary in 100μF position.
- To improve the measurement accuracy of small value capacitors, press
with the test leads open to subtract the residual capacitance of the meter and leads.
- The remaining voltage of capacitance, insulated impedance and dielectric absorption could cause measuring errors.
- Only Auto ranging mode is available in capacitance measurement.
Measuring Frequency and Duty Cycle Ratio
In voltage and current (DC mV excluded) measurement, press to display frequency->duty cycle ratio->voltage (current),
frequency, duty cycle ratio, and then back to voltage (current).
Notice
Please select the proper range in voltage or current function before measuring frequency and duty cycle ratio.
Measuring Resistance
Warning
To avoid possible damage to the meter or to the equipment under test, or to the equipment under test, disconnect circuit power and discharge all high-voltage capacitors before measuring resistance.
The meter’s resistance ranges are 400.0Ω, 4.000kΩ, 40.00kΩ, 400.0kΩ, 4.000MΩ and 40.00MΩ.
To measure resistance, proceed as follows:
- Set the rotary switch to
position (Default value in this function).
- Insert the black lead into "COM" terminal, and the red lead to into the "ΩV" terminal.
- Connect the leads to the tested power.
- Read the measuring results from the screen.
Caution
- "OL" appears on the display if the resistance under test is open or the value surpasses the maxim range.
- The test lead can add 0.1Ω to 0.2Ω of error to resistance measurements. To test the leads, touch the probe tips together and read the resistance of the leads. If necessary, you can press to automatically subtract this value.
- Wait for several seconds for stable reading when measuring resistance more than 1MΩ.
Measuring RTD
- Set the rotary switch to position, and press blue button () three times to select diodes testing.
- Insert the black lead into "COM" terminal, and the red lead to into the "ΩV" terminal.
- Connect the leads to the tested RTD.
- Read the measuring results from the screen.
Measuring TC
- Set the rotary switch to position, and press blue button () to select TC measurement.
- Insert TC into "COM" and "ΩV" terminals, make sure the TC jack with symbol "+" is connected into the "ΩV" terminal.
- Read the measuring results from the screen.
The temperature degree is shown on the primary display, the TC value on the secondary display and Fahrenheit degree on elapsed time display.
When the output jack is open circuit, the screen displays OL.
Warning
To avoid possible electric shock or personal injury, do not connect the TC with the live circuit.
Testing Diodes
Warning
To avoid possible damage to the meter or to the equipment under test, disconnect circuit power and discharge all high-voltage capacitors before testing diodes.
Use the diode test to check diodes, transistors, and silicon-controlled rectifiers (SCR), and other semiconductor devices. The test sends a current through a semiconductor junction, and then measures the junction’s voltage drop. A typical junction drops 0.5V to 0.8V.
To test a diode, proceed as follows:
- Set the rotary switch to position and press blue button () to select diodes testing, and the symbol "" will be shown on the left part of the screen.
- Insert the black lead into "COM" terminal, and the red lead to into the "ΩV" terminal. The polarity of the black lead and red lead is "-" and "+" respectively.
In a circuit, a similar diode should still indicate a forward bias reading of 0.5V to 0.8V; however, the reverse-bias reading can vary depending on the resistance of other pathways between the probe tips.
Note
In the live diodes testing, the resistance of other pathways and between the probe tips will affect the reading of reverse-bias voltage.
Testing for Continuity
Warning
To avoid possible damage to the meter or to the equipment under test, disconnect circuit power and discharge all high-voltage capacitors before testing for continuity.
Continuity is the presence of a complete path for current flow. The continuity test features a beeper that sounds if a circuit is
complete. The beeper allows you to perform quick continuity tests without having to watch the display.
To test continuity, proceed as follows:
- Set the rotary switch to position, and press blue button () twice to select continuity check and the symbol "
" will be shown on the left part of the screen.
- Insert the black lead into "COM" terminal, and the red lead to into the "ΩV" terminal.
- Connect the leads to the two ends of the tested circuit.
- The inner beeper sounds when the tested circuit resistance is less than 50Ω, which indicates the circuit is through.
