Micronta 22-204A range doubler multimeter instructions, manual, circ...
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02/05/2010 16:45
2. Leave the Range Doubler switch in the V-
Ω
-A position. Set Range switch to one of the positions; touch
the test probes together and adjust the OHMS ADJ. control to bring the pointer to the "0" on the top
(green) OHMS scale.
3. Now, connect the probe tips across the circuit or part under test.
4. Read the resistance on the green OHMS scale, use the proper multiplier to obtain the correct value (R
"times" 1, 10, 100, 1000 or 10.000, depending on the position of the Range switch).
NOTES: When you are unable to adjust the pointer to "0" on the OHMS scale in the Rx1, Rx10, Rx100 or
Rx1K pbsitions, the penlight battery must be replaced. When you are unable to adjust the pointer to "0" on
the OHMS scale when in the Rx10K position, replace the 9-volt battery. When measuring resistance, it is
best to disconnect one side of the part under test (thus the remainder of the circuit will not interfere with
the readings).
THE RANGE DOUBLER SWITCH MUST BE LEFT IN THE V-
Ω
-A POSITION FOR ALL
RESISTANCE MEASUREMENTS.
DC CURRENT MEASUREMENTS
1. Plug the test leads into the correct jacks (Black into COM and Red into +V.
Ω
.A).
2. Set the Range switch to the 500m DC A position (500 milliamp). Or, if the current will be greater than
500 mA, use the 10A jack (instead of the +V.
Ω
.A) and set Range to 10A. Always start at the top and work
down.
3. Open up the circuit in which you want to measure current and connect the black lead to the negative
side and the red lead to the positive side of the circuit.
4. Apply power to the circuit under test. Set Range and Range Doubler switches as required to obtain a
meter reading in the upper 1/2or 1/3rd of the scale.
5. Read the current on the black DC scales. If the Range Doubler switch is in the V.A/2 position, be sure
to divide the Range switch setting by 2 and read on the appropriate scale.
NOTES : Do not attempt to read AC current. For currents above 500 milliamps, use the 10A Range
switch setting and the 10A jack (instead of the V.
Ω
.A jack). Use the appropriate setting of the Range
Doubler switch.
DECIBEL MEASUREMENTS
You can probably completely ignore the dB scale, most people will never need it.
1. Plug the test leads into the correct jacks (Black into COM and Red into +V.ohms.A).
2. Set the Range and Voltage Doubler switches as required to obtain a meter reading in the upper half of
the scale.
3. Read dB on the dB scale, adding the appropriate number of dB to the dB scale reading as noted on the
chart at the lower right on the meter face.
NOTE : For absolute dB measurements, circuit impedance must be 600 ohms.
0 dB = 1 milliwatt dissipated in a 600 ohm impedance (equivalent to 0.775 volts across 600 ohms).
The original manual text above about decibel measurements could be a bit confusing.
To try to clarify, 1mW into 600ohms is 0dBu not 0decibels. A decibel on it's own is allways a relative
measurement, not an absoloute measurement.
The dB scale could be used for relative power measurements in decibels, eg if you are measuring the
voltage across a resistive load and the needle goes up so
that it reads 6dB higher on the dB scale that means the voltage has doubled so four times more power is
being delivered to the load which is a 6dB increase.
