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5.8 Frequency, Duty Cycle and Pulse Width Measurement
Turn the Rotary Switch to the “Hz” Range and pressing the “SELECT” push button to change
the function among Frequency, Duty Cycle and Pulse Width.
5.8.1 Frequency Measurement (Auto range)
To measure frequency, insert the test probes into the sockets of “COM” and “V
Ω
”.
Note:
1. Frequency Range: 2Hz, 20Hz, 200Hz, 2KHz, 20KHz, 200KHz, 2000KHz, 10MHz.
2. At low frequency measuring (less than 200 Hz), better accuracy can be obtained with square
wave.
5.8.2 Positive Duty Cycle Measurement
To measure Duty cycle, insert the test probes into the sockets of “COM” and “V
Ω
”.
5.8.3 Positive Pulse Width Measurement (Auto range)
To measure Pulse Width, insert the test probes into the sockets of “COM” and “V
Ω
”.
Note:
Pulse Width Range: 20, 200, 2000ms.
5.9 Logic Measurement
To measure frequency, insert the test probes into the sockets marked with “COM” and “V
Ω
” at
the lower-end of the meter and turn the Rotary Switch to one of the “
” Range.
When measured value of voltage is TTL logic high, the annunciator “
S
” shows at the
left-middle of LCD.
When measured value of voltage is TTL logic low, the annunciator “
T
” shows at the
left-middle of LCD and sound continuous.
In this range, can be measurement frequency (auto range, TTL level):
Frequency range: 20KHz, 200KHz, 2000KHz, 10MHz
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5. Selection of Measuring Functions
Turning the Rotary Switch to the position of the range you are going to measure. Unit (shown
at right hand side of LCD) and position of decimal point will change corresponding to the
range selected by rotary switch.
5.1 Voltage and Current Measurement
Range Selection:
Select a proper range by turning the Rotary Switch to one of the Voltage ranges (600, 200, 20,
2000m, and 200mV) or Ampere ranges (200u, 2m, 20m, 200m and 10A).
AC or DC Selection:
Pressing the “DC/AC” push button changes the range between DC and AC. Indication of
“AC” or “DC” is shown at left hand side of LCD.
Probe Positions of Voltage Measuring:
Before measuring voltage of AC or DC source the test probes should be firmly inserted in the
sockets marked with “COM” (for ground of DC source) and “V
Ω
”.
Probe Positions of Current Measuring:
Before measuring current of AC or DC source the test probes should be firmly inserted in the
sockets marked with “COM” and “A”(for the range of 10A) or “uA / mA” (for the ranges of
200uA, 2mA, 20mA and 200uA).
Note:
1. When measuring at range of 2000mV, due to the relatively high input impedance, Model
48R is sensitive to noise, and result in unstable at last digit. To avoid electric overload to
rotate the rotary switch the maximal range if the voltage is unknown.
2. To avoid electric overload to rotate the rotary switch the maximal range (10A) if the current
is unknown.
3. Remove power from the circuit under test and open the normal circuit path where the
measurement is to be taken.
4. Connect the meter “in series” with the circuit.
5.2 ADAPTER I/P Mode Measurement:
1. In DC 2000mV, pressing the “SELECT” push button to change the range for ADAPTER
I/P: 1A, 100mA, 10mA, °C and °F per 1mV (Ref. 6.1.7).
2. In AC 2000mV, pressing the “SELECT” push button to change the range for ADAPTER
I/P: 1A, 100mA and 10mA per 1mV (Ref. 6.1.7).