6.4. Logic Frequency/Duty Ratio Measurement
The frequency range is of 20 Hz ~ 220 MHz
（
V
pp
3V), while the duty ratio measurement range being
of 5% ~ 95%. And the measurement methods are as follows:
1.
Set Function-
switch to the “Hz/duty” position.
2.
Insert the red testing line into the mV/
Ω/Hz end and the black testing line into the
COM end.
3.
Press “Hz/duty” until “Hz” appears in the display.
4.
Read the measured value from the display screen. If the frequency of the measured signal is
lower or higher than the meter’s measurement range, the reading will be displayed as “OL”. If
the amplitude of signal is to low or the low level is larger than 1 volt, the reading will displayed
as zero.
5.
This measurement is of automatic range. Manual range-selection is deactivated.
6.5. Checking Diodes
This function lets you check diodes and other semiconductors for opens and shorts. It also lets you
determine the forward voltage for diodes. You can use this function, when you need to match diode.
Before test, disconnect all power to the circuit to be tested and discharge all capacitors thoroughly.
Follow these steps to measure the frequency of a signal:
1. Set Function-Switch to
-position.
2. Press MODE-button to select the diode-test-function
3. Plug the black test lead into the COM-terminal and the red test lead into the mV/
-terminal.
4. Connect the test lead to the diode to be checked and read the display.
Notes:
*
If you check a diode´s forward voltage, you will measure voltage of approx. 1,25 V (Germanium)
or 0,7 V (Silicon) if the diode is not defective.
*
If "OL" is displayed, it means the diode is open or above 2,0 V forward voltage. However, if the
display shows a value between 0 V and approx. 2.0 V, it means a forward drop voltage.
The instrument supplies enough forward voltage to light most LED´s. However, if the LED´s
forward voltage is greater than 2.0 volts, the instrument incorrectly indicates, that the device is
open.
6.6. Checking Continuity
Continuity testing verifies that circuit connections are intact.
Warning!
Never perform a continuity checking on a circuit, that has power connected.
Follow these steps to perform audible continuity test:
1. Set Function-Switch to
-position.
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