User`s guide
U1251A and U1252A Quick Start Guide
Frequency and Frequency Counter Measurements
Square Wave Output (for U1252A only)
WARNING
Use the frequency counter for low voltage application. Never use the
frequency counter on line power system.
Frequency Measurement
During AC/DC voltage or AC/DC current measurements, you can
measure the relevant frequency by pressing at anytime.
Frequency Counter Measurement
1 Set the rotary switch to .
2 Press to select the frequency counter (Hz) function. “—1—” on the
secondary display means the input signal frequency is divided by 1.
This accommodates for higher frequency range of up to 2 MHz.
3 Connect the red and black test leads to input terminals V(red) and
COM(black) respectively.
4 Probe the test points and read the display.
5 If the reading is unstable or zero, press to select divison of input
signal frequency by 100. This accommodates for higher frequency range
of up to 20 MHz.
6 The signal is out of specification if the reading is still unstable after
Step 5.
1 Turn the rotary switch to position. Default display setting
is 600 Hz on secondary display and 50% duty cycle on primary
display.
2 Press or to scroll through the available frequencies (there
are 28 frequencies to choose from).
3 Press to select duty cycle (ms) on primary display.
4 Press or to adjust the duty cycle. Duty cycle can be set for
256 steps and each step is 0.390625%. The display only indicates
the best resolution with 0.001%.
NOTE
Pressing is the same as pressing .