Fluke 83V FE 83V & 87V Users Manual - Page 35
Measuring Frequency, Measuring Duty Cycle. Pressing
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Measuring Frequency The Meter measures the frequency of a voltage or current signal by counting the number of times the signal crosses a threshold level each second. Table 6 summarizes the trigger levels and applications for measuring frequency using the various ranges of the Meter's voltage and current functions. To measure frequency, connect the Meter to the signal source; then press G. Pressing Eswitches the trigger slope between + and -, as indicated by the symbol at the left side of the display (refer to Figure 9 under "Measuring Duty Cycle"). Pressing Dstops and starts the counter. The Meter autoranges to one of five frequency ranges: 199.99 Hz, 1999.9 Hz, 19.999 kHz, 199.99 kHz, and greater than 200 kHz. For frequencies below 10 Hz, the display is updated at the frequency of the input. Below 0.5 Hz, the display may be unstable. Making Measurements The following are some tips for measuring frequency: • If a reading shows as 0 Hz or is unstable, the input signal may be below or near the trigger level. You can usually correct these problems by selecting a lower range, which increases the sensitivity of the Meter. In the L function, the lower ranges also have lower trigger levels. • If a reading seems to be a multiple of what you expect, the input signal may be distorted. Distortion can cause multiple triggerings of the frequency counter. Selecting a higher voltage range might solve this problem by decreasing the sensitivity of the Meter. You can also try selecting a dc range, which raises the trigger level. In general, the lowest frequency displayed is the correct one. 27