Fluke 28IIEX Fluke 28IIEx User Manual - Page 41

Frequency Measurements, under Duty Cycle. Push

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Frequency Measurements For frequency measurements, the Product counts the number of times the signal crosses a set voltage level each second. Table 7 summarizes the trigger levels and applications for frequency measurements in the ranges of the voltage and current functions of the Product. To measure frequency, connect the Product to the signal source. Next push G. When you push E, the trigger slope switches between + and -, as shown by the symbol at the left side of the display (refer to Figure 9 under "Duty Cycle"). Push D to stop and start the counter. The Product autoranges to one of five frequency ranges: 199.99 Hz, 1999.9 Hz, 19.999 kHz, 199.99 kHz, and >200 kHz. For frequencies less than 10 Hz, the display is updated at the frequency of the input. Less than 0.5 Hz, the display can be unstable. True-rms Digital Multimeter How to Make Measurements Some guidelines for frequency measurements are: • If a measurement shows as 0 Hz or is unstable, the input signal can be below or near the trigger level. To correct these problems, go to a lower range, which increases the sensitivity of the Product. In the L function, the lower ranges also have lower trigger levels. If a measurement is a multiple of what you expect, the input signal can be distorted. Distortion can cause multiple triggers of the frequency counter. Select a higher voltage range to decrease Product sensitivity to try and repair this problem. You can also set a dc range to increase the trigger level as a possible solution. In general, the lowest frequency shown in the display is the correct one. 31

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True-rms Digital Multimeter
How to Make Measurements
31
Frequency Measurements
For frequency measurements, the Product counts the
number of times the signal crosses a set voltage level
each second.
Table 7 summarizes the trigger levels and applications for
frequency measurements in the ranges of the voltage and
current functions of the Product.
To measure frequency, connect the Product to the signal
source. Next push
G
. When you push
E
, the
trigger slope switches between + and -, as shown by the
symbol at the left side of the display (refer to Figure 9
under "Duty Cycle"). Push
D
to stop and start the
counter.
The Product autoranges to one of five frequency ranges:
199.99 Hz, 1999.9 Hz, 19.999 kHz, 199.99 kHz, and
>200 kHz. For frequencies less than 10 Hz, the display is
updated at the frequency of the input. Less than 0.5 Hz,
the display can be unstable.
Some guidelines for frequency measurements are:
•
If a measurement shows as 0 Hz or is unstable, the
input signal can be below or near the trigger level. To
correct these problems, go to a lower range, which
increases the sensitivity of the Product. In the
L
function, the lower ranges also have lower trigger
levels.
If a measurement is a multiple of what you expect, the
input signal can be distorted. Distortion can cause
multiple triggers of the frequency counter. Select a higher
voltage range to decrease Product sensitivity to try and
repair this problem. You can also set a dc range to
increase the trigger level as a possible solution. In
general, the lowest frequency shown in the display is the
correct one.