Measuring Frequency And Period; Measuring Resistance - Fluke 8845A User Manual

Measuring Frequency and Period

The Meter measures the frequency, or period of ac signals between 3 Hz and 1 MHz,
applied between the Meter's HI and LO connectors.
The G key not only activates the Meter's Frequency/Period function, but also toggles
the Meter's primary display between the signal's frequency and period measurement.
Therefore, whether a frequency or period measurement appears after pressing G
depends on the condition this function was left in the last time it was used.
To make a frequency measurement:
1. Press G.
If S is displayed, press G again to switch the primary display to frequency.
2. Connect the Meter to the signal as shown in Figure 4-1.
To make a period measurement:
1. Press G.
If HZ is displayed, press G again to switch the primary display to period.
2. Connect the Meter to the signal as shown in Figure 4-1.
Each press of G switches the measurement between frequency and
period.
Function modifiers:
APERTURE Displays three different gate time selections: 0.01, 0.1 and 1 second.
2ND MEAS Cycles the secondary display through the measurement functions

Measuring Resistance

The Meter is capable of making two-wire and four-wire resistance measurements. Two-
wire measurements are easy to set up, and will make accurate measurements in most
applications. In a two-wire resistance measurement, both the source current and sensing
is done through the INPUT HI and LO terminals. A four-wire resistance measurement
0.000000
F1 F2 F3
Note
These selections set the minimum amount of time the Meter takes to
measure frequency. Shorter gate times result in lower measurement
resolution.
listed below, and then off. When a second measurement function is
selected, the 2ND MEAS soft key label is highlighted.
Period – If a frequency measurement is in the primary display, the
period of the signal appears in the secondary display when the
2ND MEAS soft key is pressed.
Making Measurements

Measuring Frequency and Period

Hz
F4 F5
4
caw06f.eps
4-7