Fluke 8845A User Manual page 74

8845A/8846A
Users Manual
Function modifiers:
4-6
Displays the filter menu. For best accuracy and stable readings,
Filter
choose a filter based on the lowest frequency to be measured and the
performance needed.
3HZ SLOW Provides higher measurement accuracy on ac signals
20HZ
200HZ
Displays the measured voltage as a decibel value referenced to a
dB
stored relative value (dB = 20 log(Vnew/Vstored). The stored value is
obtained from the first measurement the Meter makes after pressing
the dB soft key. All future measurements are displayed using the
stored value as an offset. To take the Meter out of dB mode, press the
dB soft key.
Displays the measured voltage as a power decibel value referenced to
dB€
1 milliwatt (dBm = 10 log(power of Vnew into the reference
resistance / 1 mW) or 10 log(V
To accommodate the various impedances that a dBm measurement
can be made across, the Meter allows for the selection of 21 different
impedance values.
To set the dB reference impedance:
1. Press L.
2. Press the soft key labeled dB€ Ref.
The available impedance settings are presented in sets of three
values. To move to a higher set of impedance values, press ++
-->. Press <-- -- to go to a lower set of impedance values.
3. With the impedance highlighted, press the soft key under the
value selected.
2ND MEAS Cycles the secondary display through the measurement functions
listed below, and then off. When a second measurement function is
selected, the 2ND MEAS soft key label is highlighted.
VDC - Displays the dc voltage on which the ac signal may be riding.
ACV/DCV dual mode should not be used at frequencies
below 10 Hz.
Frequency - Displays the frequency of the ac signal applied to the
Input HI and LO connectors of the Meter.
between 3 Hz and 20 Hz. However, the measurement
cycle time is longer than it is when using the 20 Hz
filter.
Provides higher measurement accuracy on ac signals
between 20 Hz and 200 Hz. The measurement cycle
time is longer, however, than it is when using the
200 Hz filter.
Provides accurate measurements on ac signals 200 Hz
and above.
2
/R*1 mW) where R is the resistance.
Note