Fluke 8845A, Руководство пользователя

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8845A/8846A
Users Manual
4-6
Function modifiers:
Filter
Displays the filter menu. For best accuracy and stable readings,
choose a filter based on the lowest frequency to be measured and the
performance needed.
3HZ SLOW
Provides higher measurement accuracy on ac signals
between 3 Hz and 20 Hz. However, the measurement
cycle time is longer than it is when using the 20 Hz
filter.
20HZ
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.
200HZ
Provides accurate measurements on ac signals 200 Hz
and above.
dB
Displays the measured voltage as a decibel value referenced to a
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.
dB€
Displays the measured voltage as a power decibel value referenced to
1 milliwatt (dBm = 10 log(power of Vnew into the reference
resistance / 1 mW) or 10 log(V
2
/R*1 mW) where R is the resistance.
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.
Note
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.