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BASIC DMM OPERATION
Clarifications of TRMS ACV Spedfications:
"
2.8.8 Current Measurements
(DC or TRMS AC)
Msximum Allowable Input-The
following graph sum-
marizes the maximum input based on ~the lWV*Hz
specification.
The Model 196 can m&e DC or TRW AC current measure:
ments from lnA (at 5Yrd resolution) to 34. Use the follow-
ing procedure to make current measurements.
MAXIIIUH
INPUT
TRt4S AC VOLTS
I
FREOUENCY-HZ
CAUTION:
MAXIMUM CONTINUOUS INPUT=3A
1. Select the DC current or AC current function by press-
ing the DCA or ACA button respectively.
2. Select a range consistent with the expected current or
use autorange.
3.
Select the front or rear panel input terminals using the
INPUT switch.
4.
Connect the signal to be measured to the selected input
terminals as shown in Figure 2-7.
5.
Take the reading from the display.
~. .-
_ ._..
I
I
Settling Time-lsec
to within 0.1% of change in reading.
This the specification is for analog circuitry to settle and
does not in&de
AID conversion time.
Figure
2-7.
Current Measurements
Notes:
2.8.9 dB Measurements
1. See paragraph 26.10 for TRMS measurement conSid&
&iOllS.
2.
When making TRMS AC voltage measurements below
45Hz, enable the front panel filter modifier to obtain
stable readings. A filter value of 10 is recommended.
3.
To make low frequency AC mea%uenients in the range
of lOHz to 2oH.z:
A. The ACV function must be selected.
B. Digital filtering must be used to obtain a stable
reading.
C. Allow enough settling time before taking the reading.
The dB measurement mode makes it pocisible to compress
a large range of~measurements into a much smaller scope.
AC dB measurements can be made with the instrument in
the
ACV
or AC4 function. The relationship between dB
and voltage and currentxan
be expressed by the follow-
mg equations:
dB = 20 log .%
0 V w
2-13
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