Keithley 197 User Manual

D. Connect the test leads to the current source as shown in
Figure 2-8.
If an overrange indication is displayed,
select a higher range until a normal reading
is shown.
Use the lowest possible range to obtain the best resolu-
tion.
E. Take the reading from the display.
Linear
~ Counts
10-99
100-999
1000-9999
10000-220,OOO
1. Measure and record the TRMS AC component as des-
2. Measure and record the
DC component as described in
3. Compute the rms value from the following equation:
Em, =UE~D~ + E~AC
cribed in paragraph 2.7.4.
paragraph 2.7.3.
Resolution Accuracy
0.ldBrn k IdBrn
0.OldBrn +O.ldBrn
0.01 d
Brn -t 0.02dBrn
k 2dBrn typical
IdBrn
-CAUTION: MAX INPUT = IOA
MODEL 197
Figure 2-7. Current Measurements Between
2000mA and 20A
Figure
2-8. Current Measurements up to 2000mA
2.7.8 AC Plus DC Measurements
2.7.9 dB Measurements
The dB function makes it possible to compress a large range
of readings into a much smaller scope. The relationship bet-
ween dB and voltage can be expressed by the following equa-
tion.
VIN
dB = 20 log-
VREF
Tables 2-4 and 2-5 list the dB specifications for DC volts and
AC volts.
The Model 197 can make
dB measurements referenced to the
standard
600Q impedance or to other impedances. The
relative feature allows measurements in
dB independent of
impedance.
The basic procedure
for placing the instrument in the dB
mode is
to first select AC or DC volts and then press the dB
button. Note that once dB is selected (dB annunciator on),
pressing in the
Q or A function pushbuttons will turn dB off.
Table 2-4. dB Specifications for DC Volts
(600Q Ref)
Use the Model 197 to measure TRMS on a signal which has
both AC and
DC components.
2-10
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Keithley 197 Specifications

General

Brand	Keithley
Model	197
Category	Multimeter
Language	English