23
NOTE:
The maximum voltage ratio that can be measured is +50 dB on the 0-250V
range.
e.
If dB measurements are being made to a 0.006 watt into 500 ohm reference
level, su7 dB from the reading obtained on the 260.
4.9
Direct Current Measurement
a.
Do not change the range setting of
the range or function switches while
the circuit is energized.
b.
Never disconnect test leads from the
circuit under measurement while it
is energized.
c.
Always turn the power off and dis-
charge all the capacitors before the
setting of the switches is changed,
or the leads disconnected.
d.
Never exceed the circuit-to-ground
voltage of the instrument (1000V
Max., Table 1-1, Item 16).
e.
Always connect the instrument in se-
ries with the ground side of the cir-
cuit.
f.
In all direct current measurements,
make certain the power to the circuit
being tested has been turned off be-
fore connecting and disconnecting
test leads or restoring circuit conti-
nuity.
4.9.1 Direct Current Measurement 0-50
μ
A Range
a.
Set the function switch at +DC.
b.
Plug the black test lead into the -COMMON jack and the red test lead into the
+50
μ
AMPS/250mV jack.
c.
Set the range switch at 50
μ
AMPS (dual position with 50V).
d.
Open the ground side of the circuit in which the current is being measured.
Connect the VOM in series with the circuit. Connect the red test lead to the
positive side and the black test lead to the negative side.
e.
Read the current on the black DC scale. Use the 0-50 figures to read directly
in microamperes.
NOTE:
For polarity reversing see paragraph 4.2
.
4.9.2 Direct Current Measurement 0-1mA Through 0-500mA
Range
a.
Set the function switch at +DC (Figure 4-12).
b.
Plug the black test lead into the -COMMON jack and the red test lead into the
+ jack.
c.
Set the range switch at one of the four range positions marked 1 mA, 10 mA,
100 mA or 500 mA
!
500 MA.
2.5 V.
10 V.
1V.
25 V.
50 A.
AMPS.
250 V.
500 V.
I000 V.
+
COMMON
-
A.C. VOLTS
ONLY
DB
260
ALL TERMINALS 1 V MAX
Figure 4-11. Jacks and Switch
Positions for Measuring Decibels
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