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MODEL 6COA EIJXlTROMETER
OPERA!CION
(2)
FAST method (low7 to lo-l3
amperes full
scale).
Proceed as above except with the FAST-NORMAL switch at FAST. The inout
drop is now negligible
and the inout circuit
time constant is reduced
at least 100 times.
Observe the following
cautions:
(a)
Use only the ZERO CHECK switch to check zero.
Do not short the input.
(b)
The low side of the output is no longer at ground.
Therefore,
a recorder attached to the output must
not be grounded to the Model 6COA.
(c)
Do not use this method for the measurement of
capacitor
leakage.
E.
-----
MEASURING OHMS
(1)
NORMAL method
(10K
to lo11 ohms full
scale).
Turn RANGE switch to desired OHNS range.
Make sure that NORMAL-FAST
switch is in the NORMAL position.
Connect resistance
sample to be measured only after
ZERO CHECK switch
has been locked.
The test voltage at full
scale is the setting
of the
MULTIPLIER switch.
Before reading OHMS, turn RANGE switch to the ap-
proximate range of the unknown resistance.
By manipulating
the NULTI-
PLIER and the RANGE switch,
the sample can be tested at a number of test
potentials,
if desired.
This two terminal method is the simplest-and will
wcrk quite satis.fac-
torily
up to about 1011 ohms. At resistances
greater than 1011 ohms,
it is desirable
to employ a GUARD connection both to speed up the re-
sponse of the instrument and to nullify
the error of leakage across
the electrometer
input insulation.
(2)
GUARDED method (10"
to lo13 ohms full
scale).
Proceed as with the two terminal
method with the exception that the
sample is connected between the INPUT terminal
and the GUARD terminal
on the rear panel.
The FAST-NORMAL'switch must be set at FAST.
(3)
EXTERNAL VOLTAGE method,
Any external voltage may be used.
The unknowo is connected between
the test potential
and the INPUT terminal
of the electrometer.
The
current is then measured, using the NORMAL or FAST method, and the
resistance
calculated.
og62R
3-3
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