Introcuction - Keithley 610 Manual

SECTION I INTRODUCTION
The Keithley Model 610 Electrometer is an ultra-high impedance
voltmeter with full-scale ranges of 0.01, 0.03, 0.10, 0.30, 1.0,
3.0,
10, 30, and 100 volts.
Accuracy is within 2% of full scale
on all ranges.
The maximum input resistance is greater than lo14 ohms; in addi-
tion, the input resistance may be varied in decade steps from one
ohm to 1011 ohms by means of the shunt resistors built into the
instrument.
Thus, the 610 is not only appropriate for lreasure-
ment in high-impedance circuits,
but also can be used where a high
input impedance would merely introduce unwanted pickup.
The 610 may be used as a direct-reading ammeter from 3 amperes
to lo-13 ampere full scale.
This &-decade range is covered in
overlapping 3x and 10x scales.
from 3 amperes to lo-8 alnpere,
Accuracy is within 3s of full scale
and 4$ of full scale from 3 x 10-Y
to lo-13 ampere.
Two current measuring methods are available to the user of the 610.
They are selected by a slide switch at the back of the instrument.
Normally, current is determined by measuring the voltage drop across
a resistor shunted from input to ground.
to lo-l3 ampere ranges,
Alternately, on the 10e4
negative feedback can be applied to the in-
put of the voltmeter through the current measuring resistor. This
largely eliminates the input drop and increases rceasuring speed,
particularly on the more sensitive ranges.
The 610 measures 0.2 ohm to 1011 ohms with a two-terminal input.
With a guarded input, its range is extended to 1014 ohms.
volt external supply wouId further
extend the range to 10 1%
lOOO-
ohms.
Unlike conventional ohmmeters,
information is presented on the
same linear scales used for current and voltage readings. Accu-
racy is within 3% of full scale up to 3 x 100 ohms, within 5%
beyond.
As a
dc
preamplifier, the 61.0 has a maximum gain of 1000, obtainable
in 9 steps of 01, 0.3, 1, 3, 10, 30, 100, 300, and 1000.
Gain
accuracy is within l$ on all gain steps.
The continuing stability
of the gain is assured by a feedback factor in excess of 100 on any
range.
The output is either 10 volts for driving high impedance devices
such as oscilloscopes or pen recorder amplifiers, or 1 ma for
driving low impedance recorders or similar devices. A calibration
Potentiometer is provided with the I. ma position for calibrating
recorders.
A slide switch next to the output connector permits
selecting the desired output.
I -1