Keithley 2701 User Manual

3-16 Basic DMM Operation Model 2701 User’s Manual
Widely varying temperatures within the circuit can also create thermal EMFs. Therefore,
maintain constant temperatures to minimize these thermal EMFs. A shielded enclosure
around the circuit under test also helps by minimizing air currents.
The REL control can be used to null out constant offset voltages.
AC voltage offset
The Model 2701, at 5½ digits resolution, will typically display 100 counts of offset on AC
volts with the input shorted. This offset is caused by the offset of the TRMS converter.
This offset will not affect reading accuracy and should not be zeroed out using the REL
feature. The following equation expresses how this offset (V
OFFSET
) is added to the signal
input (V
IN
):
Example: Range = 1VAC
Offset = 100 counts (1.0mV)
Input = 100mV RMS
= 0.100005V
The offset is seen as the last digit, which is not displayed. Therefore, the offset is
negligible. If REL were used to zero the display, the 100 counts of offset would be
subtracted from V
IN
, resulting in an error of 100 counts in the displayed reading.
Displayed reading V
IN
()
2
V
OFFSET
()
2
+=
D
isplayed reading 100mV()
2
1.0mV()
2
+=
Displayed reading 0.01V 1 10
6–
V×()+=

Keithley 2701 Specifications

General

Max Voltage	300 V
Max Current	3 A
Frequency Range	3 Hz to 500 kHz
Frequency Accuracy	0.01%
Weight	3.6 kg
Measurement Functions	Frequency, Temperature
Interface	IEEE-488 (GPIB), RS-232
DC Voltage Range	300 V
DC Current Range	3 A
AC Voltage Range	300V
AC Current Range	1 μA to 3 A
Resistance Accuracy	0.01%
Channels	10
Dimensions	213mm x 88mm x 370mm