DATA PRECISION 1350 User Manual

62-5008
MODEL 1350
2.7.3 Making "Floating" Measurements
In a floating measurement, sucti as In Figure 2-5, It Is possible to Intro
duce a common mode voltage by reactive coupling ttirough the AC
power line when that source of power Is connected. As In paragraph
2.6.2, although this effect Is small. It may be avoided almost completely
by disconnecting the AC power source and reverting automatically to
battery power.
2.7.4 Making High Resistance Measurements
a. When making measurements of very high Impedance sources, as
when required to measure resistance on the tOMfl range, the Input cir
cuit may be susceptable to noise. The effect of voltage-producing noise
fields on the probe leads may tse sufficient to Introduce significant
changes In the least significant digit of the display.
b. Measurement errors may be kept to a minimum under these circum
stances by keeping the lead as short as possible (do not use any exten
sions on the probes), and by twisting the probe leads so as to equalize
any field effects on the signal Input leads.
2.7.5 Makng Very Low Voltage Measurements
Problems may arise when measuring very low voltages because of the
differences In temperature of the probe contact points. Both probes are
plated brass, and If the HI protje Is In contact with copper In a high am
bient temperature (for example. In a computer tape drive mechanism),
while the LO probe Is grounded at a very much cooler steel cabinet
frame, then a difference In emf of several hundred microvolts may re
sult, changing the least significant digit. In order to minimize such errors,
connect the prot)es wherever possible at approximately the same
temperature.
NOTE:
It Is good practice to twist probe leads whenever possible In
order to equalize any field effects on the signal Input leads.
'CopyiBr't 1977. Oats Precition Corporation. All righta ratsrvad.
2-9

DATA PRECISION 1350 Specifications

General

Brand	DATA PRECISION
Model	1350
Category	Multimeter
Language	English