Section 3: Operation
Model 2000-SCAN Scanner Card User's Manual
3-20
2000-SCAN-900-01 Rev. A / April 2018
The following figure shows how to connect several instruments together to eliminate this ground loop
problem. Here, only one instrument is connected to the power line ground. Ground loops are not
typically a problem with instruments with isolated LO terminals. However, all instruments in the test
setup may not have isolated terminals. When in doubt, consult the manual for each instrument in the
test setup.
Keeping connectors clean
As is the case with any high-resistance device, the integrity of connectors can be compromised if they
are not handled properly. If the connector insulation becomes contaminated, insulation resistance will
be substantially reduced, affecting high-impedance measurement paths. Oils and salts from the skin
can contaminate connector insulators, reducing their resistance. Also, contaminants present in the air
can be deposited on the insulator surface. To avoid these problems, never touch the connector
insulating material. In addition, the scanner card should be used only in clean, dry environments to
avoid contamination.
If the connector insulators should become contaminated, either by inadvertent touching, or from
airborne deposits, they can be cleaned with a cotton swab dipped in clean methanol. After thoroughly
cleaning, they should be allowed to dry for several hours in a low-humidity environment before use, or
they can be dried more quickly using dry nitrogen.