Keeping Connectors Clean; Ac Frequency Response - Keithley 7021 Instruction Manual

Ground loops are not normally a problem with instruments
having isolated LO terminals. However, all instruments in
the test setup may not be designed in this manner. When in
doubt, consult the manual for all instrumentation in the test
setup.

Keeping connectors clean

As is the case with any high-resistance device, the integrity
of connectors can be damaged if they are not handled prop-
erly. If connector insulation becomes contaminated, the
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 insulat-
ing material. In addition, the multiplexer-digital I/O card
should be used only in clean, dry environments to avoid
contamination.
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If the connector insulators should become contaminated, ei-
ther 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.

AC frequency response

The AC frequency response of the Model 7021 is important
in test systems that switch AC signals. Refer to the specifi-
cations at the front of this manual.
Operation
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