Model 6517B Electrometer User's Manual
Section 3: Connections
6517B-900-01 Rev. B August 2022
3-7
Noise shield
A noise shield prevents unwanted signals from being induced on the electrometer input. Effective
shielding encloses the circuit or device under test (DUT) and extends to the 6517B input through a
triaxial cable. The generic connection for the noise shield is shown in the following figure.
Figure 17: Noise shield
1
Device or circuit under test
2
Metal noise shield
3
Connect to 6517B LO, chassis ground, or both using a triaxial cable
Use a noise shield for:
•
Unguarded voltage measurements
•
Unguarded current measurements (below 1 µA)
•
Low-level charge measurements
Typically, the noise shield is connected to 6517B input LO. However, sometimes better noise
performance can be achieved by connecting the noise shield to both 6517B LO and chassis ground.
The 6517B LO can be connected to chassis ground at the rear panel of the 6517B by installing the
ground link between the COMMON binding post and the chassis ground binding post. You may have
to experiment to determine which method provides the best noise performance.
Do not make floating measurements with 6517B LO connected to chassis ground. If the
rear-panel ground link is installed between COMMON and chassis ground, remove it before
floating the instrument.
