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Keithley 6485 Low Noise Cable

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Keithley 6485 Low Noise Cable

Post by ak47raj » January 26th, 2016, 11:07 am

Does anyone know how better the Keithley cable kit 4803, with low noise cable performs in place of usual coaxial cable? It is too small for our lab but I would still like to put some effort into it, if it is worthwhile. I am measuring low level currents (100 fA-100 pA) over long distance (distance due to laboratory constraints) and facing severe noise at low current levels. As we want fast measurements (100ms) we are not able to put digital filters also. Seeking kind advice of experts.
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Dale C
Keithley Applications
Keithley Applications
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Re: Keithley 6485 Low Noise Cable

Post by Dale C » January 27th, 2016, 5:48 am

Standard coax cable will allow you to measure to about 1nA without leakage, noise or drifting.
Low noise cable from Keithley(model 4801 or 4803) which has graphite lubrication on the shield braid greatly reduces the tribo electric effect can get you down to about 100fA. The cable must be rigidly supported.
The longer the cable the more chance for noise, drift and leakage and longer settle times.
Hope this helps.

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