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6221/2182a Sheilding

2182 Series Support
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6221/2182a Sheilding

Post by physknoll » April 7th, 2014, 3:07 pm

Hey forum, So I am preparing a homemade PPMS system with a CC refrigeration liquid helium system, temperature controller, 9 Tesla magnet, and this 6221/2182A measurement system. As I want the lowest noise floor possible I was considering placing both meter/source inside a metal shielded box. The sample environment will already be shielded and the only connections outside of the shield to the meters/source will be one triax and one coax. Will this cut down on the noise or is the case shielding already enough and anymore is useless? Thanks!

Dale C
Keithley Applications
Keithley Applications
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Joined: June 10th, 2010, 6:22 am
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Re: 6221/2182a Sheilding

Post by Dale C » April 8th, 2014, 10:57 am

The inner shield of the triax should surround the inner conductor of the triax on the 6221 all through the circuit if sourcing less than 1nA(1e-9A).
The 2182A is low noise but if you are measuring low voltage <1mV then the coax shield should surround the HI of the 2182A through the circuit.
What is the source resistance?
Cooling things down will help also help.
But the extra shield is probably not helping much.
So it is like this
for high resistance >1G ohm the inner shield of the triax is important.
for low resistance <1 ohm, the Model 2182A input shield is important.
Betweeen the two, the shields are not much of noise deterent.

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