PPMS interface box

The purpose of this box is rather important yet its design is quite simple. The PPMS that the MRSEC acquired in fall 2001 has two major components: the control unit and the refrigerator. There are a number of leads that attach to the sample before it is inserted in the refrigerator. These leads run to a connector on the top of the refrigerator where a cable from the controller is attached. Generally, once the leads are attached to the sample and it is inserted into the refrigerator there is no flexibility in their attachment points. A great deal of time and energy is required to take the refrigerator down to the necessary test temperature and the turnaround time to warm it back up is rather long as well.

There were many design considerations that had to be taken into account. The lead wires are in pairs (either voltage or current pairs) and run as twisted pairs within the cable and box. Maintaining the pairs is important to ensure precise measurements. The cable that was constructed had to be of the same type as the cable that already runs between the controller and refrigerator. This cable is necessary to make the additional run between the interace box and controller; the original cable runs between the refrigerator and the interface box.

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Finished box.	Inside the box
Finished cable	DB-25 connector closeup