[time-nuts] Heat sinking for the FEI FE-5650A

Mark Sims holrum at hotmail.com
Tue Jun 10 23:12:38 EDT 2008

Decent thermal management of the FE-5650A can be a problem.  It is a small,  compact object dense with electronics and the rubidium physics package that runs at over 100 degrees C.  There are two metal plates in the unit.  One is the baseplate of the physics package.  It is bolted edge on to the voltage regulator baseplate that forms the bottom (well autally one edge) of the unit.

It does not look like the FE-5650A is meant to attach to a heat sink by securing the large flat face of the regulator baseplate to a heat sink.  There are no mounting holes on it for securing it flat face down (that would also block the 20 pin cable connector).  

The only mounting holes on the regulator baseplate are along the edge of the plate where it would be rather difficult to attach an effective heat sink.  The holes along three edges of the baseplate are used for attaching the cover.  This leaves only one edge for mounting the device to a chassis.  This gives only a tiny amount of surface area for heat transfer.

The only way to get the regulator baseplate in effective contact with a heat sink is to not use the 20 pin cable/connector and to remove the two countersunk screws that secure the regulator baseplate to the edge of the physics package baseplate.  By replacing these two screws with longer ones,  a heatsink could be attached to the the regulator baseplate.  It would be even better to drill and tap a couple more screw holes so that better contact can be made to the plate.  Also good thermal transfer compound should be used.

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