Would it be possible to customize the baseplate for the few modules that draw high power? It would be nice to machine the baseplate and heat sinks as one chunk of metal instead of the existing method of having several individual heat sink pieces. I would like to see the PCB laying flat on top of the baseplate with milled cutouts to accommodate any devices attached to the bottom side. In a perfect world there would be no components on the bottom and the PCB would make contact with the baseplate across the entire surface. Another possibility that might be worth considering would be the ability to include "U" shaped heat sinks that would bridge over the top side of hot components and attach to the baseplate through holes cut into the PCB on either side of the component. Thermal gap filler could allow room for CTE mismatches so that the device isn't crushed.

On 10/15/07, Dick Jansson-rr <rjansson@cfl.rr.com> wrote:

Bob:

Shown in this message is a picture of the revised module design that you and I have been working on in the last few days. The revised cover has not yet been done but its features are implicated in this current view. The machined base plate has robust beams around three sides. Further, there are stiffening beams machined on the bottom side of the baseplate. The side to side dimension of the baseplate is shown at 141mm, reduced from its previous 147mm. This step was needed to accommodate the cover screw heads now on the side of the module.

Shown also is a revised connector plate, which is increased in width from the previous 122mm to the 141mm of the baseplate. This should ease the connector space issue a little as the cover PEM nuts have accordingly been moved out leaving a 125mm wide clear space for connector activity, an increase from 106mm.

The PCB is unchanged, however its standoff posts are now 6.4mm (1/4 inch) from the previous 4.8mm (3/16 inch), a step needed for connector plate screws.

The cover will slide over the assembly shown and it will have only one flange, along the rear side. The long sides will use screws placed into the edges of the assembly (formerly a flanged side). This means that there will not be mechanical loading on the baseplate caused by irregular flange bends, as in the present cover design.

Regarding this design of module, the PCB access has been fully maintained, but the cover cannot be removed while the module is installed into the spacecraft, a feature that had been planned with the current design.

Discussion is invited.

Dick Jansson, KD1K

kd1k@amsat.org

kd1k@arrl.net

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