Bob:
In response so some of Chuck's, Juan's and other's suggestion, I have updated the 125x180 module to incorporate integrally machined support posts and revised the cover attachment to the connector plate. While making this change permanently attaches the posts to the baseplate, it also means that there is no flexibility in omitting any posts.
For Chuck's information the nomenclature of the module is the PCB size, as it has been for seven years. There may possibly be PCBs that would be 75mm larger, totaling to be a 200x180mm PCB, but I certainly would not expect anything larger than that. Also note that the depth of the cavity below the posts is 6.35mm, save for in the very center where there is an attachment for the connector plate that is located 0.75mm below the PCB for a space in the center that is 10mm wide by 6mm deep from the connector plate. I was loathe to locate such a piece here but felt the need for a third attachment for the connector plate.
For Juan, the use of socket heat cap screws is not out of the question, I just did not replace them in this assembly at this time.
For John, I will have to create a revised footprint of the baseplate interface to the bottom of the PCB, which obviously is not quite as limited as just some 0.250inch cylindrical posts. I kept the basic pad of that same general size, but the machining aspects of things get in the way of keeping it quite to the same exact area of spots.
Bob Davis and I discussed extensively the issue of being able to remove the cover while the module is mounted in the spacecraft. To achieve a relief in the issue of the cover dictating the shape of the baseplate, instead of the converse, this feature had to be sacrificed. I well remember the discussions of earlier this century, but the issues that Juan raised seemed to overpower the need to remove the cover while still in the spacecraft. To accommodate the side-mounted screws the sides of the module were "pulled in" by 3mm on each side, with the finished module now being 141mm plus 2x0.5mm for the cover (=142mm) and plus screw heads, instead of the former 147mm overall. (Now don't get bent all out of shape on that fuzzy math. No comments thereof will be accepted.) The module mounting pitch is 150mm leaving 8mm between adjacent modules for two sets of screw heads.
One type of module will, however, have to retain its removable cover feature, however, and that for the power modules as the heat sink screws must be accessed in order to mount the module into the spacecraft. What this design is to look like has not been redetermined at this point.
Dick Jansson, KD1K mailto:[email protected] [email protected] mailto:[email protected] [email protected]