After posting the last entry, I remembered that i'd recently been upgrading the fans on my PC, and that some left over bits were on my shack desk. Amongst these were four self tapping screws, which turned out to be a perfect fit for the fan on the SMPSU build! So that fan is now very securely fitted.
After a bit of playing about with other things, such as testing the NEL Tornado coil on my detector in the garden (and finding 5p!), I returned to the problem of how to secure the SMPSU module in the case without being able to tighten anything up inside. A bit of pondering and measuring later, and I had the two mounting holes on the power supply module drilled out (in the case of the one that was a whole hole) or filed out (the other one, and open 'fork' type mount) to 5mm and a pair of Nutsert rivets installed. Now, the module had a pair of M3 tapped nuts permanently attached.
Quite a while was then spent deciding on the exact position of the module inside the case. I wanted to provide maximum airflow around it, but also keep it clear of the mains socket connections by at least a quarter of an inch. Having decided where it would go, the next difficulty was measuring and marking out where to drill the two mounting holes.
It is now fixed in the case. It will come out of course for the installation of other parts, for wiring up, and for testing. Still to be fitted are the output fuse holder and indicator, output 'on' and cooling 'on' switches, and the 12V regulator to drive the fan. I 'might' also provide a 12V output DC barrel connector socket, since the 12V will be available. I cant decide whether to mount these on the 'top' of the case, as seen when in use with the radio on a bench, or the bottom of the battery case.
I also have a problem in that im not sure if I should connect the DC negative lines to chassis! Something to research. If not, then i'll need to find an insulating kit for the regulator!