First thanks, i'm anytime be glad for answer! And these kind of answer is still hepl me. So thanks.
ok, sorry but what is the word "Finals" ,in your post, mean for? Do you mean the IRF510? The heatsink and the metal case doesn't have contact but when this was corectly built up, so is there more insulation at anypoint a must be? like the board screw holes when mounted on bottom alumium plate, like other conections there?? For real its only the concact between the heatsink of both IRF510 to the back plate and when it's securly built up, then it should be all fine, or does i missed up anything?
The ventilation in my case is on bottom many little holes and on back plate are ventilation lines milled, in the hight of the 2 heatsinks. I work on the idea to install a little processor fan.
But in my workshop room it's caos.. (When you look at my profile pic, and make bit larger you can see the workshop room a little bit, ok not much you can see on it, but the milling machine should be able to see. I have in times before come to HAM, learned Metal-Worker Job and it was a interest to make little things from metal with mill and lathe or other machine.. But now when then ubitx works anyday i want to build a few Antenna and Variable Capacitor for Mag Loop with the mill, so i was lucky to bought these machine and hasn't do waste the money for party or so, in years ago, when have the job and was able to bought this things for look at future. Now i'm proud about that i was think so and see a chance for work with this things on HAM homebrew build things...) Just a story about this..
ok back to topic..
These things like Ground Loops and Grounding a was better understand if i see a shematic which descripe this.
The modes i want do, is SSB mainly and CW in next time when learned this better... But a important thing for me is to make WSPR in next time..This was very nice for me to do it self one day..
ok i hope you can descripe the insulation of the heatsink to the metal case, a little more information for this from your mind was nice.