It took a week of spare time, 10 ECOs, to go from
to
Nasty: parts on both sides with complicated clearance issues, picosecond stuff, crosstalk, serious thermals, panel arrangement issues, all sorts of things.
It was part tedious and part a lot of fun. I enjoy PCB layout for some reason, sort of a game like chess with more pieces.
There's a sort of DPAK thick-film 50 ohm resistor, bottom side lower right, that gets heat sinked to the box through giant copper pours.
I may not be able to keep it cool worst-case, so there's a thermistor R14 to shut things down if it gets too hot.