on the TDA2003. pin-3 is common ground, and also common with the backside.
no need to insulate. (usually, maybe) I was using these devices in modulators
years ago. I would just bolt it to the chassis with a light coat of heatsink
compound, since I designed it all for the chassis to be RF ground as well
as DC ground, which is normally the case.
[ATTACH=full]70367[/ATTACH]
so you can just get a metal washer, with the right thickness,
and width to cover the back side of the TDA2003
to mount it for better heat transfer. Also, it may not be
getting that hot.
(nothing like them modualtor/regulator
transistors in them RCI/Galaxy radios!)
But! this will put the radio chassis at DC ground at this point.
The power supply goes to earth ground at the wall outlet.
Should be no problem, on paper. and you may have your
coax shield grounded to earth and your 60 Hz 120 VAC line.
