Reply To: Why +12V max? Store › Forums › QRP Transceivers › Why +12V max? › Reply To: Why +12V max? July 27, 2017 at 6:34 am #3552 on7basMember My guess is that it is more about heat dissipation than actual operating voltage, 4 W out is pretty good without heat sink in such a confined space. But I can’t speak of experience, my MTR3B is on it’s way to Belgium. 72 Yves ON7BAS This reply was modified 4 years ago by on7bas.