Going over 12v can overheat Q13 and/or R141:
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I'd recommend an LM2940T-12 regulator between your power supply and the Bitx40's main 12V in. ?The IRF510 final's 12V-PA should not go through this regulator. ?Dropout voltage through the LM2940 will be under a couple hundred millivolts when the battery falls to 12v or less, far better than an LM7812 would give you. ? Provides reverse battery protection and limits current in the event of a short on the board, shuts down if it gets too hot. ?Not a bad idea to put this on every Bitx40. ?The TO220 case has the tab at ground potential. ?Datasheet recommends at least a 22uF cap at the output to keep it stable, and should have a 0.47uF cap at the input.?
Jerry, KE7ER?
