Update:

Alright, I realized something. I might have misunderstood something. The analog radio circuitry is supposed to be turned off thru the power MOSFET 2SJ615, marked Q1008 in the circuit. This is contrary to my previous understanding that the circuitry in question remains on regardless the state. The MOSFET is driven directly by a pin in the microcontroller. The signal line is called “REG SW” in the circuit diagram, which I am guessing signifies “Regulator Switch”.

Therefore, in my renewed understanding, the 13.8V power should only goes to three different paths:

• the power MOSFET, that gatekeeps it from the rest of the analog circuitry on the main board
• the logic board, where the microcontroller lies, with its own set of power regulation
• the final RF amplifier (irrelevant for this matter)