My paramotor helmet requires a 3.3 to 5 V power supply for its microphone preamplifier. Theoretically, Baofeng UV-5R’s connector is compatible with Kenwood’s, as shown in the schematic:
In fact, Baofeng UV-5R (circuit board revision VER17) and Baofeng UV-5X do output 3.3 V on their respective 3.5 mm jack tips, but through 10 kΩ resistor. It seems that the tip is used for dual PTT functionality, as shown in the second schematic:
If you don’t need dual PTT, it is very easy to add a constant 3.3 V output. Just add a small value resistor (I used 100 Ω, but 22, 33 or 47 Ω would be better) between the pins marked with red circles in the photo. One pin is 3.3 V, and the other is the tip of the 3.5 mm jack.
You have to disassemble the radio first, as shown in this teardown video on YouTube. This mod forces 3.3 V on the second PTT input, which disables it permanently. The Baofeng UV-5X has exactly the same circuit board, and the teardown process is the same as well.