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:
![Kenwood/Baofeng/Wouxun 3.5 mm 2.5 mm jack connector pinout.](baofeng-kenwood-connector-pinout.jpg)
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:
![Baofeng 3.5 mm 2.5 mm dual-PTT jack connector pinout.](baofeng-connector-dual-ptt-pinout.jpg)
![](baofeng-uv-5r-constant-3v-supply-connector-hack-min.jpg)
![](baofeng-uv-5r-constant-3v-supply-connector-hack-2-min.jpg)
![](baofeng-uv-5x-constant-3v-supply-connector-hack-min.jpg)
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.
![Baofeng UV-5R connector modification, which allows constant 3.3 V power supply on 3.5 tip.](baofeng-uv-5r-constant-3v-connector-mod.jpg)
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.