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I've seen many Chinese HTs (Baofeng, Puxing, Wouxun, QuanSheng etc.) using the so-called "Kenwood connector", which has a 2.5 mm TRS connector and a 3.5 mm TRS connector. It looks something like this:

Kenwood connector

I've seen it used for serial ports, speakers, microphones, PTT devices and similar.

My question is: What's the exact pinout of this connector?

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This is the one I use for my Baofeng UV-5R.

enter image description here

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  • $\begingroup$ Thanks! Another nice site with some more info is available here. $\endgroup$ – AndrejaKo Jun 18 '14 at 16:07
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Here is a Diagram from page 11 of The (Chinese) Radio Documentation Project's Baofeng UV-5R Manual PDF: enter image description here

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FWIW: The Baofeng UV-5R HT supplies 3.3V through 100(*) ohms on the tip of the 3.5mm connector, not 5V as documented above. Also, the PTT is pulled up thru 10K to 3.3V, and the MIC+ connection line also has a more complex (constant current source?) pullup to 3.3V. [This is nice, as the PTT line can directly connect to a Raspberry Pi GPIO pin!]

There's a (wrong in several places, but you can get the idea of the general functions) schematic at http://static2.rigreference.com/manuals/baofeng/baofeng-uv5r-circuit-diagram.pdf

(*) Correction! The schematic says it's a 100 ohm pullup, one radio measured 10K and the other measured 100K, so it's anyone's guess what a particular radio might have installed. I'm going to mark this pin as "Not Useful".

Further study shows a DC bias of about half the battery voltage across the speaker due to the external speaker being connected to only half of the bridged output amplifier, so you might want to use a DC blocking capacitor.

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  • $\begingroup$ Hello and welcome to ham.stackexchange.com! $\endgroup$ – rclocher3 Apr 19 at 15:45
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The origin of this connector is Kenwood. We work with Kenwood and build custom headsets for Kenwood. This link is pretty much up to date and definative. https://www.wildtalk.com/knowledge-base/kenwood-2-pin-wiring-data/

The 5V pin has varied over time. Initially this was via a 100 ohm limiting resistor to provide power to an external VOX unit. More recent models have either a 10ohm resistor or direct connection to a dedicated regulator to power more power hungry items like GPS mic.

In our experience most copy radios don't have the 5V pin.

Mic Bias (Phantom power) and PTT pullup probably varies across Kenwood radios but has never been an issue to custom headsets that we have built.

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    $\begingroup$ Hello and welcome to ham.stackexchange.com! Would you please consider copying the relevant data from the other site to your answer? Answers that are mostly links are discouraged, in part because links tend to rot. $\endgroup$ – rclocher3 Jun 30 at 14:57

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