Saturday, August 9, 2014

APRSDroid Audiocable ( 3.5mm 4-pin / TRRS ) for Kenwood/China handy

Tested with various handy
This is a short post on how to do a DIY audiocable for APRSDroid on Kenwood / China handy type ..

We use the Yaesu VX-8G as the receiver for our APRS test and tested with a few common China handy like Wouxun and TYT.

Thanks to info from 9W2KHN, he mentioned this site have made an audiocable for TRRS phones.

There are basically two types of connectors for the four pin 3.5mm plug.. the only differences are the Ring-2 and Sleeve ... either mic or ground.

4-pin 3.5mm pinout

Kenwood / China PTT pinout

As most of the phones are either Samsumg, iPhone (including XiaoMi ), we decided to make the audiocable for Samsung/iPhone called the TRRS connector.

I did not follow the components used by the circuit on the above mentioned site but just the connection. Do NOT max out your handy might blow your Android smartphone microphone.

For the handy settings, turn ON VOX to 3 to 5 ( depending on the handy sensitivity ) ...

If you are not getting anything out from the radio, change your APRSDroid Preferences on the following :-

Connection Protocol :- AFSK via Speaker/Mic
Connection Preferences :- Frame Sync Prefix ( default is 1000ms, you can change to a higher value if your handy is not triggering the VOX within 1 secs )

To troubleshoot, you can hear the output sound before plugging in the TRRS connector.

TRRS Pinout

Here are some pictures of cables professionally done by 9W2WHT..

Unsoldered connectors

Nicely heatshrink wrap connector

The final version look so professionally done cable by cutting the PTT handsfree cable..
Cut from the PTT
Special thanks to 9W2CEW, 9W2KHN and 9W2WHT for the testing on various handy.



  1. Do you do consignment cable work? I have tried and the connections are just way to small for my skip level.. :(

  2. Thanks for taking the time to post this, I'm about to build one right now.

    I had seen another post for making the cable and someone commented a capacitor should be used on the ground to the 2.5mm jack that is on the radio side. However if this is proven to be working, then perhaps that cap is not required?

  3. Hello,
    where can I buy a two pin (Kenwood/Baofeng) plug
    like the one pictured in the last photo?
    Thank you very much!

  4. Hello.
    I had to make a cable to connect my Xiaomi phone to a UHF radio and use the AFSK protocol with aprsdroid.
    the uhf radio has a PJ068 3 pole jack with Ground/Mic/Ptt
    So i connected with a 4 pole 3.5mm jack -->
    Ground with ground(3)
    Mic with Mic(4)
    Ptt with right audio (2)

    No the aprsdroid PTTs the radio and then sends the signal...So i dont use a vox function.

    sorry for my bad english.