The AT5888-UV has become my take-along radio for operating portable at events. It's always good to also have access to packet radio in the field, so I decided to investigate integrating a Mobilinkd TNC with the AT5888.
I subscribe to Temporarily Offline Ham on Youtube and saw a video on creating a cable for the Retevis RT95. The microphone is identical to the one used by the AT5888, so I was able to use the pinout he discovered to create my Mobilinkd cable.
The microphone has the ability to have audio output to a small speaker embedded inside while also using the speaker on the radio itself. For a while I've had the idea that it would be nice to have a cable to connect a TNC using just the one mic jack as opposed to connecting to both the mic and speaker out on the back of the radio.
|AT5888-UV Mic Pinout|
The official diagram for the mic connector doesn't show anything about audio output, just the usual MIC/PTT pinout. But according to Steve from the TOH video, pin 5 is the one that carries audio to the microphone. It would have been nice of AnyTone to label this as "UP/Audio Out."
|Steve from TOH showing the pinout he used.|
With that information, it was pretty simple to create a compatible cable to the Mobilinkd.
|3.5mm TRRS Plug Connector|
|Soldering Leads to the TRRS Connector|
The pinout of the RJ45 connection on the AT5888 is:
8 Orange/White -> NC
7 Orange -> NC
6 Green/White -> NC
5 Blue -> Tip
4 Blue/White -> NC
3 Green -> Ring 2
2 Brown/White -> Ring 1
1 Brown -> Sleeve
|TRRS connection covered in heat shrink.|
|Cable used for testing|
The TRRS connectors I found were a bit hard to solder and I couldn't get the nice looking plastic cap back on the connector. Instead, I simply put glue on the connections and covered everything with heat shrink tubing. I'll probably remake the cable in the future to make it more sturdy.
|AT5888 HND SPK Setting|
Using the cable with the AT5888 requires a change in the "HND SPK" setting. By turning this setting on, audio is sent to both the radio speaker and to the RJ45 mic jack on the side of the radio.
|AT5888 Connected to the Mobilinkd TNC4|
I tested the setup by using WOAD to send and receive some Winlink emails using my phone. It immediately connected and worked well. I'll be sure to keep the cable with me in my bag so I can use it while out at public service events.