About a decade ago I bought a TNC-X from Coastal Chipworks. I used it for a fill in digi for Laguna Niguel for a while. I bought the X-Track and X-Digi add-on boards for the TNC-X as well. Unfortunately, when I tried to add a larger 5V regulator to power an external GPS, my dyslexia got the better of me and I ended up letting the smoke out of most of the ICs on the board. I have since bought a new TNC-X to replace this one! And, I am still planning on repairing the one that I blew up!
Always looking for a good Raspberry Pi project, when I saw that John Hansen from Coastal Chipworks had a new Raspberry Pi based TNC product in 2013, I bought one of his kits and put it together. The TNC-Pi board was designed with a stacking header that allows it to mount on the 26-pin GPIO header of an early Raspberry Pi. Using I2C, you could stack multiple TNC-Pi boards on top of each other if you needed multiple radio interfaces.
I used an instrument case for the project and it made a nice portable full featured APRS setup using Xastir software. The older Raspberry PI had reasonable performance, but not great.
In 2017 when John introduced the updated TNC-Pi2, I bought a couple of those. In 2019, I assembled one and built a custom 3D printed case for it. It uses a much faster Raspberry Pi single board computer and has excellent performance. Using the Yet Another APRS Client (YAAC) software, the functionality is excellent also.
Instead of stacking the boards, I designed a case that allowed me to mount them side-by-side with only a few pins needed for the TTL UART wiring, power and status LEDs to the GPIO pins.
For the radio transceiver, I’ve built cables for a Kenwood TM-261 mobile radio and Icom-style Handie Talkie with integrated PTT/Mic-audio connections. Both work great.
In early 2020, when I heard that Coastal Chipworks was closing down, I bought a couple more TNC-Pi2’s and built a few more of them.
For more information about my various APRS projects, and a presentation on APRS I gave at SOARA Saturday, visit my web site
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