Packet radio is a particularly fun part of the ham radio hobby. Once upon a time, you might have squirted data about the airwaves using something like the Heathkit HK-21 Pocket Packet. Heathkit stopped being a going concern some time ago, but [btech] has now recreated the device with modern hardware.

[btech] has called the project the Pocket Pico, and like the hardware that inspired it, it acts as a terminal node controller for amateur packet radio. It literally runs the same firmware as the real HK-21. It achieves this by using the Raspberry Pi Pico to run a Z80 processor emulator that can run the same code, while also using the microcontroller to do the work of modulating and demodulating Bell 202 audio tones at 1200 baud to avoid the need for a dedicated modem chip.

Thanks to running the same firmware as the HK-21, you can use the Pocket Pico with lots of old packet radio software. It’s fully capable of doing APRS as well as AX.25 Level 2, and has a built in Personal Bulletin Board System for other stations to leave messages.

If you’re looking to get into packet radio, you might just find this project to be useful. Alternatively, you might like taking a look at some other projects we’ve featured in this space, like the capable OpenModem project. Video after the break.

[Thanks to btech for the tip!]