The design

Here is a "safe" APRS interface for BaoFeng and other radios.

Sample schematic:

    / [pdf]

Render

TheDigitalInterface-2026

Motivation

https://github.com/skuep/AIOC works but it seems to have a couple of problems:

  1. RF feedback problem with monopole antennas

  2. Hard-to-source exact 3.5mm and 2.5mm audio connectors

  3. Mechanical fragility of these "half-cut" (chopped off) and then only SMD-style soldered TRS connectors

    Chopped off 'SMD' connectors

  4. Reliance on the PCBA process to get a working product. In contrast, we want our users to be able to homebrew the digital interface (if desired).

I believe we can reduce the cost by a lot and also make the whole thing homebrew-able without placing a JLCPCB PCBA order.

Also, we are hoping that we might be able to use ready-made off-the-shelf audio cables in our design.

BOM

  • Waveshare RP2040-Zero Clone - 200

  • Ambrane 3.5mm to 3.5mm male aux stereo cable TRS - 130

  • 2.5mm to 3.5mm aux stereo cable - 250 (element14)

  • PCB - 150

  • Components - 70

  • Case - 100 INR

Total - 900 INR or less

Pros

  • No cables to make. No cables to cut up!

  • THT audio connectors which can handle rough handling.

Our competition is with Digirig (70 USD). Our product is 1/6th the cost of Digirig and is "software configurable" with many "gears".

References