WB2CBA ADX — Arduino Digital Modes HF Transceiver

Overview

The ADX (Arduino Digital Xceiver) is an open-source HF transceiver designed by Barbaros Asuroglu (WB2CBA) of the Ankara Amateur Radio Club (ANTRAK). Inspired by Hans Summers' QDX from QRP Labs, the ADX was created with a singular mission: build the simplest, most accessible digital mode HF transceiver possible.

The ADX uses an Arduino Nano, Si5351 clock generator module, and CD2003GP receiver chip to create a complete digital modes transceiver for under $25 in parts. It employs AFP-FSK (Audio Frequency Processed Frequency Shift Keying), a technique developed by Burkhard Kainka (DK7JD), to generate USB-compatible signals through audio tone detection without traditional SSB mixing.

Key Features

• Supports FT8, FT4, JS8Call, and WSPR digital modes
• Operates on 80m, 40m, 30m, 20m, 17m, 15m, and 10m bands via interchangeable LPF modules
• CAT control emulating Kenwood TS-2000 (9600 bps serial)
• Approximately 5W RF output
• Build cost under $25 (excluding shipping)
• Only 2 modules, 2 ICs, and 4 MOSFETs needed
• Simple one-time calibration procedure
• Direct audio connection to PC sound card for WSJT-X

Design Philosophy

The ADX was intentionally designed to be:

• Simple to procure — not affected by chip shortages
• Simple to build — minimal components
• Simple to setup — single calibration procedure
• Simple to operate — plug into sound card and go

WB2CBA made the design explicitly free and open source with no usage restrictions, aiming to attract young amateurs to the hobby through accessible DIY radio engineering.

Community Impact

The ADX spawned an entire ecosystem of derivative designs including the ADX-MINI (KJ7NLA), ADX-S (BD6CR/CRKits), ADX-POCKET (WB2CBA), ADX-UnO, and the ADXI (VK2DIY). Multiple ham radio clubs worldwide have organized buildathon events around the ADX platform.