usdx-mini.2.6-fit-filter

The Mini-v2.6 uSDX is an open-source, low-power (QRP) Software Defined Radio (SDR) transceiver designed for amateur radio enthusiasts seeking a compact, cost-effective, and high-performance solution for High Frequency (HF) communications. Inspired by the innovative work of Guido (PE1NNZ) and Manuel (DL2MAN), with contributions from the global amateur radio community, this project builds upon the uSDX design, an evolution of QRP Labs' QCX. The Mini-v2.6 uSDX combines simplified hardware with advanced digital signal processing, leveraging an Arduino Nano (ATmega328P) microcontroller to deliver a multimode (SSB, CW, and digital modes) transceiver with excellent performance for QSOs in various scenarios, including contests.

The primary goal of the project is to provide an accessible and easy-to-build HF transceiver that balances simplicity, functionality, and performance. The Mini-v2.6 uSDX is ideal for hobbyists, makers, and radio amateurs who wish to explore building modern SDR-based radio equipment while keeping costs low and the design open for customization.

Project Story

The uSDX project originated as a derivative of the QCX, a high-quality CW transceiver developed by QRP Labs. Guido (PE1NNZ) introduced a groundbreaking approach by shifting much of the hardware complexity to software, using the ATmega328P microcontroller to implement SSB signal generation through Digital Signal Processing (DSP) techniques. Subsequently, Manuel (DL2MAN) enhanced the design with an optimized PCB layout and a Class-E power amplifier, making the uSDX more efficient and accessible to the community. The Mini-v2.6 uSDX is a compact iteration of this project, designed to operate on three bands (80m, 40m, and 20m) and fit into a small enclosure (110x70x24 mm, available on AliExpress), making it perfect for portable and experimental operations.

In this revision, a manual RF filter selection module was added, allowing the user to manually switch the band-pass filters for each band. Additionally, an external SPI programming header was included to facilitate firmware updates or ISP programming directly, without removing the Arduino Nano.

The Mini-v2.6 uSDX upholds the open-source ethos, with schematics, firmware, and documentation publicly available, enabling community contributions and adaptations. This project reflects the global collaboration of radio amateurs, with contributions from enthusiasts like Barbaros Aşuroğlu and UD3SBV, who helped refine the design for various configurations and use cases.