H.F SPECTRUM Analyser PCB KIT

Full pcb kit designed by 9H5BM. The control board features a 2 in1 board where it can be used as a band sweeper. 

The Specan spectrum analyzer by VU2ESE is a fully homebrew RF measurement instrument inspired by the legendary W7ZOI/K7TAU design. Built for amateur radio enthusiasts and RF experimenters, it delivers professional-grade performance at a fraction of the cost of commercial equipment.

At its core, Specan is a double-conversion superheterodyne receiver modified to function as a spectrum analyzer. It uses an Arduino microcontroller for control, an Si5351 synthesizer for precise frequency generation, and an AD8307 logarithmic detector to convert RF signal strength into a readable dB output. The system operates from DC to 70 MHz, making it ideal for HF and low VHF applications.

One of its key strengths is its flexibility. It offers two resolution bandwidths (300 kHz and 1 kHz), allowing users to switch between fast scanning and high-precision measurements. The analyzer can display results on a built-in LCD or plot them on a PC via USB, enabling real-time spectrum visualization.

The Specan is capable of measuring harmonics, spurious emissions, IMD distortion, filter responses, amplifier performance, and antenna characteristics. With a dynamic range exceeding 70–80 dB and an input intercept point around +15 dBm, it performs surprisingly close to commercial-grade instruments in many amateur radio applications.

Unlike expensive lab equipment, Specan is designed for home construction using readily available components and simple tools. It emphasizes modular building, shielding techniques, and step-by-step calibration, making it an educational and practical RF engineering project.

This project not only provides a powerful measurement tool but also serves as a deep learning platform for receiver design, RF filtering, oscillator design, and spectrum analysis principles. It is widely regarded as one of the most advanced DIY spectrum analyzer projects in the amateur radio community.