This repository is an open-source hardware collection of RF front-end modules for low-cost RTL-SDR receivers, not a software application or data research pipeline. It is classified as application because its primary deliverable is a set of manufacturable PCB designs, schematics, and assembly documentation for discrete SDR building blocks. The repo contains complete design packages for an HF upconverter, multiple low-noise amplifiers with bias-tee powering, an SPDT antenna switch, a Mini-Whip active antenna, a balun, a PI attenuator, an RF power limiter, and fixed-voltage coax power supplies. Each module follows a consistent directory pattern: EasyEDA source files, Gerber exports, PDF schematics, component lists, datasheets, assembly guides, and enclosure model files. The RF signal flow runs from antenna through Mini-Whip, upconverter, filters, LNA, and protection stages into an RTL2832U-based SDR, with power injected over coax via bias-tee circuits. The real value of this repo is its modular, reproducible hardware architecture: well-documented bias-tee/power-over-coax designs, Mini-Circuits-based LNA and limiter circuits, and reusable RF layout techniques such as via stitching, ground pours, and controlled-impedance traces. The EasyEDA JSON files are tool-specific but self-contained and importable, and the Gerbers are ready for fabrication. Markdown guides cover component sourcing from LCSC, PCB ordering from JLCPCB/PCBWay, and Linux RTL-SDR setup, including known pitfalls like rtl_biast breakage after sudo make install. The project is explicitly described by the author as a final stable release with support ended, though recent commits in 2026 added new balun and RF power limiter designs, so the repository remains active. Limitations: this is hardware design data, not executable software, so there is no code to run, test, or integrate. The EasyEDA JSON format and .ftr filter design files are proprietary, some component choices (BF998, J310, ADE-1+, DF782, TC9-1+) are at risk of obsolescence, and the repository mixes EasyEDA editor versions from 2020 and 2026. For an engineer, the most reusable assets are the bias-tee power supply schematics, the balun and LNA reference designs, and the consistent module packaging pattern that makes each board a drop-in SDR building block.