A collection of amateur‑radio projects and step‑by‑step instructions for building various Radio Direction Finder (RDF) systems.
This document provides detailed construction guides for several Radio Direction Finder (RDF) projects, including simple and 555‑based Time‑Difference‑Of‑Arrival (TDOA) units, tape‑measure beam antennas, and multiple FOX transmitter designs. Each project includes circuit diagrams, parts lists, PCB layout tips, and practical building advice.
Additional sections cover the HANDI‑Finder kits, frequently asked questions about RDF hunting, hardware resources for home builders, and auxiliary tools such as an RF sniffer with tone output and an audible S‑meter.
| Gain (Yagi antenna) | 7.3 dBd |
|---|---|
| Front‑to‑Back Ratio | >50 dB |
| E‑plane Beamwidth | 67.5° |
It switches the receiver between two antennas at about 500 Hz; the resulting tone’s phase is processed by a synchronous detector to drive a center‑scale meter that points toward the transmitter.