DIY Antennas, QRP, SDR & Ham Radio Projects from VU3DXR
Stop guessing if your quartz crystals are dead or alive! Learn how to build a Simple UJT Crystal Checker circuit to test your components like a pro. This DIY guide includes a full schematic, 2N2646 UJT tips, and step-by-step instructions for quick troubleshooting.
HydraSDR RFOne is a fully open-source 24 MHz–1.8 GHz SDR receiver with 10 MHz bandwidth, 12-bit ADC, and USB-C — a high-performance wideband platform for satellite, VHF/UHF, and RF research
Ready to go on a “Fox Hunt”? Whether you are tracking down a hidden transmitter for a local Ham radio competition or trying to find a mysterious source of RFI in your shack, you need a tool that is more sensitive than a standard field strength meter.
Boost your HF reception with this classic Active Antenna circuit covering 0.5 to 30 MHz. Learn how to build a high-gain, low-noise wideband antenna perfect for SDRs and shortwave receivers in space-constrained environments.
Discover how to build a Logarithmic Audio Compressor circuit for smooth, natural-sounding audio. This guide features a high-performance schematic using precision op-amps and log-antilog transistors to prevent distortion while maintaining consistent signal levels for amateur radio and pro-audio projects.
Learn how to build a simple and effective Audio Clipper Circuit using BC547 transistors and 1N914 diodes. This DIY guide covers schematic details, component selection, and how to prevent overmodulation in amateur radio transmitters for clearer, peak-limited audio.
Learn how to build a compact, high-sensitivity Miniature FM Transmitter with this DIY electronics guide. Featuring a simple transistor-based schematic and an electret microphone, this project is perfect for beginners exploring RF circuits and wireless audio.
The circuit shared here is a Microphone Preamplifier with Audio Peak Limiter, often used in audio recording, amateur radio, or intercom systems. It amplifies weak microphone signals and includes peak clipping diodes to prevent signal distortion from loud inputs. Looking to boost your microphone signal while keeping audio distortion in check? This two-stage transistor microphone […]
Build a high-sensitivity DIY 3-Transistor FM Bug Transmitter using a piezo microphone. This step-by-step guide includes a stable schematic, BC547 transistor tips, and frequency tuning advice for crystal-clear long-range audio monitoring.
There is something magical about hearing your own voice or music coming through a vintage tube radio from across the room—or across the neighborhood. While many low-power “flea” transmitters struggle with range, this 3-Watt AM monster brings some real “punch” to the Medium Wave band.
In this project, we’re stepping up the power. Using the classic BD139 transistor and a rock-steady crystal oscillator, we’ll build a transmitter that balances simplicity with performance. Whether you’re a Part 15 enthusiast or just want to experiment with AM modulation, this circuit is the perfect way to become your own local broadcaster. Let’s get on the air!