DIY Antennas, QRP, SDR & Ham Radio Projects from VU3DXR
PortaRF is a compact all-in-one portable SDR combining HackRF-class wideband RF (≈1 MHz–6 GHz) with integrated PortaPack Mayhem firmware and battery operation. A handheld spectrum analyzer, receiver, and signal tool for RF exploration, field testing, and wireless research.
LARCSet is a $39 open-source 40 m SSB/CW transceiver kit from HF Signals delivering 5 W QRP output with simple BITX-style architecture. Beginner-friendly build-it-yourself radio designed to make affordable HF operation accessible to new and homebrew amateur radio operators.
The broadband butterfly (bi-square) antenna uses two connected square loops to deliver stable 50–75 Ω impedance, low noise, and several dB gain over a dipole across VHF/UHF bands. Simple bidirectional design requires no tuning and scales easily for 144 MHz and 430 MHz operation
Common-mode currents are a well-known enemy of clean RF communication. When RF travels along the outside of your coaxial cable, it causes feedline radiation, noise pickup, RFI in the shack, audio distortion, and unpredictable SWR variations. To solve this, radio amateurs typically install a CMC choke (also called a current balun or common-mode filter) at […]
Build a low-noise VHF RF preamplifier using the MAX2633 MMIC to improve receiver sensitivity and antenna signal strength on 144–148 MHz. Simple biasing and matching provide wideband gain for FM, repeater, and weak-signal reception.
PhaseLatch Mini is a compact STM32-based SDR digitizer with dual 12-bit simultaneous ADCs and 210 kS/s USB I/Q streaming. Designed for use with PhaseLoom front-ends, it delivers clean HF/VHF signal capture for GNU Radio, GQRX, and SDR experimentation.
The dual-band 144/430 MHz Square Loop Antenna is one of the most efficient and compact VHF/UHF antennas that amateur radio operators can build at home. Designed to cover both the 2-meter and 70-centimeter bands, this antenna offers excellent gain, low noise reception, and impressive SWR when constructed correctly.
Ditch the lossy traps and discover the Morgain Antenna—a clever, compact dual-band dipole for 40m and 80m. Operating at just 20 meters long, this wire-only design uses folded elements to achieve resonance without bulky coils. The ultimate space-saving solution for your HF station
Limited on space but want to get on 40m? Learn how to build a high-performance, reduced-size 40m antenna using high-Q loading coils. This guide covers calculations, coil winding, and tuning techniques to fit a 20-meter band antenna into a compact 10-meter footprint.
Low on space but want to reach the 80m band? This technical guide walks you through building a shortened Inverted V antenna for 3.700 MHz. Using high-inductance loading coils, you can fit a full 80m radiator into a restricted urban footprint while maintaining a low SWR