DIY Antennas, QRP, SDR & Ham Radio Projects from VU3DXR
The RA9SUS simple loop is a compact HF antenna covering 14–30 MHz using a 4.7 m rectangular loop and variable capacitor tuning. Ideal for balconies and small spaces, it enables efficient multiband operation without large wire antennas or ground systems
ZBITX is an ultra-portable 5 W all-band HF SDR transceiver with built-in FT8, CW, and digital modes powered by Raspberry Pi. Pocket-sized QRP radio for POTA/SOTA field operation without a laptop.
Full-size Delta Loops for the 40-meter band normally require around 42 meters of wire—often impossible for operators with limited space. To overcome this challenge, Andy (2E1TAP) documented his attempt at constructing a space-efficient, shortened 40-meter Delta Loop.
Compact 4 m shortened vertical antenna for the 80 m band using a 64 µH loading coil and LC base matching network. UR0GT design enables efficient 3.65 MHz operation in small spaces with full-size radial system for strong HF performance.
The Alpha 1 release of the Nextion Emulator for CEC firmware — a Python-based emulator that brings full desktop simulation of CEC/uBITX radios with Nextion HMI.
Compact dual-band RW4HFN antenna covering 145 MHz (2 m) and 430 MHz (70 cm) with a center-fed element and integrated matching section. Single-feed 50 Ω coax design provides versatile VHF/UHF operation for base, portable, and repeater use.
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 […]