DIY 80 m magnetic loop antenna: 1.5 m copper tubing loop with gamma-style feed and air-variable capacitor, delivering low-noise 3.5 MHz HF performance in small areas
QRP
The QRP section is dedicated to low‑power HF and VHF operating, with a heavy focus on simple transmitters, minimalist transceivers, and practical on‑air results. Here you’ll find classic designs like the Mighty Mite, OXO transmitter, Mosquito TRX, and modern SDR‑based rigs such as sBitx and ZBitx tuned for portable use, all built around parts that are easy to source and experiment with. Articles emphasise repeatable circuits, clean keying, stable oscillators, and output filters so that your 1–5 W signal is both efficient and pleasant to copy at the other end
sBitx v5.301 Update: New Features and Improvements Explained
sBitx v5.301 update refines the v5.3 platform with FT8/FT4 stability fixes, UI polish, improved logging/UDP integration, and CW decoding tweaks — enhancing reliability of the Linux SDR transceiver
Building the LARCSet v3.0: Real-World Problems and Proven Fixes from the BITX20 Community
Troubleshooting guide for the LARCSet V3.0 40 m SSB/CW transceiver kit covering common failures, low mic gain, tuning issues, and PA faults. Community-proven fixes and mods from BITX20 builders improve stability, audio, and output power.
Mighty Mite 5W Crystal Controlled QRP CW Transmitter
The Mighty Mite 40 Meter QRP CW Transmitter is a legendary low-power Morse code transmitter widely built by amateur radio operators for portable, minimalist, and educational operation.
Build a Powerful FM Radio Bug Transmitter
Three-stage FM bug transmitter using BC547 audio preamp, RF oscillator/modulator, and 2N3563 power amplifier for strong 100 MHz transmission. High-performance DIY wireless microphone circuit with improved range and signal stability.
RW4HFN Balcony Antenna for the 20-Meter Band
Discover the RW4HFN balcony antenna design for the 20-meter amateur radio band—ideal for limited spaces. Includes schematic, dimensions, and inductance values
Mosquito TRX: Single-MOSFET 40-Meter (7030 kHz) CW Transceiver
Mosquito TRX is a single-MOSFET 40 m CW transceiver for 7030 kHz using crystal control and direct-conversion reception — an ultra-simple QRP rig and SDR front-end for sound-card radios
Curumim Transceiver – World’s Smallest QRP CW Transceiver
Discover the Curumim Transceiver, an ultra-minimalist QRP CW rig for 7.030 MHz that combines a single-transistor crystal oscillator and LM386 audio amplifier into one of the world’s smallest working HF transceivers, ideal for homebrewers, educators, and portable CW enthusiasts
Shortened G5RV Antenna – DX Power in a Smaller Package
Shortened G5RV antenna design: a compact multiband HF dipole covering 20m–6m bands with ladder-line matching and 4:1 balun for portable or small-yard installs.
Aperiodic Multiband Wire Antenna: A Simple and Effective Design
Aperiodic multiband wire antenna design by HB9KX/DK7ZB: 10.5 m asymmetrical dipole with resistive loading for broadband HF coverage without complex tuning