DIY Antennas, QRP, SDR & Ham Radio Projects from VU3DXR
A detailed look at a compact 29 MHz AM transmitter for the 10-meter amateur band, covering the BD136 crystal oscillator, BD135 RF stage, modulation, output filtering, component values and construction techniques. <p>The post Simple 29 MHz AM Transmitter first appeared on DXR Electronics Bits .</p>
TinyDX is an incredibly compact open-source HF digital modes transceiver designed specifically for FT8 and FT4 operation. Powered entirely from a USB connection and small enough to fit in your pocket, it demonstrates just how capable modern QRP radio design has become. <p>The post TinyDX: A Palm-Sized HF Digital Modes Transceiver That Fits in Your Pocket first appeared on DXR Electronics Bits…
Discover the compact SM0VPO miniature magnetic loop antenna for the 80-metre amateur band. This guide explains its construction, dimensions, tuning method, operating principles, advantages, limitations and practical tips for successful operation. <p>The post Miniature 80-Metre Magnetic Loop Antenna first appeared on DXR Electronics Bits .</p>
Pebble HF is an open-source, single-band 20m QRP transceiver built by the Ham Radio Duo — Becky (N4BKY) and Mike (N4FFF) — in collaboration with Barb (WB2CBA), who did the hardware design, and Guido (PE1NNZ), whose uSDX firmware forms the software backbone. <p>The post Pebble HF: The $50 Open-Source QRP Transceiver That Wants to Get You on HF first appeared on DXR Electronics Bits .</p>
A complete walkthrough of building a web-accessible SDR receiver using the RTL-SDR V4 dongle and OpenWebRX — covering both the official Raspberry Pi image and Docker installation methods, SDR device configuration, antenna and noise-reduction tips, and a practical comparison of which Raspberry Pi model actually suits your setup. <p>The post Setting Up OpenWebRX with the RTL-SDR V4 Dongle: A…
sBitx 5.4 is a major release for this open source HF transceiver, adding FM mode, CESSB audio shaping, new display support, and automatic power safeguards. The update also rebuilds core signal processing, adds an SWR sweep tool, and brings HPSDR networking support. Here's a full breakdown of what changed and where to download the new SD card image. <p>The post sBitx Version 5.4 Released: New FM…
Ever wondered how classic audio gear tames loud volume spikes without complex integrated circuits? This vintage-style two-transistor microphone preamp uses a clever pair of Germanium diodes to limit signal peaks automatically. Let's break down the schematic piece by piece. <p>The post Classic 2-Transistor Microphone Compressor first appeared on DXR Electronics Bits .</p>
Learn how to build a simple and effective 40-10m Off-Center Fed (OCF) Dipole antenna. This guide covers the design, the crucial 4:1 balun, and construction tips for your ham radio station. <p>The post 40-10m OCF Antenna: A Simple, Multi-Band Wire Antenna first appeared on DXR Electronics Bits .</p>
This guide walks you through a simple FM receiver circuit built around a BF256 FET and LM386 audio amplifier IC. Whether you are a beginner hobbyist or an electronics enthusiast, this project delivers clear audio from FM broadcasts using minimal, easy-to-source components. <p>The post Simple FM Receiver with Audio Amplifier first appeared on DXR Electronics Bits .</p>
Five space-saving HF antennas for city hams: Mini G5RV, Shorty 4020, UA6CA Windom, Window Loop, and 40m Mag Loop. All buildable on small rooftops or balconies, with links, specs, and real-world tips from VU3DXR. <p>The post Urban HF Antenna Problem: 5 Proven Builds for Small Rooftops first appeared on DXR Electronics Bits .</p>
Struggling to choose between FT8 and FT4 for your weak-signal amateur radio operations? This article breaks down the key differences in speed, sensitivity, and application, helping you decide which mode is best for your specific needs, whether it's casual DXing or contesting. <p>The post FT8 vs FT4: Choosing the Right Digital Mode for Weak Signal Success first appeared on DXR Electronics Bits…
The June 2026 firmware V4 turns your pocket ESP32-S3 / SI4732 receiver into a standalone image decoder. Learn how to modify your radio with a $2 I2S microphone to receive weather faxes and amateur radio color photos directly on the device <p>The post ATS Mini Radio Gets SSTV & Weather Maps Image Decoding first appeared on DXR Electronics Bits .</p>