DIY Antennas, QRP, SDR & Ham Radio Projects from VU3DXR
This TL071 audio compressor circuit uses a single-supply design with a TL071 op-amp as a voltage-controlled amplifier to manage audio levels. It includes input coupling, peak detection, and RC timing networks to control compression, delivering stable, low-noise dynamic range control for audio and radio applications.
ATS-20 is a compact SI4732-based multiband DSP receiver covering FM, MW, SW, and SSB â a highly sensitive portable radio with external antenna support and mod-friendly firmware
This simple AM transmitter uses a crystal-controlled oscillator and transistor stages to generate and amplify a stable RF signal, then modulates it with audio through a transformer. Powered by 12V, it offers a practical introduction to radio transmission using basic, easily available components.
This microphone audio compressor uses an LM324 op-amp with multi-stage amplification, diode-based gain control, and buffering to regulate signal levels. It smooths volume by reducing loud peaks and boosting weak input, improving clarity for voice, recording, and radio applications with a stable 12V supply
LILYGO T-Embed SI4732 combines an ESP32-S3 microcontroller with a DSP multiband radio (AM/FM/SW/LW + SSB), IPS display, and wireless connectivity â a compact programmable receiver for makers and radio enthusiasts.
This FT8 digital interface connects a computer to a transceiver using a USB sound card, audio transformers, and optocoupler-based PTT control. It enables clean audio exchange and safe isolation, allowing reliable weak-signal digital communication modes like FT8 through proper level control and synchronization.
This simple CW transmitter uses a 74HC240 buffer IC as both oscillator and driver to generate a stable RF signal around 7.023 MHz. A crystal ensures frequency accuracy, while keying enables Morse transmission, making it a compact, low-power QRP project for beginners.
This micro power AM transmitter uses a crystal-controlled oscillator and a 2N2222 transistor stage to generate a stable RF carrier, then modulates it with audio input. A tuned tank circuit and variable capacitor optimize output, enabling low-power short-range broadcasting for experimentation and learning
This article explains how the HydraSDR RFOne enters the SDR market as a direct competitor to the Airspy R2, offering similar core performance with a few key differences.
It highlights a wide frequency range (24 MHzâ1.8 GHz), 12-bit ADC, and up to 10 MSPS sampling, making it suitable for spectrum analysis and amateur radio use. The main differentiator is its open-source firmware, which allows customization and community-driven development
NOAA-15 & NOAA-19 shutdown in Aug 2025 ends APT signals. Hobbyists: explore Meteor-M2, GOES, & SDR skills to keep decoding weather satellites data.