This site provides schematics of various radio projects that you can experiment yourself.
Tuesday, 10 March 2026
The Half Square Antenna: Low-Profile DX Wire for HF Bands
Monday, 9 March 2026
W3DZZ Multi-Band Antenna 80m-10m Trapped Dipole
Build a Classic Multi-Band HF Antenna!
Discover the W3DZZ Multi-Band Trapped Dipole covering 80m to 10m in this detailed guide from DXR Electronics Bits. Learn how this legendary antenna uses 7 MHz traps to electrically divide the dipole, allowing efficient operation across multiple HF bands with a single wire. The article explains trap construction, antenna dimensions, tuning tips, and installation advice, making it a great DIY project for amateur radio operators who want reliable multiband performance without complex tuners.
🔧 Perfect for hams looking for a compact, efficient, and time-tested HF antenna design.
👉 Read the full guide: https://vu3dxr.in/w3dzz-multi-band-antenna-80m-10m-trapped-dipole/
Sunday, 8 March 2026
Getting Started with AIS: Track Ships from Your Shack with a RTL-SDR
Microphone compressor using two transistors
Radio Waves Weekly — Issue #007
Sunday, 1 March 2026
Sporadic E Propagation: The Science Behind Long-Distance FM Radio Reception
📡 Why did you just hear a radio station from 1,000 km away?
It sounds like magic — but it's pure atmospheric science. Sporadic E Propagation (Es) happens when dense ionized clouds form in the E layer of the ionosphere, bending FM signals back to Earth far beyond their normal range.
This in-depth article from vu3dxr.in covers everything: ✅ The science behind Es clouds ✅ Peak seasons (hint: June solstice is prime time!) ✅ Skip zones and multi-hop paths ✅ Best receivers, SDRs & antennas for FM DX ✅ Pro tips for catching openings in real time
Whether you're a seasoned ham or just curious about that mysterious distant station — this is a must-read!
🔗 https://vu3dxr.in/sporadic-e-propagation-the-science-behind-long-distance-fm-radio-reception/
#HamRadio #RadioDX #SporadicE #FMRadio #RadioPropagation #SDR #AmateurRadio
Friday, 27 February 2026
Build a Multi-Band Doublet Antenna for Wideband HF Operation
Thursday, 26 February 2026
Sporadic E Propagation: The Science Behind Long-Distance FM Radio Reception
Monday, 23 February 2026
Baofeng UV-5R Mini: Compact Dual-Band Powerhouse
Saturday, 21 February 2026
Join the 8-Meter Experiment: Monitor FT8 on 40.680 MHz with WQ2XDM
Friday, 20 February 2026
FT2 Digital Mode: Speed King With Serious Growing Pains
Thursday, 19 February 2026
FT2: The Fastest Digital Mode in Amateur Radio
Wednesday, 18 February 2026
FT2 – A New Digital Mode Hams Are Starting To Spot
Beginner’s Guide to HF SSTV Setup with SSB Transceivers
Slow Scan TV (SSTV) with HF SSB Transceivers: A Comprehensive Guide
If you are interested in transmitting images across the globe using radio waves, Slow Scan TV (SSTV) is an excellent mode to explore. The latest guide on VU3DXR.in provides a detailed walkthrough on how to interface your HF SSB transceiver with your PC to begin sending and receiving images.
Key Topics Covered:
Hardware Requirements: Detailed information on necessary equipment, including Signalink, various rig interfaces, and DIY cabling options.
Software Configuration: A step-by-step guide to setting up standard software like MMSSTV or QSSTV.
Operating Frequencies: Guidance on finding active SSTV frequencies, such as the 14.230 MHz USB hotspot on the 20m band.
Signal Optimization: Instructions on managing ALC and audio levels to ensure high-quality image resolution.
Why Operate SSTV? Unlike text-based digital modes, SSTV allows operators to share personalized QSL-style images, weather data, or station photos. It offers a unique combination of analog signal characteristics and modern digital processing, providing the satisfaction of seeing an image resolve line-by-line from a distant station.
This guide is designed for both experienced DXers and those new to amateur radio who wish to expand their technical capabilities.
Read the full tutorial here:
Tuesday, 17 February 2026
Setting Up SSTV with HF SSB Transceivers: A Comprehensive Guide
Monday, 16 February 2026
Build Your Own Indoor Antenna for 7 MHz HF Band
DIY 145 MHz Twin Delta Loop Antenna for Ham Radio Operators
Sunday, 15 February 2026
The Complete Guide to HF SSTV: From History to Your First Transmission
Friday, 13 February 2026
Reverse Beacon Network: The Ultimate Guide for Ham Radio Operators
Thursday, 12 February 2026
uBITX Microphone Preamplifier
Wednesday, 11 February 2026
Bi-Square Antenna: A High-Gain design for upper HF and VHF
Building HF Linear Push-Pull Amplifier with IRF510 MOSFETs
Tuesday, 10 February 2026
Microphone Preamplifier with Diode Clipper for SSB Transceivers
Practical guide to receiving HF weather fax WEFAX / Radiofax
Weather Facsimile—commonly known as WEFAX, HF-FAX, or Radiofax—is easily one of the most rewarding niches in the shortwave hobby. There is a certain “magic” in tuning your receiver to a scheduled frequency and watching a high-resolution synoptic chart or satellite image slowly materialize on your screen, line by line, over several minutes.
While it feels like a relic of a pre-internet era, Radiofax remains a vital, free resource for mariners and a fascinating challenge for radio enthusiasts. This guide covers everything you need to get started in 2026, from understanding the signal to troubleshooting your first decode.
Monday, 9 February 2026
DIY 80m Magnetic Loop Antenna: A Compact Solution for Low Bands
sBitx v5.301 Update: New Features and Improvements Explained
Sunday, 8 February 2026
Simple CW 74HC240 Transmitter using buffer IC
Simple CW 74HC240 Transmitter using buffer IC
Exploring the LILYGO T-Embed SI4732 Radio Receiver
Building Steve Quest’s Simple AM Transmitter
Friday, 6 February 2026
Microphone compressor using two transistors
LILYGO T-Embed ESP32 SI4732 Radio: In-Depth Technical Analysis & User Review
Building End Fed Half Wave antenna (EFHW) for 40M – 10M
Wednesday, 4 February 2026
Near Vertical Incidence Skywave (NVIS): The Definitive Guide to Reliable Regional HF Radio
Ever wonder why your HF signal skips over the next town but hits the next continent? 🌎
Master NVIS (Near Vertical Incidence Skywave) to close the gap! Perfect for regional nets and emergency comms when the repeaters go down.
Check out the definitive guide here: 👇
#HamRadio #RadioOperator #NVIS #VU3DXR #AmateurRadio
Simple UJT Morse Code Practice Oscillator Circuit
Build Your Own Solar Powered Radio
Tuesday, 3 February 2026
27MHz AM Transmitter Circuit for hobbyists
DIY Active Antenna: Boost Weak HF/VHF Signals
Monday, 2 February 2026
Mini Radio Pocket SI4735 Dual Core – Latest Firmware Update Brings EiBi Extensions & Power Saving Mode
sBitx v5.3: A Detailed Look at the New Software Release
Saturday, 31 January 2026
Near Vertical Incidence Skywave (NVIS): The Definitive Guide to Reliable Regional HF Radio
Friday, 30 January 2026
ADSBee 1090: An Open-Source ADS-B Receiver Built for Modern Aviation Tracking
Thursday, 29 January 2026
Evolution of the ATS Mini: A Technical Deep Dive into V1 through V4
Wednesday, 28 January 2026
Dynamic speech compressor with audio preamplifier
Boost your radio's "talk power"! 📻🔊
Check out new project: A Dynamic Speech Compressor + Audio Preamp. Perfect for DIY transmitters and improving SSB/AM audio quality. Clearer communication starts here.
Full schematic and details: 🔗https://vu3dxr.in/dynamic-speech-compressor-with-audio-preamplifier/
Simple two stage one watt AM transmitter
Back to basics! Today on the blog, we’re diving into a Simple Two-Stage Transistor AM Transmitter.
While modern radio is moving toward digital, there is something incredibly satisfying about building a classic 1-watt analog transmitter using discrete transistors. This project is a great way to sharpen your soldering skills and learn how RF stages work together to boost a signal.
Ready to build? Grab your soldering iron and head to the link in bio!
Highlights: 🔹 Two-stage design for better stability. 🔹 1-watt power output. 🔹 Clear, easy-to-follow schematic.
Find it at:https://vu3dxr.in/simple-two-stage-transistor-one-watt-am-transmitter/
Noise Cancelling Condenser Microphone
Build a High-Sensitivity Regenerative Receiver with 2N7000 MOSFET
VK4FUQ Optimized sloper antenna for 3.5Mhz
G4RAW 80M QRP TAG CW Transmitter
Full Wave Loop Antenna for VHF, UHF & FM Radio Bands - Ready to Upgrade Your Radio Experience?
Check out our detailed guide with step-by-step instructions, calculations, and tips to build your own full-wave loop antenna!
👉 Read the full guide here: https://vu3dxr.in/full-wave-loop-antenna-for-vhf-uhf-fm-radio-bands/
Whether you're a seasoned radio operator or just getting started, this project is perfect for improving your station's performance. The best part? You'll learn valuable antenna theory along the way!
Monday, 26 January 2026
Building the LARCSet v3.0: Real-World Problems and Proven Fixes
Working on the LARCSET v3.0?
The Bitx20 community is full of brilliant minds, and many of us have faced similar challenges when putting this version together. I’ve compiled the most frequent problems and their proven solutions into one guide to help fellow builders.
From troubleshooting common errors to fine-tuning for better performance, this post is meant to be a "workbench companion" for your project.
Read more here:
Let me know in the comments what your experience has been with the v3.0 so far! 73! 📻
#HamRadio #Homebrew #Bitx20 #RadioBuilder #VU3DXR
Sunday, 25 January 2026
Simple series modulated AM QRP HF Transmitter
Simple mic compressor using 3 Transistors for HF rigs
VK3YE’s AGC circuit for ubitx
Friday, 23 January 2026
Terminated End Fed Vee Antenna (TEFV)
It is a travelling wave antenna, which has a constant current distribution along its length. Antennas usually used by radio amateurs are resonant standing wave types like dipoles. It is built to a specific tuned length so that a standing wave is set up on the antenna element. This is efficient and narrow band, only works on the fundamental frequency. In a travelling wave antenna there are no standing waves on the antenna element as the power that would be reflected back from the end of the antenna is absorbed by the terminating resistor. Typically this is 25% of the power applied to the antenna.
The polarization of the TEFV ( Terminated End Fed V Antenna) is a mixture of vertical and horizontal that results in a kind of elliptical polarization. The main advantages of terminated end fed V antennas are its broadband nature and no tuner requirement. It provides a non-resonant antenna with exceptionally wide bandwidth, matching a 50 ohm coaxial cable transmission line with a VSWR of less than 2:1 from 1.8 MHz to 30 MHz.
The critical parts in TEFV antenna are 9:1 unun transformer and terminating resistor. Main problem was in constructing 9:1 Unun with correct size wire for windings. Winding with wrong wire size resulted in poor impedance transformation and high through loss. The resistor value should be 10% higher than the transformer output impedance. So for a 9:1 transformer (50 ohms to 450 ohms) the termination should be 500 ohms
G4RAW 80M QRP TAG CW Transmitter
Circuits – Sovina2 40M Class E Transmitter
Do it yourself Shortwave Transmitter circuit
Thursday, 22 January 2026
40m Vertical Antenna: Compact Base-Loaded Design for Powerful HF Operation
The 40m vertical antenna is one of the most effective solutions for amateur radio operators who want strong DX performance without needing a full-size tower or large open yard. The 40-meter (7 MHz) HF band is prized for its reliability—offering both daytime regional communication and long-distance propagation at night. Yet, a full quarter-wave vertical requires around 10 meters of height, which can be impractical in residential areas.
That’s where a base-loaded 40m vertical antenna comes in—shortened to just 3.4 meters tall, it uses a coil at the base to achieve electrical resonance, allowing operators to enjoy 40m contacts from almost anywhere.A practical solution is a base-loaded vertical antenna, which uses an inductive loading coil at the base to achieve electrical resonance with a shorter radiator. The design shown above, originally credited to PY7NQ, is a compact yet efficient vertical antenna optimized for 40m HF operation.
This antenna is a base-loaded quarter-wave vertical for 40m, physically shortened to just 3.4 meters in height. The missing electrical length is compensated using a loading coil placed at the base.
Microphone compressor using LM1458
👉 https://vu3dxr.in/microphone-compressor-using-lm1458/
Fixing Poor Audio Quality in uBITX V6.1 HF Transceiver
Mighty Mite 5W Crystal Controlled QRP CW Transmitter
Tuesday, 20 January 2026
Build Your Own Multiband G5RV Antenna: A Classic Ham Radio Project
📡 Build your own classic Multiband G5RV Antenna and work multiple HF bands with a single wire setup! Simple, effective, and perfect for both beginners and seasoned hams. A great DIY project to boost your station and explore the airwaves. 🌍🔧
👉 Get the guide here: https://vu3dxr.in/build-your-own-multiband-g5rv-antenna-a-classic-ham-radio-project/
#HamRadio #G5RV #DIYantenna #AmateurRadio
Getting Started with FreeDV: A Beginner’s Guide to Digital Voice on Amateur Radio
If you’re an amateur radio operator looking to explore digital voice modes beyond the usual FM repeaters, FreeDV offers an exciting opportunity to experiment with open-source digital communication. This guide will help you understand what FreeDV is, why it matters, and how to get started with this fascinating mode.