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The 1 watt 20 meter QRP transmitter with VXO. This is a nice QRP transmitter that can be used in combination of one of the simple receivers.

Programming software for the Icom IC-R2 handheld receiver and scanner.

How to solve the problems with the ICOM IC R7100 receiver that every time the squelch opens or closes, it produces a clicking noise.

Icom IC-R9500 Professional Receiver with 5 roofing filters, 48 kHz DSP

This project revisits a minimalist software-defined radio (SDR) receiver built using a Raspberry Pi Pico, now optimized for simplicity and affordability. Designed for breadboard assembly with through-hole components, the receiver covers 0–30MHz, supporting CW, SSB, AM, and FM modes with an OLED display and spectrum scope. Key improvements include enhanced frequency accuracy, reduced op-amp saturation, and lower-cost components. Powered by three AAA batteries, it delivers standalone operation for global signal reception. Ideal for hobbyists, the design fosters experimentation and is documented with firmware and schematics available online.

RSP1A receiver with LoG (Loop On Ground) antenna in quiet QTH - southeastern Poland. Very low QRM!

Review of the excellent ICOM IC-R8600 Wide Band SDR communications receiver. Featuring Direct Sampling SDR below 30 MHz Hybrid Superhet / SDR above 30 MHz.

Digirig is an open-source integrated digital modes interface for amateur radio. As a differentiating feature, Digirig only requires a single USB connection to the computer with all the digital goodness packed in a single small enclosure. The internals include a USB hub, audio codec, a fully featured serial CAT (Computer Aided Transceiver) interface, and potentially other modules such as GPS receiver for time synchronization.

A simple superheterodyne receiver (3.5–30 MHz) for amateur radio achieves stable SSB-CW reception using modern BJTs, an AD831 mixer, a 6-pole quartz filter, and Seiler oscillators. Designed with high IF (4.5 MHz), compact AM-FM variable capacitors, and modular resonant circuits, it ensures selectivity, image rejection, and stable tuning. Built in a copper-lined wooden case, it features practical assembly techniques but lacks advanced features like AGC or S-meter. Effective on basic antennas, it achieves global reception.

Cavity is often required at a busy site to not only prevent its receiver from being overloaded by off-frequency signals, but also be a good neighbour and prevent low-level signals from your transmitter from getting into other users receivers - not to mention the preventing of those other signal from getting back into your transmitter to generate spurious signals in its own right.

ToyNTP is a simple freeware time server for Windows that implements the SNTP protocol and uses a GPS receiver, Garmin GPS 18x LVC, as time reference. ToyNTP was designed to be used with Faros in the locations where access to the SNTP servers on the Internet is not available, but it may be used for other purposes as well, in particular, it may be configured to keep the PC clock synchronized to a GPS receiver.

Review of the ICOM IC-R9500 Wide Band DSP Receiver

A 3.5–24 MHz regenerative receiver for amateur bands was recently constructed, inspired by a 1934 design. The project was both challenging and rewarding, requiring precise tuning and high-quality components. The receiver successfully captured QSOs from across the globe, such as New Zealand communicating with Panama. The simplicity of the design and the satisfaction of building a functional, compact wooden box with handmade resonant circuits were highlights. This project demonstrates a meaningful way to reconnect with the roots of amateur radio.

Since 2012, the RTL-SDR is the simple and cheap way to give Software-Defined Radio a try. For about 25 euro you get a receiver covering much of the VHF and UHF range, and by either adding an upconverter, or using the direct sampling option, also the HF bands. They are so cheap because they are mass-produced as DVB-T receivers.

A guest review of the FLEX-6400M DSP HF Trasnceiver considering just the receiver part of this radio.

Amateur radio SDR Receiver and Transceiver manufacturer , makers of the Silphase R1 an innovative HF receiver with high performance real-time spectrum scope.

tk8500 is open source software designed to control and program the ICOM IC-R8500 receiver.

Arduino Digital Transceiver (ADX) is a low-cost HF transceiver for digital modes. This Arduino-based project, inspired by QDX, features four bands, including 80m and 20m, supporting FT8, FT4, JS8call, and WSPR. Designed for simplicity and affordability, it uses an Arduino Nano, SI5351 module, and CD2003GP receiver. The ADX project emphasizes easy procurement, construction, setup, and operation, making it an accessible option for QRP enthusiasts. The firmware update enhances functionality, including CAT control support.

Explaining ARRL Technical Reviews of Radios a brief tutorial on radio testing. The ARRL Lab tests radio equipment according to standardized test procedures, using calibrated professional test equipment. Info on transmitter and receiver tests

A 70cm / 432 MHz Transverter Project transverter circuit is an electronic device that converts a radio signal from the 2 meter to the 70 centimeter band and vice versa, allowing a single transmitter/receiver to be used for both bands. It consists of an IF stage, local oscillator, frequency multiplier, and amplifier. The circuit must be designed for minimal signal loss, noise and intermodulation distortion.

Review of the 150 kHz to 30 MHz Ten-Tec receiver

The 222 MHz Transverter project, based on Zack Lau's (W1VT) original July 1993 QEX magazine design, provides an IF of 28 MHz for both transmit and receive paths. Rick Bandla (VE3CVG) contributed supplemental notes and construction details, including modifications to achieve 10 mW output power from an initial 4 mW PEP. The design incorporates three distinct boards: a Local Oscillator (LO), a Transmitter (Tx), and a Receiver (Rx), with an estimated parts cost of just over $150 CDN, significantly less than commercial kits. Construction involves both through-hole and surface-mount components, with specific guidance on mounting MAV and MAR devices, grounding techniques, and component selection. The project details include parts lists, schematics for the LO, Tx, and Rx, and board layouts. Troubleshooting advice emphasizes sequential testing, starting with the LO, then Tx, and finally Rx, using a 194 MHz and 222.100 MHz capable FM handheld for signal tracing. Further enhancements are discussed, such as an optional Tx driver stage to boost output to 100 mW and the potential modification of a Motorola Maxor 80 PA for 222 MHz SSB/CW operation. The resource also covers practical aspects like power attenuation pads for IF radios (e.g., FT817) and considerations for enclosure design, including repurposing a Maxor 80 case. Performance reports indicate successful 70 km contacts with only 4 mW output.

This PDF article introduces a series of dual-tuned bandpass filters designed for input tuning in amateur band receivers. Developed by Stefen Niewiadomski, these filters feature 50-ohm input/output impedance and can be cascaded for improved roll-off outside the passband. The designs use readily available TOKO coils, with taps on the tuned winding for matching input circuits with impedances around 1k ohm. The inductors are core-tuned, with average inductance values provided for easier matching to other inductors.

This project focuses on testing and comparing various antennas for receiving ADS-B (Automatic Dependent Surveillance-Broadcast) signals, utilizing software tools like RTL1090 and Virtual Radar with an RTL-SDR dongle. The goal is to evaluate the reception range ("ReceiverRange") and performance of different antenna types when tracking aircraft signals, particularly around the Amersfoort area. The project includes a comprehensive photo album documenting the antenna designs and setup processes, serving as a valuable resource for enthusiasts building ADS-B reception systems

This study details a reception comparison between vertical and horizontal active loop antennas, specifically two identical _Wellgood active loop antennas_, on various HF bands. The experiment, conducted in a densely populated QRM-prone area, monitored FT8 signals over a 24-hour period using two identical receivers. The methodology involved direct comparison of signal reception across the HF spectrum, aiming to identify performance differences based on antenna orientation. The results indicate that vertical loops demonstrated superior performance on higher bands (10m, 15m, 20m), while horizontal loops excelled on lower bands (30m, 40m, 160m), particularly for receiving long-distance (DX) signals. The horizontal loop's advantage on lower bands is attributed to potentially better low-angle performance and reduced sensitivity to man-made noise, yielding a **2-3 S-unit** improvement on 160m. The study provides practical insights for optimizing antenna placement in challenging urban environments, noting that the horizontal loop consistently showed a **10-15 dB** signal-to-noise ratio improvement on lower bands.

This guide explores the captivating hobby of shortwave listening (SWL), offering insights for beginners and enthusiasts alike. It covers key shortwave broadcast bands, essential tools like antennas and receivers, and practical tips to enhance listening experiences. Recommendations include budget-friendly SDR receivers, traditional radios like the TECSUN PL-680, and antennas suited for various environments. Additional resources, such as the World Radio & TV Handbook and online tools like Short-Wave.Info, are highlighted to help identify signals and maximize the enjoyment of SWL.

The JUNIOR-2 presented here is a competition direction finder receiver that is easy to build and tune, but has all the features of the "big" receivers. It is especially suitable for beginners, young people or youth groups who have so far refrained from purchasing a 2m direction finder receiver for financial reasons.

The page presents JRX, a virtual radio receiver interface written in Java that can connect to about 200 ham radio transceivers and receivers using the Hamlib library. It offers features like 200 read/write memories, a programmable scanner, and spectrum scope, making it easier to use than traditional radios. The article explains the benefits of virtualizing a radio with controls and highlights the advantages of using JRX, especially for radios requiring computer control. Author P. Lutus provides insights on the development of JRX and its improvements over previous virtual radio projects.

A webSDR receiver running on 8 HF Bands based in Bordeaxu France

This page by Lajos Hoss, HA8HL, provides a detailed guide on how to build a simple direct receiver using FT8QRP CAT control support. The author shares his experience in making QSOs with FT8, WSPR, and JT65 modes during the Covid-19 lockdown. Modifications to the VFO, transmitter design using BD329 transistor Class A amplifier, and the challenges faced in achieving clean output signals within legal limits. This project is interesting for those hams that are interested in experimenting with DIY transmitter projects and understanding CAT control support for various amateur radio modes.

This article explores the revival of the classic 3 Transistor Short Wave Radio kit originally offered by Radio Shack in the late 1960s. Updated with modern silicon transistors and components, the design retains its educational charm while enhancing performance. Detailed assembly instructions and illustrations are provided to facilitate replication. The project not only pays homage to nostalgic electronics but also serves as a practical introduction to radio theory, including modulation techniques and receiver types, fostering a hands-on learning experience for enthusiasts.

This a well performing, simple two band transceiver. The transceiver design is inspired by the S7C superhet. A dual-band transceiver with a crisp receiver and a clean SSB signal

Quisk is a Software Defined Radio (SDR) and is the software that controls my receiver and transmitter. Quisk can control the HiQSDR, Hermes-Lite hardware, SoftRock hardware, SDR-IQ by RfSpace

Learn how to build a simple tuned loop antenna for the AM broadcast band to improve the performance of your radio receiver. Discover how to construct a loop antenna with readily available materials, such as balsa and basswood, without the need for specialized woodworking tools. Follow step-by-step instructions to create a portable loop antenna that offers good gain and directivity, ideal for pulling in weak stations. Enhance your Ultralight DX'ing experience and explore the world of FSL antennas through this practical DIY project.

The Specan is actually a very simple but robustly built receiver. it is, in essence, a double conversion superhet receiver with 112 Mhz and 12 Mhz Intermediate frequencies. The first mixer uses an Si570 as the local oscillator. The Ardiuno that controls the Specan is a very flexible microcontroller board that you can program in simple C language

Radio Frequency Interference (RFI) has always been a source of concern for the Radio Amateur. Until the recent introduction of complex circuitry in the home, our communications gear has been the main source of potential RFI. In this computerized age of ours, increasingly complex and sensitive receivers are being barraged by these and other sources of RFI.

A two tone generator is an essential test gear made with just four transistors that helps you evaluate your amplifiers, mixers, receivers for distortion. Distortion makes all the difference between a pleasant receiver and a horrible sounding one, between a clean transmitter and bad, splattering one on air.

This article explores the nuanced design challenges of Band Pass Filters (BPF) in radio receivers, balancing low insertion loss, high stop band rejection, and narrow bandwidth. The focus is on the "Series-Trap, Shunt-C" topology, resonator count impact, and meticulous layout design for superior stop band performance across various frequency bands

Listen to HF communications via the KiwiSDR online receiver located in Badgad IRAQ locator LM23fh. This web receiver is running a MLA 30+ antenna and can be tuned easily on all HF bands from 10 to 80 meters.

The article discusses the use of SDR# (SDR SHARP) software for SDR receivers, highlighting its Band Plan feature that visually represents RF spectrum allocations. The author modified SDR# to display detailed IARU HF band plans, creating three XML files for different IARU regions. These files include various operational modes and specific frequency allocations. Despite potential errors, the modifications aim to enhance the usability of SDR# for ham radio operators. The article includes references and download links for the XML files and IARU band plans.

Adding a custom GPS receiver to the Yaesu VX-8DR

The recognition of telegraphy masked by noise at 40 and 80 signs/min telegraphy speed was studied in 10 normal-hearing subjects at different sound pressure levels (25-85 dB SPL in steps of 5 dB) as well as at different test frequencies (2000, 1000, 800, 630, 500 and 250 Hz). The ability to recognize the signs varied with varying SPL. Recognition for most of the subjects was best at an SPL close to 70 dB. All subjects improved their recognition as the frequency was lowered to 500 Hz, some even at 250 Hz. These facts should be taken into consideration when training telegraphy operators as well as in the construction of radio receivers to permit listening at low frequencies. Furthermore, the critical ratio was calculated at the different test frequencies.

This page provides a detailed guide on how to receive WWVB 60 KHz time signals using the Everset ES100 module with an Arduino Due microcontroller. It explains the background of time standards and the significance of WWV radio stations in maintaining these standards. The content is useful for ham radio operators interested in time synchronization, scientific research, navigation, and radio communications. The article is written by Keith Greiner, who shares his project inspired by his passion for the subject. For more projects by the author, visit the provided links.

Kanga Products offers a diverse range of kits and pre-built items for amateur radio operators, including Morse tutors, keys, antenna tuners, and dummy loads. Their products cater to both beginners and advanced users, with options for practice oscillators, receivers, and various electronic components. The company provides detailed instructions and supports DIY projects, making it a go-to for hobbyists seeking practical and educational tools.

This document outlines various miniature projects undertaken by Mike Markowski to enhance his skills in GNU Radio. Key projects include an FM stereo receiver and an AM radio receiver, featuring advanced functionalities like pilot tone recovery and RDS integration. Additional experiments involve generating Gaussian noise, chirp signals, and Morse code decoding, emphasizing hands-on learning and customization in GNU Radio. The author encourages feedback and shares flow graphs and Python code for each project, aiming to foster community engagement and knowledge sharing.

Direct conversion receivers (DCR) are gaining renewed interest due to advancements in semiconductor technologies and their suitability for integration in compact, low-cost, multi-standard applications. Unlike traditional superheterodyne receivers, DCR eliminates image frequencies and bulky off-chip filters but introduces challenges like DC offsets, nonlinearity, and noise issues. This tutorial explores DCR's historical development, compares it with other receiver architectures, and addresses its inherent obstacles. DCR's potential for integration and compatibility with software-defined radio highlights its role in modern communication systems despite its technical complexities.

The RTL-SDR tuner dongle is a popular tool for amateur radio enthusiasts, transforming a $10 device into a wide-band software-defined radio. This guide outlines using the RTL-SDR as a full-band pan-adapter for conventional receivers, focusing on hardware setup and software integration with HDSDR. Future sections will address RTL-SDR performance compared to native receivers, enhancing digital mode operations with virtual serial ports and audio cables.

This loop antenna is intended to be connected as an antenna for receivers that do not have a built-in antenna such as an HF set or an old tube radio. This square barrel is wound on a wooden frame. It consists of two windings that are galvanically isolated from each other, a main and a coupling winding. The diameter is about 40 cm.

Effective suppression of harmonics and parasitic radiation from HF transmitters is crucial, especially with the increasing sensitivity of VHF/UHF radio channels to interference. This project details a hybrid low-pass filter (LPF) designed to operate across the HF bands up to 51 MHz, making it suitable for 6-meter band operations while providing deep VHF/UHF suppression. The design addresses the challenge of modern interference landscapes, where even microvolt-level signals can disrupt wireless sensors and other simple VHF/UHF receivers. The filter utilizes a single elliptic link, combining high cutoff steepness with robust suppression in the hundreds of megahertz range. A key feature is the use of only two standard capacitor values, simplifying construction and component sourcing. The article provides a detailed schematic, performance characteristics, and _RFSim99_ model file, demonstrating a reflection coefficient S11 below 0.017 (VSWR < 1.03) across 1-51 MHz, ensuring minimal degradation to the antenna system. Construction notes include coil winding specifications and capacitor selection guidance, with recommendations for _FR-4_ assembly. Two capacitor sets are presented, with the first variant recommended for its lower RF current demands, keeping currents below 3 A at 1 kW passing power at 51 MHz. Fine-tuning involves adjusting frameless coils, with considerations for capacitor tolerance and high-frequency capacitance measurement accuracy.

This article details the design and construction of a compact 20-meter QRP SSB transceiver by Pete Juliano, N6QW, measuring just 2 x 4 x 2 inches—small enough for a shirt pocket. Inspired by a 1963 QST design and refined from a prior version, it employs bilateral circuits, a 4.9152 MHz homebrew crystal filter, switched-crystal VXO for 60 kHz coverage (14.160-14.220 MHz), and standard components like ADE-1L mixers and IRF510 PA for 1W output. Key innovations include a double-sided PCB skeletal frame for shielding and isolation, Vectorboard sub-assemblies, and ultra-miniature relays. The bilateral receiver/transmitter shares stages, omitting AGC for simplicity, while a W3NQN LPF and optional 10W external amp enable DX contacts. Tune-up focuses on crystal matching and bias for linearity. Videos on YouTube demonstrate performance, confirming excellent stability and audio. Total cost nears $100, prioritizing portability over features like CW.