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A cheap rf signal generator for 2.4 GHz

A simple PSK31/digital interface which can connect your transceiver to a PC soundcard for digital modes.

The use of dummy load is mandatory for off-air adjustment of the transmitters. Build one.

This circuit came out of some work done for two antenna analysers

May 2015 Radcom Article on common-mode chokes that can be used for control cables, phone lines, but mostly on typical HF antenna systems. This article explain what common mode chokes does, why you meay need one, properties common mode chokes should have, how to build and measure performances.

A amateur radio guide to RFI, ferrites, baluns, and audio interfacing by K9YC

Building a Resonant Feed line Dipole for 2 Meters

Chesterfield Islands DXpedition 2000

This is a concept paper, not a constuction article. There are too many variables to propose a one size fits all design. However, this paper should give you the basic idea how to do it

Pictures and description of a homemade 1.3 GHz and 2.4 GHz RF Signal Source

Tri-Cities Frequencies, Live Scanners, CTCSS information and more

This article describes a generalised unit for interfacing a transceiver's TTL/CMOS interface to RS-232.

Homebrew your PC sound card to radio interface with this circuit obtained from the pages of Ernie Mills WM2U.

Trained amateur radio communicators under ARES, RACES and Skywarn serving Harford County, Maryland communities

Demonstrates a range of specialized radio frequency equipment and consulting services for amateur and professional applications. The offerings include _Vector-Finder_ direction finding antennas, various test equipment such as _gate dip meters_ and RF sniffers, and communications receiving adjuncts. Additionally, the company produces satellite antennas for weather satellite reception, voice amplification devices like the _Flex-Mike_, and custom prototype circuit boards. The company's product line addresses needs for precise RF measurement, signal detection, and specialized antenna systems, particularly for direction finding and satellite communications. Their historical association with National Radio (HRO) suggests a legacy in radio technology. The site also highlights a subsidiary, Sierra Mountain Products, which offers outdoor recreational gear, indicating a diversification beyond core RF manufacturing.

This test circuit is easy to duplicate, and demonstrates the extreme voltages that appear in an amplifier when the load is improper for the amount of drive power applied.

ABR Industries specializes in providing high-quality coaxial cable and related components for the amateur radio community and beyond. Their product line includes various types of _coaxial cable_, such as LMR-400 equivalent and RG-8X, designed to minimize signal loss and ensure efficient power transfer. The company also offers custom cable assemblies, allowing operators to specify exact lengths and connector types for their unique shack configurations or field deployments. Beyond bulk cable and assemblies, ABR Industries supplies a range of RF connectors, including PL-259, N-type, and BNC, compatible with their cable offerings. Their manufacturing process emphasizes durability and performance, crucial for reliable operation in diverse environments, from fixed station installations to portable operations. The company's focus on quality control ensures that products meet specifications for impedance matching and shielding effectiveness, which are vital for achieving optimal signal integrity and reducing interference in radio systems.

Introduction to the use of clusters and Packet Radio, hardware, settings and commands by ON4SKY

Practival project that contains two isolation transformers, one for AF from the tranciever to the line in on a soundcard, and one from the audio out of the soundcard back to the mic / data input of the radio. Both of which are variable inside the interface via two preset resistors.

CAT and Digital modes interface for the Yaesu FT-817

A simple RF sweep generator circuit diagram by JF1OZL

Installing mobile radios in your new megabucks car can be a frightening proposition - especially if RF from your rig could damage your shiny new roadster

The function of the XPhase is based on the fact that the interfering signal, received by an auxiliary antenna, is added phase-shifted to the signal received from the main antenna. When the phase-shift is more or less 180°, the interfering signal is canceled out.

Radio Free Europe / Radio Liberty is an international news and broadcast organization serving Central and Eastern Europe, the Caucasus, Central Asia, Russia, the Middle East and Balkan countries.

Cushcraft A3S performances with the A743 kit to add 30 and 40 meters

An home made low pass filter for 70 MHz by IK0VAQ

This project is an interface box for the Yaesu FT-817 that includes a band output port, a computer serial interface, and a remote interface for the FL-7000 solid state power amplifiers.

Understanding and eliminating RF Interferences caused by your home devices

Using Andrew FSJ1-50A 1/4" Superflex Heliax with PL-259 Connectors

This article describes the details of the design, which can be easily scaled for just about any HF band. The antenna described in this article is for the 20 meters band.

RF Systems develops and produces antennas and accessories for governmental and military organisations, shortwave and scanner listeners, radio amateurs, yachting circles and professional users of receiving and transmitting equipment.

Experiences with the end-fed dipole based on the concepts presented by J. Taylor in an article titled RFD-1 and RFD-2: Resonant Feed-Line Dipoles in QST. August 1991.

This circuit will let you look at the signal and frequency output of your transceiver.

Constructing a high-power 70cm solid-state amplifier presents unique challenges, particularly when aiming for 500 watts output using modern LDMOS devices. This resource details the author's experience building a 70cm amplifier based on a _Freescale MRFE6VP5600H_ transistor, initially from an RFHAM kit. It meticulously outlines the necessary modifications to achieve advertised performance, including optimizing input and output matching, correcting bias circuitry, and ensuring proper output balun connections for stability. The author shares specific adjustments, such as trimming the prototyping board for better transistor fit, drilling additional mounting holes for improved heat sinking, and replacing original matching capacitors with a single _20pf MIN02 metal mica_ for superior output. A critical fix involved jumpering gate decoupling pads to balance the push-pull transistor halves, which increased output to 580W and improved IMD. The resource also highlights a crucial correction to the output balun connection, initially reversed in the _Dubus_ article schematic, which resolved intermittent stability issues. Test results are provided, showing input power, output power, and drain current at 50V, demonstrating the amplifier's performance after modifications. This practical account offers valuable insights for hams undertaking similar high-power UHF amplifier projects, especially those working with LDMOS devices and kit-based constructions.

A DIY Automatic Band Decoder (ABD) project, designed for dual-radio operation, addresses the common challenge of integrating band data with older transceivers lacking dedicated outputs. This particular build utilizes an AVR AT90S8515 microcontroller and a 16x2 Liquid Crystal Display (LCD) to provide band information, specifically targeting Kenwood rigs via a computer's LPT port. The design aims for cost-effectiveness while maintaining functionality, offering a solution for hams seeking to add automatic band switching capabilities to their station without significant expense. The project outlines the core components required, including the microcontroller, LCD, and an enclosure, noting that the Printed Circuit Board (PCB) fabrication and AVR programming might present challenges for some builders. It details the input requirements, such as a four-pin input and PTT for each radio, along with a 13.8V DC power supply. The decoder provides 2x6 outputs capable of sinking 500mA, suitable for controlling external devices like antenna switches or filters. Despite the original unit being damaged by a lightning strike in 2004, the author confirms its successful operation prior to the incident and mentions plans for a revised version. The resource includes a schematic in PDF format and images of the finished PCB and assembled unit, demonstrating the practical implementation of the design.

RFI mailing list at contesting.com

PTT and souncard interface for the kenwood TM255 and TM455

With the bluecat interface it is possibile to connect a Yaesu FT 817 857 897 to a computer or a android smartphone without any cable or interface, using a bluetooth wireless connection

Excellent article and guide to choose the best RF power amplifier that fit your needs by ON4SKY

Radio for Peace International (RFPI) is a Global Community Radio Station located in Costa Rica, Central America that broadcasts progressive news on shortwave radio and the internet on topics of Peace, Human Rights and the Environment. RFPI gives a voice to the voiceless by promoting democratic communication.

Auroral Large Imaging System, ALIS

How to connect a mose key to a pc using the standard RS232 serial ports by F8EHO

The current, the voltage, the impedance, the bandwidth, the polarization, and how the earth influences the famous radiation pattern.

Complete guide to receive weather satelite images with a RTL SDR dongle and free software

About DRM, the DRM standard, emission types, upfrading your old HF RX to DRM

This video will provide a foundation for understanding how power amplifier circuits work. If you are new to High Frequency Power Amplifier Circuit Design, this is the place to start.

The Megacycles combine the hobbies of amateur radio and bicycling. This group is not a club as there are no officers, dues or by-laws.

Will additional coax stubs improve Band Pass Filter performance?

A MacOSX antenna design and electronics/electrical tool package. It is a multipourpose application that allow antenna design and comomn calculations

Home Brew a 4-1000A RF power amplifier project by W4NFR