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This page provides information on how to design an Off-Center-Fed Dipole (OCFD) antenna, suitable for amateur HF bands like 80 meters or 40 meters. The antenna design allows for VSWR minima on multiple bands, making it a good choice for multi-band use. Learn how to create an OCFD antenna in either flat-top or inverted-Vee form using a single support. The page also offers tools to generate radiation patterns, VSWR charts, and antenna current diagrams for your specific antenna design, helping hams understand performance factors. Ideal for ham radio operators looking to build their own effective antennas.

The DIY Power Meter project utilizes the _INA226_ high-side power monitoring chip, paired with an ATtiny85 microcontroller, to measure voltage, current, and power, displaying the results on a 128x32 OLED screen. The INA226 communicates via an I2C interface and is programmed with a calibration factor based on the shunt resistance and current register LSB. The project is designed to handle a maximum current of 500mA using a 0.16ohm shunt resistor, which can be adjusted to a 0.2ohm resistor, reducing the full-scale current range to 409mA with a resolution of **12.5uA**. The shunt resistor dissipates only 33mW at maximum current, making 1/4 watt resistors suitable for the setup. The PowerMeter.ino sketch configures the shunt resistance and maximum design current, automatically calculating the calibration factor. The project can be prototyped on a breadboard using an Arduino Uno, employing the Wire library for INA226 and OLED communication, and the u8g2lib library for the OLED display. For the ATtiny85 version, the Adafruit-TinyWireM and Tiny4kOLED libraries are used. The power meter is independently powered by a 3V CR2032 cell, with power switching options including manual switches or DC switched jacks. The low-side n-channel MOSFET switch configuration is tested but introduces voltage drop issues, making manual switching a more reliable option until a suitable DC switched jack is found. DXZone Technical Profile: INA226 | ATtiny85 | OLED Display | Power Meter

The _DX EXPLORER_ blog serves as a personal chronicle of amateur radio experiences, particularly emphasizing homebrew projects and DIY radio equipment. It provides insights into constructing various transceivers and receivers, such as the Minimalist CW Transmitter and the Sputnik Regenerative Receiver, offering practical guidance for those new to the hobby. The content often details the assembly and operation of low-cost kits like the $3 Pixie Transceiver, demonstrating accessible entry points into radio construction. Beyond building, the site also features reviews of commercial gear, including the Tidradio TD-H8 Radio, providing an operator's perspective on performance and utility. The author, YO6DXE, shares a learning journey, aiming to inspire fellow enthusiasts to engage with the technical aspects of amateur radio. This resource covers a range of topics from basic circuit explanations to practical operating tips, fostering a deeper understanding of radio principles. The blog's focus on personal experimentation and project documentation makes it a relevant resource for hams interested in hands-on learning.

Understanding radio wave propagation is fundamental for effective HF communication, and this guide from the Galway Radio Club elucidates the principles behind _Near Vertical Incidence Skywave_ (NVIS) operation. It begins by contrasting NVIS with line-of-sight and surface wave propagation, highlighting its utility for reliable regional coverage, particularly in challenging terrains or within the skip zone. The document explains how NVIS leverages high-angle radiation, refracting signals from the ionosphere to return to Earth within a circular region, typically up to **650 km** (400 miles) from the transmitter. The guide delves into critical factors influencing NVIS, such as the _critical frequency_ (Fo) and the Maximum Usable Frequency (MUF), emphasizing their dependence on solar activity, time of day, and season. It provides practical advice on frequency selection, noting that 40 meters is often the highest daytime NVIS band, with 60 meters and 80 meters favored as darkness falls. The author, EI5DD, suggests using an ionogram for real-time propagation data, considering it more reliable than generic ham-clocks. Antenna considerations are also covered, recommending dipoles, inverted vees, or phased dipoles positioned 0.1 to 0.25 wavelengths above ground for optimal high-angle radiation. The document mentions mobile NVIS setups, including military configurations and commercial options like the Barrett Communications roof-rack antenna, which can cost around **£2000.00**. It concludes by reinforcing NVIS as an essential technique for national emergency communications, with 5 MHz (60m) and 80 meters being primary bands for daytime and nighttime operations, respectively.

Volda is specialized in telecom tower antenna line accessories such as cable hangers, coaxial jumpers, grounding buss bar kits, pole clamps.

Demonstrates the capabilities of DXtreme Monitor Log 14, a specialized software application designed for radio spectrum monitoring and logging. The resource details its core functionality, which includes logging stations across various bands and supporting multiple transmission modes such as AM, CW, FM, LSB, USB, and RTTY. It highlights features like the ability to select country formats for new databases and the **Schedule Checker** tool, which assists users in identifying broadcast stations for monitoring. The software facilitates tracking **Maidenhead grid squares**, particularly useful for VHF and UHF monitoring activities. It also supports QSL management and offers tools for efficient contact logging, catering to both amateur radio operators and shortwave listeners. Specific information includes its version number, Monitor Log 14, and its utility for DXers and other radio enthusiasts in managing their monitoring experiences and logging contacts effectively.

If your FT-817 has stopped powering up from the internal battery but works from external power, then maybe the internal battery fuse has blown. There is a small PCB mounted fuse to protect the battery and radio. This fuse can blow, if it does your radio will not work from battery power. This page will describe how to test the fuse and describe how to make a repair.

A guide to programming a Yaesu FT5DR under Ubuntu Linux using CHIRP and the USB-68 Cable. This operation that is usually very simple and easy to do under Windows, need more configuration efforts under linux os.

Discover a comprehensive solution for mapping Australian ham radio entities using data from the ACMA Public Register. This tool, developed in Delphi 7, generates KML files for Google Earth, showcasing repeaters, beacons, and operators across different prefixes. While respecting privacy regulations, the files provide valuable insights into the amateur radio landscape.

FT-240 toroids measurements. The data was measured using well-calibrated HP instrumentation. All plots have been adjusted to a frequency range of 1-100 MHz on the horizontal axis and a resistance/impedance range of 10-1,000 ohms on the vertical axis. This adjustment facilitates comparison among different materials and aids in determining their suitability for use on the HF ham bands.

This program simplifies the complex jumper calculations for the PRF1520 radio, which can be a pain to determine manually. It supports common crystal frequencies and channel spacings, advising if a desired frequency is achievable. A recent feature allows determining unknown frequencies of a newly obtained radio by setting the jumper positions and other parameters.

The FT101ZD DDS VFO project replaces the original VFO in the Yaesu FT101Z/ZD rigs with an AD9850 DDS module, providing enhanced frequency control. It uses the original optical encoder and clarifier for compatibility, with a custom 6V power supply modification. The project includes selectable step sizes, a frequency save function, and works with both RX and TX modes. The design involves mechanical and electronic modifications, including SMD components and a custom PIC processor. Calibration ensures accurate frequency output, with further improvements under consideration.

Examining the demographic shifts within amateur radio, particularly concerning **radiosport** participation, this resource analyzes survey data from the National Contest Journal (NCJ) and two regional ARRL surveys. It focuses on the relationship between age and engagement in contesting, presenting findings that suggest older amateur radio operators tend to participate in more contests annually. The author, a spatial demographer, details the methodology, including data consolidation, georeferencing, and statistical analysis performed in collaboration with Dr. Scott Wright K0MD, covering ARRL November Sweepstakes participants from 2000 to 2020. The analysis also addresses the limitations inherent in using voluntary response samples rather than random samples, which may influence the generalizability of the results. Furthermore, the resource investigates the preferred sources of contest information among different age groups, noting that older contesters frequently rely on traditional publications like the NCJ, while younger participants show a preference for online platforms. This demographic review provides insights into the evolving landscape of **amateur radio contesting** and the generational differences in information consumption.

This project details an automatic roger beep circuit for VHF/UHF contests. Built around a Microchip PIC microcontroller, the design detects PTT (Push-To-Talk) activation and generates a brief tone upon release, mimicking a "roger beep" to signal the end of transmission. The circuit utilizes readily available components and includes downloadable resources for PCB layout and firmware.

Learn how to enhance your 160 meter reception by building and using a custom band pass filter. Discover how this filter can reduce interference from strong AM broadcast signals, improving the overall performance of your receiver. Find out about the challenges of creating a filter that balances signal loss and attenuation at specific frequencies, and how it can benefit hams operating near powerful transmitters. Whether you're experiencing IMD issues or looking to optimize your 160 meter setup, this article provides practical insights and solutions for ham radio operators.

The Olivia digital mode, a **Multi-Frequency Shift Keying (MFSK)** radioteletype protocol, is specifically engineered for robust communication under difficult propagation conditions on shortwave radio bands from 3 MHz to 30 MHz. Developed by Pawel Jalocha in 2003, Olivia signals can be decoded even when the noise amplitude exceeds the digital signal by over ten times, making it highly effective for transmitting ASCII characters across noisy channels with significant fading and propagation phasing. Early on-the-air tests by Fred OH/DK4ZC and Les VK2DSG on the Europe-Australia 20-meter path demonstrated intercontinental contacts with as little as one-watt RF power under favorable conditions. Common Olivia modes are designated as X/Y, where X represents the number of tones and Y is the bandwidth in Hertz, with examples including 8/250, 16/500, and 32/1000. The resource clarifies that Olivia, unlike some other digital modes, produces a constant envelope, allowing RF power amplifiers to achieve greater conversion efficiencies and making it less prone to non-linearity. Operators are advised that **Automatic Level Control (ALC)** can be set higher than no meter movement for MFSK modulation, as long as it's not driven past its high limit, contrary to common misinformation about other digital modes. The Olivia community encourages voluntary channelization on suggested calling frequencies, such as 14.0725 MHz for 8/250, to facilitate initial contacts, especially for signals below the noise floor. The Olivia Digital DXers Club provides links to Groups.io, Facebook, and Discord for community engagement and offers details on QSO parties.

An FT-817 ceased transmission on the VHF 2m band, despite the other HF, UHF, and 50 MHz bands operating correctly. Suspecting an excess of input signal during FT-8 mode transmission, they conducted measurements with an oscilloscope, revealing a burnt-out PIN diode, identified as D3003, type HSU277, on the PA unit board. Following the replacement of this surface-mounted diode, their FT-817 resumed operation on the 144 MHz band.

SKY Audio is a duplex remote audio software for Windows, allowing two-way audio transmission between devices. Users can send and receive audio, as well as engage in PTT functionality. The program offers low audio latency and the ability to configure connection settings. The freeware software can be downloaded from the provided link.

If you are a RemoteQth server user, and own a Prosistel rotor, you will have to deal with the problem of remoting your rotor. The solution suggested by RemoteQth is to build the K3NG interface that allows you to control any types of rotor.

This project presents a compact QRP SWR meter featuring a 0.96" OLED display (128x64 pixels) for high-contrast visibility, updated with software fixes for display compatibility, improved low-power performance, and support for ATtiny45/85 microprocessors. A 1.3" OLED version accommodates visibility needs. Designed for HF QRP transmitters (3-15W), it uses a Breune coupler with germanium diodes for accurate SWR measurement. Powered by a AAA battery, the meter offers a standalone solution for impedance matching, with a 3D-printed enclosure enhancing portability.

A quick fix for a Yaesu FT-757GXII blank display

Online impedance calculators grouped by types like Wire inductances, Toroid incuctances, Plane, PAD, Strap inductances, but even Core and Coax Inductances. Air core inductances and mutual inductance groups are also availbale. All these calculators let you input specific paramenters based on the inductor selected and will calculate specific incutance and related dimensions.

Integrating a _Software Defined Radio_ (SDR) into an existing ham radio setup involves connecting it with a standard transceiver (TRX), power amplifier (PA), and antennas. The core component is a splitter box that facilitates the connection between the TRX and the SDR, allowing for simultaneous operation without modifying existing equipment. In receive mode, the splitter ties the antenna inputs of both the TRX and a direct conversion receiver (DC RX) together. During transmission, the DC RX input is grounded via a fast telecom relay controlled by the transceiver's -SEND signal, incorporating a 10ms delay for safety. The splitter box includes a 3.7 dB input attenuator for impedance matching and acts as a protective fuse for the DC RX input. Ground loops are mitigated using common mode balun transformers, while the DC RX input is insulated with a broadband transformer. An audio switch box complements the setup, enabling users to listen to either the main transceiver, the SDR output, or both simultaneously. This configuration ensures noise immunity and safety, with the splitter housed in a screened box made from PCB material. On-air tests, such as the CQ WW 160m CW DX Contest, demonstrate the system's effectiveness, showcasing the SDR's ability to handle crowded band conditions with superior selectivity and dynamic range. The SDR's narrow bandwidth filters and waterfall display provide significant advantages, allowing operators to detect weak signals amidst strong interference. The integration of SDR with conventional radios offers enhanced operational flexibility and performance in challenging environments.

The K5USS 6 Meter Hentenna Project page on Hamuniverse provides detailed instructions on how to build a 6 meter directional antenna with 3.5 dBd gain. The project is presented with permission from K5USS, Charlie of Richardson, Texas. This directional antenna is a full wave loop on 6 meters, horizontally polarized but mounted vertically, with a 50 ohm impedance, ideal for 6 meter SSB operations. The page is useful for hams looking to construct their own directional antenna for improved performance on the 6 meter band.

Let this microprocessor controlled MFJ Contest Voice KeyerTM call CQ, send your call and do contest exchanges for you in your own natural voice

This article demonstrates how to convert an existing tower into a dual-band vertical antenna for 80- and 160-meter DX operation. Using EZNEC modeling and practical design principles, the authors achieved a low-profile, efficient setup with a single coax feed line, no moving parts, and optimal radiation patterns. The system integrates an 80-meter vertical wire and a 160-meter shunt-fed gamma match for simultaneous operation. Detailed construction insights, including feed system and capacitor configurations, offer a reliable, full-legal-power solution.

Repairing a non-functional Yaesu FT857 by identifying and replacing two damaged components crucial for powering the device. Using discrete components, author constructed replacements for the DAN222 and RT1N241 ICs, successfully restoring the rig's functionality. This DIY approach not only fixed the issue but also provided a satisfying and cost-effective solution

The Acom 1500 HF+6M Linear Amplifier is a high-quality and user-friendly amplifier that provides excellent performance and reliability. G6NHU, who previously owned an Acom 1000, upgraded to the Acom 1500 after nine years and has been using it for about eighteen months. Key features highlighted include the ability to connect three antennas internally, straightforward tuning process, robust construction that can handle high SWR, quiet operation, fast and quiet switching for efficient CW operation, and clean output signal even when driven hard. G6NHU highly recommends the Acom 1500 and states they would not hesitate to purchase another one in the future.

The Beam project offers various features for controlling antenna rotators, including support for 2 or 4 line LCD displays, software or hardware clocks, open collector drives for azimuth and elevation control, and internal calculations for tracking the sun and moon. It can also track satellites and supports "Flip Mode" for inverted antennas. The 4-line version provides detailed readouts while the 2-line version offers a more compact display. New versions now support PWM and I2C H-bridge modes for adjustable speed control at the end of a move.

This page provides instructions for unlocking additional frequency bands on your IC-7610 transceiver to access the 60m band. The step-by-step guide is useful for hams looking to expand their operating capabilities and communicate on this popular band. By following these instructions, you can ensure that your transceiver is set up correctly to operate within the regulations of the 60m band.

National Communications Magazine is a subscription-based weekly publication on Substack, focusing on scanner radios, CB radio, GMRS, FRS, and MURS. Transitioning from print to an online PDF format in 2012 and to Substack in April 2023, it delivers timely content for radio enthusiasts. Edited and published by Chuck Gysi, the magazine provides in-depth coverage and updates across diverse communication services.

Operating amateur radio repeaters involves understanding frequency offsets, CTCSS tones, and the basic signal flow through a repeater system. This resource details the fundamental concepts of repeater operation, including the distinction between input and output frequencies, the role of **CTCSS (Continuous Tone-Coded Squelch System)** for access, and the typical frequency bands utilized for local communication. It clarifies terms such as "simplex" versus "duplex" operation and provides a diagram illustrating the signal path from a handheld transceiver to a repeater and back to another station, emphasizing the range extension repeaters offer. The article further explains practical aspects like identifying a repeater's offset (e.g., +600 kHz for 2-meter band) and the necessity of programming the correct tone. It compares the operational benefits of using repeaters for local communication over direct simplex contacts, highlighting how repeaters overcome line-of-sight limitations. The content is structured to assist new licensees in confidently making their first repeater contacts, providing a foundational understanding of how these critical infrastructure components facilitate wider area coverage for VHF/UHF amateur radio.

Explore VK5DJ's experiments with the si5351a frequency synthesizer, a versatile device capable of generating frequencies from 8kHz to 200MHz. Learn how this I2C configurable clock generator can replace crystals and oscillators in various applications, providing stable and precise outputs. Discover how to program the si5351a for your own signal generator projects and repeater site setups. Utilize the affordable and efficient Adafruit module for reliable performance. Enhance your understanding of PLL/VCXO architectures and fractional dividers for frequency generation. Join the PDS Forum community in experimenting with this innovative technology.

Setting up the Yaesu FT-817 and Signalink for data mode communication. Hardware and software required for data mode communication, connect and configure FT-817 and Signalink

This article will introduce total beginners to Amateur Radio, more commonly known as ham radio or DXing. That includes the basic definition - what DX is, where it came from, and the couple primary types (passive and active DXing). A Very Historical Past Radio Home!! The different kinds of DXing are well separated, indicating that you are either just listening to more distant stations, or engaging in a direct communication with another amateur. Ham Radio DXers: Importance of the Internet While the article glosses over the technical aspects of Ham radio equipment much like several of his articles, it does touch on how important the internet is to DXers. These include link to locate active stations, learn signal proagation, and be a part of the Ham community online.

This is another variation on the parallel resistor, dummy load. It is perfect for QRP HF operation of 5-watts or less average power, and should be adequate for continuous operation at that level. It's light and compact, about 2-1/2 in length overall.

Tar Heel Designs offers a range of quality products for ham radio operators, proudly made in America. Watch a raw, unedited product video from the 2025 Orlando Hamfest. For more information or to shop online, visit their website powered by eDirectHost, an info & ecommerce website builder. Find everything you need for your ham radio hobby in one convenient location.

145 MHz is the target frequency for this 2-meter Skeleton Slot Yagi Stack antenna project. The design focuses on feeding two stacked Yagi antennas using a skeleton slot radiator, which is a unique approach for VHF enthusiasts. The project details the construction process, including the loop tapered matching section for impedance matching, ensuring optimal performance. The use of specific components like the EH789 element holder and MB456 main mast bracket is highlighted, providing clarity on the assembly process. The construction utilizes 20x20 box aluminum bar for durability and precision. Key dimensions, such as the element length (ER-ED4) and main boom spacing (MM123), are meticulously outlined. This attention to detail aids in replicating the antenna design accurately. The downloadable PDF offers comprehensive instructions, making it accessible for amateur radio operators interested in VHF antenna construction. This project is particularly beneficial for those looking to optimize their 2-meter band operations. The inclusion of a skeleton slot radiator and loop tapered matching section demonstrates advanced techniques in antenna design, catering to both intermediate and advanced builders.

This **PDF report** documents a _maritime mobile_ DXpedition operating from the _Southern Ocean_ near Antarctica, detailing antenna deployment strategies on a sailing vessel. It addresses power management systems for remote operations and propagation characteristics specific to polar regions on **20m and 40m** bands. Operational strategies include managing high-density pileups using split frequency operation and maintaining signal integrity during periods of high aurora activity. Equipment considerations cover specific transceiver models like the Icom IC-7300, antenna types optimized for marine vessel installation, and battery power systems for extended periods without shore power. The resource also examines the use of satellite communication for real-time log uploads and QSL confirmation from remote locations, and discusses mitigating signal degradation from ice accumulation on antennas. DXZone Focus: PDF report | Maritime Mobile DXpedition | Polar Propagation | Split Frequency Operation

Testing of real antennas is fundamental to antenna theory. The most common and desired measurements are the antenna radiation pattern including antenna gain and efficiency, the impedance or VSWR, the bandwidth, and the polarization. The procedures and equipment used in antenna measurements are described in this page.

The CW keyer with memories, inspired by SOTA activities, features three on-the-fly programmable memories for hands-free operation during logging or specific calls. Designed for low power consumption, it uses AAA batteries and an Arduino Mini, optimized for minimal energy use with a sleep function. The compact design fits in a small TEKO box, with a printed circuit board for easy assembly. The keyer includes customizable software for various CW modes and settings, programmable via paddles and command mode. It's an efficient, portable solution for amateur radio enthusiasts seeking enhanced CW functionality.

Using Gordon West study manuals in your amateur radio classes offers your students the very best in study materials available today

The resource details HF time broadcast stations, categorizing them into "Standard Frequency & Time Signal Broadcast" and "Time Signal Broadcast" types. Standard Frequency & Time Signal Broadcasts, like those on **2.5 MHz** and **5 MHz**, originate from official time observatories and offer continuous standard frequencies, time signals, and often voice announcements, potentially including meteorological data. These stations operate in the SW band. Time Signal Broadcasts also provide continuous time signals, typically with voice announcements, but without the strict observatory origin requirement. The list includes specific frequencies such as 3.33 MHz, 4.996 MHz, 7.85 MHz, 9.996 MHz, 14.67 MHz, 14.996 MHz, 15.006 MHz, and 20 MHz, alongside the primary standard frequencies. Each entry specifies the station's ID time, call sign, geographic coordinates, and operational notes, including languages like _English_, Chinese, Portuguese, Korean, and Spanish. Some entries also indicate decommissioning dates, such as the station on 3.33 MHz scheduled for 2026-06-22.

This page discusses the potential risks and safety concerns related to antenna installations for ham radio operators. It emphasizes the importance of following electrical codes and regulations to prevent property damage, injuries, or even loss of life. The author shares personal experiences and advises against using trees for antenna support near power lines. The content serves as a cautionary resource for hams planning antenna setups to ensure safety and compliance with regulations.

This blog post from KA7OEI covers the author's initial exploration into the world of Arduino, a popular open-source electronics platform. The post likely discusses the author's experiences, challenges, and successes with Arduino projects, particularly in relation to amateur radio or other technical hobbies. It may provide insights, tips, or inspiration for hams interested in incorporating Arduino into their own projects. The content is likely informative, personal, and geared towards amateur radio operators or electronics enthusiasts.

Repair of a Yaesu FT-1000 MP Mark V probably struck by lightning.

This project goal is to construct a versatile and informative RF power meter. The user-friendly interface, comprehensive power measurement capabilities, and AM detection function make it a valuable tool for various RF applications

Ham radio communication in the VHF and UHF bands, which was previously dominated by analog Frequency Modulation (FM), is increasingly incorporating Digital Voice (DV) modes. DV transceivers digitize audio and offer benefits like as signal integrity, encoded caller ID, and bandwidth savings. Today D-STAR, DMR and Yaesu System Fusion (YSF) are popular DV formats, each with its own set of features but mainly incompatible with the others. Internet access with Voice Over Internet Protocol (VoIP) expands DV communication worldwide. Repeaters and personal hotspots expand DV capabilities, enabling seamless worldwide connections. However, implementing DV frequently necessitates learning new technologies and negotiating network complexity.

The amateur radio club serving Johnson County Tennessee and northeastern Tennessee and southwestern Virginia. Open to all licensed hams.

This page showcases the use of ChatGPT for quickly creating a prototype application that maps out individual QSOs from a CZML map. The author details the process of using ChatGPT to generate code that positions and frames a Cesium Ion map based on data from a czml file. The page includes links to the original map, the prototype app, a video demonstration, and the mapped QSOs output. The content is aimed at hams interested in experimenting with AI tools for ham radio applications.