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This page allows hams to design a vertical-plane delta-loop antenna for a single amateur HF band in different configurations. By choosing different feed-point positions, operators can observe variations in polarization properties, radiation patterns, and feed-point impedances. Users can generate radiation pattern plots, VSWR charts, antenna current diagrams, and Smith charts for their antennas over various ground types. Through adjusting the antenna's physical dimensions and refreshing the plots, hams can gain insights into the antenna's performance in the field. The page also discusses how elevation radiation patterns may change based on the antenna configuration and feed-point position.

The program was developed for radioamateurs who participate in the RDA and RAFA diploma program. The program sends your current coordinates to the TNXQSO.com server and receives your current RDA, locator and RAFA in response. Information update - every 10 or 60 seconds.

This page provides updated data and statistics about United States amateur radio operators, including historical totals, demographics, and geographic distributions. It also explains the Amateur Radio Service, highlighting its role in promoting wireless communication and technological advancements. The page is a valuable resource for hams interested in understanding the current landscape of amateur radio in the United States.

This page provides detailed information on the 4DX directional wire beam antenna designed by LZ1AQ, LZ1ABC, VK6LW, and DD5LP. It explains how to create this antenna for single or multiple bands using four separate sloping wires. The page includes instructions on achieving directionality, gains, and F/B ratios, as well as generating radiation patterns, VSWR charts, antenna currents diagrams, and Smith charts. It is a valuable resource for hams interested in building and optimizing their own directional wire beam antennas for improved performance and long-distance contacts.

This comprehensive three-part guide examines baluns (balanced-to-unbalanced devices) and their critical role in ham radio antenna systems. The author explains how baluns prevent common-mode currents on feedlines, which can distort radiation patterns and cause unwanted RF in the shack. Various balun types are analyzed, including coiled coax chokes, ferrite-core designs (W2DU), and toroidal-wound versions (Guanella/Ruthroff). Construction techniques for 1:1, 4:1, 6:1, and 9:1 current baluns are provided with practical guidance on wire selection, winding methods, and ferrite core properties. The article emphasizes that proper balun implementation is essential for optimal antenna performance, especially with directional arrays.

DX Data provides a unified view of real-time DX spots, aggregating data from **DXSpider**, the **Reverse Beacon Network (RBN)**, and PSK Reporter. This online service offers advanced filtering capabilities, allowing amateur radio operators to refine spot displays by DXCC entity, band, mode, CQ zone, and continent. It addresses the challenge of sifting through numerous DX spots by presenting a consolidated stream, enabling DXers to efficiently identify active stations across various bands and modes. The platform integrates with Club Log, which assists in fine-tuning band-entity combinations based on a user's logging history, thereby reducing irrelevant spot noise. Key features include DX email alerts, PSK Reporter tracking, and a custom watchlist for monitoring specific stations or regions. The service also incorporates a live news feed from DX World, providing current information relevant to the DXing community. This design aims to streamline the DX spotting process, offering a responsive interface for identifying operating opportunities.

This article addresses the issue of unwanted RF in amateur radio setups and introduces a practical method to measure common-mode currents (CMC) using a homebuilt RF meter. The meter, constructed with readily available materials, measures unwanted RF on the coaxial cable shield by inductively coupling to the shield using a split-bead ferrite. The article provides detailed instructions on building the meter, interpreting measurements, and using ferrite chokes to mitigate RF interference. Emphasis is placed on the importance of verifying CMC levels and installing chokes to improve equipment performance.

Examines current amateur radio satellite operations as of May 2026, providing a practical overview for hams interested in making their first satellite QSOs. The resource differentiates between Low Earth Orbit (LEO) satellites, such as the _ISS_, SO-50, RS-44, FO-29, AO-7, and GreenCube, and the geostationary QO-100. It highlights the distinct operational requirements for each, noting that LEO birds necessitate real-time tracking, antenna rotation, and Doppler compensation. The article emphasizes the critical practice of listening before transmitting and outlines methods for monitoring QO-100 in real time via the Goonhilly Earth Station WebSDR. It also covers tracking LEO satellites using tools like N2YO.com, Heavens-Above, and amsat.org/status. The author's experience with these platforms informs the guidance on equipment considerations and operating practices, ensuring hams understand the nuances of satellite communication in 2026, including the significant impact of QO-100 since its 2019 launch.

Learn how to design a Hentenna antenna, a portable asymmetrical double-loop antenna ideal for amateur HF or VHF bands. This page provides details on constructing and optimizing the antenna for maximum performance in DX communications. Discover how altering the antenna's vertical feed section can adjust the VSWR resonant frequency and how changing the support pole's position can alter the beam direction. Originally developed by Japanese 6-meter operators, the 'Hentenna' offers a unique design that allows for horizontal polarization when vertically oriented. Explore radiation patterns, VSWR charts, and antenna currents diagrams to optimize your antenna's performance for long-distance contacts.

Chokes and isolation transformers are essential for receiving antennas to mitigate common mode current, which induces noise and interferes with signal quality. Common mode chokes, formed by winding feedline through ferrite cores, block unwanted current effectively. Proper selection of core material and winding turns ensures resonance near the operating frequency, reducing interference. Isolation transformers further minimize interference, crucial for multi-transmitter stations.

Presents a dynamic platform for real-time amateur radio contest scoring, enabling participants and enthusiasts to monitor ongoing competition results. The system processes submitted contest data, displaying live scores and competitor standings as they update. Users can observe the progress of various contests, gaining immediate insight into the competitive landscape. This resource serves as a central hub for following _DX contests_ and other operating events, offering a transparent view of current standings. It facilitates an engaging experience by providing up-to-the-minute score updates, reflecting the intensity of _on-line contesting_ and the efforts of operators globally. The platform's utility extends to both active participants submitting scores and observers interested in the competitive dynamics. It aggregates data from multiple sources, presenting a consolidated view of contest activity. The system's design emphasizes rapid data processing and clear presentation of results, crucial for high-stakes events like the _CQ World Wide DX Contest_.

The Ukrainian Contest Club (UCC) website details contest activities, including a March 2026 contest calendar compiled by _UW3WF_ that excludes specific "exotic" tests, mini-tests, sprints, VHF competitions, and events organized by Russian entities. It lists major contests such as the ARRL International DX Contest, Stew Perry Topband Contest, and CQ WPX SSB Contest, providing dates, times, modes, bands (e.g., **10-160m**), organizers, log submission methods, and deadlines. The resource also highlights Ukrainian participation in various international contests, noting specific callsigns that represented the UCC, and acknowledges new Ukrainian records, such as UW5Y's new record in the ARRL DX CW Contest. The site presents contest results and rankings, including the top 20 Ukrainian contesters in the World Amateur Radio Contesting Association (WARCA) rating for 2019-2024, with _UW1M_ ranked #18 globally and #1 in Ukraine with **26,490.32** points. It also details the club's 12th place finish among 155 clubs worldwide in the CQ WPX Contest 2024 (CW + SSB). The resource includes information on WRTC 2026 participants from the club and lists members excluded due to collaboration with adversarial entities, reflecting the current geopolitical context.

VFC has grown to become the national leader in the lightning protection industry. Protecting facilities and equipment from lightning and transient current by designing and installing lightning protection, grounding, surge protection and lightning warning systems.

This page provides guidance on designing an End-Fed Half-Wave (EFHW) or Random-Length antenna for amateur HF bands, such as 80 or 40 meters. The content explains how to optimize the antenna for multi-band use and match it to a 50-ohm system using an unun. Hams can generate radiation patterns, VSWR charts, and antenna current diagrams for their customized antenna designs. Understanding how antenna dimensions affect performance is essential for successful field operations. The page caters to ham radio operators looking to build efficient and effective HF antennas for their stations.

DIY project of a QRP Balun. Using a high permeability ferrite rod and an old B&W dipole center insulator, he constructs a choke type balun for QRP use. The balun aims to create as much inductance as possible at HF, offering a high impedance to common mode currents

OpenRTX is a free and open source firmware for digital ham radios. The firmware is designed with a top-down approach with the objectives of modularity, flexibility and high performance. Currently, it targets some Tytera Radioddity Baofeng digital radios

Well, firstly the 12 Volt source will typically vary anywhere from 11 Volt to 15 Volt, and then a battery needs a controlled charge current and voltage, which cannot result from connecting it directly to a voltage source.

A cost-effective alternative to the Optibeam OB10-3W, a high-performance but expensive tri-band Yagi antenna for the 20, 17, and 15-meter bands. The original Optibeam, featuring three full-size elements on each band, delivers strong forward gain and front-to-back ratio but comes with a high price tag. To address this, a custom design was developed, offering similar performance at a fraction of the cost. Using accessible materials and a simple 1:1 current balun, the homemade version proved highly effective, making it a practical solution.

Chavdar Levkov, LZ1AQ, presents an experimental comparison of small wideband magnetic loops, building on his previous work on wideband active small magnetic loop antennas. His research focuses on increasing loop sensitivity by maximizing the short-circuit current, which is directly tied to the "loop factor" M = A/L, where A is the equivalent loop area and L is its inductance. Levkov's methodology involves reducing inductance and increasing area through parallel or coplanar crossed (CC) configurations, comparing these designs against a reference single quad loop of 1 m2 area. Experimental verification included testing three distinct loop types: a simple quad loop, two coplanar crossed (CC) loops, and eight parallel loops, all designed to have a total geometric area of 1 m2. Measurements were conducted at 1.8, 3.5, 7, and 10 MHz using a small transmitter 270 meters away, with a Perseus direct sampling receiver for precise signal level assessment. The results consistently showed that CC loops, particularly Loop 5 (two CC circular loops with 1.44 m2 total area), yielded significantly higher currents, up to 9.1 dB over the reference loop at 3.5 MHz, validating M as a reliable predictor of loop sensitivity. Numerical simulations using MMANA further corroborated the experimental findings, demonstrating an almost perfect correlation between the calculated M factor and the induced loop current for 15 different loop models. Levkov concludes that CC loops offer superior sensitivity for a given loop area, while parallel loops are advantageous for minimizing physical volume. Practical recommendations suggest using loops with an M factor greater than 0.5 uA/pT for quiet rural environments, and he provides a spreadsheet tool, WLoop_calc.xls, to aid in optimizing loop configurations for specific operational needs.

In this article, the current consumption for a selection of popular HF transceiver was examined to determine, via an on the field comparison, whether they were right for portable operation. The radios evaluated include the Yaesu FT-857D, Kenwood TS-590SG, Icom IC-7100, and Kenwood TS-480SAT. The measurements were taken beginning frok 5W in 5W increments up to 100W. The results showed that the Kenwood TS-590SG had the highest current use while the Yaesu FT-857D had the lowest. The current consumption of all radios increased as the power output increased.

Operating on the HF and VHF bands, the URE WebCluster serves as a real-time DX spotting network for amateur radio operators. It aggregates DX spots from various sources, presenting them with detailed information such as DX callsign, frequency, mode, and spotter details. The platform integrates essential propagation data, including current solar indices like _K-index_ and _A-index_, alongside visual propagation maps, which are crucial for planning long-distance contacts. Users can submit new DX spots, contributing to the collective intelligence of the amateur radio community, and filter existing spots by band, mode, or callsign, enhancing operational efficiency. This resource enables operators to monitor band openings and identify active DX stations, significantly aiding in _DXCC_ pursuit and contest operations. The integration of solar-terrestrial data directly within the cluster interface allows for immediate correlation between propagation conditions and observed DX activity, a feature not universally present in all web clusters. By providing both raw spot data and contextual propagation information, the URE WebCluster offers a practical tool for real-time decision-making during operating sessions, allowing hams to quickly adapt to changing band conditions and target specific _DX_ entities.

Online browser-based resource for your computer, tablet or other mobile device. Use this review and practice exam resource with the current editions of ARRL License Manuals.

Facilitate seamless communication in the world of packet radio with PoPT, a versatile terminal program designed for AX.25 protocol enthusiasts. Operating across multiple platforms, including Windows, Linux, macOS, and Raspberry Pi, it caters to a wide range of users. The program supports various connection methods such as KISS over TCP/Serial and AXIP over UDP, ensuring compatibility with Linux AX.25 devices. This flexibility allows operators to maintain robust connections in diverse environments. Developed with Python 3.11, PoPT is currently under active development, reflecting a commitment to staying at the forefront of technological advancements. Its multi-platform nature ensures that operators can leverage their existing hardware setups without the need for additional investments. The program's ability to handle different connection types makes it a valuable tool for those engaged in packet radio operations, whether for personal experimentation or more structured communication networks. PoPT's ongoing development promises future enhancements and features, making it a dynamic choice for operators looking to explore the capabilities of AX.25 packet radio. Its adaptability and support for modern systems position it as a practical solution for contemporary amateur radio enthusiasts.

The Union of non-governmental organizations "The Ukrainian Amateur Radio League" (UNGO "UARL") was founded in December of 2015. Currently, there are about 1500 members in the League, representing most regions and cities of Ukraine.

The article by Guy Olinger, K2AV, published in the May/June 2012 National Contest Journal, introduces the Folded Counterpoise (FCP), a compact 516-foot single-wire counterpoise elevated at 8 feet, designed for 160-meter operations on small lots like 100x150-foot backyards. Originating from efforts to revive Top Band for W0UCE on a postage-stamp property, the FCP uses strategic folds to cancel ground fields within 33 feet of center, minimizing losses to 0.13-0.53 dB—outperforming sparse or on-ground radials by up to 15 dB in poor soil—while mimicking opposed radials for efficient feedpoint impedance. Paired with a critical 1:1 or 4:1 isolation transformer (e.g., trifilar on T300-2 toroid) to block common-mode currents on coax feeds, it delivers proven results: K2AV's #8 North America low-power contest score, 7+ dB gains at W4KAZ and K5AF, and over 10,000 global web hits for DIY instructions using bare 12 AWG wire and weatherproof enclosures. Ideal for acreage-challenged hams, the FCP also excels on 80 meters with scaled dimensions, offering a low-loss alternative where full radials are impractical

In this study, the author builds upon Muncy's research, demonstrating that radio-frequency current on cable shields affects audio systems through the "pin 1 problem" and shield-current-induced noise (SCIN). An enhanced equivalent circuit for ferrite chokes is proposed, addressing dimensional resonance and inductor self-resonance. Field tests confirm that chokes reduce interference across 500 kHz to 1,000 MHz. Guidelines for diagnosing and mitigating EMI from various sources are provided for product development and field installations.

open890 is a web-based UI for the Kenwood TS-890S amateur radio, and features good usability, clean design, and high-speed bandscope/audio scope displays, among other features not available either on the radio itself, or in the ARCP remote control software. It is currently only designed to interface with the TS-890 via a LAN (or wifi) connection, and not a USB/serial connection. It may work with the TS-990, as the command set is very similar, but is currently untested.

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.

The Thevenin equivalent simplifies a complex circuit into an equivalent circuit with a voltage source and resistor for easy analysis of voltage and current at any point in the circuit. Use this online Thevenin calculator

AllScan is a free and open-source web app for AllStar nodes that provides Favorites Management features, AllStarLink Stats integration, and connection monitoring and control functions. Shows your favorites in a Dashboard summary table with Keyed status, Connected Node count and other statistics. Continually scans the status of each favorite using ASL's Stats API data showing which favorites are active and have recently been active. Allows favorites to be connected with a single click (optionally automatically disconnecting any currently connected nodes first). Allows the Favorites Table to be sorted by Node#, Name, Description, Location, etc. Favorites can be added/deleted simply by entering the node# and clicking a button. These features finally give AllStar nodes similar memory management and scan capabilities that analog radios have had for decades. AllScan is mobile-friendly and optimized for ease of use on both small and large screens. AllScan follows the latest web development standards, with PHP, JavaScript, HTML, and CSS cleanly partitioned, runs on both ASL and HamVOIP, and is very easy to install, configure, and update.

Solar Wind Velocity and Auroral Storm Potential the website provides also current magnetic indices like last Kp values and predicted Kp values.

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

Detecting stray RF voltages on station grounds, chassis, and interconnecting cables is crucial for preventing program and hardware failures in the shack. This article details the construction and application of an LED RF V-probe, which offers significantly higher sensitivity compared to conventional neon lamp indicators. The probe leverages two specific properties of modern red LEDs: their ability to glow at microampere currents and their rectification capability at frequencies up to tens of megahertz. The design features a simple circuit with two LEDs, allowing for indication of both positive and negative RF voltage half-waves. The minimum detectable RF voltage is approximately 2 V, a substantial improvement over the 40-60 V threshold of neon bulbs. The resource illustrates the probe's physical construction on a PCB and provides a direct comparison demonstrating its superior sensitivity in detecting RF fields near a coil. Two operational modes are described: a non-contact mode for high RF voltages (above 15-20 V) and a direct-contact mode for measuring lower RF voltages, with a safety caution for the latter. Practical examples show the probe's use in analyzing RF voltage distribution across a radio station setup at 1.84 MHz and 24.9 MHz, revealing insights into common-mode current issues and the effectiveness of mitigation strategies like adding radials.

A versatile digital VFO design utilizing the Silicon Labs Si5351a oscillator chip and Nokia 5110/3310 graphics LCD display, operating from 1-160MHz with dual VFO capability. This microcontroller-based system, powered by an ATmega328 processor, features rotary encoder tuning, selectable step sizes, RIT control, and comprehensive band memory functions. Drawing less than 40mA at 3.3V, it significantly improves upon previous DDS designs' power consumption while offering advanced features like S-meter display, VFO lock, and programmable BFO/CIO offsets. The design achieves flexible functionality through simple hardware implementation and efficient software architecture, making it particularly suitable for QRP and portable amateur radio applications.

A modern, free online study tool for US amateur radio exams. It provides current NCVEC question pools for all license classes (Technician, General, and Extra). Features include a smart practice mode that tracks your weak areas and provides detailed explanations to help you pass faster.

DF6QV's 4-Square antenna analysis begins with a two-element array simulation, demonstrating azimuth and elevation plots for various phase differences, including a 75-135 degree range. The document then delves into the core components of a 4-Square system, such as radiators, couplers, phasing lines, and ground systems, referencing W1HKK's 1965 QST article on an 80m phased array. It explores the influence of ground conditions and element spacing on antenna performance, presenting EZNEC analysis for an 80m 4-Square with an elevated radial, showing how gain and beamwidth vary with spacing. Various 90-degree couplers, including the 3 dB hybrid coupler and the Reed Fisher coupler, are analyzed using LTSpice, detailing power splitting, phasing, and bandwidth characteristics. The resource quantifies power, voltage, current, and losses within a 4-Square system, addressing relays, capacitors, inductors, radiator radial systems, and cable losses. System impedance, bandwidth, SWR, isolation, and mutual coupling are discussed with practical construction aspects covering common mode chokes, phasing boxes, and remote control systems. Field test observations for 40m 4-Square antennas are included, with specific examples from DXpedition operations like 5A7A and VP6DX, providing real-world context to the theoretical and simulated results.

The Zeppelin antenna, a J-type design, is presented as a two-band HF dipole, offering independent operation on harmonically related frequencies. This resource details its electrical configuration, comprising a half-wave radiator end-fed by a quarter-wave matching section, and explores its historical evolution from early Zeppelin airship applications to modern amateur radio use. The article specifically examines how a Zepp antenna tuned to 28.4 MHz (10 meters) exhibits a harmonic relationship with 15.4 MHz (20 meters), noting a frequency ratio of approximately 1.84:1, which deviates from a perfect 2:1 due to factors like elevation, wire separation, velocity factor, and end-effect. Antenna modeling results, including SWR sweeps at 28.4 MHz (1.1 SWR) and 15.4 MHz (1.6 SWR), are provided through Graph 1 and Graph 2, illustrating the antenna's performance across these bands. Current distribution patterns for both the 28.4 MHz (second harmonic) and 15.4 MHz (first harmonic) operations are visually represented in Figure 2 and Figure 3, respectively. The author also includes a 4NEC2 model's "Symbol Conversion file" definitions and calculated #14 wire dimensions for achieving resonance at 28.4 MHz, with the antenna positioned at a height of 33 feet. The discussion further highlights the antenna's versatility, suggesting its potential as a single-band, center-fed, 15.4 MHz half-wave folded end dipole when fed at a specific low current point. This analysis provides practical insights into constructing and optimizing a multi-band Zepp antenna for HF operations, emphasizing its unique harmonic characteristics and physical compactness.

An Arduino-based interface provides a remote tuner call command for Icom **IC7700** and **IC7800** transceivers, addressing the lack of a built-in function for external tuners such as the MFJ 998RT. This setup initiates a low-power transmit signal, typically 15 watts, allowing the remote autotuner to perform its matching sequence. The article details the required CI-V line communication and modifications to existing Arduino code, specifically referencing contributions from Jean-Jacques ON7EQ for improved Icom interrogation routines. The system involves a sequence of steps: storing the transceiver's current mode and power, disabling the internal autotuner, activating a control relay to interrupt the amplifier line, switching to RTTY mode at low power, and initiating transmit. The transmit duration is manually controlled by the operator, observing the SWR meter until a low SWR is achieved, then a second button press stops the transmission. A built-in 4-second transmit limit provides a safety measure. After tuning, the routine restores the original mode and power settings, re-enables the internal autotuner, and performs a brief 2-second RTTY transmission for internal tuner adjustment. The circuit diagram includes a Panasonic form 2 relay for amp control and emphasizes critical delays in the Arduino code for stable operation at 9600 baud CI-V communication. Compatibility with logging software like DXLab, N1MM, and N3FJP is noted, with specific interrogation time settings required to avoid conflicts.

Website dedicated to weekly space weather forecast and updates on current solar activity. Dr Skov provides video forecasts and weekly audio forecasts

This online tool is a specialized web-based utility for orchestrating multi-operator HF contest and DXpedition activities. This tool, _Rig2Cast_, assists station managers in meticulously planning operator shifts, ensuring adequate rest periods, and crucially, preventing operational conflicts such as assigning a single operator to multiple radios concurrently. It integrates support for SO2R operations and offers real-time simulation of operator requirements, a feature I've found invaluable in pre-event planning. The scheduling engine incorporates five distinct algorithms: greedy fairness balancing, round robin, maximum coverage, simulated annealing, and a fatigue-aware model. These algorithms enforce critical constraints like minimum/maximum shift durations and mandatory rest times across all radios, which directly impacts operator performance over long events. My field experience confirms that such robust constraint management is essential for maintaining peak efficiency during intense operations. Key features include distributed multi-station support, printable per-operator cards, flexible band activity windows, and real-time editable operator slots. The drag-and-drop shift management, coupled with full cross-radio swap support and smart constraint feedback (valid targets in green, invalid in red), streamlines complex scheduling tasks. The system's design ensures user data privacy, as no information is stored on the server; schedules are saved and reloaded locally.

The **5-Port 12 Volt DC Power Strip Kit (Rev 4)** offers a practical solution for managing shack power distribution, providing one input and five fused outputs. All connections utilize the ubiquitous Anderson PowerPole connectors, a standard for many amateur radio operators, ensuring a clean, organized, and safe way to power multiple 12 VDC transceivers and accessories from a single source. This design mitigates the common issue of tangled wires and overloaded connections in a typical ham shack. Rated for a maximum current of 20 Amps at 12 VDC, the strip incorporates an integrated LED to indicate when external power is applied. Each output is individually fused, a critical safety feature that protects connected equipment from overcurrent conditions without affecting other devices on the strip. This level of protection is essential for preserving sensitive radio gear during operation. Assembly requires basic soldering skills and hand tools, with a high-power soldering iron and wide chisel tip specifically recommended for best results. The kit's compact dimensions of 4.13" x 1.78" allow for flexible mounting via screw holes, making it suitable for various shack configurations and portable operations.

AA9PW offers free practice exams for all three US license classes plus international licenses like Canadian and Australian. The site generates random tests from the current question pools, simulating the actual exam experience. You can choose between online exams or printable PDF versions for offline study. The site maintains a simple, no-frills interface that loads quickly even on slow connections. Practice tests provide immediate feedback with score reports highlighting areas needing improvement.

Callook provides a **USA amateur radio callsign lookup service** with data current as of March 25, 2026. The platform allows users to search for valid callsigns and retrieve detailed information, including geographic coordinates sourced from the Bing Maps API. A mathematically calculated **grid square** is derived from these coordinates, though accuracy is not guaranteed due to reliance on external services. The service supports multiple access methods, including a browser search plugin, direct API access with a reference, and plain text output for integration into other applications or scripts. This tool facilitates rapid identification of US amateur radio operators, offering an alternative to other callbook services. Its API access enables developers to integrate callsign lookup functionality into custom applications, streamlining data retrieval for logging software or contest management. The direct presentation of FCC data, combined with grid square calculation, assists DXers and contesters in verifying contact information and location details during on-air operations.

Learn about the HAMTV Digital Amateur Television (DATV) transmitter on the International Space Station (ISS), transmitting video and audio in MPEG-2 format using the DVB-S protocol. Discover its history, installations, failures, and repairs, as well as the current status and live video feed. Explore the technical details and challenges of the HAMTV transmitter, including power output, polarization, and antenna location. Find recordings of previous transmissions and understand the potential signal reflections caused by various ISS components. Stay updated on the latest developments and activities related to HAMTV from the ISS.

Swan provides a real-time, browser-based visualization of **meteor radiants** and forward scatter corridors, serving as a modern re-imagining of the classic Virgo meteor sky visualization tool. It displays meteor radiant and radio scatter geometry, offering both visual and numerical skyview data. The tool updates in real-time, showing current sky conditions and allowing users to pause and review specific timeframes for analysis of meteor shower activity and potential radio propagation paths. This enables operators to identify optimal windows for **meteor scatter** contacts. Operators can utilize Swan to predict and optimize their meteor scatter DX attempts by understanding the geometry between their station, meteor radiants, and potential receive stations. The interface presents critical data points for assessing forward scatter opportunities, which is crucial for maximizing short-duration meteor burst communications. By observing the real-time skyview, users can correlate meteor activity with observed signal enhancements, refining their operating strategies for specific meteor showers or random meteor pings.

The article details the repair of an Elecraft K3 transceiver experiencing an "ERR 12V" issue, causing reduced output power. The problem, common in these units, stems from inadequate pin strips carrying high DC current to the PA unit, leading to overheating and poor conduction. The author identified the faulty connectors and implemented a bypass using existing PCB pads, effectively rerouting the power and resolving the error. This straightforward fix highlights the importance of robust electrical connections in high-current applications, restoring the K3's full functionality.

Demonstrates the design and modeling of a **160m** vertical antenna, dubbed the "WindoVert," specifically for urban amateur radio operators with limited space. The resource covers the theoretical underpinnings of antenna height and radiation patterns, using EZNEC software to analyze current distribution and 3D radiation patterns for various configurations, including a Marconi-style "T" antenna. It details the integration of existing antenna components, such as a Carolina Windom balun and line isolator, into the new vertical setup, and the practical measurement of feedpoint impedance using an antenna analyzer. The article further explores the challenges of achieving low-angle radiation on Top Band, emphasizing the critical role of radial systems and mitigating ground loss. Author VE1ZAC presents EZNEC models illustrating the impact of lumped components and discusses the practical considerations of resonant frequency adjustment and impedance matching for **QRP** operation. The text details the calculation of required loading coil inductance and capacitance, and shares field results, including successful DX contacts on 160m and unexpected excellent performance on 30m.

SDR Television v1.0 operates as a DVB-S2 / AAC / H264 / H265 program, specifically engineered for QO-100 satellite Digital Amateur Television (DATV) operations. It provides a full-duplex solution on modern x86 computers running Windows 10 or 11 (64-bit, 8+ cores, AVX2 support recommended), leveraging DLLs from _SDR Console_ for control of devices like _Pluto_ and _LibreSDR.TV_. The software requires installation of the SDR Radio kit for wideband mode support. Initial development focused on a proof-of-concept for QO-100, with future enhancements planned to include H266 / AV1 / Opus codecs and an improved cross-band user interface. The current stable release functions reliably for QO-100 DATV. Users must install the SDR Radio kit, followed by the SDR Television kit, into the same directory. Support inquiries are handled via the SDR-Radio.com mailing list, ensuring direct assistance for operational questions.

Ham Exam provides adaptive practice tests that adjust difficulty based on your performance. The site offers all current question pools and calculates your probability of passing the actual exam based on your practice results. It includes detailed explanations for each answer and tracks your progress across specific subelements of the exam. The clean, distraction-free interface makes it easy to focus on studying, and no registration is required to use the basic features.