Search results

DF0WD/DL4YHF's Longwave Overview details amateur radio operations on the 135.7 to 137.8 kHz segment in Germany. The author outlines the "inofficial" European band plan, specifying segments for QRSS, TX tests, beacons, conventional CW, and data modes. Early LF activities at DF0WD began with a 20-watt CW transmitter, later upgraded to a homemade linear transverter capable of 100 watts, driven by an Icom IC706 on 10.137 MHz. The station's antenna system includes a 200-meter wire, approximately 10 meters above ground, supported by football field light-masts. Despite its length, the antenna's efficiency is noted as very low due to the immense wavelength of about 2.2 km. The author's experience highlights the significant challenge of achieving effective radiated power (EIRP) on LF, estimating DF0WD's EIRP at around 80 milliwatts based on field strength measurements from PA0SE. DF0WD/DL4YHF has successfully worked numerous countries on 136 kHz CW, including DL, F, G, GI, GM, GU, GW, HB9, HB0, LX, OE, OH, OK, OM, ON, OZ, PA, and SM. The author also mentions ongoing efforts to log contacts with CT, EI, LA/LG, and to complete a two-way QSO with Italy, demonstrating persistent activity on this challenging band.

Clarifies the intricate process of calibrating the _Elecraft K2_ dial, addressing common user challenges and lively discussions on the Elecraft reflector. Wilhelm, W3FPR, dissects the K2's PLL synthesizer design, chosen for its low phase noise, kit-friendly duplication, and cost-effective components. The resource emphasizes the critical role of the 4000.000 kHz reference oscillator's accuracy during CAL PLL, CAL FIL, and CAL FCTR functions, noting its dependence on temperature and crystal stability for optimal performance. Explaining the K2's frequency display, the document reveals it relies on microprocessor-driven look-up tables generated by CAL PLL for VFO values and CAL FIL for BFO values. In SSB and RTTY, these combine, while CW and CWr modes also factor in the sidetone pitch. The author details inherent limitations, such as the 10 Hz increment resolution of the dial and varying PLL step sizes—from 3 Hz on 160 meters to 10 Hz on 10 meters. BFO increments range from 20 to 35 Hz, collectively limiting practical dial accuracy to within **20 Hz** with diligent effort, or **30 Hz** for a slightly less demanding task. The guide outlines a four-step calibration procedure: setting the reference oscillator, running CAL PLL, running CAL FIL, and setting all BFOs. It highlights the _N6KR Method_ as a particularly easy and accurate approach, requiring only the K2 and a known frequency source like WWV for zero-beating, eliminating the need for external test equipment.

The Burlington Amateur Radio Club (BARC) provides a community hub for amateur radio operators in Burlington, Ontario, Canada, offering regular meetings, educational programs, and a dedicated hackspace for electronics and radio experimentation. The club operates several repeaters, including a 2m repeater (VE3RSB) on 147.210 MHz with a +600 kHz offset and 131.8 Hz tone, which supports AllStar node 542490. Additionally, BARC maintains a UHF repeater on 444.825 MHz with a +5 MHz offset and 131.8 Hz tone, and a 1.25m (220 MHz) repeater, facilitating local communication and digital mode access. BARC hosts multiple nets, including a Fusion Net on Mondays at 8:00 p.m. via VE3RSB-Room 61272, a Regular Wednesday Night Net on the VE3RSB system at 7:30 PM, and a 220 Net on Thursdays at 7:00 p.m. The club also runs a CW/SSB HF Net every Thursday at 7:00 p.m. local time on 40m, utilizing 7.125 MHz for LSB and 7.124.3 MHz for CW check-ins. These activities promote on-air participation, technical skill development, and social interaction among members, supporting both VHF/UHF local operations and HF DXing.

Constructing a dual-band antenna for 40 and 20 meters often involves compromises in size or complexity. This resource presents a compact _open sleeve dipole_ design that addresses these challenges by using 450-ohm ladder line and folded elements to achieve a total length of approximately **17.17 meters**, significantly shorter than a full-size 40-meter dipole. The design leverages electromagnetic coupling, where a primary radiator handles the 40-meter band, and a second conductor resonates on 20 meters without direct electrical connection. This configuration eliminates the need for traditional traps, loading coils, or switching components, simplifying construction and reducing potential loss points. The antenna is fed with RG-58C/U coaxial cable, and a common-mode choke is recommended at the feed point to suppress sheath currents, ensuring a cleaner radiation pattern and minimizing RF in the shack. The design is well-suited for portable operations, field deployments, temporary installations, and restricted urban environments where space is a premium, offering solid performance on both HF bands.

DxDozer is a Windows-based amateur radio logbook designed for both new and experienced DXers, featuring a robust logging system with extensive search capabilities. It offers seamless integration with FT8, displaying received stations from WSJT-X in a DX Cluster-like view, indicating LoTW status and prior contacts, and initiating QSOs directly. The software supports an unlimited number of callsign logbooks and allows multiple operators to log simultaneously to a single database, enhancing its utility for multi-operator stations or contest operations. The application includes a sophisticated DX Cluster with highly configurable filters based on band, mode, continent, worked/confirmed status, and LoTW participation, enabling users to monitor specific calls or countries. DxDozer simplifies QSL management by facilitating one-button uploads to LoTW and ClubLog, and downloads of new confirmed QSOs, with a dedicated field for QSL medium. The software provides both 'Easy' and 'Expert' modes to cater to different user proficiency levels, and is available via a yearly subscription after an initial free trial period.

Accessing current operational statistics for a DXpedition is crucial for DXers planning their next contact. This Club Log page provides a detailed, real-time overview of the 3Y0J Bouvet Island operation, a highly sought-after DXCC entity. It presents a dynamic dashboard showing total QSOs, unique calls worked, and duplicate contacts, all updated as logs are uploaded from the remote location. Users can observe the expedition's progress and strategize their operating times. The interface features interactive charts and graphs, allowing operators to analyze the _3Y0J_ log data by band and mode, including CW, FT8, and SSB. A breakdown of QSOs by continent provides insight into propagation patterns and where the expedition has focused its efforts. The page also includes a map for checking real-time propagation conditions to Bouvet Island, which is invaluable for optimizing contact attempts. Further details include the first and last QSO times, total operating days, and the impact on users' DXCC totals, such as new bands, modes, or DXCC entities worked. This resource is a vital tool for the DX community, offering transparency and actionable intelligence for chasing one of the rarest entities on the air.

This article describes a simple yet effective multi-band vertical HF antenna design that performs exceptionally well across 80m to 10m bands. The antenna consists of a 13.4m wire mounted on a 12.4m Spiderpole, complemented by four 12m radials and a ground rod. Initially tuned with a manual LC circuit, it was later upgraded with a CG3000 remote auto ATU for convenient band switching. Despite antenna modeling software suggesting limited performance on higher frequencies, the system demonstrated excellent DX capabilities across all bands, outperforming more complex vertical antenna designs.

This is a small collection of K9YC info and my experiences. Problems by feed lines of 1/2 lambda length. CMCs in transmitting and receiving systems. Antenna unbalance, Maximal allowed power, Choke winding tips.

Over 15 years of continuous operation, Ham365 provides a web-based logging solution for Amateur Radio Operators, allowing them to maintain and share their QSO records online. Originally launched as the online logbook component of Ham Radio Deluxe, it has since evolved into an independent platform, now integrating with numerous other logging applications. The platform shares its database with HRDLOG.net, ensuring that operations performed on one site are reflected on the other, maintaining data consistency for users. Key features include an overview of the latest hour's activity, a display of the most recent QSOs, and a map visualizing recent contacts. It also highlights "Most Wanted" entities and ongoing DXpeditions, providing a dynamic view of current amateur radio activity. The logbook supports various operating modes, including SSB, RTTY, PSK31, and FT8, and handles ADIF data for interoperability. Users can manage their logbooks, track DX activity, and utilize features like OQRS (Online QSL Request System) through its integrated functionalities. The system is designed to be accessible to a wide range of operators, from casual ragchewers to avid DXers and contesters.

DXFile is a Windows shareware application designed for amateur radio operators, providing comprehensive log management capabilities. The software, developed in Pascal, facilitates real-time and deferred QSO entry, automatically populating fields like frequency, mode, and DXCC country based on user input and system time. It includes features for searching, modifying, and deleting QSO records, with options to sort logs by date, callsign, or entry order. The program offers various printing functions, including QSL card labels in multiple formats, and can generate standard logbook printouts. Beyond basic logging, DXFile integrates modules for tracking progress towards major operating awards such as DXCC, _IOTA_, WAZ, WAS, DDFM, and DIFM. It provides detailed summaries of contacts by band and mode, including graphical representations of HF traffic. A dedicated QSL Manager module assists in processing received QSLs, allowing users to mark confirmations and print multi-line QSL labels. The application also incorporates a DXCC list viewer, which can be updated to ensure accurate country and zone data for logging and award tracking. A distinctive feature is its HF propagation prediction module, which calculates optimal frequencies and signal levels for paths between **250 km** and **6000 km**, considering both E and F layer ionospheric conditions. This module helps operators determine the best times for long-distance contacts. Additionally, DXFile includes a _Web-Cluster_ interface, enabling connection to various DX cluster servers like DXLITE, DXSCAPE, and NC7J for real-time spot information.

Integrating a **160-meter vertical wire antenna** with an existing 80-meter Yagi system presents unique challenges for Top Band operation. This project outlines the author's experiences with seasonal antenna removal and reinstallation, a necessary task for agricultural land use. It details specific issues encountered, such as incorrect coil sizing and relay configuration problems, providing practical insights into common pitfalls. The article describes the iterative tuning process, comparing **NEC model** predictions with actual on-air performance. It emphasizes the importance of precise measurements and adjustments to achieve optimal resonance and impedance matching. The author shares lessons learned from troubleshooting, including the impact of ground system integrity and feedline considerations. Concluding with an antenna checkup, the resource addresses long-term maintenance aspects, including galvanic corrosion prevention and general upkeep for reliable operation.

World Wide Digi DX Contest 2019 The contest will occur over 24 hours on August 31 and September 1, 2019 using the FT4 and FT8 modes on the 160, 80, 40, 20, 15, and 10-meter bands.

This article is an attempt to shed some light on this misunderstood component, covering topics like why you need a common mode coke, what it does, what properties it should have, ho to build one and how to measure its performance.

Power Solutions for Durable Communication Systems. Founded in Sep. 1992, DuraComm Power Supplies is a worldwide recognized leader in ultra-reliable AC-to-DC switch mode power supplies commonly used in the communications industry.

Reviving the spirit of early ham radio experimentation, the CW Flea is a contemporary Morse code transmitter. Utilizing an Arduino Nano, Si5351 clock generator, and innovative design, this open-source project offers simplicity, flexibility, and easy tuning for aspiring radio enthusiasts.

A Magnetic Loop Controller project details the construction and operation of an automatic tuning system for magnetic loop antennas, which are resonant circuits using an oversized inductor and an adjustable capacitor. The system employs a stepper motor to precisely adjust the variable capacitor, maintaining optimal resonance across the HF bands. It integrates with various transceivers, including _Icom_, _Kenwood_, and _Yaesu_ models, by monitoring the VFO frequency and adjusting the loop's tuning accordingly. The project provides comprehensive building instructions, a PowerPoint-style presentation, and the full source code for the controller's firmware, enabling hams to replicate and customize the design. The controller's firmware offers diverse functionality, including automatic frequency tracking, manual tuning, and SWR monitoring, significantly enhancing the operational efficiency of magnetic loop antennas, particularly for QRP and portable operations. The design emphasizes accurate capacitor positioning, crucial for achieving low SWR and maximum radiated power. Comparisons with manual tuning methods highlight the benefits of real-time adjustment, especially when operating across different bands or making frequent QSYs. The project's detailed documentation and available source code facilitate experimentation and modification by advanced builders, allowing for tailored performance characteristics.

Early pictures and presetation of the Icom the IC-705, new all bands all modes QRP transceiver introduced at Tokio HamFair on August 31st September 1st 2019.

A data converter for the Tandy WM918 weather station. The Weather APRS data converter project aims to create an interface to interpret data from the popular Tandy WM918 weather station and format it for transmission over packet radio. The South East Radio Group in South Australia has established a network of these weather stations to provide amateurs with regularly updated weather data. However, the WM918's data output is not structured for APRS weather reporting. This project describes a solution using a PIC microcontroller to convert the WM918 data into APRS-compatible strings that can be sent as beacons or connected packets. The interface offers features like position/positionless data, connected/beacon modes, and metric/imperial units. The goal is to create an interconnected weather reporting system for amateur radio operators

System Fusion is a digital communications mode for voice and data, including pictures. It utilizes a customized, yet open, C4FM FDMA standard. An introduction to Yaesu System Fusion by Wireless Society of Southern Maine

This article details a ham radio operator’s experience setting up HF antennas in an antenna-restricted community. Initially using an AEA Isoloop magnetic loop for QRP PSK, the author later built an attic antenna system, including dipoles for multiple HF bands and a slinky dipole for 40 meters. The setup allowed for operation on six bands with acceptable VSWR. Despite space constraints and some compromises, performance was effective. The article highlights practical strategies, emphasizing experimentation and antenna modeling for optimizing performance in limited-space environments. A valuable guide for ham radio operators facing similar restrictions.

N6CTA provides a comprehensive tutorial on manually configuring NTP synchronization for Debian Linux, ensuring accurate system time for FT8 and other amateur radio modes. The guide covers updating the system, installing and enabling NTP, verifying the timezone, and using the iputils-clockdiff tool for precise time comparison. A script is included to check and sync system time, enhancing the performance of synchronous modes like FT8.

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.

CTR2-Mini is a small radio controller based on the Seeed Studios Wio Terminal. It can control many radios including FlexRadio 6000s. Multiple Minis can be used to control multiple slices on the Flex. It also has a special mode that allows two CTR2-Minis to control the Main and Sub VFOs on the FTdx101. An article on CTR2-Mini appears in the September 2022 issue of QST.

Unveil the secrets of efficient Magnetic Loop Antenna control systems, eliminating the hassle of frequent retuning. With real-time tracking and compatibility with various transceivers, including popular models from Elecraft, ICOM, Kenwood, and Yaesu, this controller ensures seamless frequency adjustment. Explore its high-resolution stepper motor and versatile communication capabilities, revolutionizing amateur radio operation.

From March 2 to March 11, 2018, a Norwegian team operated as Z2LA from Zimbabwe, focusing on 160m through 10m bands using SSB and CW modes. The operation, described as "holiday style," aimed to provide contacts for DXers worldwide seeking a rare DXCC entity. Key equipment included a SUNSDR PRO II, an Elecraft KX3, and an Icom 706 MK2G as a spare radio, supported by two Juma 1000 amplifiers for robust signal output across the bands. Antenna systems were tailored for multi-band operation, featuring an Inv L for 160m and 80m, sloping dipoles for 30m/40m, and a _Hexbeam_ from SP7IDX Technology covering 20m to 10m. For improved reception, the team deployed a SAL 30, two reversible BEV antennas from remoteqth.com, and a BOG from K1FZ, enhancing their ability to hear weak signals. QSL information directs operators to Clublog for log search and M0OXO Charles for OQRS, explicitly requesting no bureau cards. The team comprised LA7THA Rune, LA7WCA Arne, and LA9VPA Thor, successfully making numerous contacts and contributing to the DX community's pursuit of _Zimbabwe_ as a DXCC entity.

The XX9D Log Online provides a direct log search function for the DXpedition to Macao, specifically detailing operations conducted in 2017 and 2019. This service allows amateur radio operators to verify their contacts (QSOs) with XX9D, a critical step for QSL card management and award applications. Users are explicitly advised to consult the online log to prevent duplicate contacts on the same band and mode, optimizing efficiency during active DXpedition periods. This online tool supports the "DX Code Of Conduct," promoting ethical operating practices within the amateur radio community. The platform facilitates the Online QSL Request System (OQRS), streamlining the process for requesting QSL cards without the need for traditional bureau or direct mail methods. Operators are instructed to defer OQRS submissions until the conclusion of the DXpedition, ensuring all logs are finalized. The log search interface is powered by CMSimple, a content management system, indicating a straightforward, database-free web application. The resource is designed for ease of access, providing a clear method for DXers to confirm their contacts and manage QSL requests efficiently.

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.

Robust PACKET, developed by Spezielle Communications Systeme GmbH & Co. KG (SCS), is an OFDM variant of the amateur PACKET mode specifically engineered for HF operation. This mode utilizes a 500 Hz bandwidth with 60 Hz carrier spacing, employing OFDM with 8 DBPSK or DQPSK carriers. It supports 200 bps using BPSK and 600 bps with DQPSK, with each subcarrier operating at a constant rate of 50 Bd. Robust PACKET leverages the AX-25 frame protocol for data transmission, similar to standard PACKET. Compared to traditional PACKET, Robust PACKET demonstrates enhanced resilience against multipath propagation and fading effects, critical for reliable HF communications. It also exhibits a more efficient spectral footprint, with sidebands extending only to 500 Hz, whereas 300 Bd FSK PACKET can produce sidebands up to 730 Hz. Operational frequencies for Robust PACKET include 3.61 MHz, 7.0473 MHz, 10.1473 MHz, and 14.1033 MHz, with specific regional frequencies also documented. Decoding software options for Robust PACKET include Wavecom W-Code and Wavecom W-Spectra. The mode is primarily supported by SCS's 'Tracker / DSP TNC' hardware.

This article details the development of an 80-meter antenna within the confines of a restrictive covenant community. Faced with limited space, the author explores various options before implementing a clever hybrid design: a short 30-foot vertical wire running discreetly down the building's exterior combined with a capacitive top hat installed in the attic. Computer modeling confirmed the superiority of capacitive loading over inductive loading, increasing radiation resistance from 6 to 14 ohms. The perimeter wire top hat, naturally supported by the attic structure, resonates effectively at 3.5 MHz. The system is completed with four buried 60-foot radials installed "after dark" to maintain compliance with community restrictions.

Find specialized searches and information for Yaesu System Fusion-equipped repeaters.

his historical account traces the development of car radios from Marconi's mobile wireless telegraph station on a steam engine vehicle in 1901 to Motorola's iconic car radio models in the 1930s. It highlights key milestones such as Alfred Grebe's radio-telephone experiments on Long Island and the introduction of Marconi-Phone 8 radios by the Daimler Company in England. The narrative explores technological advancements, including the transition from TRF to Super-Heterodyne circuitry and the integration of push-button controls. The evolution from vacuum tubes to transistors and compact discs is also documented, showcasing the continuous innovation in automotive entertainment systems.

This article presents a novel Top Loaded End-Fed Half-Wave (TLEFHW) antenna design for 20-meter ham radio operation. The antenna features a compact 14-foot vertical radiator with a capacitance hat configuration, eliminating the need for radials or ground systems. Using EZNEC modeling and field testing, the design achieves a 1.5:1 SWR across the 20m band with a 4.11 dBi gain. Key features include quick deployment, lightweight construction, and directional radiation pattern with 110-degree beamwidth. The design, while requiring a 45-foot footprint due to the top hat, offers an effective portable solution for amateur radio operators seeking a no-ground, no-tuner 20m antenna option.

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.

SvxLink is an advanced software suite for the ham radio community, initially launched in 2003 as an EchoLink application for Linux. Now a comprehensive voice services system, the SvxLink Server functions as an advanced repeater controller and can operate on simplex and duplex channels. It acts as an intermediary between transceiver hardware and applications, offering essential system services. The modular architecture of SvxLink supports customization, with modules in C++ or TCL. Key modules include a help system, parrot mode, EchoLink connectivity, DTMF repeater, voice mail, propagation warnings, and selective calling sequences. SvxLink's development and source code are available on GitHub, promoting open-source collaboration in the ham radio community.

The QubeDX is a modular CubeSat-style QRP transceiver designed for digital mode operation with remote Wi-Fi control via VNC. This project integrates a QRPLabs QDX 5W transceiver, an ATU-100 antenna tuner, and a Raspberry Pi 5 in a custom 14x14x14cm 3D-printed enclosure inspired by CubeSat design. Prioritizing affordability and functionality, the system operates on a single 13.8V power supply and includes auto-tuning and software like WSJT-X. With a total cost of under €250, it offers a decorative and portable ham radio solution.

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.

M17 is a community of open source developers and radio enthusiasts. We are building understandable systems in support of the hackers and experimenters' history of ham radio. M17 is developing open source hardware, software, and offers a complete digital radio protocol for data and voice, made by and for amateur radio operators. M17 voice mode uses the free and open Codec 2 voice encoder.

The Aziloop DF-72 antenna system provides 72 K9AY headings and 36 loop axes, allowing for rapid switching in 60 ms. It integrates a switchable 18 dB preamp, a 4-step attenuator (0-18 dB), and four 7-pole preselection filters to optimize receiver performance. The K9AY load is adjustable from 250 Ohm to 950 Ohm in 50 Ohm increments, offering flexibility for various receiving conditions. Control is managed via an intuitive Windows UI, supporting Local, Client, or Server modes, with headless remote operation possible through the built-in Ethernet Server. _Omni-Rig_ support facilitates auto-filter selection, PTT muting, and Rig-Sync functionality, enhancing integration with existing station setups. Designed by _GW4GTE_, the system utilizes a low visual impact, small-footprint antenna with orthogonal loops and an earth connection. It is suitable for general monitoring, co-channel station resolution, basic direction finding, and interference reduction across the VLF to HF spectrum.

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

This article details an Inverted-L antenna design optimized for 160-meter band operation, consisting of a 10m vertical section and a 28m horizontal section supported by Spiderpoles. Despite its relatively low height compared to the wavelength, the antenna has demonstrated impressive DX capabilities, achieving contacts up to 3,453 miles into Asiatic Russia. The system incorporates a Pi-Network ATU at the base for tuning flexibility. While modeling shows a radiation pattern favoring the South, practical operation indicates effective all-round coverage on Top Band.

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.

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.

This project outlines a simple Lead Acid/SLA battery monitor, designed to alert users when battery voltage falls below 10.6V. The monitor, based on a PIC16F1827 microcontroller, checks the voltage of up to five batteries and triggers an alarm if any drop too low. The system operates in various modes, including self-test, monitoring, and alarm. This updated version improves upon the original 1999 design, offering a more modern microcontroller and extended functionality for workshop use, with minimal impact on battery charge.

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 influence of temperature changes in Common Mode Chokes. To get an indication of the impedance behavior when the core temperature changes, the author tested a CMC by heating it with a hairdryer, and measuring its temperature with an infrared thermometer. When the CMC temperature rises from 30C to 90C, the frequency of maximal impedance shifts down from ca.10 MHz to ca.7.2 MHz, or by a factor 1.4.

The ICOM IC-745 is a durable 1980s HF transceiver, ideal for enthusiasts who enjoy restoration. While lacking modern serial control, it supports digital modes with modifications like sound card connections and frequency stabilization. Enhancements like an RTL-SDR panadapter can also be added, making it a versatile and valuable radio for contemporary use.

Manually programming a Yaesu FTM-100 with hundreds of channels can be very fustrating. In this article the author highlights the difficulty of entering data with small buttons and the need to look up information for each channel. To avoid this tedious process author used RT Systems software as a solution. This program simplifies programming by allowing selection based on the radio model, download of frequencies from resources like RFinder, and quick loading onto the radio. While paid unlike the free CHIRP software used previously, the author emphasizes the time saved compared to manual entry, making the cost worthwhile.

This paper presents an 80 meter wire 3-element beam antenna in an inverted-V configuration, designed for limited-height towers. Using EZNEC modeling, the antenna features a central parasitic reflector and two switchable driven elements at each end, enabling NE/SW coverage without moving parts or networks. Element lengths are optimized for SSB (3.8 MHz) and CW (3.5 MHz) operation, with a 50 Ω feed and rope-supported boom. The design delivers high gain, effective takeoff angles, and excellent reception, confirmed in real-world DX contest operation. Its simplicity, reliability, and ease of construction make it ideal for operators seeking performance without complex matching systems.

This comprehensive article dispels common misconceptions about Standing Wave Ratio (SWR) in amateur radio. The author explains that SWR is not an antenna property but a measure of the entire antenna system, representing the mismatch between transmission line and load impedance. Contrary to popular belief, modest SWR values (under 3:1) typically cause minimal power loss in HF applications. The article demonstrates mathematically why obsession with achieving 1:1 SWR is often unnecessary, explains when SWR matters more (QRO, QRP, VHF/UHF), and explores effective matching techniques including proper ATU placement and quarter-wavelength transformers.

VE1ZAC's analysis details the performance of **MFJ927** and **SGC239** autotuners with portable HF vertical antennas, specifically comparing 31 ft and 43 ft configurations. The resource originated from challenges encountered during a Maritime QSO Party roving operation, necessitating a lightweight and easily deployable antenna system. Target bands for the contest included 80, 40, 20, 15, and 10 meters, with a maximum power handling of 100 W CW. The author utilized a 30-foot carbon fiber push-up pole to support a vertical wire element, noting its 2 lb weight and reliability. EZNEC modeling was employed to predict performance, showing favorable results for a 30-foot vertical with elevated radials, particularly on 40 and 20 meters. Feedpoint impedance measurements, taken with an AIM4170C, are presented for various HF bands, both with and without a 41-foot RG6 stub designed to reduce reactance on 80 and 20 meters. The stub significantly improved matching on these bands, easing the tuner's workload. Operational tests revealed issues with the MFJ927's reliability during contest setup, leading to reliance on the K3's internal tuner. The SGC239, tested post-contest, performed flawlessly. A detailed side-by-side comparison covers mechanical aspects, connection options, power bias, impedance range, board quality, and documentation. Modifications to the MFJ927, including a new aluminum case, white paint for heat reduction, and upgraded impedance-measuring resistors, are also described.