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The article discusses the construction of a UHF band-stop stub filter to protect an APRS receiver from potential damage during a balloon launch. The author, who communicates using a 441 MHz transmitter, needed to ensure that the RTL-SDR dongle receiving at 144 MHz wouldn't be damaged by the transmissions. The solution involved creating a quarter-wavelength open stub filter using coaxial cable, which attenuates the 441 MHz signal while allowing the 144 MHz signal to pass through. The filter's design is based on the principles of constructive and destructive interference, with careful measurement and trimming to achieve the desired frequency response. The final filter provided 34.8 dB of insertion loss at 441 MHz and minimal loss at 144 MHz, effectively protecting the receiver.

This page by ARCTICPEAK provides a calculator for determining ERP and EIRP (Effective radiated power and effective isotropic radiated power). The tool is designed to help hams calculate and understand the power radiated by their radio equipment. The content is useful for ham radio operators who want to optimize their transmission power and comply with regulations. LA8OKA Martin has created this resource to assist hams in accurately measuring their radio signals.

HamStream, a versatile ham radio control software, integrates real-time DX cluster data directly into the operator's workflow, eliminating the need for constant alt-tabbing. As an Extra Class operator, I appreciate how it instantly displays callsign, country, distance, bearing, and QRZ profile data for spotted stations, mirroring the efficiency of a well-organized shack. The software acts as a comprehensive radio controller, reading frequency, mode, and S-meter in real time from connected rigs, supporting CAT via serial, CI-V, _HAMLIB_, and direct connections to _FlexRadio SmartSDR_ and Apache Labs ANAN (via Thetis). Key features include instant QRZ lookups, distance and bearing calculations with a live great-circle minimap, and favorite alerts for specific callsigns. The one-click logging functionality is particularly useful, populating callsign, frequency, and mode into _N1MM+_, Log4OM, DXKeeper, Logger32, StationMaster Pro, and Ham Radio Deluxe via UDP, streamlining contest and casual logging alike. Its smart radio auto-detection for port, baud rate, and model simplifies setup, a welcome relief from manual configuration. Beyond core operating, HamStream also displays 'Also on this frequency' information and can tune the radio to spotted frequencies, enhancing situational awareness. For those who stream their operations, it offers an OBS overlay with live viewer counts and chat integration, making it a compelling tool for modern amateur radio engagement.

Constructing a **J-Pole antenna** from 450 Ohm ladder line for 2-meter (144 MHz) and 70-centimeter (440 MHz) operation involves specific calculations and assembly steps. The design, based on an earlier KD6GLF concept using 300 Ohm twinlead, features a ¾ wavelength radiator and a ¼ wavelength matching stub, functioning as an end-fed half-wave antenna without requiring ground radials. It offers a gain of 2.4 dB over isotropic. The resource provides the formulas for determining the lengths of the ¾ wave radiator and ¼ wave stub, incorporating a velocity factor of 91% for 450 Ohm ladder line. For 146 MHz, the radiator measures 55 3/16 inches and the stub 18 3/8 inches. Construction details include cutting a 57¾-inch piece of ladder line, stripping 4 inches from one end, and attaching a 24-inch section of RG58 or RG8X coax with a 3-5 turn RF choke. SWR adjustment is achieved by sliding a shorting bar or by incrementally trimming the elements at a 1:3 ratio (stub to radiator). The goal is a 1:1.1 SWR at 146 MHz, which typically yields 1:1.2 at 446 MHz. The article also discusses power handling, noting that while 10-15 watts is fine, 50 watts may increase SWR to 1:2.1, and advises keeping the antenna away from other objects to prevent coupling and SWR degradation.

MeshCom 4.0 facilitates off-grid text messaging and data exchange via _LoRa_ radio modules, operating on low-power, low-cost hardware to establish networked communication capabilities. The system transmits messages, GPS positions, sensor values, and telecontrol data over significant distances with minimal power consumption. MeshCom modules can autonomously form a mesh network or integrate into a broader message network through MeshCom gateways, which ideally connect via _HAMNET_ to link disparate radio networks. Recent updates include MCMAP features, support for Lilygo T-Connect-Pro, and new firmware for T-ECHO, enhancing the system's versatility. The project provides basic specifications, detailed protocol information, and installation instructions for MeshCom 4.0, including guides for RAK WisBlock and HELTEC V3 hardware. Firmware and companion Android/iPhone applications are available for download, supporting a range of **10-20 km** line-of-sight communication.

The Pressure Paddle V2.0 simplifies the original 2019 design by using MOSFETs’ unique properties for reliable, minimalistic switching. When pressure sensors detect a press, they reduce resistance, activating the MOSFET and lowering voltage until it stabilizes at the MOSFET’s threshold. This ensures consistent “key down” signals for the transceiver. Compatible with 3-5V logic systems, the circuit operates independently of pull-up resistor size. The PCB is lightweight, easy to assemble, and can be packaged in heat shrink or mounted. This version maintains durability with fewer components and flexible packaging options.

A common mode choke/balun, essential for mitigating common mode current on antenna feedlines, is detailed in this construction and measurement guide. It utilizes eight Fair-Rite #2643167851 Mix 43 ferrites housed within a Hammond 1598JSGYPBK plastic case, with RG-8X coax cable forming the windings. The document references design principles from Ian White, GM3SEK's article on cost-effective ferrite chokes. Specific construction details include the layout of three coils to minimize inter-coil coupling and methods for securing the ferrites with foam tape. The resource presents comprehensive measured data, including isolation impedance (magnitude, real, and imaginary components), Q factor, inductance, and phase angle across various frequencies. It also covers the choke/balun's coax frequency response and return loss characteristics. Techniques for measuring choking impedance are thoroughly explained, focusing on S21 transmission measurements with a Vector Network Analyzer (VNA) and testing ferrite beads in both S11 and S21 modes. The guide describes a practical setup using an aluminum sheet or baking foil for measurements and outlines the calculation of series impedance from attenuation in a 50-ohm system. Additionally, it details a method for determining the balun's equivalent L and C around resonance by adding a parallel capacitor.

The Gemini Amplifier Remote Control software operates on Windows 7 and above, facilitating remote management of the Gemini HF-1K and DX-1200 amplifiers. Users connect via Ethernet, configuring the amplifier's IP address through the front panel. The software allows seamless band and antenna selection, saving settings for each band without requiring transmission. Integration with _OmniRig_ from Afreet Software, Inc. enables automatic band adjustments based on the radio's frequency changes. Users can configure serial or virtual serial connections, with tracking options accessible through the ribbon bar. The software supports speech functionality, enhancing accessibility for operators. Firmware updates, such as version 2.5Ee, introduce features like background datalogging and power output control, uploaded via FTP. Version 1.2.0 allows users to offload internal parameter data for support purposes. The firmware upload process requires the amplifier's IP address and port 21, taking approximately 90 seconds. Users are encouraged to upgrade to the latest firmware for improved performance and remote diagnostics.

Cloudlog Helper addresses the need for streamlined, automated logging of amateur radio contacts, particularly for operators utilizing digital modes like FT8 or those with limited system resources. This utility syncs real-time rig data and QSO information to various logging platforms, including _Cloudlog_ and Wavelog, supporting mainstream transceivers. It integrates seamlessly with popular digital mode software such as JTDX and WSJT-X, ensuring that contact details are captured and uploaded without manual intervention. Operators can compile the software themselves and configure essential settings, including their Maidenhead locator, Cloudlog server address, API key, and station ID. The application's design prioritizes efficiency and portability, making it a practical solution for hams who prefer automated logging processes. While an unofficial community project, Cloudlog Helper provides a robust framework for automating the often-tedious task of logging, supporting multiple logging services beyond its primary integration. It offers a direct method for hams to maintain accurate and up-to-date logbooks with minimal effort, potentially improving their DXCC or other award tracking by ensuring no QSO is missed.

The Elecraft KX2 and AX1 portable field kit is reviewed for its efficacy in rapid Parks On The Air (POTA) activations, focusing on a specific outing by _K4SWL_. The resource details the setup, including the _Elecraft KX2_ transceiver, _AX1_ antenna with a 3D-printed bipod, _Begali Adventure Dual_ paddles, and various accessories like the Windcamp X2 Side Rails and Tufteln KX2 Protective Cover. It outlines the practical considerations for a quick deployment, such as avoiding tree-thrown lines due to back pain, and emphasizes the minimal setup time required to get on the air. The activation described involved 11 contacts logged on 20 meters within 14 minutes, demonstrating the system's efficiency for "grab-and-go" operations. A QSO map visualizes the contact locations, and an unedited video documents the entire activation process. The review highlights the kit's reliability and compact nature, making it suitable for urban parks or situations where rapid deployment and minimal footprint are essential. The author expresses appreciation for the kit's tidy organization and consistent performance over several years of portable use.

Gordon West Radio School provides comprehensive study materials including books, audio courses, and practice exams. "Gordo" is renowned for his ability to explain complex concepts in memorable ways, often using humor and mnemonics. His materials include insider tips from his decades of teaching experience and administering exams. The audio courses are especially popular among commuters who can study while driving. The site offers package deals combining different media formats for various learning styles.

Version 0.7 of Open Tuner, released on April 27, 2023, marked a significant milestone by introducing proof-of-concept dual tuner functionality for the BATC Minitiouner. This C# client, inspired by Heather Lomond's _Longmynd_ project, aims to leverage both tuners and demodulators within the NIM module, a capability crucial for advanced Digital Amateur Television (DATV) operations on QO-100 and terrestrial links. My own experience with DATV often involves juggling multiple receive paths, so a unified client like this simplifies the workflow considerably. Further enhancing its utility, version 0.9 (February 11, 2024) integrated support for the Raspberry Pico, utilizing Colin (G4EML)'s _PicoTuner_ firmware. This offers a more accessible and cost-effective alternative to the traditional FTDI module, streamlining dual tuner setups with a single USB cable. The project's evolution reflects a practical approach to overcoming hardware availability challenges. The software is developed using Visual Studio 2019/2022 and .NET Framework 4.7.2, requiring specific Nuget packages like VLC/Websocket and an ffmpeg folder for full operation. It's an active, community-driven effort, with the source code openly available on GitHub for contributions and bug reporting, embodying the collaborative spirit of amateur radio development.

This online construction guide details the assembly of a signal generator specifically for the **13cm band** (2.4 GHz). The curriculum focuses on the integration of a Voltage Controlled Oscillator (VCO), specifically the ROS-2400, to produce a stable RF signal. The resource outlines the necessary components for frequency generation and output, including the use of a Mini-Circuits MMIC amplifier for signal conditioning. The construction protocol involves configuring the ROS-2400 VCO to operate within the 2.3 GHz to 2.45 GHz range, ensuring frequency coverage for amateur radio _microwave experimentation_. The guide specifies the output power level, approximately 70mW, directly from the MMIC stage, indicating its application as a low-power instrumentation source rather than a transmit-capable device. This project provides a practical example of constructing a dedicated test instrument for microwave frequency measurements and system alignment on the **13cm band**. DXZone Focus: Construction Guide | 13cm Signal Generator | VCO Integration | Microwave Experimentation

Navigating the complex legal landscape of **antenna zoning** and permit acquisition for amateur radio installations requires specific knowledge, which Fred Hopengarten, K1VR, provides through his resource. This content details the essential steps and regulatory considerations for securing permits for antenna support systems and towers. It focuses on the legal and procedural requirements, offering insights into local ordinances and federal regulations that impact amateur radio operators seeking to erect significant antenna structures. K1VR's expertise as a telecommunications lawyer is evident in the practical advice offered, drawing from real-world scenarios in permit applications. The resource equips hams and their legal counsel with the information needed to successfully navigate municipal zoning boards and secure necessary approvals, contrasting with purely technical antenna design guides by emphasizing the administrative and legal pathways to installation.

The resource details the use of LoRa for AX.25 packet radio and APRS, focusing on practical implementation. It specifies UK LoRa APRS frequency and modulation settings: **439.9125 MHz**, 125kHz bandwidth, SF12, and CR 4/5. The content provides a mini how-to for setting up an iGate using VS Code and _Platformio IDE_, with specific instructions for a Lilygo LoRa32 V2.1_1.6 board, including configuration for Wi-Fi, beaconing, and APRS-IS passcode. It also covers tracker setup using a Lilygo T-Beam Supreme, detailing firmware flashing and configuration for mobile operation. The guide differentiates LoRa APRS from traditional connected-mode packet radio, explaining why common LoRa APRS firmware is unsuitable for full AX.25 packet due to its TNC2-style payload structure. It explores alternative solutions for true LoRa packet radio, such as using an _RNode_ TNC or Raspberry Pi LoRa TNCs, and provides commands for RNode firmware installation and configuration for serial KISS operation. The resource also touches upon licensing requirements for unattended Digipeaters in the UK, noting the need for ETCC coordination and MB7Uxx callsigns.

Receiving Digital Amateur Television (DATV) signals requires specialized software to interface with hardware tuners and decode the video stream. The _MiniTioune_ software, developed by F6DZP, serves this purpose, providing a Windows-based application for DVB-S and DVB-S2 reception and analysis. It is designed to work in conjunction with _MiniTiouner_ hardware, enabling hams to monitor DATV transmissions, including those from the QO-100 geostationary satellite. The resource outlines the initial setup process, including connecting the MiniTiouner hardware via a high-quality USB2 mini cable and running diagnostic test software. It details how to configure essential parameters such as symbol rate (SR), FEC rate, and DVB mode for various signal sources, from domestic satellite dishes to local DATV transmitters. Troubleshooting steps for common issues like "no video displayed" are also provided, often pointing to corrupted software filters or incorrect _Auto PID_ settings. Advanced features like the Web monitor for remote signal reporting and integration with _VLC_ media player for more tolerant decoding of non-DVB compliant signals are covered. The document also references a comprehensive user guide by W6HHC for the _MiniTiouner-Express_ system, which utilizes the same software, offering further in-depth assistance for operators.

Demonstrates an online calculator for determining _Effective Isotropic Radiated Power_ (EIRP) and Effective Radiated Power (ERP) in radio and antenna systems. Users input transmit power in dBm, antenna gain in dBi or dBd, and feeder loss in dB, with the tool converting between dBm, watts, and milliwatts. It also calculates power density in µW/cm² and equivalent field strength in V/m at a specified distance, applying feeder loss before the EIRP calculation. The resource provides a quick reference table for common dBm to watt conversions, such as **30 dBm** equaling 1 W, and clarifies that 3 dB of loss halves radiated power. The calculator distinguishes between EIRP and ERP, noting that ERP is always **2.15 dB** lower than EIRP due to its half-wave dipole reference. It explains the importance of understanding the difference between dBi and dBd, as a 30 dBi antenna is not the same as a 30 dBd antenna, with the latter being 2.15 dB stronger. The page includes a table of typical EIRP limits for various bands and regions, such as 36 dBm for 2.4 GHz ISM US, FCC Part 15.247, and offers insights into regulatory considerations and the limitations of power density figures for safety compliance.

Operating an **Echolink** gateway on the 4-meter band presents unique opportunities for extending VHF communications, as demonstrated by the EI4FMG node. Situated at Fieldstown, Monasterboice, this gateway provides coverage across a significant portion of Ireland's east coast, leveraging a Tait TM8100 radio and an EI4JR Echolink interface logic. My own experience with similar setups confirms the importance of strategic site selection for maximizing reach, particularly with a 122-meter elevation above sea level. Access to the EI4FMG gateway, identified by node 57006, requires a **CTCSS** tone of 88.5 Hz, a standard practice for managing access and minimizing interference on shared frequencies. The system transmits with 15 watts of power and utilizes a Sigma CAT70 @5MAGL antenna, a configuration well-suited for regional VHF coverage. The gateway also features an auto-ID every 8 minutes, ensuring compliance and clear station identification. Users can interact with the gateway using various DTMF commands, allowing for connections to specific nodes, random repeater/link or conference nodes, and managing disconnections. These functionalities streamline the process of linking into the broader Echolink network, enabling local VHF operators to communicate globally through the internet backbone.

The State QSO Party Challenge is an annual program recognizing amateur radio operators' participation in U.S. State and Canadian Province QSO parties. To qualify for the SQP Challenge, participants must make at least two QSOs in a minimum of two SQP Approved QP contests and submit their scores to 3830Scores.com. The site details the SQP Mobile/Portable Challenge, an overlay competition encouraging mobile/portable operations, with scoring identical to the main SQP Challenge: (Number of QPs entered) x (Number of QSOs) = Score. Eligibility for the Mobile/Portable Challenge requires prior qualification for the SQP Challenge. The website also mentions a State QSO Party Club Challenge and provides contact information for questions. The 2026 SQP Challenge will be dedicated to Stan Zawrotny, K4SBZ, a key team member instrumental in the program's development. Participants are recognized for reaching five levels of achievement: Bronze, Silver, Gold, Platinum, and Diamond. Scores are calculated by totaling reported contacts and multiplying by the number of SQPs entered year-to-date, encouraging more entries and longer operating times. The Worked All QSO Parties (WAQP) program, sponsored by Icom America, offers certificates for participating in at least 50% of approved contests, with a goal of participating in all. WAQP requires submitting a log with at least two valid contacts to the contest manager, in addition to the 3830scores.com submission.