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SPX Communication Technologies, operating under the TCI International brand, presents a range of radio frequency (RF) solutions primarily for government, defense, and commercial sectors. The offerings include advanced systems for spectrum monitoring, communications intelligence (COMINT), and high-frequency (HF) and medium-frequency (MF) broadcasting and communication antenna systems. Specific product lines encompass _Blackbird_ COMINT systems, _Scout_ spectrum monitoring receivers, and various antenna arrays designed for robust performance in challenging RF environments. The resource details the capabilities of these systems, such as wideband signal detection, direction finding (DF), and signal analysis, crucial for intelligence gathering and regulatory compliance. It also highlights the engineering behind their antenna designs, which are optimized for specific frequency ranges and operational requirements, including high-power broadcast applications and secure military communications. The information presented emphasizes the integration of hardware and software for comprehensive RF situational awareness. The company's focus on empowering partners to "Command the Spectrum" underscores its commitment to delivering critical tools for signal interception, analysis, and management across diverse operational landscapes.

Evaluates the **LDG Z100 autotuner**, a device designed to automatically match antenna impedance for optimal transmission efficiency. The review discusses its performance in comparison to the MFJ-902, noting that while the Z100 is a reliable autotuner, it does not match the range of impedances that the MFJ-902 can handle. The Z100 is suitable for operators seeking a 100-watt autotuner that covers HF bands, providing a practical solution for those who require automatic tuning without manual adjustments. The review highlights the Z100's operational context, focusing on its use in HF bands and its practical application in amateur radio setups. While it offers a straightforward tuning process, the Z100's limitations in impedance matching are noted, making it less versatile than some competitors. This comparison provides valuable insights for operators considering an upgrade or replacement for their current autotuner. The Z100's performance is positioned within the broader market of autotuners, offering a clear perspective on its strengths and weaknesses in real-world amateur radio operations.

The F5GIT blog documents the amateur radio pursuits of Tony, F5GIT, offering insights into his DXpedition experiences and contest operations. It presents detailed accounts of his participation in events like the _CQ WW DX Contest_ and the _IARU HF Championship_, often including specific callsigns worked and operational strategies employed. The resource covers various aspects of station setup, antenna configurations, and radio equipment used for achieving contacts across different bands. Content includes discussions on antenna performance, such as a **2-element Yagi** for 10/15/20 meters, and operational challenges encountered during remote or portable setups. The blog also serves as a personal log, chronicling significant QSOs and providing a historical record of his amateur radio journey. It details specific locations operated from, like _Île de Ré_, and the unique challenges presented by such environments. Furthermore, the blog provides practical information on optimizing station efficiency and maximizing contact rates during high-intensity operating periods. It reflects a dedicated approach to improving radio skills and contributing to the global amateur radio community through active participation and sharing experiences.

This resource compiles claimed scores, often referred to as "rumor scores," for numerous amateur radio contests, providing a historical snapshot of competitive activity from 1993 through 2007. It lists entries for prominent events such as _CQWW CW_, _ARRL Sweepstakes_, _IOTA Contest_, and various _NAQP_ events, categorized by year and contest. Each entry typically includes the contest name and the month/year of operation, allowing users to quickly navigate to specific contest periods. The site also references the _3830 Web Page_ on Contesting.com as the primary submission portal for these claimed scores. The collection offers a unique perspective on contest participation and performance trends over more than a decade, preceding the widespread adoption of real-time score reporting systems. While not official results, these rumor scores provided early indications of top performers and overall activity levels for a wide array of HF and some VHF contests, including _ARRL 10M_ and _CQWW VHF_. The historical data can be useful for analyzing past contest popularity, identifying consistently strong operators, or simply reminiscing about earlier competitive eras in amateur radio.

The CQ World Wide DX Contest records page details the highest scores achieved in the CQ WW DX Contest across various categories and years. It systematically lists records for both SSB and CW modes, segmenting results by entry class such as Multi-Multi, Multi-Two, Multi-Single High, Multi-Single Low, Single Operator High Power, Single Operator Low Power, Single Operator QRP, Single Operator Assisted High, Single Operator Assisted Low, and Single Operator Assisted QRP. Each record entry specifies the callsign, the operator's callsign in parentheses if different, the year of operation, and the total score achieved. The data is further broken down by individual amateur radio bands, including 160m, 80m, 40m, 20m, 15m, and 10m, allowing for granular analysis of performance within specific frequency segments. The page also includes records for the "ALL" band category, representing cumulative scores across all operational bands. The presented records span from 1948 to 2025, providing a historical perspective on contest performance. This resource also references other CQ contests like CQ WPX, CQ WW RTTY, CQ WPX RTTY, CQ 160, CQ VHF, and WW DIGI, indicating a broader context of contest record keeping. It explicitly states that late logs are not included in the records, ensuring data integrity. The page is maintained by the World Wide Radio Operators Foundation, Inc.

1500 watts PEP SSB is the power handling capability of the MFJ-989C HF Antenna Tuner, a popular choice among amateur radio operators. Users have shared a wide range of experiences, with some praising its durability and performance over decades of use, while others criticize its build quality and accuracy. The tuner features a built-in dummy load, SWR-wattmeter, and a balun for balanced line feeders, making it versatile for various antenna setups. However, discrepancies in RF power readings and SWR measurements have been noted, with some users finding the dual scale meter to be off by about 20% compared to a Bird wattmeter. Long-term users report that the MFJ-989C performs well with proper antenna setups, but caution against tuning at high power without initial adjustments at lower power levels. Some have experienced issues such as arcing when exceeding 400 watts, while others have had no problems even at higher power levels. The roller inductor and capacitors are functional, though some users have had to perform maintenance like tightening screws or cleaning components to ensure reliable operation. Despite mixed reviews, the MFJ-989C remains in production, suggesting continued demand. It's a tuner that requires careful handling and possibly some DIY fixes to achieve optimal performance.

A cavity filter, often a critical component in _duplexer_ designs, functions as a sharply tuned resonant circuit, allowing only specific frequencies to pass while attenuating others. These filters are essential for maintaining signal integrity in environments where multiple transmitters and receivers operate simultaneously on closely spaced frequencies, such as in repeater stations. The article details how these filters, sometimes referred to as _notch filters_, achieve high Q factors, which are crucial for their performance. Understanding the principles of cavity filters is fundamental for any amateur radio operator involved in repeater operation or designing custom RF front-ends. The discussion covers the basic circuitry and operational characteristics that enable these devices to provide significant isolation, often achieving **-80 dB** or more between transmit and receive paths. This level of isolation is vital for preventing receiver desensitization and intermodulation distortion. Properly tuned cavity filters ensure that a repeater can transmit and receive simultaneously on different frequencies without self-interference, a common challenge in VHF/UHF operations.

The CQ World Wide DX Contest records document top scores, with the Multi-Multi SSB category showing CN8WW achieving **78,170,508 points** in 2000. These records span from 1948 to 2025, categorizing results by region, operating class (e.g., Single Operator High Power, Low Power, QRP, Assisted), and specific bands like 10M, 15M, 20M, 40M, 80M, and 160M. For instance, EF8R (E77DX) holds the All-Band High Power SSB record with **25,747,775 points** in 2025. Each entry includes the callsign (with operator callsign in parentheses for guest ops), year of operation, and total score. The _CQ WW DX Contest_ also features records for the RTTY and VHF contests, alongside the main SSB and CW categories. QRP records demonstrate significant achievements, such as P40W (W2GD) with 5,097,780 points in the All-Band SSB QRP category in 2000. Multi-Two and Multi-Single categories are also detailed, providing a comprehensive overview of competitive performance.

J49I operated from Crete Island (EU-015, KM25PH) during the 2008 _CQ WW DX CW Contest_, focusing on multi-operator category participation. The station's activity centered on maximizing contacts and multiplier acquisition across various HF bands during the competitive event. Operators aimed to achieve a high score by leveraging the island's DXCC entity status. The team, comprising Greek and Italian amateur radio operators, utilized the J49I callsign for this specific contest operation. Their efforts contributed to the overall contest results for the 2008 CW segment, with logs submitted reflecting their performance from the European continent.

Installing a mobile rig in a vehicle requires careful planning and execution to ensure optimal performance and safety. The process begins with selecting the right equipment, such as the ICOM IC706MKII for low bands and the ALINCO DR-610 for VHF/UHF operations. Proper mounting is crucial; both radios are strategically placed under the back seat of the Silverado, allowing for a clean installation while maintaining passenger comfort. The Hustler antenna, equipped with various resonators, ensures coverage across multiple bands, while the LDG automatic antenna tuner fine-tunes the match for efficient operation. A remote head for the tuner enhances accessibility, making adjustments easier while driving. Each step of the installation is documented to provide insights and tips for fellow operators looking to enhance their mobile setup. The experience shared here reflects practical knowledge gained through hands-on work, aiming to inspire others in the ham community to undertake similar projects.

Presents field test results for an **elevated SuperAntenna MP-1** portable antenna, configured on a tripod for HF operations. The resource details the antenna's setup and performance during a portable activation, focusing on its use across the 40-meter, 20-meter, and 17-meter amateur bands. It includes observations on signal reports and operational considerations for this specific portable antenna configuration. The content provides practical insights into deploying the MP-1 antenna in a non-ground-mounted setup, which is often a point of interest for portable and QRP operators. It documents the author's experience with the antenna's tuning and effectiveness for making contacts under real-world conditions, offering a user-perspective review of its capabilities. The article also features photographic evidence of the antenna's deployment, illustrating the tripod mounting and the overall portable station setup.

The Japanese-made Maldol MFB-300 HF vertical antenna offer extremely wide-band performance, with a specified frequency range of 1.0-60 MHz.

RF amplifier products from NP Technologies, Inc. encompass a wide array of specialized designs, including highly linear Class A broadband amplifiers, crucial for maintaining signal integrity across various frequencies. Their portfolio also features cell band amplifiers, specifically engineered for cellular communication infrastructure, and pulse amplifiers, which are vital in applications requiring high-power, short-duration signal bursts. The company's manufacturing capabilities extend to AM and FM broadcast amplifiers, supporting radio transmission systems, and military VHF amplifiers, designed to meet rigorous defense specifications for robust and reliable communications. NP Technologies, Inc. emphasizes comprehensive development, design, manufacturing, and testing processes for all its RF amplifier offerings. This integrated approach ensures that each product, from initial concept to final deployment, adheres to stringent performance and reliability standards. The company's expertise in these areas allows for the creation of custom solutions tailored to specific client requirements, addressing complex RF challenges in diverse operational environments. Their product range demonstrates a commitment to serving multiple sectors, including commercial broadcasting, telecommunications, and defense. The focus on specialized amplifier types underscores their technical depth in RF engineering.

Designing and constructing a two-element receiving loop antenna array for HF operation involves specific considerations for achieving high directivity and noise reduction. This resource details a homebrew system comprising two 30-inch diamond-shaped loops, spaced 20 feet apart, which are fed through mast-mounted preamplifiers and passive signal combiners. The operational principle relies on adjusting phase delays between elements via precise _Belden 8241_ coaxial cable lengths, optimized for specific bands from 160m to 20m. Performance data, derived from _EZ-NEC_ modeling, illustrates consistent 90° azimuth-plane beamwidth and low take-off angles across the target bands, with _Receiving Directivity Factor_ (RDF) values comparable to a 300-foot Beverage antenna. The article presents detailed elevation and azimuth plots for 20m, 30m, 40m, 80m, and 160m, demonstrating the array's ability to provide strong response at low DX angles while also supporting _NVIS_ signals. Key components like the _DX Engineering RPA-1_ preamplifier and _DXE RSC-2_ signal combiner are discussed, alongside the importance of impedance matching to preserve antenna patterns. The construction emphasizes self-contained elements that do not require ground radials, offering a compact solution suitable for suburban environments and stealth installations, with a focus on optimizing receive performance independently from transmit antennas.

The **LDG Z100 Autotuner** review by GW6ITJ details the unit's practical application and performance in a ham shack environment. Initially acquired to replace an MFJ-902, the Z100 is noted for its ease of use, though the author observes it doesn't quite match the impedance range of the older MFJ unit. This hands-on assessment provides a real-world perspective on its capabilities for 100-watt operation across the HF bands. GW6ITJ specifically mentions the Z100's suitability for 3.5 MHz and higher frequencies, indicating its utility for common HF operations. The review focuses on user experience rather than technical specifications, directing readers to the LDG website for detailed data and manuals. This approach highlights the tuner's operational characteristics from a user's perspective. The author's experience with the Z100 suggests it's a reliable choice for general amateur radio use, particularly for those seeking a straightforward autotuner. The comparison to the MFJ-902 offers a valuable benchmark for hams considering a similar upgrade or new acquisition, emphasizing practical differences in impedance matching.

This DIY vertical multi-band Windom antenna offers a practical and effective solution for amateur radio enthusiasts seeking a versatile and compact antenna for HF communications. Its simplicity of construction, multi-band capability, and favorable performance make it a valuable addition to any radio shack. The article provides detailed instructions on constructing the antenna and balun, along with diagrams and component specifications. Field tests demonstrated successful contacts with stations across Europe and North America on 14, 18, and 28 MHz. The antenna exhibited comparable performance to a W3DZZ dipole and outperformed a Cobweb antenna on 18 MHz. Low noise levels were observed, effectively suppressing background noise.

AmTOR may be considered as the next development from RTTY. AmTOR was introduced to overcome the problems with RTTY. As a result of its performance, it has become popular on the HF bands because it gives more reliable communication, especially when interference is present. It achieves this by using a coding system that allows errors to be detected and corrected.

Presents an alternative construction method for isolated element Yagi antennas, specifically for VHF/UHF operation. The technique utilizes commercially available vibration damping clamps (resin support blocks) to isolate 1/4-inch aluminum rod elements from a 1-inch square aluminum boom, simplifying the build process by eliminating the need for custom-machined insulators. This approach is demonstrated through the construction of 6-element Optimized Wide-Band (OWA) Yagis for the 2-meter, 1.25-meter, and 70-centimeter bands, which are well-suited for portable contesting arrays due to their light weight and decent gain. The document provides detailed specifications for element and boom materials, along with step-by-step procedures for cutting, drilling, and tapping. It also covers the fabrication of a feedpoint bracket for a direct 50-ohm SO-239 coax connection and discusses considerations for horizontal versus vertical polarization, including mast placement. The resulting 6-element models achieve an average free-space gain of 10.2 dBi and a 25 dB front-to-back ratio, with the construction technique being scalable for higher gain designs. Included are parts lists with sources, detailed mechanical drawings for each band, and EZNEC data for the 2-meter and 70-centimeter designs, showing both free-space and 30-foot elevation performance. The designs are optimized from W4RNL's original concepts using HAMCALC, ensuring good gain, passband characteristics, and front-to-back ratios for wideband Yagi operation.

Showcasing innovative RF solutions, Hofi Hochfrequenztechnik manufactures high-quality _antennas_ and RF switches. Their products, including the **versatower** and **fritzel** brands, cater to both casual operators and serious DXers. With a commitment to performance, Hofi's offerings enable operators to achieve optimal signal gain and reliability in various conditions. The company's expertise in antenna design ensures that users can effectively communicate across _HF_ bands, enhancing their overall operating experience. Whether setting up a new station or upgrading existing equipment, Hofi provides essential tools for successful ham radio operations.

Constructing an End-Fed Half-Wave (EFHW) antenna offers a practical solution for HF operators seeking a multiband wire antenna without the need for extensive radial systems. This design typically employs a high-impedance transformer at the feed point, matching the antenna's inherent high impedance to a 50-ohm coaxial feedline. The article specifically details a 2012 approach, focusing on a transformer with a 49:1 turns ratio, which is a common configuration for EFHW antennas. The resource outlines the construction of a wire element cut for a half-wavelength on the lowest desired band, with specific coil arrangements enabling operation on harmonically related bands such as 40m, 20m, and 10m. It discusses the physical dimensions and winding details for the matching transformer, often utilizing a ferrite toroid core to achieve the necessary impedance transformation. The content provides insights into the operational principles and practical considerations for deploying such an antenna, including methods for tuning and optimizing performance across multiple amateur radio bands. While acknowledging that the presented information from 2012 may be superseded by newer insights, it serves as a foundational reference for understanding EFHW antenna theory and construction.

_AT Auto_ is an automatic antenna tuner designed for amateur radio enthusiasts seeking efficient and reliable tuning solutions. This device automates the tuning process, allowing operators to focus on communication rather than manual adjustments. The tuner is compatible with a range of transceivers, enhancing its versatility in different shack setups. Its design incorporates advanced circuitry to ensure optimal performance across various bands. The _AT Auto_ tuner is particularly useful for those operating in HF bands, providing seamless transitions between frequencies. Its integration capabilities with other shack automation products make it a valuable component for modern amateur radio stations. The tuner supports multiple modes, including _SSB_ and _CW_, catering to diverse operating preferences. Its robust construction and user-friendly interface contribute to its appeal among both seasoned operators and those new to the hobby. Kessler Engineering's focus on innovation and quality is evident in the _AT Auto_'s design. The tuner is part of a broader product line that includes shack automation solutions, reflecting the company's commitment to enhancing amateur radio operations. Despite the website redesign, the tuner remains a key offering in their product portfolio.

Coaxial cable stripping for PL-259 connectors requires precise measurements to ensure optimal RF performance and mechanical integrity. For RG-8X, the outer jacket is stripped 1/2 inch, the braid 5/16 inch, and the dielectric 1/8 inch, leaving the center conductor exposed. RG-58 preparation involves a 1/2 inch jacket strip, 1/4 inch braid strip, and 1/8 inch dielectric strip. These specific dimensions facilitate proper soldering and crimping, minimizing impedance discontinuities at the connector interface. Different coaxial cable types, such as RG-8 and RG-213, necessitate varied stripping lengths due to their construction. The _PL-259_ connector, a common UHF type, relies on these exact preparations for a secure fit and low-loss connection. Incorrect stripping can lead to high SWR, RF leakage, and mechanical failure, impacting overall station efficiency. The guide details these critical dimensions for several popular coax cables. Using a dedicated _coax stripper_ tool or precise measurements with a utility knife improves consistency.

Specialist UK manufacturer of high performance compact HF antennas

If you thought you knew everything about balun performance characteristics, there is an important figure of merit you may have neglected

The CobWebb antenna project is a compact, multiband HF solution ideal for amateur radio operators. Covering 14-28 MHz, it features a square dipole array with near-omnidirectional coverage and unity gain. This guide details a DIY approach, using a 1:4 current balun for impedance matching. Construction involves aluminum and fiberglass tubing, with optimized element tuning for SWR performance. Weather resistance improvements and resonance shift considerations are also discussed. Build your own CobWebb antenna for an efficient, space-saving HF experience.

The Baofeng UV-5R handheld transceiver, introduced around 2012, operates across the 2-meter (144-148 MHz) and 70-centimeter (420-450 MHz) amateur bands, offering dual-band receive and transmit capabilities. This review provides an early assessment of the radio's form factor, user interface, and general performance, noting its compact size and the inclusion of a **VFO/Memory mode** button for frequency management. The device supports both FM and narrow FM modes, with a reported power output of 4 watts on VHF and 3 watts on UHF, making it suitable for local simplex and repeater operations. Key features discussed include its 128-channel memory capacity, a built-in VOX function, and a **DTMF keypad** for tone dialing and repeater access. The review highlights the radio's ability to scan frequencies and memories, along with a dual-watch function allowing simultaneous monitoring of two frequencies. Battery life is addressed, with the standard 1800 mAh Li-ion pack providing several hours of operation depending on transmit usage. Initial impressions cover the radio's construction and the clarity of its LCD display, which shows both A and B band frequencies.

Mitigating impulse-type noise, a common challenge in the **HF radio spectrum**, often requires specialized processing before the signal reaches the transceiver's receiver stages. The NR-1 addresses this by functioning as an RF interference removal device, specifically a noise blanker, targeting transient noise sources. Its operational range extends from 1.6 MHz to beyond 70 MHz, making it suitable for various amateur radio bands and general shortwave listening applications. Unlike QRM eliminators or X-phasers, the NR-1 does not require a separate noise antenna for its operation, simplifying its integration into existing station setups. The device's design focuses on wideband performance, allowing its use both within and outside the allocated amateur radio frequencies. Documentation detailing its operation is available, providing insights into its technical specifications and deployment. This unit is a hardware product, conceptualized and implemented by SV3ORA.

A deep analysis of UHF connectors performance tests, including return Loss of UHF Connectors, Mismatch Loss of UHF Connectors, SWR of UHF Connectors

Exaustive review of the self-contained, top-performance HF/6m transceiver Icom IC-7700

High Speed Multimedia (HSMM) radio, as introduced by John Champa, K8OCL, represents a significant advancement in amateur radio's digital capabilities, moving beyond traditional keyboard modes like packet radio. This initiative, driven by ARRL's Technology Task Force, focuses on developing high-speed digital radio networks capable of up to 20 megabits per second. HSMM primarily facilitates digital voice (DV) and digital video (ADV), enabling real-time video transmission from emergency scenes to an EOC without expensive ATV gear, often requiring only a laptop, a PCMCIA card, a digital camera, and a small antenna. The working group's initial efforts concentrate on cultivating microwave skills within the amateur community to build and support portable and fixed high-speed radio-based local networking, or **RLANs**. These networks prove invaluable for RACES and ARES organizations, as well as homeland security and other emergency communications. Field Day exercises and simulated emergency tests (SETs) are encouraged to hone skills in rapid site surveys and deploying broadband HSMM microwave radio networks, with examples like linking Field Day logging stations or antenna test results at the Midwest VHF-UHF Society Picnic 2003. Getting started with HSMM often involves adapting off-the-shelf **IEEE 802.11** (WiFi) equipment to comply with amateur radio regulations, typically operating in the 2.4 GHz ISM bands. While consumer WiFi gear has range limitations under Part 15 rules, proper setup under amateur regulations can extend coverage significantly, with test networks like the Hinternet achieving 5-15 mile ranges at 54 M bit/s using small mast-mounted dish antennas. Careful selection of equipment with external antenna ports, high transmit power, and low receive sensitivity is crucial, along with using low-loss coaxial cable like LMR-400 for optimal performance at these frequencies.

256 memories enable the _AT-AUTO_ to recall settings across multiple bands, making it efficient for operators who frequently change frequencies. The tuner is compatible with various antennas and amplifiers, such as the Mercury LUX, and integrates seamlessly with radios like the FLEX 6400 using an RS232-USB connection. This integration allows the tuner to follow frequency changes without additional input, enhancing operational efficiency. Despite being out of production, the _AT-AUTO_ remains supported by Kessler Engineering, which offers firmware updates and repair services. The tuner features a cross-needle SWR meter, providing quick visual feedback during tuning. It also includes a QRO keyline circuit to protect amplifiers during tuning. Users appreciate the tuner's ability to track radios via CAT control, avoiding automatic tuning during QSOs, a common issue with other models. The _AT-AUTO_ is praised for its durability and performance, with many users noting its reliability over years of use. Its ability to handle legal limit power and its balanced line output make it a versatile choice for serious operators. Although it lacks some features like multiple coax outputs found in other models, its robust build and continued support make it a valuable tool for HF enthusiasts.

This type of antenna is a popular antenna design as the performance is very good across the HF bands and requires little or no tuning. It’s a dipole fed off center with a 4:1 balun at the offset feed point. The antenna shown covers 80, 40, 20 and 10 meters. The formula can also be used to adjust the overall length to cover more or fewer bands and the resulting overall length. 160-10m, 80-10m or 40-10 meters depending on your available space. Other bands will require a tuner.

A W8JK/Moxon antenna variant with 400cm long monopoles is detailed, demonstrating a **1dbd** gain improvement over the traditional Open-Folded W8JK. This design, relying on the _Moxon principle_, achieves higher radiation impedance, leading to increased antenna efficiency and reduced losses. The article includes VNA output data for various HF bands, showing impedance characteristics from 10.1 MHz to 50.1 MHz, and provides NEC model wire definitions for the antenna structure. Field tests performed by F6IIV, Marc, compared his W8JK Moxon style antenna against a Cobweb antenna at the same height. Results indicated the W8JK Moxon variant provided a **6dB** (1 S-meter point) advantage on most bands from 20m to 10m, and a significant 10dB (1.5 S-meter points) advantage on 15m. The antenna features a 2.70m boom and a turning radius of less than 3 meters, making it suitable for limited space installations while maintaining bi-directional performance on most bands.

Presents various amateur radio topics through blog posts, detailing operational experiences and technical insights from the perspective of SV2YC. The content frequently discusses antenna projects, such as a **portable 20m/40m dipole** designed for rapid deployment, and explores the performance characteristics of different wire configurations in varied field conditions. Observations on propagation and band activity across the HF spectrum are also regularly documented, providing practical context for fellow operators. Specific entries often include detailed accounts of **DX contacts** and participation in minor contests, outlining station setup, power levels, and antenna choices. The blog also covers modifications to commercial transceivers and homebrew accessory construction, offering practical advice on improving station efficiency and functionality. Further posts delve into software applications for logging and digital modes, sharing configurations and operational tips for maximizing their utility in daily amateur radio activities.

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.

The Bazooka antenna, a coaxial dipole, functions as an omnidirectional antenna with vertical or horizontal polarization. Patented in 1939 and refined in 2006, it features a quarter-wavelength coaxial cable with separated conductors. The outer conductor connects to a sleeve, while the inner conductor extends vertically. Initially complex, it has been simplified for versatile use, including military applications. Adding elements can modify its behavior for NVIS or Yagi-Uda configurations. Experiments in 2007 at the Campus de Pesquisas Geofísicas in Paula Freitas-PR demonstrated consistent VHF and UHF performance, showing reliable return loss measurements despite variable weather.

Messi & Paoloni offers a range of RF coaxial cables, including the _Ultraflex_ series, specifically engineered for amateur radio applications. These cables feature advanced dielectric materials and high-density braiding, resulting in significantly reduced attenuation across HF, VHF, and UHF bands. For instance, the Ultraflex 7 exhibits a loss of only **2.5 dB per 100 feet** at 144 MHz, making it suitable for demanding DX and contesting operations. The company's product line also includes specialized connectors, such as N-type and PL-259, designed to maintain optimal impedance matching and minimize signal reflections. Each connector is precision-machined to ensure a secure, weather-resistant termination, crucial for outdoor antenna installations and long-term reliability. Messi & Paoloni emphasizes rigorous quality control, with all cables undergoing testing to ensure consistent performance and durability, supporting effective two-way radio communication.

A distance of 1/8 lambda between the antenna and the vehicle roof is suggested for optimal performance, with slight adjustments possible to lower the take-off angle for terrestrial contacts. This resource details the adaptation of an _Eggbeater_ antenna for mobile use, specifically for VHF operation, leveraging the car's metal roof as a ground plane. It illustrates the mounting method, repurposing a magnetic ski carrier base, and describes the integration of coaxial relays for polarization reversal, a feature also applicable to UHF versions as discussed in "_Eggbeater Antenna VHF/UHF – Part 2_". This mobile configuration proves effective for satellite communications, such as through the International Space Station (ISS), while also maintaining strong performance for land-based radio contacts. The inclusion of switches with indicator lights for VHF and UHF polarization control, powered by the vehicle's battery, highlights practical considerations for field deployment. The system's adaptability for portable operations underscores its versatility beyond fixed mobile installations.

Installation and modification of the popular Butternut HF9V antenna with the optional 160 meter addon. Article includes a modification to improve the performance on the top band

Discovering a solution for limited space, the inverted L HF antenna emerges as a stellar performer. Half the size of a dipole, it ensures optimal installation in restricted areas, maintaining superb transmission (TX) and reception (RX) characteristics. Spectrum Communications' multi-band version, featuring traps, proves even more space-friendly without compromising performance. A fiberglass pole offers sturdy support, while proper grounding, an RF choke, and occasional tuning contribute to a high-performing and reliable antenna system.

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.

The MiniPA Linear Amplifier for HF page discusses the popularity of QRP for HF among ham radio operators, such as those using the Yaesu FT818 or low power SDR transceivers. It explores the use of cheap kits from eBay or Chinese suppliers to build a 70-100W SSB amplifier using IRF530 MOSFET transistors. The article provides a review of the MiniPA design, including its features, components, and assembly process. It also highlights the importance of using a heatsink and forced air cooling for optimal performance. This page is useful for hams looking to enhance their HF rig with a budget-friendly amplifier.

Constructing a directional antenna for VHF operations, particularly for 2-meter band contests or local communication, often involves balancing performance with ease of build. The Moxon rectangle, a compact two-element beam, offers a good front-to-back ratio and gain in a smaller footprint compared to a Yagi, making it suitable for portable or temporary setups where space is limited. This design typically uses a driven element and a single reflector, bent into a rectangular shape to achieve its unique radiation pattern. The article details the construction of a 2-meter Moxon antenna, specifically for 144 MHz, utilizing readily available materials like PVC pipe for the frame and copper wire for the elements. It outlines the dimensions for the driven element at 970mm and the reflector at 910mm, with a spacing of 140mm between them, and a 50mm gap at the element ends. The feedpoint is a direct 50-ohm connection, simplifying matching requirements. The project includes a parts list, a basic diagram illustrating the element layout and dimensions, and photographs of the completed antenna. The author notes the antenna's performance during a QRP contest, achieving contacts up to 100km with 5 watts, demonstrating its effectiveness for low-power VHF work.

Home brewing a high performance, high power common mode choke for HF bands

The PAC-12 Antenna, a multi-band portable vertical, is meticulously detailed in this construction article by James Bennett, _KA5DVS_. The design emphasizes ease of homebrewing using readily available components from local hardware stores, including replaceable loading coils. It outlines the preparation of the 72-inch telescoping whip (originally from Radio Shack, with an alternate source now provided by _Pacific Antenna_), the construction of the loading coils from PVC risers, and the fabrication of the aluminum rod base sections. Specific instructions cover threading aluminum rod with a _1/4-20 threading die_ and assembling the feedpoint insulator with a BNC connector, along with recommendations for radial deployment. KA5DVS, an avid traveler and QRP enthusiast, developed the PAC-12 to address the bulkiness of random wire setups and the limitations of commercial portable antennas like the Outbacker or SuperAntennas MP1. His goal was a lightweight, packable antenna that disassembles into 12-inch sections, achieving an assembled length of approximately 8 feet. The design strategically places the loading coil away from the base for improved efficiency. The PAC-12 notably placed first in efficiency compared to a quarter-wavelength wire vertical at the HFPack antenna shootout during the Pacificon conference in October 2001, demonstrating its practical performance for field operations. Appendix C showcases various _NJQRP Club_ members' PAC-12 constructions, including a 20m beam made with multiple PAC-12 elements.

TelExpress provides a wide array of RF and data connectivity products, including various coaxial cables like LMR-series equivalents, fiber optic cables, and Ethernet solutions. Their inventory supports diverse amateur radio and telecommunications requirements, from antenna feedlines to network infrastructure. The site emphasizes bulk cable availability and custom assembly services, catering to both individual hams and larger installations. Key offerings include _low-loss coax_ for HF and VHF/UHF applications, along with a comprehensive selection of RF connectors. They also supply patch panels, Ethernet cables (Cat5e/Cat6), and general wireless and telecom hardware. Customers can find components for building robust station infrastructure, ensuring signal integrity across various frequency bands. The platform facilitates procurement of essential parts for new builds or upgrades, supporting reliable RF system performance.

Experimental Long Boom Antennas - CP, LPDA, multiband with several NEC Files for 50MHz 144MHz 222 MHz 432MHz but also 902MHz and 1296 MHz Antenna projects. Includes also for each antenna model, in a general comparison table each antenna characteristics including Directive Gain, G/T, E-F/R, H-F/R abd Boom Length. This is a great value comparison table of several commercial and home made VHF UHF antenna projects.

Learn how to easily improve your handheld VHF performance on the 2-meter band with the Flowerpot antenna. This simple DIY antenna made from coaxial cable requires minimal tools and materials, providing a big range upgrade compared to standard rubber-duck antennas. Discover how to build, tune, and optimize the Flowerpot antenna for excellent performance. Ideal for hams looking for lightweight, portable solutions for handhelds, mobile rigs, home stations, SOTA/POTA activations, and emergency communication.

Operating an amateur radio station effectively requires reliable coaxial cable to minimize signal loss between the transceiver and antenna. SIVA Cavi, an Italian manufacturer, produces a range of coaxial cables, including specific 50 Ohm low-loss types suitable for amateur radio applications. Their product line features cables like **RG 58 SHF1**, **RG 213 SHF1**, and **RF 400 SHF1**, which are commonly deployed in HF and VHF/UHF setups. The company also offers specialized cables such as the **HF 214 UF Ultraflex**, a high-performance broadband low-loss 50 Ohm cable designed for flexibility and reduced attenuation across various amateur bands. These cables are engineered with solid or foam dielectric materials, impacting their electrical characteristics and suitability for different power levels and frequency ranges. For instance, foam dielectric cables often exhibit lower loss at higher frequencies, a critical factor for VHF/UHF operations. Beyond amateur radio, SIVA Cavi manufactures cables for digital video broadcast, offshore marine use, and fire detecting systems, demonstrating a broad engineering capability in coaxial cable technology.

The _G3TSO_ Mobile Antenna Page details construction and tuning methods for mobile antennas operating across **10 to 160 metres**. The content describes a Hustler-based design, optimized for RF performance and vehicle speeds, featuring centre loading. For optimal operation on various bands, the loading coil placement requires clearance from the vehicle body. Antenna resonance is critical for efficient mobile operation. A mobile antenna's base impedance may be as low as 27 ohms, requiring specific matching to achieve maximum radiation, as a minimum SWR at the transmitter does not always indicate resonance or maximum output. Tuning involves physical adjustment of antenna length to achieve resonance at the operating frequency. The _G3TSO_ page outlines a tuning procedure utilizing a low-power signal source and a field strength meter to identify maximum radiation before impedance matching. Loading coil placement, either at the base, center, or top of the antenna, influences radiation efficiency and mechanical stability for mobile installations. Centre-loaded whips, such as the Hustler design, offer a compromise between efficiency and stability, often for single-band operation. Helically wound antennas, including those for **28 MHz**, may present base impedances around 17 ohms, resulting in a 3:1 SWR at resonance. Low resistance grounding at the antenna base is also specified for optimizing performance and minimizing RFI during mobile operation. DXZone Focus: Mobile | Any | Antenna Tuning | HF