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- Internet and Radio
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Building an omnidirectionnal antenna for the 23 cm band, 1240 - 1270 Mhz
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Distance and directions calculation program using both Spheric, the perfect round earth model, and Vincenty's inverse ellipsoid algorithm, the WGS 84 earth model.
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Practical and usable direct conversion receiver for the 40 m CW band
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6m (50Mhz) Long wire antenna There is another form of long wire antenna which provides uni-directional coverage and is easy to build. Description by Arnie Coro CO2KK
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This online guide details the microphone pinout for the Kenwood TR-7950 transceiver, specifically addressing the wiring configuration for a dynamic mobile microphone with a **500 Ohm** impedance. It provides a pin-by-pin breakdown for the 6-pin microphone connector, identifying the function of each active pin. The resource specifies that Pin #1 is for the microphone audio (white wire), Pin #2 controls the _PTT_ (black wire), Pin #3 activates the memory down function (blue wire), and Pin #4 controls the memory up function (red wire). Pin #6 is designated as the ground connection, while Pin #5 remains unused in this configuration. The document focuses on the physical wiring necessary to restore microphone functionality to the Kenwood TR-7950, a transceiver capable of **45 watts** output on the _2m band_. It directly addresses the technical challenge of re-establishing correct electrical connections after microphone wires have been disconnected from the connector. The information facilitates proper microphone operation for simplex QSOs and other voice communications. DXZone Focus: Online Guide | Microphone Pinout | Kenwood TR-7950 | PTT Wiring
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The G5RV multiband HF antenna, designed by Louis Varney (G5RV) in 1946, is a popular compromise antenna offering good overall performance on most HF bands when paired with an external antenna tuner. The basic full-size G5RV measures 102 feet across the top for 80 through 10 meter operation and is fed at the center via a 34-foot low-loss feed-stub. This interaction between the radiating section and the feed-stub facilitates matching across 80-10 meters with a standard tuner, often eliminating the need for ladder line directly to the shack. The antenna's design center frequency is 14.150 MHz, configured as a 3/2-wave dipole on 20 meters, with its 102-foot length derived from long-wire antenna formulas. Construction details emphasize the matching section, which can be open wire, ladder line (window-type), or TV twin lead. Each type has a specific velocity factor (VF) affecting its physical length for an electrical half-wave on 14 MHz; for instance, open wire requires 33.7 feet (VF 0.97), ladder line 31.3 feet (VF 0.90), and TV twin lead 28.5 feet (VF 0.82). The article provides formulas for calculating these lengths and discusses the antenna's behavior on individual bands, from 3.5 MHz where it acts as a shortened dipole, to 28 MHz where it functions as two three-half-wave long-wire antennas fed in-phase. Practical construction notes include recommendations for vertical descent of the matching section, sealing the coax junction, providing strain relief, and winding a coaxial choke coil to mitigate common mode current. The resource also presents dimensions for double-size (204 ft) and half-size (51 ft) G5RV versions, along with their corresponding matching section lengths for various line types, making it a versatile reference for hams considering this classic wire antenna.
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The GW3YDX Super Moxon antenna design improves upon the standard Moxon Rectangle by incorporating additional directors in a rectangular configuration, yielding enhanced directivity and gain. For the 6m version, modeling with 4NEC2 and EZNEC+ indicated a 3dB gain increase and a 26.5dB front-to-back ratio, with VSWR below 1.5:1 between 50.0 and 50.3MHz when optimized for 50.1MHz. This design achieves a narrower -3dB power point beamwidth of 60° compared to the original Moxon's 80°, contributing to better QRM rejection. The boom length for the enhanced design is just under 2m, approximately double the original Moxon's, with no increase in wingspan. Construction details include tubing lengths for 6m, 4m, and 2m versions, with specific dimensions provided for elements A through M, measured to tubing centers. For instance, the 6m version uses a 2160mm element A and a 2140mm element H. The design maintains a 50-ohm feed impedance, with practical models showing VSWR plots consistent with simulations after minor adjustments to driven element lengths. The article also references Moxgen software for initial Moxon parameter calculation and NEC/EZNEC model generation. The 2m Super Moxon version measures approximately 30" x 25", demonstrating the compact nature of the design across different VHF bands. The article highlights the antenna's performance in real-world DX contacts on 6m, achieving contacts with over 80 stations in the USA from a modest QTH.
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Operating in the Nordic region often requires specific call sign lookup tools, and this resource offers a dedicated search service for Swedish amateur radio operators. Users can query the database by entering a call sign, a family name, or a city, facilitating the identification of hams within Sweden. This functionality is particularly useful for DXers attempting to confirm contacts or for local hams seeking to connect with others in their area, leveraging the official data provided by the Swedish Amateur Radio Society (_SSA_). Such a lookup service streamlines the process of verifying contacts for awards like _DXCC_ or for general QSLing purposes. While many global callbooks exist, a national service like this often provides more granular and up-to-date information for its specific region. The ability to search by city can be especially beneficial for local rag-chewing or for coordinating activities within a specific geographic area, offering a practical complement to broader international databases.
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At the moment the most used program is UA1AAF. It is an excellent program written by Boris, UA1AAF, to handle ARI International DX Contest. It can simulate K1EA or N6TR workings; it will be possible to connect the RTX to the computer using a standard interface in such a way as to transmit directly in CW from the keyboard; most of the controls are like K1EA's CT and N6TR's TR ; on line help provides almost all the information necessary for using the program. Is possible to insert QSO after the contest. An appropriate utility in included for conversion in ADIF format. The program is very small and therefore works without any problems on any IBM compatible computer with DOS 3.3 and over or Windows 95/98.
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DX_Central, a compact desktop application, provides amateur radio operators with critical propagation data by aggregating solar statistics and imagery from various authoritative sources. This includes real-time information from agencies like NOAA and NIST, offering insights into current space weather conditions that directly impact HF propagation. The software is designed for both Linux and Windows operating systems, making it accessible to a broad range of hams. It presents a concise overview of solar activity, which is essential for planning DX operations and understanding band openings and closures across the HF spectrum. Operators can utilize the displayed solar flux index, K-index, and other relevant parameters to make informed decisions regarding their operating times and target bands, optimizing their chances for successful long-distance contacts.
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A complete DIY Raspberry Pi Weather Station including software, capable to read wind speed, wind direction, rain gauge and with a temperature and humidity sensor along to a camera.
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The HB9DHG Contest Calendar aggregates contest information, offering direct links to official rules and past results for various amateur radio competitions. It features a curated list of events, with a focus on HF and digital mode contests, ensuring that operators can quickly access relevant details for upcoming and historical events. The calendar is regularly updated to reflect the latest contest schedules and rule changes. Each entry typically includes the contest name, dates, and a direct link to the sponsoring organization's page, such as ARRL or DARC, where full regulations and scoring information are available. This resource streamlines the process of finding contest specifics, which is crucial for effective pre-contest planning and post-contest analysis. Validation and checking of contest information are emphasized, providing a reliable source for operators planning their contest activity throughout the year. The calendar supports both CW and SSB modes, alongside various digital modes.
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A 4 elements handitenna for 70 cm band. This is my version of the K5OE Handitenna. This one is a four Element instead of three, as I had less of a crunch on space than he did. The 1st three elements (Reflector, Driven Element, and Director 1) are the same dimensions as his were.
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A Useful Horizontally Polarised Omni-directional Antenna with Gain for 144 MHz
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Controlling amateur radio transceivers remotely often requires dedicated software to interface with the radio's CAT (Computer Aided Transceiver) system. CATSPAW is a software utility specifically developed by N2OHZ for the Yaesu FT-100, facilitating computer-based control over various radio functions. The software provides an interface for adjusting parameters such as frequency, mode, and other operational settings, which can be particularly useful for remote station operation or automated tasks. While the specific features and user interface details are not extensively documented on the download page, the primary function centers on providing a digital control layer for the _FT-100_. This allows operators to integrate the transceiver into a larger station setup that might include logging programs or digital mode applications, enhancing the overall operational flexibility. The utility's design focuses on direct control, leveraging the radio's internal command set. As a downloadable executable, _CATSPAW_ represents a common approach to radio control software from its era, offering a direct link between a personal computer and a specific transceiver model.
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VectorFox is a software born to incorporate a PC into the fox hunting environment. VectorFox is able to take inputs from up to 5 sources, such as a 2m beam, a 2m signal meter, a TDOA, etc, and display the results on the screen. VectorFox also accepts Agrelo inputs. From these results the operator can choose which indication is best and have a line drawn on the map in the direction of the signal.
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Presents a dedicated online callbook for Romanian amateur radio operators, compiling an extensive database of YO callsigns. It details information sourced from the _Agentia Nationala de Comunicatii_ (ANCOM) and user submissions, including callsigns, names, postal addresses, email contacts, and even photographs. The resource currently lists **10,768** YO callsigns, with **4,987** authorized by ANCOM, offering a centralized lookup for the Romanian amateur radio community. This platform also includes special event callsigns like _YR8D_, acknowledging their importance for QSL information sought by international DXers. It provides categorized lists of YO hams by county, a section for SWLs (radioamatori receptori), and a directory of YO radio clubs and associations. Users can submit updates or corrections via an online form, with validation typically processed quickly, often within minutes, ensuring the database remains current.
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Antenna gain directly impacts Effective Radiated Power (ERP) by concentrating RF energy along the horizon, increasing signal strength in specific directions without altering the transmitter's output power. For instance, a 4-watt transmitter coupled with an antenna exhibiting 10 dB of gain achieves an ERP of 40 watts, while 20 dB of gain results in 160 watts ERP. The relationship between antenna gain in decibels (dB) and the watt multiplier is logarithmic, where each 3 dB increase in gain approximately doubles the ERP. The provided table illustrates this principle, showing how a base 4-watt transmit power is transformed into significantly higher ERP values across a range of antenna gains from 1.2 dB to 100 dB. A 1.2 dB gain yields 4.8 watts ERP, whereas a 100 dB gain results in 400 watts ERP. This technical documentation from _Firestik Antenna Company_ clarifies the practical implications of antenna selection on signal propagation.
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The basics of what is a discone antenna for wide band or bandwidth omnidirectional applications.
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New England Repeater Directory (NERD) is the most accurate and up to date amateur radio repeater database available in our region. It is maintained by local volunteers of the amateur radio community. The listings are a reflection of each repeater's true status, regardless of their coordination
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The resource details the construction of a 3-element Yagi antenna specifically designed for the 6-meter band, providing coverage across 50-54 MHz. This antenna design, originally featured in _QST_ August 2007, emphasizes a short boom configuration while maintaining a wideband response. Key specifications include a 50 Ohm SWR of less than 2:1 across the entire band, achieved through specific element lengths and spacing. The design utilizes aluminum tubing for elements and boom, with detailed dimensions provided for the driven element, director, and reflector. Performance characteristics indicate a forward gain of approximately 7.5 dBi and a front-to-back ratio of 18 dB at 50.125 MHz, according to _NEC2_ modeling. The antenna's compact size, with a boom length of 1.83 meters (6 feet), makes it suitable for portable operations or installations with limited space. Construction involves standard amateur radio workshop tools and materials, with a gamma match for impedance transformation to 50 Ohms. The design prioritizes ease of construction and repeatable performance for the 6-meter enthusiast.
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The Yagi-Uda antenna, information on basic design, project and measure of Yagi-Uda antenna, include free repository/sample of beam antenna.
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The _Egyptian Amateurs Radio Association (E-ARA)_ provides a directory of its members, detailing callsigns such as SU1AL and SU1ER, along with their full names and QSL routing instructions. Each entry typically includes a postal box or street address in cities like Giza, Cairo, and Port Said, facilitating direct QSL card exchange. Specific entries indicate QSL via home call for operators like SU1BH (A71BH) and SU1DZ (9K2DZ), while others, such as SU1MR and SU1SR, route QSLs through SU1ER. The list also contains details for operators with international home calls, including SU2RS, who QSLs via OE6EEG. This resource serves as a basic callbook for the Egyptian amateur radio community, offering essential contact information for local and international hams seeking to confirm contacts or establish communication.
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The Cushcraft X7 Tribander assembly and installation manual (P/N 951470, 12/97) provides comprehensive instructions for constructing this 20-15-10 meter seven-element beam antenna. It details the sequential assembly of boom sections, individual elements, and the feed system, including the _MNX7 Matching Network_. The document emphasizes critical safety precautions regarding power lines and RF exposure, alongside recommendations for proper antenna system planning and grounding. Key sections cover verification of parts, detailed boom assembly using specific aluminum tubing (e.g., BA, BB, BC, BD, BE) and brackets, and element construction with various aluminum tube sections (e.g., EA, EB, EC, ED, EE, EF) and traps like the _15 Meter Director Trap_ (TB) and _10 Meter Director Trap_ (T9). It also specifies the use of _NOALOX® conductive lubricant_ for telescoping sections and hardware to prevent galling. The manual outlines the feed system assembly, which includes feed-straps (FL1, FL2, FL3), tuning-tube insulators, and the matching network. It also mentions the optional X740 40-meter add-on kit, which requires a separate coax feed. Detailed diagrams and parts lists with metric equivalents facilitate accurate construction and ensure the antenna performs as specified.
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Examines the four basic components of a mobile antenna system: the antenna, coaxial cable, antenna stud, and the mount, emphasizing mount selection as the most complex decision. Modern vehicle designs, including the absence of metal rain gutters and specific trunk configurations, often preclude traditional mirror, trunk lip, ball, or gutter mounts, necessitating universal mount designs. Discusses the economic challenges of designing vehicle-specific mounts due to tooling costs versus production runs, citing exceptions like Dodge Ram hood mounts and GM truck mirror mount brackets. The article acknowledges the difficulty for manufacturers to recommend specific mounts without direct vehicle inspection, given the vast array of vehicle designs and individual installation restrictions. Advises users with mechanical aptitude to study available mounts and assess possibilities directly on their vehicle. Recommends visiting a local communications store for personalized assistance if self-assessment proves difficult, highlighting the value of expert advice to avoid performance issues or equipment damage.
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This publications page lists articles on surface mount devices, amateur radio, soldering, shunts, and measuring large direct currents.
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Details the Northern Amateur Relay Council of California (NARCC) as the regional coordinating body for amateur radio repeaters operating on the 10-meter band and above. It outlines NARCC's function in managing frequency allocations to minimize interference and ensure efficient spectrum use across Northern California. The resource specifies that NARCC operates in cooperation with the FCC and ARRL, indicating its recognized authority within the amateur radio community. The organization's role centers on repeater coordination, a critical aspect of VHF/UHF operations where multiple stations share limited frequency segments. It highlights the support received from local amateur radio operators, underscoring a community-driven approach to spectrum management. The site serves as a primary reference for hams seeking to establish or operate repeaters within the designated service area. NARCC's activities directly impact the operational landscape for _VHF_ and _UHF_ enthusiasts, providing essential guidelines and coordinated frequencies. This ensures orderly communication and prevents conflicts, particularly in densely populated areas of Northern California.
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Demonstrates the construction of a 144 MHz turnstile antenna, detailing its design for omnidirectional, horizontally polarized VHF operation. The resource outlines the physical dimensions and materials required, including specific lengths for the radiating elements and the use of _RG-58_ coaxial cable for phasing. It covers the assembly process, emphasizing the critical spacing and connection points to achieve the desired radiation pattern and impedance matching for the _2-meter band_. The article presents measured _SWR_ performance across the 144-146 MHz segment, showing a low SWR of 1.2:1 at 144.5 MHz, which is suitable for general VHF use. It compares the turnstile's performance to a 9-element Yagi, noting the turnstile's advantage in providing consistent signal strength from all directions without requiring a rotator. Practical application for local FM simplex and repeater operations is implied, offering a simple yet effective antenna solution for fixed or portable stations.
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Here are some lengths and spacings for various direct connect beams.
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For amateur radio operators engaged in **radio direction finding** (RDF) and **transmitter hunting** (T-hunting) activities, this resource provides a catalog of printed circuit boards (PCBs) for constructing various DF and foxhunt-related projects. The offerings include PCBs for 80-meter fox transmitters and receivers, UHF fox transmitters with audio recording capabilities, and several designs for general-purpose radio direction finders. Specific projects like the "Simple 80M ATX-80 Transmitter" and the "N0GSG DSP Radio Direction Finder" are listed, along with attenuator boxes and specialized components for Doppler DF systems. The catalog details PCBs for projects published in prominent amateur radio magazines such as *73's*, *CQ*, *QST*, and *PE*, indicating their origin and design pedigree. For instance, the "Montreal Fox Controller" is sourced from the *Homing-In* column by Joe Moell, K0OV. The resource also lists components for advanced Doppler DF systems, including main boards, LED display boards, and antenna switch boards, with options for programmed PIC microcontrollers. Pricing for each PCB is provided, allowing hams to acquire the necessary components for their DIY RDF endeavors.
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Accessing local public service communications often requires specific frequency data, and this resource provides extensive scanner frequency lists for the Greater Cleveland area. Originally compiled by Russell Imburgia, _N8RI_, these compilations were previously hosted on the now-defunct Greater Cleveland Hamnet BBS. The data is presented in two distinct formats: one sorted alphabetically by city and another organized numerically by frequency, allowing users to quickly locate specific channels based on their preferred lookup method. These lists are noted for their thoroughness in covering local public safety, business, and utility communications within the region. While the primary lists are copyrighted by N8RI, permission is granted for non-commercial reproduction, provided the copyright notice remains intact. The page also directs users to an external frequency database maintained by Jon Anhold, _N8USK_, offering an additional avenue for frequency information.
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One point eight MHz to 30 MHz is the operational bandwidth for this 4:1 Ruthroff voltage balun, designed to interface an unbalanced T-Match network with a balanced antenna system. The project details the construction using a _T200-2_ powdered iron toroid core, tightly wrapped in PVC electrical tape for insulation, and wound with 17 double bifilar turns of 1.25mm enamelled copper wire. This outboard balun offers flexibility, allowing hams to trial various baluns based on antenna system and impedance characteristics, rather than integrating it directly into the tuner. The resource includes a schematic of the balun, a wiring diagram showing winding connections, and a table suggesting alternative toroid cores like the T80-2 or T400-2 with corresponding winding counts. Component sourcing is straightforward, listing items such as the _Amidon_ T-200-2 core, SO-239 connector, and a sealed polycarbonate enclosure from Jaycar. Performance evaluation was conducted using an _AIM 4170C_ antenna analyser, demonstrating efficient 1:4 voltage transformation across the specified HF spectrum. Further efficiency tests involved measuring RF power loss at various frequencies, revealing minimal loss—less than 0.7 dB from 3.6 MHz to 30 MHz, and only 2.0 dB at 1.8 MHz. These measurements, performed under ideal 50-ohm conditions, confirm the balun's effectiveness as a low-loss interface for multi-band antenna systems. The page also links to several other balun and unun projects, including 1:1 current and voltage baluns, and 9:1 voltage ununs, providing a broader context for impedance matching solutions.
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Hidden transmitter hunting, often called fox hunting or Amateur Radio Direction Finding (_ARDF_), presents a unique challenge for radio amateurs. This resource details the _PicCon_ controller, a specialized device designed to automate the transmission of signals for such events. It integrates with a standard radio transceiver, functioning similarly to a packet radio TNC, by controlling the Push-To-Talk (PTT) line and injecting audio tones or modulated CW Morse code into the microphone input. The _PicCon_ unit is field-programmable using DTMF tones received via the radio, storing all settings in EEPROM for power-off retention. Its compact design and low power consumption (a few milliamps from a 7-35VDC source) make it suitable for remote deployment. An onboard LED indicates operational status, and a push-button allows manual start/stop of transmissions without DTMF. Typically supplied as a kit, _PicCon_ includes a PCB, components, and a comprehensive manual (available in HTML, RTF, and PDF formats). The kit provides a six-conductor interface cable, but users must supply radio and power plugs due to varied configurations. Byon, _N6BG_, developed this controller, which is available from the Byonics website.
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The resource presents a detailed schematic for constructing a dual-band vertical antenna, specifically designed for operation on the 2-meter and 70-centimeter amateur radio bands. It illustrates the physical layout, critical dimensions, and component placement necessary for successful replication. Key elements such as the radiating elements, phasing sections, and feed point are clearly depicted, providing a visual guide for radio amateurs undertaking a homebrew antenna project. The diagram specifies the lengths for the VHF and UHF sections, indicating how these elements are integrated to achieve dual-band functionality from a single coaxial feedline. It also implies the use of common materials readily available to most experimenters, focusing on simplicity and effectiveness in its design. The visual format of a GIF image ensures direct access to the construction details without requiring extensive textual interpretation. This schematic serves as a practical reference for hams interested in building a compact, efficient vertical antenna for local and regional FM communications, offering a proven design for immediate implementation.
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A 2-meter Moxon beam antenna, designed for the _144 MHz_ band, is detailed, originating from a desire to participate in the PW 2m QRP contest. The design, based on a Moxon Rectangle, offers a compact directional solution for VHF portable operations. The author, G0KYA, constructed the antenna using readily available materials like 15mm plastic conduit for the frame and 1.5mm copper wire for the elements. Initial testing with an MFJ-259B antenna analyzer showed a **1.2:1 SWR** at 144.300 MHz, indicating good resonance. The antenna's compact size, approximately 70cm x 40cm, makes it highly suitable for portable QRP work, providing a significant advantage over an omnidirectional vertical. The project includes practical advice on element spacing and construction techniques, emphasizing ease of assembly for field deployment. Field results from a local hilltop demonstrated the Moxon's directional characteristics, allowing for effective nulling of local noise and improved signal reception from specific directions.
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Similar to Tiny 2 but this three element direct connect antenna utilizes a reflector and a director to achieve gain.
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SecondHandRadio.com provides a platform for the amateur radio community to buy, sell, and swap used, surplus, and obsolete electronics and electrical equipment. The site facilitates transactions for a wide range of items, including ham radio transceivers, test equipment, shortwave receivers, antennas, and vintage radio components like tubes. Users can place classified advertisements with photos at no cost, catering to individuals, radio clubs, and commercial dealers seeking to liquidate or acquire gear. The platform emphasizes ease of use with a straightforward sign-up process and no associated fees or commissions for listing or selling items. It positions itself as a primary resource for used electronics within the USA, fostering a direct connection between sellers and buyers without intermediary charges. The service supports various categories beyond amateur radio, extending to military radios and antique equipment, thus serving a broad spectrum of radio enthusiasts and collectors.
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Demonstrates a practical online tool for locating amateur radio operators by geographic area, specifically using US ZIP codes. This utility allows users to input at least three digits of a desired ZIP code to retrieve a list of active licensees. Search results can be sorted by _call sign_, name, license expiration date, or ZIP code, providing flexibility in data organization. The service offers two primary output formats: direct display in a web browser, which omits address details for privacy, or export to a tab-delimited file, which includes full address information suitable for import into spreadsheet or database applications like _Excel_. This lookup service proves useful for local club organizers seeking to identify potential members within their service area or for hams planning local nets or events. The ability to export data with address details facilitates direct mailings for club newsletters or event announcements, while the browser view maintains privacy for casual lookups. The tool's design prioritizes ease of use, requiring minimal input to generate relevant local amateur radio contact information.
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A live map of current KiWiSDR receivers available on the network. It allows users to explore a directory of web-controlled receivers for listening to HF and VHF stations worldwide. The site provides access to remote ham radio stations online, making it a valuable resource for amateur radio operators.
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Examines Kiwa, a global entity specializing in **Testing, Inspection, and Certification (TIC)** services across diverse sectors. The resource details Kiwa's operational scope, which encompasses quality assurance, safety compliance, and sustainability solutions for industries such as Food, Feed and Agriculture, Digital and Cyber Solutions, Energy Transition, Industrial Services, and Medical Devices. It highlights the company's role in ensuring product, service, process, and system integrity through rigorous accreditation and notification processes, operating in over 35 countries worldwide. The content presents specific examples of Kiwa's engagement, such as food safety certification for HortaPronta in Portugal, explanations of the Digital Battery Passport requirements, and contributions to floating offshore wind energy development. It also outlines the company's approach to biological evaluation of medical devices according to **ISO 10993** and its commitment to ESG principles, as detailed in its online ESG magazine, Trace. The resource provides access to a certificate finder and a testing directory with over 3000 capabilities across 80 laboratories.
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Manufactures and sells coaxial connectors, coaxial adapters, coaxial cables, attenuators, directional couplers, fiber optic connectors, fiber optic adapters, fiber optic cables, coaxial switches, terminators, twinax connectors and cables and tools.
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Detailed online and searchable maps, driving directions and city guides
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Transmission Line Details. This utility program shows the impedance and SWR at both ends of a transmission line and the details of power loss in the line. It includes characteristics for over 40 built-in line types. You can modify these values to see how small changes affect the results or to specify custom lines. All program inputs may be changed directly or you can use spin buttons to make the changes. If you are using a moderately fast computer you can hold down a spinner and "watch the movie" on the charts as the results are recomputed. By AC6LA
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A web site dedicated to hex beam homebrewing. The hexagonal beam has become a wildly popular antenna. It is a directional antenna that provides great performance and does not require a full scale, expensive tower.
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A 6 dB gain Moxon rectangle antenna, designed for the 2-meter band, offers an excellent solution for hams seeking a compact, directional antenna for **SSB** operation, particularly in restricted spaces like an attic. This design emphasizes ease of construction using readily available materials such as 4mm OD brass tubing and plywood, making it an accessible project for many radio amateurs. The antenna's inherent characteristics, including a high front-to-back ratio of 37 dB and a 50-ohm feed impedance, contribute to its effectiveness in mitigating local noise and focusing radiated power. The project leverages the free MoxGen program for precise dimension calculations based on the desired frequency and wire size, and utilizes 4nec2 for pattern analysis, confirming a 3 dB beamwidth of 80 degrees. Construction involves bending brass tubing for the driven and passive elements, mounting them on an 800 x 350 mm plywood boom, and securing them with cable clips and epoxy resin. Initial SWR measurements at 144.3 MHz showed 1.6:1, which improved to 1.3:1 at 145.3 MHz across a flat band from 144.1 MHz to 145.5 MHz after adding a **coaxial choke** to mitigate common mode current.
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Operating an 80/40/20M fan dipole for DX is analyzed through EZNEC modeling, focusing on the antenna's performance in a real-world, low-height installation. The resource details the physical construction and SWR measurements of the fan dipole, comparing them against EZNEC simulations. It also incorporates High Frequency Terrain Analysis (HFTA) data to illustrate typical DX elevation angles for various regions from New England, providing a crucial context for evaluating antenna patterns. The analysis presents EZNEC-generated azimuth and elevation patterns for each band (80M, 40M, 20M) at specific frequencies, showing gain figures at different elevation angles relevant to DX propagation. It compares the modeled SWR with measured SWR, attributing discrepancies to coax attenuation. The study concludes with observations on the antenna's azimuth performance (omnidirectional within ±1.5 dB) and its less optimal elevation gain at desired DX angles, highlighting the impact of low antenna height on DX capabilities.
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Demonstrates the construction of a double bazooka antenna, detailing its historical development from MIT radar applications in the 1940s to amateur radio use in the 1950s. It explains the antenna's operation as a 1/2 lambda coaxial section with open-ended stubs, acting as a shortened quarter-wave stub at resonance, presenting high impedance. The resource provides formulas for calculating total length (LT = 140/Freq) and coaxial length (LC = 99/Freq) for RG58 CU, along with specific instructions for cutting and soldering components, including a central insulator and end wires. Compares the double bazooka to a standard dipole, highlighting its 98% efficiency and twice the bandwidth. It claims a +3.6dB gain over a dipole (dipole gain 2.15dB) and a 6dB reduction in reception noise due to its closed design, which also minimizes harmonics and TVI. The antenna handles over 1.5kW (2kW PEP) without performance degradation and is effective for DX with a low radiation angle, especially when configured as an inverted V between 90° and 120° with ends 2 meters above ground. It eliminates the need for a balun and can be fed directly with 50-ohm coaxial cable.
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Demonstrates how to construct an automatic band decoder, moving beyond manual selector switches for antenna and filter control. It addresses the challenge of varying band data outputs from different transceivers: Icom rigs provide voltage values, Yaesu rigs use Binary Coded Decimal (BCD), and Kenwood rigs lack direct band data output. The resource highlights a clever solution utilizing logging software like _CT (K1EA)_ and _DX4WIN_ to emulate Yaesu's BCD output via a PC's printer port, making the decoder compatible with any rig. The author details experiences building decoders based on designs by Bob _K6XX_ and Guy _ON4AOI_, noting K6XX's simple TTL chip design and ON4AOI's more comprehensive, opto-isolated unit capable of controlling ten outputs and bandpass filters like the _Dunestar_. It also references a _W9XT_ board design, which Steve Wilson, G3VMW, modified with BD140 transistors for source drivers, emphasizing safety. The author successfully cased an ON4AOI-based decoder in an old modem case, connecting it to an FT1000MP or a PC printer port to drive remote relays and a Dunestar Band Pass Filter.
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The original article of the progressive system, composed by a direct conversion receiver and multiband superetherodyne by W7ZOI and K5IRK