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Query: LF
Links: 608 | Categories: 7
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This homebrew six-meter linear amplifier started off life as a "junker" Alpha 76PA h.f. amplfier. Power output is 800W -
A self-contained and portable SDR Transceiver using a Softrock front end and embedded Digital Signal Processing ... No PC required! -
Despite the title referencing the callsigns 3C5J and MW0BRO, the content of this resource focuses entirely on the _Cleddau Computer Clinic_, an IT services company operating in Pembrokeshire since 1999. The site outlines a broad range of computer-related services, including custom-built new PCs starting from £399, sales of used systems, and comprehensive repair and upgrade options for existing units. Services extend to anti-virus and spyware removal, system installation, and broadband connection setup. The clinic also provides tuition for hardware and software applications, website design, and video to DVD transfer. They specialize in both fixed and wireless network solutions, enabling clients to share files and broadband connections efficiently. Repairs can be conducted either in their workshop or at the client's home or office, offering flexibility. For situations where on-site repair is not feasible, the Cleddau Computer Clinic offers a temporary replacement computer service. This includes transferring essential data to minimize disruption, a practical approach for local businesses and individuals in areas like Pembroke, Milford Haven, and Haverfordwest. -
The Russian Internet Callbook, hosted at krasnodar.online.ru, offers a specialized lookup service for amateur radio callsigns within the Russian Federation. This online tool is designed to assist DXers and contesters in identifying contact information for Russian stations. The resource functions as a digital callbook, allowing users to search for specific callsigns and retrieve associated data, which is crucial for QSLing and verifying contacts. While the concept is to provide a comprehensive database for Russian amateur radio operators, the current status indicates a configuration issue, as the domain krasnodar.online.ru points to the server but the site itself is not configured. This suggests the service may be inactive or undergoing maintenance, impacting its utility for callsign lookups. The original intent was to serve as a key _DX resource_ for the region. -
A J-pole antenna plan made using a half inch copper tubing -
Broadcast Tower Specialist. Offering Manufacturing, Engineering, Erection and Tower Extension Services. Self Supporting or Guyed Towers. -
This online article provides a list of individuals who hold or have held amateur radio callsigns, detailing their public recognition. The resource identifies specific callsigns such as **K1JT** (Joe Taylor, Nobel Prize in Physics), **W6OBB** (Art Bell, syndicated radio personality), and **JY1** (King Hussein of Jordan), linking them to their non-amateur achievements. It also notes operational statuses like _Silent Key_ for deceased operators and _lapsed callsign_ for inactive licenses. The article includes information on callsign changes due to vanity callsign programs and provides examples of individuals involved in specific technical areas, such as Percy L. Spencer (**W1GBE**), inventor of the microwave oven, and Jay Kolinsky (**NE2Q**), inventor of electronic sirens. It also references amateur radio involvement in _space missions_ for individuals like Owen Garriot (**W5LFL**) and Helen Sharman (**GB1MIR**). DXZone Focus: Online Article | Famous Hams | Callsign Status | Vanity Callsigns -
A helpful guide to building your own beverage-type low noise receiving antenna for broadband use. Easy, do-it-yourself suggestions to optimize directional performance, even if you lack a farm to put it on. -
miLog provides an integrated software solution for amateur radio station management, encompassing logging, DXing, and contesting functionalities. The software is designed to operate on Windows 2000 and later versions, indicating a focus on stability and compatibility within the Microsoft ecosystem. Its feature set includes comprehensive logging capabilities, tools for DX operations, and specific modules tailored for competitive contesting, streamlining the workflow for operators engaged in these activities. The resource details the software's commercial availability and its primary functions, which extend to station control. This integration allows users to manage multiple aspects of their amateur radio operations from a single application, potentially reducing the need for disparate tools. The description also highlights support for various operating modes, suggesting flexibility for different communication protocols and techniques. While the page itself is minimal, it serves as a direct point of reference for miLog, outlining its core purpose and system requirements. The emphasis on a highly integrated approach distinguishes it as a tool aiming to consolidate essential ham radio software functions. -
Amateur radio operators frequently seek efficient methods for logging contacts, particularly during contests or DXing sessions where speed and accuracy are paramount. MiniLogBook addresses this need by providing a streamlined logging utility designed for Windows environments. The software facilitates rapid entry of QSO data, offering an automated lookup feature for previous contacts based on recent callsigns, which significantly reduces redundant data entry. The application's distinctive utility lies in its integration capabilities with other ham radio software, specifically _MRP40_. Users can select text within the MRP40 receive window and, with a double-click, automatically insert that text into MiniLogBook. This feature is particularly advantageous for operators engaged in digital modes like RTTY or PSK, where copying callsigns and exchange information accurately and quickly is critical. The tool aims to simplify the logging workflow, allowing operators to focus more on the contact itself rather than manual data transcription. While primarily a logging tool, its focus on quick entry and interoperability with specific third-party software distinguishes it from more feature-rich logging suites. The software is distributed as freeware by _Polar Electric_, making it accessible without cost. Its small footprint and direct functionality cater to operators who prefer a minimalist approach to logging, prioritizing efficiency over extensive database management or advanced reporting features. -
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Causes and advices on malfunctioning display in the control head of the FT-857, where several scan lines in the dot-matrix display cease to function, so the display seems streaked at places -
A homemade VHF/UHF vertical antenna made essentially with RG58 coax cable, with a 9 turns choke balun to prevent the shield acting as a RF Radiator. -
The 9A3MR contest QTH rental provides a fully equipped amateur radio station for DXpeditions or radio holidays on Murter Island, Croatia. The station features a Drake TR7 transceiver and a 16-meter tower with a rotator, suitable for various HF operations. Accommodations include a four-room apartment and a studio apartment, both within 200 meters of the beach, offering amenities like parking and a barbeque area. This QTH is located in Jezera, a fishing village with local stores and restaurants within a five-minute walk. While Murter Island itself does not qualify for IOTA due to a bridge connection, the Kornati Islands National Park (IOTA EU-170) is only 10 nautical miles away, with daily tourist tours available. The Krka National Park is also accessible by car, approximately 25 km distant, providing additional recreational opportunities. -
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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. -
This article document a 2 element half wave collinear J-Pole antenna by KC9EOT and KB8OJH -
If your doing any home brewing gear for ham radio its a great idea to have a dummy load. This will to your radio be the perfect antenna...it will never radiate but your radio sees a perfect 50 Ohm impedance. -
Although a magnetic loop antenna(aka small loop antenna) is very compact, its efficiency is close to a half-wavelength dipole if carefully built. -
The Peaberry SDR is the first and only do-it-yourself transceiver that doesn't require adding sound cards to your computer. -
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Centre fed half wave dipoles make great, simple and effective antennas for the HF bands. Sometimes however, the centre feed is not ideal. This great project will improve the overall antenna performance. -
How to make a half l or quarter l coax cable for a specific frequency -
An end fed 20 meter half wave antenna -
a methodology for connecting multiple LF/MF/HF receivers to a single antenna via readily available and inexpensive 75-ohm TV cable. -
How to build a simple WSPR beacon using the Raspberry Pi for the transmitter -
Lot of useful information on experiments on 136 Khz band, with antenna tips DSP infos and notes on their activity in LF. -
An easy to deploy antenna, commonly considered the best solution for portable operations. Thir article includes a simple LC parallel circuit to match the impedance by IW7EHC -
Detection and recording of Schumann resonances and other electromagnetic phenomena at frequencies below 50 Hz By Hans Michlmayr -
The Resonant Feedline Dipole (RFD) HF antenna design utilizes a single piece of coaxial cable and a stranded wire section, forming a 1/4-wavelength radiator. This configuration, based on a 1997 ARRL Handbook design (page 20.17), functions by RF traveling on the inside of the coax shield and returning on the outside, creating the second half of the dipole. A choke wound into the feedline prevents RF current from flowing back down the feedline. Construction details include using RG-58a/u coax for a 75m version, with a 1/4-wavelength section of stranded wire soldered to the center conductor. The document provides choke dimensions for RG-213, RG-8, and RG-58 coax across 3.5 MHz to 28 MHz, specifying cable length and number of turns. Dipole dimensions are also tabulated for frequencies from 3.6 MHz to 28.4 MHz, listing overall length and individual leg lengths. Field tests included deployment near Bryson City at 5 feet off the ground and as a sloper during WCARS Field Day in Asheville, yielding successful local and regional contacts. -
The 2.1 kHz wide European LF allocation between 135.7 and 137.8 kHz is detailed in this observed band plan, offering guidance for activity within this narrow segment. It specifically addresses the challenge of locating weak signals, such as those from Slow-CW stations, which can have bandwidths of only a few Hertz. The resource emphasizes the utility of precise frequency knowledge when operating with narrow DSP filters, like a 30 Hz filter for CW, to differentiate multiple stations within a very small band segment. The plan, though not officially recognized, provides practical orientation for operators, particularly those new to the _LF band_. It references a similar plan published by the _RSGB_ in the January 2000 issue of _RADCOM_, suggesting a community-driven approach to band organization. The content highlights the importance of spectral awareness, noting that multiple stations can occupy minimal bandwidth, a concept illustrated by spectrographic analysis. -
G3XBM's Amateur Radio Page - with QRP, VLF and crystal set links -
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Details Allied Wire and Cable's extensive product catalog, focusing on its role as both a distributor and manufacturer of specialized wiring solutions. The resource highlights the availability of electronic and electrical wire, various cable types, tubing, and pre-assembled cable solutions. It also specifies their capability in **custom cable design**, addressing unique requirements for specific applications. The site presents information on flexible cable options and a broad spectrum of wire and cable specifications, catering to diverse industrial and technical needs. It outlines the company's capacity to provide tailored solutions beyond standard off-the-shelf products, emphasizing their engineering and manufacturing expertise. Key offerings include **coaxial cable**, connectors, and general wiring components, positioning the company as a comprehensive source for connectivity infrastructure. The content implicitly supports applications ranging from industrial automation to specialized radio frequency installations. -
A 4 AMP / 18V regulated power supply schematic, designed by _ON6MU_, provides a detailed circuit diagram for constructing a robust power source. The design focuses on delivering a stable 18-volt output at up to 4 amperes, crucial for powering various amateur radio equipment. This resource presents a clear visual representation of component interconnections, including rectifiers, filter capacitors, and voltage regulation stages, essential for DIY enthusiasts building their shack infrastructure. The schematic's clarity facilitates understanding the power flow and component roles within the circuit. This circuit design offers a practical solution for hams needing a reliable 18V supply, potentially useful for driving specific transceivers, amplifiers, or accessory circuits. While specific performance measurements or comparisons to other designs are not detailed, the schematic itself serves as a foundational blueprint. Builders can adapt or modify the _power supply_ to suit their particular needs, such as integrating overcurrent protection or fine-tuning the output voltage with adjustable regulators. The straightforward presentation makes it accessible for those with basic electronics knowledge to assemble and troubleshoot. -
Deploying robust antenna infrastructure for both fixed and portable operations often requires specialized support structures capable of withstanding environmental stresses while providing optimal radiating element placement. SMC offers a range of solutions, including pneumatic masts and push-up masts, designed to facilitate rapid deployment and reliable long-term support for various antenna types. Their product line encompasses antenna mounts, poles, and complete antenna systems, addressing the critical need for stable and efficient RF communication. The company's offerings extend to HF antennas, including dipoles and _NVIS_ (Near Vertical Incidence Skywave) antennas, which are crucial for short-range regional communications on bands like 80m and 40m. These systems are engineered for durability and performance, ensuring signal integrity across diverse operating conditions. With over **65 years** of experience, SMC has established itself as a global manufacturer in this niche. Their product portfolio also includes antenna support towers, catering to more permanent installations requiring significant height and load capacity for multiple arrays. -
A Loop Fed Array Yagi antenna for 50 MHz featuring 11 dBi gain and 23 f/b ratio. In this excellent page the author even includes a detailed drawing in DWG format, with element lenght and spacing measures, in a separa file a full list of material list needed to build this yagi antenna including source and price, the EZnec file for this antenna plan, and a lot of pictures of this LFA Yagi for 50 Mhz. A ten page PDF file containing all infos, is also available to download. -
Definition of radio frequency bands, hf vhf uhf etc. -
A simple and awesome wire monoband antenna, very usefull for portable and dxpeditions usage, consist of two elements, a driver and the reflector. This endfed halfwave gives a very low take off angle and is very suited for chasing DX. -
Presents a curated collection of newsletters dedicated to _Earth-Moon-Earth_ (EME) communications, primarily focusing on the 432 MHz band and higher microwave frequencies. The resource details various EME DX experiences and news contributions from operators like K2UYH (W6/PA0ZN), offering insights into successful moonbounce contacts and operational strategies. It serves as an archive of specialized content for those engaged in or interested in extreme weak-signal propagation via the moon. The newsletters provide practical information on achieving EME contacts, often including details on station setups, antenna arrays, and signal reports from challenging DX. For instance, operators might report achieving contacts over **750,000 km** round trip, demonstrating the feasibility of long-distance communication on UHF and microwave bands. The content differentiates itself by concentrating on the unique technical and operational aspects of EME, which contrasts significantly with terrestrial DXing, providing a specialized knowledge base for advanced amateur radio operators. -
All antennas that are situated close to the ground are affected by that ground to some extent. This article explain effects and benefits of counterpoise. -
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Memorandum on the Beverage Wave Antenna for Reception of Frequencies in the 550 - 1500 Kilocycle Band", FCC Report 9.2.1, by Benjamin Wolf and Adolph Andersen -
Experiments on remote receiving loops antenna by Lyle Koehler, K0LR -
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A workign example of a simple half-sized, end fed halfwave for 160 meter band by N0LX -
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In response to a question about Numbers Stations, their origin and purpose, the following information should be of interest.
