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This low power transmitter is developed for ARDF exercising purposes but of course can be used as super QRP transmitter either. With 1 or 2 meter wire as antenna and a ARDF receiver with ferrite-rod antenna the range is about 100m but with better antennas and a 'real' receiver the range is probably much larger.

This is a 6 band receive only filter designed to protect your receiver front end and provide 45dB reject at the stop bands. This is a 6-band receive only filter designed to protect your receiver front end and provide 45dB reject at the stop bands. Stop band reject may be limited by the relay isolation. Worse case isolation is at 28 MHz or 35 dB or better. Relay K3/K8 protects the filter during transmit via the PTT line. A 25-50ms delay must be used between transmit and PTT. Do not rely on your radio to provide adequate delay with out using the PTT. You logging software must be set to allow a delay between PTT and time of 1st transmit. This filter will not work with VOX or QSK keying as you will damage the filter.

Differential Global Positioning Service (DGPS) is a land-based augmentation system that receives and processes signals from orbiting GPS satellites, calculates corrections from known positions and broadcasts these corrections via a Medium Frequency (MF) Transmitter to DGPS users in the Broadcast Site's coverage area.

We sell antique radio tubes and antique tube radios We have over a thousand different radio tubes in stock. We also have a large stock of globe tubes.

Learn the Morse Code. Learn from random text or simulated QSO (contact) sources. Create character sequences that you find difficult. Compare your results with what the program sent and view error statistics. Take simulated tests. Sound card not essential. Evaluation version not time limited.

A simple 40 meter CW transmitter, it sports full break-in operation and 250 mW of output power.

The QLF filter is a microprocessor based interface designed to go between a standard Morse code key and a radio transmitter

Versatile transmit interface circuit

W6/PA0ZN CATV tuner based Spectrum Analyzer Building Project

Examines the historical landscape of "boat anchor" amateur radio equipment manufacturers, focusing on the technical innovations and market dynamics that shaped the industry from the pre-WWII era through the transition to SSB. It details the origins and key product lines of prominent U.S. companies like _Collins Radio Company_, _Central Electronics_, and _Barker & Williamson_, highlighting their contributions to receiver and transmitter design. The resource contrasts early AM technology with the advent of SSB, explaining the circuit changes required in receivers and the complete rethinking needed for transmitters. It discusses the impact of military contracts on company survival and the eventual shift towards smaller, self-contained transceivers. Specific examples, such as the _Collins R-390/URR_ receiver and the _Central Electronics 100V/200V_ broadband transmitters, illustrate the engineering prowess and design philosophies of the era, offering insights into their operational characteristics and enduring appeal among collectors.

NEC4WIN is a 32 bits commercial antenna simulation software based on MININEC3 developed by the Naval Ocean Systems Center in the 70s and 80s. It runs under Windows and can be used to simulate, analyze and optimize wire antennas, beams, verticals, etc. NEC4WIN has limitations. They are the same as Mininec3 on which the engine is based.

Presents the amateur radio activities and interests of Kote, operating as 4L4KW. The page features a collection of external links relevant to the ham radio community, including references to other callsigns such as 4L1BR, 4L1W, 4L4MM, and 4L/ZL1RS, indicating potential connections or shared interests within the Georgian amateur radio scene. It also lists several well-known ham radio resources like QRZ.com, DXzone.com, and Contesting.com, suggesting an active engagement with DXing and contesting. The resource includes links to major amateur radio equipment manufacturers such as Icom, Yaesu, and Kenwood, which implies an interest in modern transceivers and station setup. The mention of DX-Summit and "fixed activity on Ham bands" further reinforces a focus on making contacts and participating in on-air operations. The page serves as a digital hub for 4L4KW's ham radio presence.

Contest logging software by N6TR, a free limited version is also available, includes some contests and a cw simulator mode.

glfer is a program for reception and transmission of QRSS/DFCW signals. It is composed of two main parts: the spectrogram window, where you can see the spectrum of the received signal vs. time the transmission functions, to emit cw characters at a slow but precisely controlled speed, using the QRSS (slow CW) or DFCW (Dual Frequency CW) modes

A very short dipole with a good radiation efficiently plus a respectable bandwidth by S. C. Chuck Smith, WA7RAI

SignalGen is a free (GPL) Linux (Xwindows GUI-based) utility that generates relatively low frequency signals with the use of a PC sound card. It is an entirely suitable replacement for a hardware signal generator if one doesn't require signals of a frequency higher than about 50 KHz. SignalGen creates any frequency between a fraction of one Hertz and an upper limit determined by your sound card's capabilities.

This resource, "Transistor Audio Preamplifier Circuits," offers comprehensive design guidelines for constructing **bipolar transistor** audio preamplifiers. It delves into critical aspects such as quiescent current setting, voltage gain calculation, and the impact of various component choices on circuit performance. The content provides several _schematic diagrams_ illustrating different preamplifier configurations, including single-stage common emitter and two-stage designs, alongside explanations of their operational characteristics and practical implementation considerations. The analysis extends to frequency response, noise performance, and distortion, providing insights into optimizing these parameters for specific audio applications. The resource presents calculated gain figures for various stages, demonstrating how to achieve desired amplification levels. It also discusses the importance of proper power supply decoupling and input/output impedance matching, crucial for integrating these preamplifiers into larger audio systems or ham radio transceivers. The practical application of these designs is evident in their suitability for microphone preamplifiers or general-purpose audio amplification.

A mobile vertical antenna for 40 meters band by W4NFR

An Attic version for limited space applications by NW9T

GW4ALG's _136 kHz Pages_ document the evolution of vertical antennas for the 2200m band, starting with a prototype mounted on a house wall. This initial design, despite achieving the first **395 km** GM-GW QSO, suffered from significant insulation breakdown, high RF losses due to proximity to the house, and difficult tuning adjustments. The author details the challenges of maintaining resonance and matching with a variometer in the loft, noting that adding three earth spikes offered no measurable improvement over a simple water tap connection. The subsequent experimental 12m vertical, relocated away from the house, significantly reduced dielectric losses and proved far more effective. This antenna enabled GW4ALG to set a world DX record on 136 kHz with a **1916 km** QSO to OH1TN, and an intra-UK record of **703 km** to GM3YXM/P. The resource further explores the use of helium-filled balloons to extend the vertical radiator, achieving heights up to 27m, typically 20m, for enhanced low-band performance. Practical advice on balloon types, inflation, and critical insulation between the wire and balloon is provided, emphasizing safety and avoiding arcing.

This article presents a technical investigation into spurious emissions from the Yaesu FT-847 transceiver when operating on the 70MHz (4-meter) band. The author discovered significant problems with both factory "UK spec" and modified units. Spectrum analysis revealed that when transmitting at 70.2MHz, the radio produces numerous spurious signals, with the most prominent emission at 45.6MHz measuring only 3dB below the fundamental frequency. The study also documents poor power efficiency on 4m (10.3% at 30W output) compared to 6m operation (23.5% at 30W). Tests verified that jumper configurations had no effect on filter selection. The author warns that using these radios on 4m may violate license conditions due to excessive spurious emissions.

Amateur Radio Station owned by Matt Strelow. The station is designed for competition in the multi-operator multi-transmitter category of high-frequency DX contests. Running with 7 towers 6 rotators, 8 beverage listening antennas, and 4 spotting verticals

A small antenna for limited space / lanai use.

List of north america beacons transmitting on vhf and uhf bands compiled by WZ1V

Presents a dynamic, searchable database of shortwave broadcast schedules from around the world, enabling users to locate active stations or plan listening sessions based on scheduled transmission periods and frequencies. The resource details specific station names, such as _Radio Habana Cuba_, _Deutsche Welle_, and _All India Radio_, alongside their operational times and assigned kilohertz frequencies. It also incorporates a distance calculator, which leverages geographical coordinates to estimate propagation paths, though it notes occasional data inaccuracies leading to transmitters appearing in oceanic locations. The platform's development log highlights continuous updates, including the integration of new seasonal schedules like "A24 frequencies" and "B23 schedule," reflecting the fluid nature of shortwave broadcasting. It documents challenges with geolocation services, particularly concerning Google API changes that impacted distance calculations and required user-side browser configuration adjustments for optimal functionality. The site owner, VAXXi, frequently communicates these technical adjustments and database updates, often acknowledging user contributions and donations. Distinctively, the resource provides a historical perspective through its update archives, illustrating the evolution of shortwave listening over more than a decade since its inception in 2011. It also mentions specific events, such as the BBC adding shortwave broadcasts for Ukraine on 5875 kHz and 15735 kHz, demonstrating its responsiveness to global events impacting broadcast schedules. The site's commitment to user feedback is evident in its bug reporting and feature request mechanisms, contributing to its ongoing refinement.

This program demodulates the telemetry data signal transmitted by the AO-40 satellite (aka Phase III-D) using the PC sound card

Ram mounting systems is a world leader for design and manufacturing of mounting applications. ram mounts offer more than 900 interchangeable components for unlimited uses and configurations.

A freeware apple Macintosh-based program that helps amateur radio contesters by converting a log from a radio contest into the Cabrillo file format which may be submitted to the contest sponsor.

Since February 2002, 3830scores.com has served as a central repository for amateur radio contest score rumors, allowing contesters to quickly post and view claimed scores and comments. The platform facilitates the sharing of **claimed scores** for numerous contests, including the ARRL DX Contest, CQ WPX RTTY Contest, and various QSO Parties. Users can access submittal forms for current and recent contests, with options to define and save default form values for efficiency. The site also provides links to the 3830 Reflector, where submissions are posted, fostering immediate community engagement regarding contest performance. Summaries of all submitted scores are instantly available, offering line scores, **band/mode breakdowns**, and compilations of operator comments. Historical summaries for major contests extend back to 2002, with all contest data accessible from 2007. The platform includes a search function to locate all postings associated with a specific call sign and a 'Compare Scores' feature, enabling side-by-side analysis of multiple calls across different contest editions or a single call's performance over several years.

Codec2, an open-source speech codec, targets low bit rate voice communication, specifically designed for digital radio applications operating within constrained bandwidths. The project focuses on achieving intelligible speech quality at data rates around 2400 bits per second, a critical parameter for efficient spectrum utilization in amateur radio. Its development addresses the need for robust voice transmission over channels where higher bit rate codecs would be impractical or inefficient. The resource details the technical specifications and implementation aspects of Codec2, including its underlying algorithms and performance characteristics. It provides insights into how the codec processes speech to achieve its low bit rate, outlining the various coding schemes and their impact on voice fidelity and error resilience. The information presented allows radio amateurs and developers to understand the codec's operational principles and its suitability for integration into custom digital communication systems. Applications for Codec2 extend to digital voice modes on HF and VHF bands, enabling more users to share limited spectrum resources. The project's open-source nature facilitates community contributions and widespread adoption, fostering innovation in digital amateur radio. It represents a significant effort to provide a freely available, high-performance speech coding solution for the amateur radio community.

Engineering Solutions for Unique Problems. Manufacturer of high Voltage, high Current, high Power Power Supply

Free memory management software for the Yaesu FT-991 and FT-991A models. It runs only on Windows 7, 8, 8.1, 10 both 32 and 64 bits, it also permits basic remote control features and allow backup and restore settings and memories. Documentation in mainly in French.

TAHO.EXE, an open-source software, facilitates the creation of APRS maps for _UI-View_ by converting free data from _OpenStreetMap_ into the required *.JPG and *.INF file formats. This utility, developed by Dimitri Junker with specific UI-View format support added at the request of HB9DTX, streamlines the process of integrating detailed geographical information into the _UI-View_ platform. It operates on Windows, generating map files with border coordinates in just a few clicks, eliminating the tedious manual creation of *.INF files for custom maps. This converter allows UI-View users to leverage the continuously updated and community-contributed data of OpenStreetMap, which often surpasses commercial map quality in specific regions. The process is straightforward, with a detailed step-by-step guide available on the OpenStreetMap wiki, translated into French and German. TAHO.EXE significantly enhances the utility of UI-View by providing a readily accessible and continuously improving source of detailed, current geographical maps for displaying APRS station positions and objects.

TX RX Systems Inc. offers a robust catalog of RF conditioning products, including **transmitter combiners**, receiver multicouplers, and various RF filters. Their extensive experience, spanning over 45 years in the RF and Land Mobile Radio (LMR) industries, underpins their specialized offerings. They provide solutions for in-building RF coverage, repeater systems, and general RF management, catering to the demanding requirements of professional radio communications. Their product line features **bidirectional amplifiers (BDAs)**, signal boosters, and cavity filters, essential components for optimizing radio system performance. The company emphasizes reliable solutions, leveraging decades of field-proven expertise in designing and manufacturing critical RF infrastructure. From duplexers to cell enhancers, TX RX Systems focuses on delivering high-quality RF components and integrated systems designed to ensure clear and consistent radio signal integrity across diverse operational environments.

Details Guglielmo Marconi's foundational contributions to radio communication, highlighting his 1898 Patent **7777** which introduced tuning circuits for independent simultaneous communications. Chronicles the historic transatlantic reception of the Morse code letter 'S' on December 12, 1901, from Poldhu, Cornwall, to St. John's, Newfoundland, a distance of over _3,500 kilometers_. The exhibit showcases early Marconi 10-inch spark transmitters, identical to those used on the _Titanic_, alongside Canadian Marconi crystal detector models. It also features high-end commercial receivers like the IP501, weighing **87 pounds** and originally priced at $595.00, demonstrating the robust construction and technological advancements of the era.

Small, but growing, group of amateur radio enthusiasts, most of whom are within 90 miles of Atlanta, are interested in promoting the development of the branch of amateur radio known as QRP - building and operating low power transmitters, receivers and transceivers.

The UK amateur radio licensing scheme features three distinct tiers: Foundation, Intermediate, and Full, each granting specific operating privileges. For instance, the **Foundation Licence** permits a maximum of 10 watts output power on most allocated bands, with restricted band access. The Intermediate Licence allows up to 50 watts, while the **Full Licence** grants access to the maximum UK legal power limits and all available amateur radio band allocations. UK call sign prefixes and formats provide insights into the licensee's class and the approximate issuance date. For example, M3, M6, and M7 prefixes with three letters denote Foundation Licences issued from 2002, 2008, and 2018 respectively. Intermediate Licences, often starting with "2E0" or "2E1" followed by three letters, were issued from 1991 onwards. Full Licences encompass a broader range of prefixes like G2, G3, G4, G0, and M0, with varying letter counts indicating different historical license classes and issuance periods, such as G3 plus three letters issued between 1946 and 1971. Special prefixes like GB are reserved for repeaters, beacons, data mailboxes, and special event stations, with specific numerical sequences (e.g., GB3 for repeaters, GB7 for data repeaters/mailboxes) indicating their function. Optional prefixes such as GC, GD, GI, GM, and GW denote specific UK countries (e.g., Wales, Isle of Man, Northern Ireland, Scotland, England) and can also signify club stations.

How to operate on 10 and 20 meters in limited space with this trapped dipole.

The two linear amplifiers are ment for use with QRP SSB/CW/FM/AM transmitters on the amateur bands 15 and 17 meters can be powered from a 12 volt DC supply by ON6MU

SimSmith is a highly interactive, real time Smith chart graphing program. Circuits are constructed using drag-n-drop. Load files can be imported from the EZNEC and CocoaNEC antenna simulation software and from the AIM4170 and miniVNApro antenna analyzers. Circuits and load files can be of any size. Key Features: SimSmith is one of the few Smith chart packages which models transmission line losses. SimSmith also allows the description of circuit elements using algebraic equations. SimSmith has only one screen and allows the screen to be resized to increase workspace or readability.

ChirpPix converts a bitmap image to a wave file, which can then be sent by a SSB transmitter and received on spectrogram waterfall displays Image Transmission using ChirpPix and ChirpHell. Click to donwload ChirpPix zip file.

Replicating vintage radio components addresses the challenge of restoring classic receivers and transmitters to their original aesthetic and functional condition. Many historical radios, particularly those from the _Golden Age of Radio_ (1920s-1940s), suffer from brittle or missing control knobs and trim pieces, making authentic restoration difficult. This resource focuses on manufacturing new parts that precisely match the originals, ensuring period-correct repairs. The service offers a vast catalog of reproduced items, with thousands of molds created since 1987. This extensive inventory includes a wide spectrum of knobs and pushbuttons, along with some plastic escutcheons, grills, and handles. The meticulous reproduction process ensures that restorers can find accurate replacements for brands like Philco, Collins, and Atwater Kent, preserving the historical integrity of these valuable pieces of radio history. The owner, Larry Bordonaro, has been in business since 1987, demonstrating deep experience in this niche.

An attic antenna for 40 and 80 meters band by NS1W

Minimal interface circuits for receiver and transmitter audio, also for PSK31

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.

Develops and manufactures radios and telecommunication devices for special applications. SDR Receivers, Digital HF transmitters, Digital SSB Exciter.

Feld hell freeware windows program that permits RTX hellschriber operations by PA3BQS

The Smith Chart was originally created many years ago as an RF engineering aid by Phillip Smith of RCA.These pages includes extesnive documentation on smith carts.

Beaconmap is a Win95/98/NT program to help listeners to identify the beacon stations of the NCDXF/IARU beacon network. The program displays a flashing dot at the location of the beacon that is currently transmitting. The call sign of the beacon, as well as the QTH is shown in the status bar. By PA1ARE

Displays the actual transmitting beacons of the NCDXF/IARU Beacon Project.