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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.

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

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

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

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.

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.

TX RX Systems Inc. manufactures signal boosters, rf antennas, transmitter combiners, cell enhancers, land mobile radios, duplexers, receiver multicouplers, bidirectional amplifiers, bda, rf amplifiers, rf filters, rf cavity filters, rf combiners, rf components, in building rf coverage, repeaters, repeater amplifiers, rf management equipment, rf systems, and rf solutions. TX RX Delivers Reliable Solutions.

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

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.

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

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

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.

This modification will allow the MkIIG to transmit on most of the frequencies that it receives on.

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.

RF and Microwave Power Amplifier and Transmitter Technologies, amplifierlinearity, efficiency and available RF power devices.

The Collins 516F-2 is a heavy-duty power supply for the KWM-2/2A transceivers and the 32S-1,2,3 series of Collins transmitters.

Simple circuit, with a simple push, transmit a memorized Cw messages

Bird Technologies supplier of RF products, like RF Meters, Bird 43, VNA, Spectrum analyzers, attenuators, transmitters combiners, dummyloads, terminators and replacement parts

Packet-Radio-Controller for amateur radio, CB and commercial applications. Data radios (transceivers), receivers and transmitters for high speed data communication Assemblies for satellite ground stations, special receivers and transmitters.

Key your transmitter from the tone output of a Morse Code generator program

Part 2 - Ten-Tec Jupiter CW copying and keyboard transmit

Iphone app for ncdxf IARU beacon monitoring, shows the currently transmitting beacon on each band, reception charts from the active monitoring stations, and latest solar flux A and K indices

How to build a simple WSPR beacon using the Raspberry Pi for the transmitter

A radio's transmitting power can be concentrated along the horizon by use of a GAIN antenna. Although you may still be transmitting with four watts of power, your effective radiated powerwill be greatly increased. This table shows the effects of antenna gain on a transmitter with 4 watts of transmit power.

The NCDXF/IARU International Beacon Project operates a worldwide network of 18 high-frequency radio beacons, continuously transmitting on 14.100, 18.110, 21.150, 24.930, and 28.200 MHz. These beacons, initially launched in 1979 with a single station and expanded to the current 18-beacon system in 1995, provide reliable signals for both amateur and commercial users to assess current **ionospheric propagation** conditions. The system's design, construction, and operation are managed by volunteers, covering hardware and shipping costs. The resource details the evolution of the beacon network, including the transition from Kenwood TS-50s transmitters to Icom IC-7200 radios with a new controller design implemented in 2015. It explains how listening for these 100-watt signals, transmitted to vertical antennas, allows operators to determine band openings and optimal propagation paths globally. The content also references three QST articles providing historical context and technical specifics of the beacon project. Practical information includes methods for identifying transmitting beacons via a schedule or specialized software like FAROS and Skimmer, which integrates with the **Reverse Beacon Network** for automated monitoring.

Maker of QRP Kits, QRP CW receiver and transmitters, audio CW Filters, antenna tuners, dummy loads, and morse code practice oscillator

One another useful Table for the HAM's practice.

40 meters band 5 watts transmitter, uses a 6L6 with a 6X5 rectifier and a 0D3 voltage regulator tube on the screen.

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.

Optimizing a G5RV or ZS6BKW multiband wire antenna for HF operation often involves addressing common SWR issues and understanding feedline characteristics. This resource chronicles the construction and performance evaluation of a G5RV, initially built for 80m, 40m, 15m, and 10m bands, by a newly licensed Foundation operator. The author details the selection of materials, including 3.5 mm stainless steel wire for the doublet arms and enameled copper wire for the open-wire feeder, and the initial decision to omit a balun based on common online information. The narrative highlights the initial disappointing performance, characterized by high receive noise and poor signal reports on 80 meters, despite the transceiver's internal ATU achieving a 1:1 match. This led to experimentation with a coax current balun and further research into G5RV myths, such as SWR claims and the necessity of a balun. The author then describes modifying the antenna to the ZS6BKW configuration, which involves specific changes to the doublet and feedline lengths, and integrating a 1:1 current balun wound on a ferrite toroid. The modifications resulted in improved reception and transmit performance across the bands.

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.

Presents a QRP AM/CW transmitter project specifically designed for the 10-meter band, utilizing a crystal oscillator and a collector-modulated AM oscillator. The design employs a 2N2219(A) transistor in a Colpitts configuration, generating 100 to 350 mW of RF output power depending on the 9-18 Volt supply voltage and modulation depth. Frequency stability is maintained by a 28 MHz crystal, with fine-tuning possible via a Ct1 trimmer capacitor for approximately 1 kHz adjustment. The resource details the RF oscillator stage, implemented with a 2N2219 NPN transistor, emphasizing frequency stability and low power dissipation. It also covers the amplitude modulation stage, managed by a 2N2905 PNP transistor, which impresses audio information onto the carrier. Selective components (C3, C4, C7, C5) enhance voice frequencies within a +/- 5 kHz bandwidth, and modulation depth is controlled by R2 and R3. The project includes a 3-element L-type narrow bandpass filter (Ct3, L3, C10) to suppress harmonics and ensure a clean output signal. The project provides a complete schematic diagram, a comprehensive parts list including specific capacitor, resistor, and inductor values, and construction notes for the coils (L1, L2, L3). It also offers practical advice on enclosure requirements, suggesting an all-metal case or a PVC box with graphite paint for RF shielding. Operational parameters such as current draw (27mA@9V to 45mA@16V) and input impedance (50 Ohms) are specified, alongside guidance on antenna matching and the importance of a valid amateur radio license for 10-meter band operation.

A switchable Magnetic Transformer for Transmitting for various impedances

Live DX spots are presented through a _web cluster_ interface, utilizing both a world map and a Google Maps display for visualizing amateur radio propagation. The system provides real-time spotting data, enabling operators to track active stations globally. Users can observe current band conditions and station activity, which is crucial for optimizing contact strategies across various amateur bands. The platform's utility extends to contest operations and general DXing, offering a visual representation of where stations are being heard. While the primary function is DX spotting, the site also includes technical articles, such as instructions for interlocking two Flex Radios for single-transmitter compliance in contests, and a guide for constructing a simple **5KW** 1:1 balun for **160m/80m** dipoles using RG400 cable. This combination of live data and practical technical content supports both operational awareness and station improvement.

This modification will allow the use of separate receive and transmit antennas on the Kenwood TS-850S/AT.

The Micro24 is a ultra compact microsize QRP SSB transceiver for the 20 meters amateur radio band. This transceiver is so small that it fits into one hand.

A free radio station that is transmitting world wide on several shortwave frequency 's with loads of pirate and freeradio information.

The Yaesu VX-5R, manufactured between 199x and 200x, offers a transmit frequency range covering 50-52 MHz, 144-146 MHz, and 430-440 MHz for European models, with US versions extending to 50-54 MHz, 144-148 MHz, and 430-450 MHz. Its receiver boasts an impressive wideband capability from 0.5 MHz to 999 MHz, with cellular frequencies blocked in some regions. The unit provides up to 5 watts RF output on 6 meters and 2 meters, and 4.5 watts on 70 centimeters, with selectable lower power settings down to 300 mW. This handheld transceiver utilizes a double conversion superheterodyne receiver system, featuring a 47.25 MHz first IF for FM and 45.8 MHz for WFM. Key specifications include a frequency stability of ±5 ppm across a wide temperature range and a current drain of 25-150 mA on receive. The VX-5R supports 220 regular memory channels with alpha tags, 3 home channels, and 10 NOAA weather channels, all stored in non-volatile EEPROM. Additional features include CTCSS/PL and DCS with tone search, ARS, ARTS, an internal voltmeter, and a Spectra-Scope. The device operates on a 7.2 VDC battery pack or 10-16 VDC external power, weighing 255 grams with dimensions of 58x88x27 mm. The VX-5R was also available as the metallic silver VX-5RS.

Article about small magnetic loop antennas with notes on realization of magnetic loops for several HF bands and the six meter band

The information in this article has come from many amateur sources, the most notable was from WA6TEY (sk 1985) Ray Frost, who was a pioneer of VHF Quad designs and one of the best Southern California Transmitter Hunters. Ray built hundreds two meter quads in single and paired configurations as well as his famous mobile radio direction finding quad.

This circuit stores a single morse code message as bits in an EPROM chip, the message is sent to a relay which can key a CW transmitter.

This is the schematic of asolid-state 7 MHz QRP CW transmitter by VU2NAN

Amateur Television products, online store for ATV transmitters receivers, LCD controllers, wireless cameras, video senders, accessories, power amplifiers based in UK

Understanding Common Mode and Differential Mode Currents on Transmission Lines by K9YC

The 80m TX described here is the well known ON7YD ATX-80 and timer, combined and re-engineered to fit a readily available enclosure by G3ZOI

Examines the Icom IC-2100H 2-meter mobile transceiver, detailing its operational characteristics and user experience. The review highlights the clear, easy-to-read display with internal labels, the button-filled microphone's functionality, and the rig's physical construction, including its weighty heat-sink and lack of a cooling fan. It also discusses memory programming, the unique amber-to-green backlight color options, and the radio's performance against _intermodulation_ in urban environments, noting it performs "pretty darn good" compared to other rigs. The analysis delves into a significant low-voltage cutoff problem, where the microphone ceases to function below approximately **12.6 VDC**, rendering the radio receive-only or causing it to stick in transmit. The author describes testing the voltage cutoff, observing it fluctuate from _12.38 VDC_ to 12.69 VDC. An update from Icom involved a "factory update" to the CPU's control code, which is strongly recommended for early-serial number units to prevent operational failure in low-power emergency scenarios.