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Circuits of SSB Transceiver, AM DSB Transmitter, Antennas, BFO, VFO, 807, FM Mike, Crystal filter and more.

Harry Lythall SM0VPO/G4VVJ homebrew web site, contains several projects, antenna notes and plans, receivers and transmitters plans, regularly updated.

Monitoring shortwave broadcast stations effectively requires accurate schedule information to identify transmissions. This online utility offers a straightforward, graphical interface designed to search for and display current shortwave radio broadcasting schedules. Users can precisely filter results by frequency, specific language, broadcaster, time of day, and even by shortwave band, which simplifies the process of pinpointing desired content. The database, last updated on March 26, 2023, details station callsigns (e.g., BBC), start and end times in UTC, days of the week, broadcast language, transmitter power in kilowatts, and azimuth. Crucially, it includes the precise geographical coordinates of transmitter sites, such as Woofferton in the UK or Al Seela in Oman. This data is invaluable for predicting signal paths and optimizing antenna direction for improved reception, a key consideration for serious SWLs. For instance, a search for BBC English broadcasts at 21:04 GMT quickly reveals multiple active frequencies like 17780 kHz from Woofferton, offering a clear overview of current transmissions. The tool processes queries rapidly, returning results within seconds, demonstrating its efficiency for broadcast listening enthusiasts seeking timely information.

This is a radio frequency propagation calculator for the transmission path between an RF transmitter and a receiver.

End-Fed antennas are NOT balanced systems; but neither are verticals, ground planes, discones, windoms, zepps, Marconis, half-slopers, et al. Additionally, the low-impedance antenna port of your transmitter/receiver is not balanced.

This article describes how to make a quadrifilar helix (QFH) antenna easily, from inexpensive materials: uPVC plumbing pipe and RG-58U co-axial cable. A low-cost, easy-to-build Quadrifilar Helix (QFH) antenna for weather satellite reception using uPVC plumbing pipe and RG-58U coaxial cable. Unlike traditional designs requiring copper pipe and plumbing skills, this approach enables construction with basic tools and minimal technical expertise. The antenna's shorter, wider proportions favor higher elevation angles, reducing interference from horizon-level pager transmitters. Electrical connections are simplified at the antenna's apex, with the coaxial cable forming the radiating elements. Testing demonstrated consistent signal strength throughout satellite passes, proving effective weather satellite reception is achievable without precision engineering to sub-millimeter tolerances.

Presents a collection of homebrew amateur radio projects and circuit ideas developed by EA5/G3PTO, a licensed operator since 1961. The resource details various transmitters and receivers constructed for frequencies ranging from 1.8 MHz to 10 GHz, emphasizing CW and BPSK31 operation. Specific projects covered include a "Bombproof 7Mhz Receiver" and several keying circuits, providing insights into designs that have proven effective over decades of use. The site also integrates personal photography, showcasing scenes from the West of England and Southeast Spain, reflecting the author's interest in connecting with other amateurs and visualizing their locations. Additionally, it offers a curated list of links to other home construction sites and DX information, serving as a hub for DIY enthusiasts and DXers. The content is distinctively personal, blending technical project documentation with a broader view of the amateur radio lifestyle and community engagement.

A very quick and easy way to get on the air is to build a "Michigan Mighty Mite" CW transmitter for 160, 80, 40 or 30 meters. It can't get simpler than this. It has very few parts, costs almost nothing, and it works! Cost estimate $10 by VE6WTF

Lots of information of hidding transmitters, building portable yagi antennas, s-meters, and much more

Presents a crystal-controlled CW transmitter design for the 40-meter band, delivering 5 to 7.5 watts output power. The circuit innovatively employs an _IRF510_ power MOSFET in the final amplifier stage, diverging from conventional bipolar transistors. This design offers high gain, nearly 90% efficiency, and robust resistance to high SWR, allowing 30-second key-down operation into an open circuit without damage. A critical aspect is the precise adjustment of the MOSFET gate bias via a 10K trimmer pot, _R10_, to maintain quiescent current between 5 and 10 mA, preventing thermal runaway inherent to bipolar devices. The prototype was constructed on a _Radio Shack universal board_ and achieved immediate operational success. The design requires a 15-volt Zener diode to protect the MOSFET gate from overvoltage. Component sourcing information is provided, including specific crystal frequencies (7.040 MHz or 7.122 MHz) available from _Dan’s Small Parts & Kits_ or Doug Hendricks. The fixed frequency can be slightly adjusted with a trimmer capacitor. A complete bill of materials, including resistor values, capacitor types, toroid specifications, and transistor part numbers, is detailed, alongside a clear schematic diagram.

Selecting an appropriate antenna system for shortwave broadcasting involves evaluating various types based on performance, cost, and operational parameters. This resource details the critical specifications for broadcast antennas, including average and peak power ratings, directivity, takeoff angle (TOA), horizontal beamwidth, and gain, emphasizing that a 100-kW transmitter requires an antenna rated for 150 kW average and 400 kW peak. It clarifies that low TOA signals travel thousands of kilometers, while high TOA is for local coverage, and nearly all modern shortwave broadcast antennas are horizontally polarized. The article explores specific antenna types, such as Log-Periodic Antennas (LPAs), which offer wide frequency ranges (e.g., 2-30 MHz) and directional patterns with 11 dBi gain, costing from $20K to over $100K for multi-curtain versions. Dipole arrays, also known as curtain antennas, are prevalent in international broadcasting, featuring steerable beams (±15° and ±30°) and mode-switching capabilities to alter TOA, with high/low pairs costing over $1 million. Fan dipoles are noted for omnidirectional patterns, smaller size, and lower cost for low-power applications, while rhombics, though simple, require resistive termination and incur several dB of I2R losses. Balun considerations are crucial, as most communications baluns are not rated for the higher average and peak powers of AM broadcast transmitters. Modern shortwave antennas utilize durable materials like Alumoweld wire rope for radiators and support elements, avoiding copper, fiberglass, or materials prone to stretching or deterioration. Feeder systems for high-power stations often require tapered-line baluns to convert 50-ohm unbalanced power to 300-ohm balanced for connection to the antenna.

BeaconSee shows you, in real time, worldwide HF band openings on your PC. Analyses the audio signals from your radio, which is tuned to the NCDXF IARU HF beacon network and shows you the signal strength received from each of the 18 beacon transmitters as a plot of frequency spectrum against time.

Repeaters, transmitters and receivers manufacturer for ham radio and commercial applications

We are manufacturers and re-sellers of a wide range of AM, FM and Shortwave broadcast transmitters, kits and related products.

This project shows how to build a 50-ohm dummy load using non-inductive resistors, oil for heat dissipation, and a simple assembly process. It enables accurate transmitter tuning, testing, and power measurement across LF to UHF bands. The setup allows meter calibration by measuring peak voltage, applying diode drop correction, and calculating RMS voltage and power precisely. Parts are inexpensive and widely available. With proper assembly, this dummy load offers extended service life, accurate readings within 2%, and a reliable alternative to costly commercial wattmeters for amateur radio applications.

Transmitter power limits and frequencies allocation by band

N6QAB Radio Direction Finding Web Site, DF vehicles, transmitters, sniffers, dopplers, TH-D7A

Easy to use double tone IQ-generator for testing direct conversion SSB-transmitters based on phasemethod etc.

Manufacturer of popular TinyTrak APRS Tracker offer Packet radio tools, wxtrack interfaces, TinyTrack3, a GPS position encoder, PicCon controller for transmitter hunting, GST-1 and GST-2 GPS format converters, and PeekPack, a packet radio monitoring tool.

Do your multiple-transmitter field day or contest efforts suffer from intrastation interference ?

The CW Decoder program facilitates copying Morse code with a computer, displaying decoded CW as text, and generating a sidetone. It incorporates a spectrum display of the audio, allowing operators to select a specific audio frequency for decoding via a sliding cursor. This utility also enables keyboard-based transmitter keying, supporting full CW break-in operation for efficient QSO management. Developed by WD6CNF, the software is a Windows-compatible application designed to assist amateur radio operators in their CW activities. Its features cater to both decoding received signals and transmitting via keyboard input, streamlining the CW operating experience. Functionality includes real-time audio analysis and signal processing, providing a visual representation of the CW signal. The program's integrated keying capability offers a direct interface for transmitting, enhancing its utility as a comprehensive CW station tool.

40 meter transmitter by K9GDT

Repeaters, transmitters, receivers, small power Amps and Controllers

Large selection of affordable and fun hobby kits as well as a really neat selection of electronic gear. Transmitters and receivers kits, test equipments, RF test enclosures.

This program will run all possible combinations of every transmitter against every receiver in its list

The article "Exploring the World of 10 Meter Beacons" by Ken Reitz, KS4ZR, provides an in-depth look at 10-meter beacon operations, focusing on their utility for propagation analysis. It details FCC Rules part 97.203 governing beacon stations, including license requirements, power limits (under 100 watts), and the specified band segment of 28.200-28.300 MHz for U.S. operations. The content highlights the diversity in beacon construction, from converted CB radios to home-brew QRP transmitters, and discusses the robust operating conditions these 24/7 stations endure. The resource presents several case studies of active 10-meter beacon operators like Ron Anderson KA0PSE/B, Domenic Bianco KC9GNK/B, and Bill Hays WJ5O/B, detailing their equipment, antenna setups, and typical signal report volumes. It also introduces the NCDXF/IARU International Beacon Project, which features 18 synchronized beacons worldwide transmitting on 28.200 MHz at varying power levels (100W, 10W, 1W, 100mW) to facilitate propagation testing. The article also covers the PropNet Project utilizing PSK31 on 28.131 MHz and the 250 Synchronized Propagation Beacon Project on 28.250 MHz. Practical advice for monitoring includes using the RST reporting method, understanding the impact of the solar cycle on 10-meter propagation, and tips for setting up a personal beacon, such as frequency selection and power output considerations. The IY4M Guglielmo Marconi Memorial Beacon Robot on 28.195 MHz is also mentioned for its automatic QSO mode. The article concludes with a list of other resources for 10-meter beacon information.

The page provides detailed information on coax stub filters for multi-transmitter setups, including specific lengths for different bands and types of coax. It also references additional technical notes for further analysis.

This resource catalogs a significant collection of historical military radio equipment, detailing various sets from World War II and the Cold War eras. It presents information on British, German, Japanese, USA, and other nations' wireless apparatus, including specific models like the _WS-19_, R1155, and WS-18, alongside clandestine spy equipment. The content covers the preservation and restoration of these historical items, with research results published on the site. The site provides dedicated sections for different national origins of equipment, such as "British sets," "German sets," and "North American sets," allowing for focused exploration of specific military communication technologies. It also features specialized pages on topics like the _Enigma machine_, PARASET builds, and historical events such as Arnhem and D-Day, contextualizing the use of these radios in significant military operations. The collection includes detailed descriptions and images of transmitters, receivers, and associated gear. The museum, located in Kidderminster, Worcs, U.K., organizes physical exhibitions and actively seeks new equipment for its collection, emphasizing its role in preserving military radio history.

Easytuner id an excel spreadsheet that tunes your radio. Works with all Kenwood and Icom receivers and transceivers that are computer-controllable. Sets receiver and transmitter frequency and mode

Constructing a Lindenblad antenna for 137MHz NOAA satellite reception involves specific design considerations for optimal performance. The resource details the use of 4mm galvanised steel fencing wire, 300-ohm television ribbon cable, and wood/plastic components for the antenna structure. Key dimensions for a 137.58MHz-resonant antenna are provided, derived from the ARRL Satellite Handbook, specifying s, l, w, and d as 42, 926, 893, and 654mm respectively. The antenna is designed for Right Hand Circularly Polarised (RHCP) signals, requiring the four folded dipole elements to be tilted clockwise by 30 degrees. A significant aspect covered is impedance matching between the antenna's 75-ohm impedance and a typical 50-ohm receiver input. A twelfth-wave matching transformer, constructed from 117mm sections of 50-ohm RG-58 and 75-ohm RG-59 coax with a 0.66 velocity factor, is described. The article also addresses coaxial cable and connector selection, recommending 75-ohm Type-N connectors for RG-6 cable in professional setups and F56/F59 connectors for general use, while strongly advising against PL-259/SO-259 connectors for VHF. Strategies for mitigating Radio Frequency Interference (RFI) are discussed, including antenna placement to shield from local TV transmitters and the use of commercial or DIY band-pass filters, such as cavity resonators or helical notch filters, along with ferrite chokes on coaxial cables. Antenna orientation is explored, noting the Lindenblad's 'cone of silence' directly overhead and its maximized sensitivity towards the horizon. An experimental vertical tilt of 90 degrees is presented as a method to improve overhead reception and reduce interference from strong horizontal signals, particularly relevant in high RFI environments like the Siding Spring Observatory site.

N7KSB used this 1/2 watt CW transmitter, with a roof-mounted ground-plane antenna to work all continents and over 30 countries

The RigPix database entry provides a comprehensive technical overview of the Icom IC-746 amateur HF/VHF transceiver, detailing its operational parameters and physical characteristics. It specifies the transmit frequency ranges across 10-160 meters plus WARC bands, 50-54 MHz, and 144-146/148 MHz, alongside receive coverage from 0.03-60 MHz and 108-174 MHz. The resource outlines supported modes including AM, FM, SSB, CW, and RTTY, noting a tuning step resolution down to 1 Hz and a frequency stability of ±5 ppm. Key electrical specifications are presented, such as a 13.8 VDC power supply requirement, current drain figures for RX (1.8-2 A) and TX (Max 20 A), and RF output power ranging from 5-40 W for AM and 5-100 W for FM, SSB (PEP), and CW. The entry details the triple conversion superheterodyne receiver system, listing IF frequencies at 69.01 MHz, 9.01 MHz, and 455 KHz, along with sensitivity ratings for various modes and bands. Transmitter section specifics include modulation systems and spurious emission levels. Additional features like a built-in auto ATU, electronic keyer, simple spectrum scope, DSP, and CI-V computer control are noted. The page also lists related documents, modifications, and an extensive array of optional accessories, including various filters, microphones, and external tuners, providing a complete profile of the IC-746.

CwType v2.35 provides a dedicated terminal interface for **CW operators**, facilitating Morse code transmission from a Windows PC. Users can input characters via the keyboard or a connected paddle, supporting iambic keying. The software manages transceiver control, including PTT and CW keying, through COM or LPT ports. It offers adjustable speed, dash/dot ratio, and inter-letter spacing, with real-time speed display in LPM and WPM calculated by the "PARIS" method. The program includes features like MOX mode for automatic TX on/off, configurable weighting to compensate for transceiver element clipping, and programmable F-key macros for sending predefined text or special sequences. CwType can integrate with logging software such as AALog (V1.0.3 and later) for data transfer, and supports various character sets including English, Russian, and Swedish. A beacon mode is also available, executing the Alt-F12 macro periodically at a user-defined interval. Audio output for monitoring can be routed through the internal PC speaker or a sound card, with options for sine waveform and smooth envelope generation for SSB transmitters. The software is compatible with **Windows XP/Vista/7/8/10** and is distributed as freeware.

Dutch society of collectors of old ex-military radio equipment and other nostalgic receivers and transmitters

RF Path design software, tower coverage mapping software to evaluate radio transmitter sites, predict and simulate radio coverage, plan land mobile radio or cellular systems. Commercial RF coverage mapping software by Softwright llc.

Manufacturers of high performance low power am transmitter products: sstran amt3000, bc-100, and the mw-250. for home and professional use.

Build this simple and cheap 70 MHz Exciter and start to transmit Digital Television by Jean-Francois Fourcadier

The project outlines the process for constructing a low-power FM broadcast transmitter using a Raspberry Pi Zero, a simple wire antenna, and battery power. It details the software installation steps for PiFM and MPG123, essential for generating and transmitting audio. The resource provides instructions for configuring the Raspberry Pi to broadcast FM signals, including command-line operations for initiating transmission and playing audio files. It specifically focuses on the Raspberry Pi Zero's capabilities for this application, highlighting its cost-effectiveness and minimal hardware requirements. The content presents a practical, hands-on approach to creating a basic FM transmitter, suitable for short-range, experimental broadcasting. It includes guidance on testing the FM output and ensuring proper operation of the software components. The project emphasizes the use of readily available components and open-source software to achieve functional RF output.

VHF quad antenna for transmitter hunting.

Now home to over 1,000 radios and transmitters dating from the spark era up to.

VU2VWN project to homebrew a CW for 40 meters band

80 metre ceramic resonator VXO CW Transmitter by VK1PK

A multi-mode QRP radio beacon built around the Arduino. This radio propagation beacon transmitter project is presented by M0XPD

FDLog, a Python-based freeware application, addresses the challenge of synchronized logging for multi-station Field Day operations. It facilitates real-time data sharing across a wireless network, enabling operators to monitor band status and active transmitters at a glance. The software's input system is optimized for minimal keystrokes, streamlining the logging process during intense contest periods. Key features include database synchronization over a wireless network, ensuring all connected computers maintain identical log data. FDLog also incorporates a time synchronization function, designed to keep client programs within a second of a designated master machine, mitigating issues previously encountered with NTP. This internal clock sync can be optionally disabled if not required by the operating setup. Developed initially on Windows 2000, FDLog has demonstrated compatibility with _Linux_ and _macOS_ environments, though some font rendering issues may occur on the latter. The program assists in preparing the ARRL Field Day entry form, simplifying the submission of contest results. User feedback and ARRL rule changes drive ongoing development, with a discussion list available for community support and input.

One specific challenge in the KazShack, operating Single Operator Two Radios (SO2R), involved sharing a K9AY receive antenna between two transceivers without direct RF connection or manual feedline swapping. The solution, detailed in this project, adapts the **W3LPL RX bandpass filter** design to split 160m and 80m signals, feeding them to separate radio inputs while maintaining isolation. This approach also addresses the issue of strong broadcast band interference from a nearby 50KW WPTF transmitter on 680kc. The construction utilizes T-50-3 toroids and NP0 ceramic capacitors, built in a "dead bug" style on copper clad board. Each band's filter coils are identical and resonated to the desired frequency using an MFJ-259 antenna analyzer. A single DPDT relay, controlled by a remote toggle switch mounted on an aluminum panel, facilitates quick band switching between radios, simplifying low-band operations. While some signal loss is noted, the expected lower noise levels from the receive antenna are anticipated to compensate, potentially reducing the need for constant volume adjustments during toggling between transmit and receive antennas.

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.

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.

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

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

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.