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The OSCAR SIERRA BRAVO is an International DX Group. We believe in promoting friendship through radio amongst all people in the world. The membership is open to ALL radio operators regardless of their nationality, age, race, religion, politacal beliefs, and their memberships with other clubs.

Processing a single RTTY signal from a transceiver's 3-kHz audio, GRITTY employs _Bayesian statistics_ for superior decoding accuracy compared to traditional trial-and-error methods. This approach not only decodes 5-bit Baudot codes but also calculates the probability of error for each bit, enabling features like color-highlighting unreliable characters and smart squelching based on error probability rather than signal amplitude. This allows decoding of very weak signals while suppressing strong, undecodable interference, resulting in minimal garbage text. The program intelligently analyzes decoded text, comparing similar callsigns bit by bit and merging probabilities using the Bayes formula. This often allows GRITTY to determine the correct callsign and place it on the call stack even when all received copies are corrupt. The same methodology is applied to correct errors in exchange numbers and CQ/DE keywords, and to fix incorrect shift states. GRITTY offers an open API interface, documented in its Help file, for integration with other programs, allowing them to receive decoded data and mouse click events.

How to cheaply track ships using AIS and a cheap $20 software radio.

Quick reference guides for yaesu radios

Mediumwave, shortwave, and amateur bands QSL cards collection

Providing quality full color QSL cards for Ham Radio operators.

The KK7UQ computer to radio interface, sound card interfaces, IMD meters interface products

Telescopic antenna towers, fixed antenna towers, stacked and sigle section antenna towers, trailer towers, cargo trailers accessories

This article describes a project of asymmetrical hatted vertical dipole, a portable antenna that can be used for field day operations, sota, campings or even for fixed installations. This is a freestanding 20-10m antenna that is really easy to build, easy to tune and relatively easy to carry.

A homebrew dummy load is usually a combination of several parallel carbon resistors, in order to be able a final resistance of 50 Ohms.

FM dx logs, MW carrier offset monitoring, lists of RDS codes in use in the UK, London pirate bandscan and much more from a London QTH.

Generates dial tones using the Soundcard. A neat tool for sending out short sequences of DTMF tones.

QRP Station in a Bag is a complete QRP station in an old laptop PC carrying case (photo). It is a true "Work in Progress" in that wd8rif is constantly changing the contents of the bag as learn what works and what doesn't.

The Clearwater Amateur Radio Society is an active amateur radio club based in Pinellas County Florida.

Audio and waterfall images of some sounds found on the RF spectrum

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.

PTT and soundcard interface schematic by ON6MU

RTL-SDR is a very cheap software defined radio that uses a DVB-T TV tuner dongle based on the RTL2832U chipset. This is a blog about rtl-sdr, software defined radio and their developments and applications.

A well documented article about construction and analysis of a horizontally polarized halo antenna for 6 meters band by Dr. Carol F. Milazzo, KP4MD

Ham Radio repair of all major brands and models, located in Carrollton, Texas, which is just north of Dallas, and have been serving the Amateur Radio community for over 20 years.

Although a magnetic loop antenna(aka small loop antenna) is very compact, its efficiency is close to a half-wavelength dipole if carefully built.

IC820H or other Icom Radios Soundcard interface for VHF EME use by DF9CY

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.

The Peaberry SDR is the first and only do-it-yourself transceiver that doesn't require adding sound cards to your computer.

QSL Cards from ALL 338 DXCC Entities, deleted countries QSL Cards, other interesting cards

Need to interface both a TNC and the computer soundcard? This is a ICOM 756PRO ACC1 audio/keying/FSK interface by WA0SXV

VoiceKeyDeluxe (VKD) will convert your sound card into a powerful and versatile digital voice keyer for contest or EME operations by N7QJP

North Carolina ARRL Section Information

The club was founded in 1981 by 17 Charlotte-area hams interested in DXing & contests

Adjusting audio output of your soundcard to obtain a perfect PSK signal from your transmission. A project to help you tuning your PSK31 emission.

Accurately determining an antenna's feedpoint impedance is crucial for optimal performance, especially when experimenting with new designs or making adjustments. While SWR meters provide basic information, a full complex impedance measurement reveals the resistive and reactive components, which are essential for proper matching. Modern antenna analyzers, like the _Palstar ZM30_ or MFJ259B, simplify this task, but measurements taken through a transmission line require careful interpretation due to impedance transformation. This resource details a calibration method to precisely account for the effects of the feedline. It explains how a transmission line can significantly alter the measured impedance, illustrating this phenomenon with a Smith Chart example where an 80m antenna's [22 + j6] Ohms feedpoint impedance transforms to [82 + j45] Ohms after a 10m line. The guide demonstrates using a transmission line calculator applet, such as the one by W9CF, to reverse this transformation. It outlines the process of calibrating a specific length of RG174 coax, showing how an initial 26ft estimate was refined to **25.85ft** to accurately predict a known 22 Ohm load, significantly improving accuracy over uncalibrated results.

Collection of telegraph keys homebrew antenna projects links to radio software

BCL group in central america, caribes, about utilities, pirates and clandestins. In spanish

SignalPoint, Caribbean Contesting Consortium. Curacao. CCC's contesting QTH is the former home of PJ9JT, John Thompson, W1BIH. This historic site has been the home of many contest wins since 1971.

Establishing a robust, interconnected communication infrastructure across challenging terrain, the Island Trunk System (ITS) provides a network of open amateur radio repeaters for general and emergency communications throughout Vancouver Island, surrounding waters, and parts of the lower mainland on the West Coast of British Columbia, Canada. This system, largely off-grid, relies on solar power and batteries, necessitating careful operation, especially during night hours and low solar charging seasons, to preserve its energy resources. Maintaining the ITS involves significant effort from many hams, who appreciate adherence to regulations, including proper station identification. The system hosts a weekly social net every Monday evening at 8 PM, welcoming all participants, and also supports a Vancouver Island Region Emergency Radio Net each Wednesday at 19:15. Experimental projects like the Newcastle Ridge webcams, linked via 5.8 GHz broadband backhaul over 206 km to Nanaimo and Comox, demonstrate the innovative spirit within the ITS community. A new VHF repeater, operating on 146.880 MHz with a 141.3 Hz PL tone, was installed in Tofino, expanding system coverage.

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.

One of several Colombian broadcasting networks heard on AM and FM and worldwide on 5076 kHz in the 60 meter band.

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.

This interface is intended to be used with all the popular digital modes like PSK31, RTTY, Olivia, etc., which modulate a continuous carrier.

Echolink, EQSO, Echostation, SSTV, WEFAX, PSK-31 other digital sound card modes

An off centre fed dipole, with 10 feet of vertical radiator. It needs no tuner on 40m, 20m and 10m by M0UKD

Amateur Radio Projects & Kits for homebrewers, includes DDS,sound card interface,programmers, hamcom, frequency counter, RF Power Meter, modems and more.

Radioberry Radio hat for raspberry pi. HF (0-30 MHz) The latest development of PA3GSB is a radio card plugged into a raspberry pi (2 or 3) , a so called rpi-hat, forming an amateur radio.

A guide on writing reports to broadcasting stations and obtaining QSL cards

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.

CARF combines the wonderful world of amateur radio with Christian fellowship and service

Generates Morse tones using the Soundcard. A neat tool for sending out short sequences of Morse tones.

Amateur radio cartoons by Woody Epp W7EPP

Search-Find-View-Download SWL/Ham Call Signs world-wide. Create-Send-Receive eQSL cards on-line - free, including bureau. Much more, ALL especially for the discriminating SWL.

The SDR-908 is a software defined radio designed specifically for portable use, without the bother of being tethered to a PC or soundcard for the modulation/demodulation processing performed in this kind of radio.