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The **Extended Double Zepp** (EDZ) antenna, a simple wire design, is presented as a means to achieve 3-4 dB of gain on 10 meters, with an overall length of just 43 feet. This resource, authored by WB3HUZ, details several gain antennas suitable for the 29 MHz AM segment, all modeled using EZNEC software at 30 feet above ground. Other designs include a compact rectangular loop, offering more gain than the EDZ and a lower take-off angle, and the **Lazy H**, a bidirectional antenna providing 6 dB gain, which is also workable on 20, 17, 15, and 12 meters. The Bisquare, a diamond-shaped open-top loop, is also featured, providing approximately 4 dB gain and requiring only a single support. These designs are primarily fed with ladder line or open-wire line to simplify matching, though a coax feed option for the EDZ is shown for 10-meter-only operation. The Lazy H, for instance, requires about 16 feet of open-wire line for its half-wavelength elements spaced a half-wavelength apart. An enhanced EDZ Lazy H variant is also discussed, achieving an additional 1-2 dB gain by extending element length to 1.28 wavelengths and increasing spacing to 0.64-0.75 wavelengths. The Bisquare, while primarily a 10-meter antenna, can be adapted for 20 meters by closing the top connection.

Presents the official download hub for the _Fldigi_ suite of amateur radio software, detailing its core components and associated utilities. The resource provides direct access to executables and source code for Linux, FreeBSD, macOS, and Windows operating systems, alongside comprehensive documentation in PDF format for each application. Specific version numbers and release dates are listed for _Fldigi_, _Flrig_, _Flmsg_, _Fllog_, _Flnet_, _Flaa_, and other tools, indicating active development and maintenance. It outlines the distinct functions of each program, such as _Fldigi_ for digital modem operations, _Flrig_ for transceiver control, and _Flmsg_ for NBEMS messaging. The site also references support communities on groups.io for Linux, NBEMS, and Windows users, fostering a collaborative environment for troubleshooting and usage guidance. Furthermore, it links to third-party repositories and mirrors, including SourceForge, for alternative download options and distribution-specific packages like RPMs for OpenSUSE and COPR for Fedora. The resource also includes links to _RigCat_ XML files for transceiver control configurations and a dedicated Wiki for _Fldigi_, offering additional technical insights and build instructions. This centralized repository serves as the primary distribution point for the W1HKJ software ecosystem, ensuring users can access current versions and support materials.

Opensource software implementation of a DRM Receiver. Digital Radio Mondiale (DRM) is a new digital radio standard for the long-, medium- and short-wave ranges

CHIRP is a free, open-source, cross-platform radio programming tool that supports a large number of transceivers from manufacturers such as Icom, Kenwood, Yaesu, Alinco, Wouxun, Puxing, and Baofeng. Chirp radio software run on Windows, Linux, and macOS, enabling users to exchange data between different radio models and interface with multiple data sources and formats. The program streamlines the configuration of memory channels, frequencies, and various settings for amateur radio handhelds. Specific models supported include the _Icom IC-7300_, _Kenwood TH-D74_, and _Yaesu FT-818_, among many others. CHIRP provides compatibility with various file formats, including Generic CSV, RT Systems CSV, ARRL Travel Plus (.tpe), and manufacturer-specific formats like Kenwood KPG-44D (.dat) and Icom Data Files (.icf). Additionally, it integrates with the DMR-MARC Database for enhanced programming capabilities. Users can download CHIRP for their platform and access extensive documentation, including a FAQ and a mailing list for support. The project encourages users to consult existing documentation and open/closed tickets before submitting new bug reports or feature requests.

FlexRadio Systems delivers the first truly open source Software Defined Radio transceiver for Amateur Radio use. Receive Only versions are also available for non Amateur Radio applications. Read the SDR Articles and the SDR-1000 Product Information.

WSJT-X, a creation of K1JT, offers specialized digital protocols meticulously optimized for challenging propagation paths such as EME (moonbounce), meteor scatter, and ionospheric scatter. This software excels at VHF/UHF frequencies, and also provides robust performance for LF, MF, and HF DXing, enabling contacts far below the audible threshold. The program decodes signals from ionized meteor trails and steady signals more than 10 dB below the audible threshold, a testament to its advanced digital signal processing. It integrates nearly all popular features from its predecessors, WSJT and WSPR, while adding comprehensive rig control and numerous other enhancements for the serious weak signal operator. Available for Windows, Linux, and Mac OS X, WSJT-X is an open-source project, allowing hams worldwide to download the latest versions and engage in cutting-edge weak signal communication.

Concentric Open Loop Antenna Fed Off-Centre similar to the cobwebb antenna but resonating on 20-17-15-10 meters band

This is a project to develop an Open Source reference design for a 1500 watt solid state linear amplifier for 10 through 160 meters by K6IF

Free german Open Source HAM Logging Program unter the terms of the GNU General Public License. CLLOG runs under MS-DOS (Windows DOS-Window under 3.x,9x,NT,ME,2000) and LINUX. All Functions for Logbook.

Demonstrates the construction and on-air performance of the _NB6Zep_ antenna, a modified 20-meter Extended Double Zepp design optimized for multi-band operation from 40 through 10 meters. The resource covers basic design principles, including dimensions of 66 feet horizontal and 5 feet vertical elements, and specifies open ladder line or TV twin lead for the transmission line. It details material selection for low-cost wire antenna construction, such as 18 AWG wire for the legs and ceramic or plastic insulators, along with practical tips for soldering connections and insulating against moisture. The author, NB6Z, shares insights from extensive _EZNEC_ modeling to optimize the antenna's total length for a 40-meter half-wave dipole footprint and feed line length for direct tuner connection. The article presents field results, including successful _PSK31_ contacts from Oregon to the East Coast on 40 and 30 meters with 50 watts, even at a low height of 6 feet. It provides detailed performance characteristics for each band, noting the _NB6Zep_'s highest gain (over 3 dB) and sharp, medium-angle lobes on 20 meters, which yielded strong DX reports to locations like Korea, Japan, and Argentina. For 17 and 15 meters, it describes a butterfly-like pattern with broad lobes, while 12 and 10 meters exhibit narrow, directional lobes in an "X" configuration. The author also shares personal experiences operating successfully for over a decade in an antenna-restricted environment using the NB6Zep and other stealth wire antennas.

The Open SDR Project

An HF QRP CW RTX built around the Arduino open-source electronics prototyping platform

The ZS6BKW multiband HF antenna, a design by ZS6BKW (G0GSF), functions effectively on multiple HF bands without requiring an Antenna Tuning Unit (ATU) for 40, 20, 17, 12, 10, and 6 meters. This antenna, approximately **27.51 meters** (90 feet) long with a 12.2-meter (40-foot) open-wire feeder, is a direct descendant of the _G5RV_ but offers superior multi-band resonance. It can be deployed as a horizontal dipole or an inverted-vee, with the latter requiring only a single support and maintaining an apex angle of at least 90 degrees to prevent signal cancellation. Performance data, recorded with an MFJ Antenna Analyser, indicates SWR values of 1:1 on 7.00 MHz (40m) and 14.06 MHz (20m), with SWR below 1.3:1 on 17m, 10m, and 6m. While primarily designed for these bands, the antenna can be adapted for 80m, 30m, and 15m with an ATU, preferably at the balanced feeder's base. The use of 450-ohm twin-lead for the feeder is recommended over 300-ohm for improved strength and reduced losses, especially in adverse weather conditions. This design, originally published in _RadCom_ in 1993 and featured in Pat Hawker’s "Antenna Topics," provides a compact and efficient solution for HF operation, particularly for those with limited space or resources.

An open source software defined receiver for Linux, Free DSP and Windows

Open source Arduino based CW (Morse Code) keyer with a lot of features and flexibility, often rivaling commercial keyers.

JTDX is an open-source software application for amateur radio weak-signal digital communication. It supports digital modes including FT8 and JT9. The software operates on _Windows_, _Linux_, and _macOS_ platforms. JTDX is designed for improved decoding of weak signals, a function also performed by WSJT-X and MSHV. The software facilitates weak signal decoding and transmission. It integrates with logging systems for QSO management and can automate tasks such as call management and remote RTX control. JTDX is utilized in contexts such as DXing and contests. DXZone Focus: FT8 | JT9 | Weak Signal | Multi-platform

CuteSDR Open-Source application for MacOSX , Linux, and Windows designed to run with RFSPace SDR receiver

Modular Software Radio, at sourceforge

Get KB1OIQ - Andy's Ham Radio Linux CD at SourceForge.net. Fast, secure and free downloads from the largest Open Source applications and software directory

An open source software decode various xMBE based modes. It support decoding QPSK, C4FM modes such as P25 Phase 2 (TDMA), MotoTRBO, NexEDGE, ProVoice and others more.

An open source Automatic Packet Reporting System tracker based on Arduino by Javier Martin

The document details the optimization and construction of the _Maria Maluca_ antenna, a compact 6-band (20m-6m) directional beam. It presents a comparative analysis of shortwave antenna principles, highlighting the efficiency gains achieved by using an open feeder line and tuner as a resonant unit, contrasting this with the losses associated with traps or capacitive loads in multiband antennas. The resource specifically revisits an older South American 2-element design for 10, 15, and 20 meters, applying modern NEC-based software to develop a six-band version. Performance data is meticulously tabulated, showing impedance, free space gain, gain at 12m height, elevation angle, and front-to-back (F/B) ratio for each band from 20m through 6m. For instance, on 15m, the antenna achieves 5.1 dBd free space gain and 13.72 dB F/B ratio. The construction section provides practical guidance on element assembly using aluminum pipes and hose clamps, detailing the use of a heavy-duty glass fiber reinforced polyamide rod for electrical separation and bending strength. It also specifies the use of 450-ohm _Wireman_ line CQ 552 for the transmission line. The document includes diagrams for rod fixing, an air-wound balun, and a vertical elevation diagram for the 15m band, illustrating its DX qualification. It also discusses the antenna's suitability for portable and expedition operations, noting its compact transport dimensions (max 1.50m length, 12 lb weight) and quick assembly time (under 15 minutes). The author, Dipl.Ing. Helmut Oeller, DC6NY, is identified as a source for material kits.

CocoaModem is an opensource MacOSX application which implements modems (modulator-demodulators) for RTTY PSK MFSK Hellschreiber CW SITOR HF-FAX provided by W7AY

The HPSDR is an open source hardware and software project intended as a next generation Software Defined Radio for use by Radio Amateurs

This resource details the computer-optimized design of the _ZS6BKW_ multiband dipole, an evolution of the classic _G5RV_ antenna. It begins by referencing the original 1958 RSGB Bulletin article by Louis Varney G5RV, explaining the operational principles of the G5RV's flat-top and open-wire feedline on 20m and 40m, noting its impedance transformation characteristics for valve amplifiers of that era. The article then transitions to the rationale for optimizing the design for contemporary solid-state transceivers requiring a 50 Ohm match. The core of the project involves using computer modeling to determine optimal lengths for the flat-top and matching section, aiming for a VSWR of less than 2:1 on multiple HF bands. It discusses the process of calculating feedpoint impedance based on antenna length and frequency, referencing professional literature from Professor R.W.P. King at Harvard University. The analysis also considers the characteristic impedance (Z(O)) of the open-wire line, identifying a broad peak of adequate values between 275 and 400 Ohms. Specific design parameters for the improved ZS6BKW are presented, including a shorter flat-top and a longer matching section compared to the original G5RV, with a velocity factor of 0.85 for the 300 Ohm tape. The article confirms acceptable matches on 7, 14, 18, 24, and 28 MHz bands when erected horizontally at 13m, and also discusses performance in an inverted-V configuration, noting frequency shifts. The author, Brian Austin ZS6BKW, emphasizes the antenna's suitability for modern 50 Ohm coaxial cable without a balun.

WSJT-X and MAP65, open-source amateur radio programs, facilitate weak-signal digital communication. WSJT-X covers VHF/UHF to HF, decoding subthreshold signals. MAP65 optimizes for VHF/UHF EME with JT65. Free and GNU GPL licensed, WSJT-X is on Windows, Linux, and OS X, while MAP65 is Windows-only, supporting SDR hardware.

Put up the longest dipole you can fit, feed it with open wire line, connect it to the balanced output of your tuner and poof! Instant multiband antenna. Is life really that simple?

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.

Restoring vintage amateur radio gear often presents challenges with accurate dial calibration due to the non-linear characteristics of analog tuning capacitors. This resource details the construction of a 100 kHz crystal calibrator, a crucial tool for precisely setting the frequency of older rigs lacking digital readouts. The design cleverly circumvents the scarcity and cost of 100 kHz crystals by utilizing a readily available 8 MHz microprocessor crystal, such as a _HC49U_ type, in conjunction with common _CMOS ICs_ like the 74HCT00 quad NAND gate and 74HCT393 dual 4-bit binary ripple counter. The circuit employs a two-stage frequency division process: the 8 MHz crystal oscillator output is first divided by 16 to yield 500 kHz, then further divided by 5 to achieve the desired 100 kHz output. A 5.1-volt Zener diode, _1N4733A_, regulates the power supply for the HCT series logic. The article also provides a modification to produce a 50 kHz calibrator by altering the counter reset logic. Installation involves feeding the output to the receiver front end, ensuring it's post-TR relay to prevent RF damage, and incorporating an ON/OFF switch for the 12V supply line.

Open source libraries and utilities to support using digital signatures for Amateur radio QSL system information like eqsl and lotw. Available for windows macos e linux.

Satellite Tracking/Orbital Prediction Program an open-source, multi-user satellite tracking and orbital prediction program written under the Linux operating system by John A. Magliacane, KD2BD. PREDICT is free software

A 90-foot vertical antenna constructed from **aluminum irrigation tubing** is detailed, focusing on its innovative raising and lowering mechanism. The resource describes a **45-foot ginpole** system, allowing a single operator to erect or lower the antenna in minutes. It covers the mechanical design, including the pivot base, insulated joints for the tubing sections, and guy wire attachment points. The antenna consists of two 30-foot sections of 4-inch tubing and one 30-foot section of 2-inch tubing, stacked with the smaller diameter at the top. The electrical design incorporates PVC "condulet" boxes at the 30-foot and 60-foot points, housing relays to change the effective height for multi-band operation on 160, 80, 40, and 30 meters. Ferrite rod inductive chokes are used for DC control and to tune out gap capacitance. The antenna is fed with 1000 feet of open wire line, connected to a matching transformer comprising stacked toroids and a coaxial/toroidal balun. Grounding is achieved with a 3x3 foot grid of 16-gauge tinned copper wires with soldered crossovers.

open source software designed to control and program the ICOM IC-R8500 receiver

Over two decades of historical DX spots and news are archived on this Japanese resource, providing a retrospective look at amateur radio propagation and activity across various bands. The content is organized chronologically, with separate sections for _50MHz_, _HF DX_, _144MHz_, _EME_, and Satellite clusters, detailing spot data from as early as 1996 through 2014. This extensive archive serves as a valuable historical record for analyzing long-term propagation trends and significant DXpeditions from a Japanese perspective, offering insights into band openings and rare entity activations. The resource also includes links to other DX news sites like _425 DX News_ and _Ohio/Penn DX Bulletin_, along with QSL manager lookups and callbook services, enhancing its utility as a comprehensive DX information hub. While the primary cluster data is historical, the compilation of external links points to active resources for current DX operations. This makes it a useful reference for contesters and DXers researching past conditions or seeking information on specific DX entities and their QSL routes.

Open source software designed to control and program the ICOM IC-R75 receiver

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.

Demonstrates the design and construction of a compact, portable multi-band mini-delta loop antenna, specifically optimized for /P (portable) operations from remote locations like Scottish islands. The resource covers the theoretical underpinnings of half-wave loops, contrasting closed and open configurations, and then details the application of a folded dipole principle to achieve a 50-ohm match for direct coax feed. It presents empirical formulas for calculating element lengths, considering the velocity factor of common wire types, and provides a detailed example for a 20m (14.175 MHz) version. The article includes a comprehensive table of dimensions and allowances for a five-band (20m, 17m, 15m, 12m, 10m) mini-delta beam, along with construction hints for the central support and balun. It specifies a 1:1 trifilar balun wound on a ferrite rod and describes the antenna adjustment process using an _MFJ-259B Antenna Analyser_. Initial test results indicate an SWR of 1:1 at resonance and a bandwidth of approximately 240 kHz on 20m, even at a low height of five feet above ground. The distinctive utility lies in its focus on a practical, easily deployable beam antenna for portable DXing, offering a viable alternative to more complex or larger arrays.

Open source software designed for the Yaesu VR-500 receiver.

Windows open source packet radio decoder. Decodes AFSK1200, AFSK2400, HAPN4800, and FSK9600 packet data with a radio connected to your pc sound device.

NetLogger displays 6 currently active nets, including the 3838 Breakfast Club on 80 meters SSB and the CornCobNet on 40 meters SSB, providing real-time updates every 20 seconds to monitoring participants. It functions as a specialized logging program designed for amateur radio nets, facilitating the transmission of check-in data via the internet. The system lists net name, frequency, band, mode, server, start time (UTC), elapsed time, number of subscribers, and the callsign of the operator who opened the net. The platform details specific net operations, such as the Florida AM Group on 3.885 MHz AM and the GRAVEYARD NET on 3.967 MHz SSB, illustrating its application across various **HF** bands and modes. NetLogger's utility extends to viewing past nets and offers a **Groups.io** integration for community interaction. It provides a practical solution for organizing and participating in amateur radio nets, offering a centralized system for tracking participants and net activity. The resource details specific net operations, such as the Florida AM Group on 3.885 MHz AM and the GRAVEYARD NET on 3.967 MHz SSB, illustrating its application across various HF bands and modes.

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.

cocoaNEC 2.0 is an opensource Mac OS X application intended primarily for the design and modeling of antennas by Kok Chen, W7AY

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.

qrq is an open source Morse telegraphy trainer which runs on several operating systems (Linux, Unix, OS X and Windows), similar to the classic DOS version of Rufz by DL4MM.

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.

The BayCom-Mailbox is an amateur radio/citizen band AX.25 Bulletin Board System with AX.25 store and forward capabilities. The software is available for Linux, DOS and Win-NT. OpenBCM is opensource and freeware.

Small and inexpensive homebrew HF radio 5W Output, CW SSB AM FM, DSP, Speech Processor, Sprectrum Scope, Watefall Display. mcHF is a small, home-brewed amateur radio project. Firmware is released as open source.

Building an Open Source Arduino APRS Tracker with LCD & GPS ( SVTrackR )

Amateur radio open source log program written in PHP. Put your log online for visitors to browse in real time. Access your log from any web browse, can run under windows linux and macos with apache, mysql and php

DX_Central, a compact desktop application, provides amateur radio operators with critical propagation data by aggregating solar statistics and imagery from various authoritative sources. This includes real-time information from agencies like NOAA and NIST, offering insights into current space weather conditions that directly impact HF propagation. The software is designed for both Linux and Windows operating systems, making it accessible to a broad range of hams. It presents a concise overview of solar activity, which is essential for planning DX operations and understanding band openings and closures across the HF spectrum. Operators can utilize the displayed solar flux index, K-index, and other relevant parameters to make informed decisions regarding their operating times and target bands, optimizing their chances for successful long-distance contacts.