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Explore this high-resolution ITU Zones Map, a critical reference resource for amateur radio operators, international broadcasters, and telecommunications engineers. Originally established by the International Telecommunication Union – Radiocommunication Sector (ITU-R) Broadcasting Services Division (1999), this chart accurately divides the globe into 90 specific CIRAF zones. This authoritative visual guide is indispensable for planning High Frequency (HF) radio propagation, scheduling international broadcasts, and verifying locations for radio contests and awards. Distinct from the 40 CQ Zones, the ITU zoning system provides the official administrative framework used for global frequency management. This digitally enhanced version ensures maximum clarity of zone boundaries and numbering (e.g., Zone 28 for Central Europe), making it an essential tool for technical accuracy in logbooks and station management. It serves as a trustworthy standard for educators, hobbyists, and industry professionals alike.

W8TTH Welding & Machining , tower plates, side mounts standoffs, house brackets, torque arms.

The Kenwood TS-570D(G) transceiver (I), by Thierry Lombry, ON4SKY

Definition of smoothed sunspot number and R12 index

Global Lightning Technology - Malaysia lightning Malaysia surge protection system

Portable SSTV camera that takes a picture and transmit it with ham radio SSTV

This article contains the measurements for building a full wave loop using wire and length of 1/4 Wave Coax Matching Transformer

Homepage of Hong Kong's elite group of DX'ers

An overview of some of the ways, and the key tips on how electronics soldered joints can be unsoldered or desoldered.

Classic Radio Restorations specialize in professional repair and restoration on all makes and models of antique radios and vintage phonographs. Since 1978.

The document titled 'Extending the Range of Your Handheld' by WG7S is a guide on how to extend the range of your handheld VHF UHF transceiver by using an external antenna. It provides information on comparing popular models, selecting the right antenna, and resources for amateur radio antennas.

The RoadTrek design presents some unique challenges to us hams. Here an example of a VHF and HF antenna installation on a VAN

QSL Information Pages QIP for BC-DXers - more than 50000 qsl logs from more than 10000 BC-DX radio stations

Problem width the memories, TS-570 Batteries, MARS/CAP Modification

Don't neglect one of the most important parts of your station!

"The DSWCI was founded 1956 and has members in 36 countries all over the world. The member bulletin ""Shortwavenews"" is published regularly in english."

The 10-minute, 25-second video demonstrates making a QSO via the VO-52 amateur radio satellite, focusing on real-time Doppler shift correction. It features Simon, 2E0HTS, operating a Yaesu FT-847 transceiver and a homebrew dual-band Yagi antenna, specifically a 10-element 435 MHz Yagi for uplink and an IO Loop for 145 MHz downlink. The video visually details the operator's technique for continuously adjusting the uplink frequency to compensate for the satellite's changing velocity relative to the ground station, a critical aspect of successful satellite communication. The demonstration highlights the practical application of Doppler compensation, showing the operator tuning the transmit frequency to maintain a stable received signal from the satellite. This approach contrasts with systems employing automatic Doppler correction or full-duplex operation, providing insight into manual frequency management for satellite passes. The video serves as a direct, observational guide for hams interested in LEO satellite operations, particularly those using non-tracking, manually tuned setups.

What become our QSL once sent ? QSL routes, IRC and green stamps, the best and worst practices.

Making portable pperations easier, N1GY present a different way to make a tilt-base and mast

Whith more than 20 years of ham practicen SWL Thierry LOMBRY, alias ONL5183, has written several technical pages about ham activities, including propagation, radio perturbations, radioastronomy, DXing, QSLing, ham-spirit, review of material and more. This very interesting website is completed by a large French section devoted to amateur astronomy illustrated with vivid colors pictures.

Kenwood TS-570 mods at mods.dk

Speakers for Amateur Radio, 2-Way Radio, Shortwave and Scanner listening

IV3GFN modification and restore of an HeathkitSB220

1500 watts PEP output from a Kenwood TL-922 amplifier requires careful attention to parasitic suppression and component selection to ensure stability and longevity. This resource critically examines common modifications, often based on anecdotal evidence rather than sound engineering principles, that can degrade performance or introduce new issues. It highlights how replacing aged components often gets misattributed to the efficacy of unnecessary modifications, leading to widespread misinformation within the amateur radio community regarding amplifier stability. The article details specific, effective modifications for the TL-922, such as shortening anode-to-chassis and anode-to-grid paths to improve VHF stability and efficiency. It addresses issues like incorrect capacitor types in the tank circuit, inadequate grid grounding, and poor RF sheet metal design, providing practical solutions like adding direct ground connections for the plate tune variable capacitor. The author also discusses proper parasitic suppressor design, emphasizing the importance of lead length and component selection for optimal performance and harmonic suppression, contrasting these with less effective or detrimental 'magical suppression kits'.

W1AW Propagation Bulletins for 2001

Modelling an horizontal Loop antenna at 3.5 MHz

Isolation vs antenna separation an interesting article by WA6ILQ

A VHF UHF handheld antenna suitable for satellite operation by LY3H include antenna plan with dimensions and pictures.

The KP3AV Systems website offers a detailed listing of amateur radio repeaters across Puerto Rico, including operational frequencies and tones for VHF and UHF bands. It features sections dedicated to digital modes like DMR and C4FM, as well as information on FRS, GMRS, and MURS. The resource also includes articles on emergency communications protocols and provides access to Spanish-language manuals for various radio equipment. Recent content covers the new open-source FT2 mode for WSJT-X Improved, upcoming 60-meter band frequency allocations and power restrictions effective February 13, 2026, and discussions on 2-meter contacts with Desecheo Island from Puerto Rico. The site also presents U.S. amateur radio band plans and highlights local contesters like Manuel WP4TZ, offering practical insights into portable operations and contest participation.

K4JRG GAP titan dx specifications

Specialist in the design and supply of Radio Communications Equipment and Systems. West Sussex England. Antennas, traps and baluns inline isolators, Outbacker Antennas, Mobile Mounts and Accessories

Dish antenna and its theory and design for high performance applications such as satellite transmission and reception as well as microwave links. Parabolic Reflector Antenna: Dish Antenna The parabolic reflector antenna which is often called the dish antenna provides an antenna solution applicable for VHF and above where high gain and directivity are needed for all type of radio communications and radio reception.

Since 1935 serving amateur radio in Worcester MA

Dragoslav Dobricic, YU1AW antennex article on influence of Boom on frequency performance and how compensate it

A Co-ax Trap Dipole For 40, 30 and 20 Meters or at last that was the intention

Ham radio manuals in italian and english for several makers and products

A 50-ohm generator feeding a 50-ohm line connected to a _quarter-wave transformer_ (150 ohms) terminated in a 450-ohm load is analyzed to understand transient behavior. The paper meticulously tracks voltage and current waves, reflection coefficients, and power levels through a sequence of events, starting from quiescent conditions. It details how incident and reflected waves combine and interact at impedance discontinuities, illustrating the dynamic changes in impedance and SWR at various points in the system. The analysis reveals that the impedance at the interface between the 50-ohm line and the 150-ohm transformer changes from 150 ohms to **64.3 ohms** after the first reflected wave arrives. Subsequent reflections cause the impedance to asymptotically approach 50 ohms, reaching **53.22 ohms** after five wave terms. The study also examines the generator's reaction to transient SWR changes, noting that a 3:1 SWR can temporarily reduce generator output to 0.75 watts, but these effects are temporary and diminish as the system approaches steady-state conditions.

Tubes and antique radio buy and sell classified ads

Alan Applegate (K0BG) article on mobile oprtations

Repairing and restoring a Yaesu FL-2100Z amplifier

The ZS6BKW multi-band antenna, an optimized variant of the classic G5RV, is presented with detailed construction and tuning instructions. This resource outlines the antenna's design principles, which were developed by _Brian Austin (G0GSF)_ using computer programs and Smith charts to achieve optimal dimensions. It provides specific guidance on calculating and adjusting the lengths of the radiators (L1) and the matching ladder line (L2), emphasizing the critical role of velocity factor (VF) in achieving resonance. The article includes a step-by-step procedure for empirically determining the VF of ladder line using an antenna analyzer, ensuring accurate physical lengths for the matching section. It details the tuning process for the radiators, offering practical tips for incremental adjustments to achieve the best SWR curve. The resource presents SWR measurement results obtained with an _AIM-4170C_ analyzer across multiple bands, alongside predicted SWR graphs from an AutoEZ model. It confirms successful contacts on 80, 40, 20, and 17 meters, including a **17-meter DX contact** to Italy. EZNEC and AutoEZ models for the ZS6BKW antenna, covering 80 through 6 meters, are provided for download, allowing further analysis and customization. The document specifies component details, such as the use of Wireman 554 ladder line and #14 AWG THHN copper wire, and discusses the antenna's performance characteristics, noting high SWR on 15 and 30 meters but successful tuning on 6 and 80 meters with an external tuner.

Founded in 1946 in the UK, the ISWL is Global. We cater for Licensed Amateurs and all types of Shortwave Listeners. Offer a comprehensive awards programme and run a very efficient QSL Bureau.

Article by VU2GT about VHF antennas, how to evaluate performances and models.

RS41 Tracker is a software running on Windows that it is able to decode telemetries generated by Vaisala RS41 radiosondes. Used with a FM radio receiver it allows to display radiosonde positions on a map.

SARA provides emergency communications for the City of Saratoga as well as for community events.

In his back office section, ON4SKY, initiates in a few articles the beginners in the art of QSLing and award chasing.

Kenwood TS-450S/TS-690S MARS modification video

The GM4JJJ VHF and EME pages document David's extensive work in Earth-Moon-Earth (EME) communication, specifically on the 144 MHz band, and his involvement in amateur radio astronomy. The resource details his station setup and operational experiences, providing insights into the technical challenges and rewards of bouncing signals off the moon. It offers a glimpse into the specialized equipment and techniques required for successful EME contacts, a niche but highly rewarding aspect of amateur radio. David's content shares practical applications and field results from his EME endeavors, which can be particularly useful for hams contemplating or actively pursuing moonbounce operations. The information, while not a step-by-step guide, implicitly compares the complexities of EME with more conventional VHF/UHF operations, highlighting the significant power and antenna gain necessary to overcome path losses. This resource serves as a testament to the advanced capabilities achievable in amateur radio.

The ARRL Foundation is devoted to providing valuable programs to serve the ham community, whether those served are ARRL members or not. Established in 1973 by the American Radio Relay League, Inc. (ARRL) as an independent and separate 501(c)(3) organization, the ARRL Foundation administers programs to support the Amateur Radio community. The ARRL Foundation advances the art, science and societal benefits of the amateur radio service by awarding financial grants and scholarships to individuals and organizations in support of their charitable, educational and scientific efforts. Funded entirely by the generous contributions of radio amateurs and friends, ARRL Foundation administers programs for Amateur Radio award scholarships for higher education, award grants for Amateur Radio projects, and award special Amateur Radio program grants for The Victor C. Clark Youth Incentive Program and The Jesse A. Bieberman Meritorious Membership Program.

Collection of radio mods for Kenwood TS-870