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Radiowave propagation in the medium and high frequency spectrum in DOC format

Receive-only loop antennas have some nice response characteristics that make them ideal when used for reception of skywave signals.

Bandplans, Beacons and many useful info on VHF operations

Modifications and improveents for the realistic DX-100L HF receiver by ON6MU

Presents a comprehensive listing of VHF and UHF repeater systems operating within Ecuador, detailing their operational frequencies and geographical coverage. The resource includes specific entries for locations such as _Guayaquil_, Cuenca, and Manta, alongside their respective frequency pairs. For instance, the Cerro Azul repeater in Guayaquil operates on **6.760- T**, indicating a transmit offset, while the Sta. Elena system utilizes a 26.660 MHz transmit frequency. The data provides essential information for local and visiting amateur radio operators seeking to utilize regional repeater infrastructure. It delineates coverage areas using two-letter provincial abbreviations, such as AZ for Azuay and GY for Guayas, facilitating route planning and mobile operation. This compilation is particularly useful for those engaged in local communications or emergency preparedness within the Ecuadorian amateur radio community, offering a practical guide to available repeater assets.

"Shows who is ""active"" on VHF in EI, Solar Auroral and Tropo information, Vhf logs and maps."

Round-Up of different HF Upconverters for RTLSDR by KF7LZE

A PIC Programmer for Windows, support for dsPIC, PIC10F, new PIC12F6xx family, PIC16F9xx, PIC18F

Reviews of the kenwood TS-940S HF Transceiver

Shortwave listeners and amateur radio operators interested in _numbers stations_ can engage with this mailing list, which serves as a platform for discussing the enigmatic transmissions. The resource facilitates the exchange of information regarding these unusual broadcasts, often associated with intelligence agencies, by allowing members to share observations, decode attempts, and theories. It provides a community space for those who monitor the HF spectrum for these unique, often automated, voice or digital signals. Participation on the list enables members to contribute to a collective understanding of numbers station activity, including changes in frequencies, broadcast schedules, and message formats. While specific technical analysis or signal processing techniques are discussed by members, the primary function is information sharing. The list is administered by csmolinski at blackcatsystems.com, and prior postings are archived for reference, allowing new members to review historical discussions and data.

Yagi with 5 Elements on 2 m, 8 Elements on 70cm and one Feedpoint by DK7ZB

VHF UHF SHF Toplist including DXCC and EME-Initials

This is a page designed to help the EMCOMM operator thinking of going portable. It will describe a way of having VHF UHF HF voice and digital in one box

Offer various contest logging programs, for scandinavian contests, SPDX, PAXX, OK/OM Contests, IARU VHF Contest, Portugal Day DX contests, HSC contest, various polish and norwegian local contests and other utilities

DK7ZB's fan dipole designs address the challenge of operating multiple HF bands with a single feedline, providing practical construction details for **multiband wire antennas**. The resource outlines specific lengths for half-dipoles across various band combinations, including 10-15-20m for classic bands and 12-17-30m for WARC bands. It emphasizes the importance of proper spacing between resonant elements to avoid impedance interaction and high SWR, a common issue when frequencies are too close. The article details the use of **current baluns** built with FT240-43 or FT140-43 cores, specifying turns and cable types for 1KW and 400-Watt power levels. It includes a correction table for adjusting dipole lengths based on frequency shifts, aiding in fine-tuning resonance. The 20+40m dipole is noted for its ability to operate on 15m with an ATU, demonstrating versatility.

What makes a good solid-state amp ? by Adam Farson, VA7OJ/AB4OJ, May 2002

Meteor scatter, gives quick view over meteor scatter and scatter events on vhf, lists email addresses of vhf radio amateurs qrv in meteor scatter

A magnetic loop antenna for the VHF band, featuring a high gain that can be compared to a quarter wave vertical antenna

Shelby amateur radio club's VHF emergency net is open to all within the repeater's coverage area. 146.880 and 147.345 are the repeater frequencies. Shelby Radio Club is the sponsor of the Shelby hamfest.

Using a PC with soundcard as a VLF receiver, how to use your PC as a receiver for narrow-band signals in the VLF radio spectrum by DL4YHF

Eham user's review on the Heathkit SB-200 HF amp

Online websdr receiver based in Rome Italy provides a nice user web interface and receiver most of the amateur radio HF bands

Ten essential tips and truisms for understanding HF antenna: Non-resonant wire dipole antennas fed with open-wire line and an antenna tuner can function effectively as multiband antennas, as detailed in "The Classic Multiband Dipole Antenna" by WB8IMY in March 2004 QST. Coaxial cable, unlike balanced parallel-wire feed lines, can cause RF to travel on the outer shield braid, leading to RF feedback to the station; a 1:1 balun at the dipole center can mitigate this by isolating the unbalanced coaxial feed line. Antenna gain is achieved by shaping and directing RF energy, with beam antennas concentrating power in a specific direction, and wire antennas also exhibiting shaped radiation patterns. An antenna tuner's primary role is to match the transceiver's 50-ohm output to the antenna system's impedance, allowing modern transceivers to deliver full power. Wire antennas do not always require center feeding; end-fed long wires or off-center-fed dipoles (like the Windom) can be used, though they often necessitate an antenna tuner and a counterpoise or radial network. Dipole antennas do not need to be perfectly horizontal; their legs can be bent or inclined, which affects feed point impedance and may require SWR experimentation with coaxial feed. Vertical antennas shorter than a half wavelength require an efficient ground system, typically comprising elevated or buried radial wires, with more radials generally leading to better efficiency. A 1:1 SWR indicates an impedance match but does not guarantee antenna efficiency; an inefficient vertical antenna with a poor ground system can show a low SWR while wasting most RF as heat. Investing in high-quality, low-loss feed line, especially coaxial cable, is crucial for maximizing RF signal transfer and overall antenna system performance.

The ATV User's Group is a subgroup of the Auckland VHF Group, Club call ZL1BQ, compromising of persons interested in the transmission and reception of Amateur Television

The **KC0KJF** personal amateur radio page provides a collection of resources for fellow hams, particularly those interested in operations within southwest Missouri. It offers detailed listings for **Missouri repeaters** on both 2 meters and 70 centimeters, serving as a practical reference for local VHF/UHF communication. The site also includes information about the operator's station setup and antenna projects, such as a dipole and a bazooka antenna, which can offer insights into basic antenna construction and deployment. Beyond local repeater data, the page features links to the FCC Part 97 rules, essential for understanding amateur radio regulations. The operator, licensed as a Technician Class since April 16, 2001, shares his journey from Citizen's Band Radio to amateur radio, driven by a lifelong fascination with shortwave listening. This narrative provides context for the resource's focus on practical operating information and foundational regulatory knowledge. Additional content covers specific equipment like the 2-meter/70-centimeter Arrow Antenna, useful for hams considering portable or fixed station VHF/UHF setups.

Irish ham and Vhf radio info. Logs and maps worked, no excuses, this is mainly a VHF site

An Antenna Mast Idea for a VHF/UHF antenna

Assembling the Butternut HF9v HF vertical antenna

Monitoring real-time amateur radio activity is essential for DXers and contesters seeking rare contacts or tracking propagation. This online service aggregates DX spots from various **DX Cluster** networks, presenting them visually on a world map. Users can observe new spots as they appear, facilitating quick identification of active stations and potential openings. The platform offers filtering capabilities, allowing operators to narrow down displayed spots by specific bands such as 160m, 80m, 40m, 20m, 10m, and even VHF/UHF segments like 70cm and 23cm. Further refinement is possible by selecting the source continent of the spotter or the continent of the DX station, which assists in strategic operating. The service also includes a "Hot Now" list, highlighting currently active stations with recent spots. This dynamic display supports informed decision-making for pursuing **DX contacts** across different bands and geographical regions.

New Zealand Amateur Radio 70, 32 & 23 cm (UHF) Repeaters

Experimentig magnetic loop antennas for VHF and HF by M0UKD

An unconventional antenna family, the VHF/UHF Zigzag Dipole Antennas. Design, theory and practical construction, transformation and balancing with a half wave balun.

K8GP web site, home of the Grid Pirates Contest Group.

This article describes the details of the design, which can be easily scaled for just about any HF band. The antenna described in this article is for the 20 meters band.

A complete restoration of a Heathkit SB-200 HF power amplifier

VHF, 50 MHz contest, gallery and six meters infos

eham users review of the Kenwood TS-570D or TS-570G HF Transceivers

eHam user reviews of the Yaesu FT-450 HF+6m t ransceiver

NBTV (Narrow Band Television) is a technique with some similarity to SSTV, and some to conventional FSTV (Fast Scan TV). Like SSTV, it operates in a narrow bandwidth, suited to an HF SSB transceiver, but rather than send individual image frames, NBTV is designed to send multiple frames one after the othe.

Eham users review of this HF/VHF/UHF All Mode Transceiver.

This Magnetic Longwire Balun (MLB) makes it possible to efficiently use a coaxial lead-in cable with all forms of longwires, T-forms or other types of wire antennas, without the need for an antenna tuner.

A quarter wave antenna with dimensions for uhf and vhf bands

Port of the popular VOACAP program, HF propagation prediction tool. It may be compiled using the GCC GFortran compiler

The 60-page PDF document, "Antenna Systems and Theory For The Non-Technical Ham" by Jim Abercrombie, N4JA, provides a foundational understanding of antenna systems. It explains basic antenna theory, including how antennas work, electromagnetic wave polarization, and the role of frequency. The resource details various antenna types such as flat top dipoles, inverted-V dipoles, shortened loaded dipoles, G5RV dipoles, Carolina Windoms, and end-fed configurations. Vertical antennas, including ground-mounted trapped verticals and inverted-L verticals, are also covered. Directional beam antennas like monoband Yagis, cubical quads, and log-periodic arrays are discussed. Propagation modes, including ground-wave, direct wave, and skywave propagation, are explained in detail, with specific attention to the D, E, and F layers of the ionosphere and their effects on HF communication. Technical concepts such as standing wave ratio, decibels, resistance, and reactance are defined, along with calculations for half-wave resonant dipole lengths. The document addresses feed-line radiation, balun applications, and critical antenna and tower safety considerations. It aims to dispel common antenna myths and educate hams on making informed antenna choices.

HFpack provides an information exchange about transceivers, antennas, systems, HF packs, propagation, new developments and techniques in HF portable operation. Radio Amateurs are invited to participate in egroup and on-the-air nets around the world.

With the bluecat interface it is possibile to connect a Yaesu FT 817 857 897 to a computer or a android smartphone without any cable or interface, using a bluetooth wireless connection

Scanecoute - French radio scanning portal, la passion des ondes VHF UHF Forum,tchat,site consacre l'ecoute des frequences a l'aide de recepteur scanner .

VHF an above weak siganl site

1500 watts of RF output on the 70cm band requires robust amplifier design, a challenge addressed by this project featuring the GS-23b / 4CX1600U Svetlana tube. The resource details the construction of a high-power UHF amplifier, providing insights into component selection and layout necessary for stable operation at these frequencies and power levels.

A well documented PDF document containing picture sequence taked during the repair of an Icom IC-7700 HF transceiver power amplifier module