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EI5FK tower project

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

Free Morse Code CW training software for Android supporting the Koch method by IZ2UUF David

Report of solar & geophysical activity

Hints about Jpole Yagi and Quad antennas

Eham reviews of the popular Yaesu FT 847

Producers of Scancat, Copycat, Magic and Distributors of HOKA's CODE-3 and CODE-30 decoders.

FT-817 product review at eham.net

The UK Scanning Directory - HF, VHF and UHF UK Scanner Frequencies Database Updated Daily by a dedicated group of Radio Amateurs and SWL Listeners

70cm-Longyagis in 28Ohm-DK7ZB-Design

Long path hf radio propagation is sometimes the best path to work dx, since the shortest path is not always the best path.

It's a whole new way of preparing for the government FCC License examination. The classroom is your home.

SDR# (read SDR Sharp) is a high performance Software Defined Radio application. SDR sharp is a fully featured SDR capable of handling samplerates from kHz level soundcards up to multi hundred MHz dedicated samplers, thanks to its multi-core architecture.

K6AER Yaesu FT-2000 review on eham

by Dr. D.T. Emerson, National Radio Astronomy Observatory (NRAO++). Antenna Compendium Volume 4, pp 64-68, 1995, published by the ARRL.

A self supporting vertical antenna for 80 meters by W9OY include pictures and construction details

The following frequencies are assigned to datacommunications in the HF bands within the UK By RSGB data communications committee information.

How to improve the gain of your 5 element Tonna yagi for 50 MHz by roughly 3 db!

Ham Radio Android Apps to displays your current QTH locator on Google Maps using the GPS or WiFi / network location.

HFUnderground.com is dedicated to documenting longwave, mediumwave, and shortwave stations, including broadcasters, utility/military stations, pirate radio and spy numbers stations.

A 37.6-meter Morgain antenna design provides dual-band operation on 80 and 160 meters without traps. The antenna uses 1.5 mm² stranded copper wire with vinyl insulation, commonly found as domestic electrical wire. Tuning involves adjusting lateral jumper wires for the 80-meter band, with initial positions 30 cm from the arm ends, yielding 3635–3715 kHz resonance with SWR below 1.5:1. For 160 meters, a straight wire length of 18.80 meters per arm is critical, achieving 1840–1850 kHz resonance with SWR below 1.1:1. The Morgain antenna exhibits a 50-ohm feed-point impedance, allowing direct connection of 50-ohm coaxial cable like RG-8X, which handles approximately 500 watts. Spacers and the central plate are constructed from 1 mm thick green fiberglass laminate, with spacers measuring 11 cm and installed every 1.90 meters. The central plate is 11 × 11 cm, designed to secure the coaxial cable mechanically. End supports utilize 3–6 mm thick bakelite terminal spacers, tensioned with nylon ropes.

TS-850S typical faults and solutions

Eham users review of the Yaesu FT-897

Eham TH-F6A reviews

Definition of antenna gain at wikipedia

Reviews of the FT-950 PEP-950 enhanced version. AKA Mark 2

Yaesu VX-3R reviews by the eham members

A multiband WebSDR receiver system, located in Bolton, England accessible via the RSGB web site

Eham review for ICOM IC-706 - All flavors

K6DQ GAP titan dx antenna repair

The "REAL TIME ANTENNA GAIN COMPARATOR SYSTEM" by IK0BDO details a low-budget amateur radio tool designed for optimizing homebrew VHF/UHF antennas. It facilitates the simultaneous comparison of two antennas, one a known reference (e.g., a dipole) and the other under test, displaying their relative gain directly in decibels. The system addresses limitations of previous measurement benches by enabling on-field optimization, accounting for balun performance, impedance mismatching, and cable losses. The core of the device is an electronic solid-state switch utilizing PIN diodes, which alternates signal sampling from the two antennas 100 times per second. This rapid switching prevents the receiver's Automatic Gain Control (AGC) from compensating for signal differences, allowing for precise comparative measurements. The document includes detailed schematic diagrams for both the RF switching unit and the associated measure unit, which employs two VU-meters to display cyclic signal levels. It also provides guidance on setting up the PIN diode switching with an oscilloscope and adjusting trimmer potentiometers P1, P2, and P3 for optimal operation. Further sections cover the construction of VHF (144.150 KHz) and UHF (432.360 MHz) beacons for testing, along with critical considerations for selecting an appropriate test range or site. Recommendations include maintaining a minimum distance of 50 wavelengths between transmitting and receiving positions, avoiding ground reflections, and using reference antennas with gains similar to the antenna under examination. The author notes satisfactory results from measurements on dipoles and other antennas, highlighting the system's ability to appreciate fractional decibel differences.

About dummy loads, what are they and how to build one

Gamma match antenna is an antenna 1/2 additional lambda with the impedance matching more flexible arrangements (var capacitor) by sliding through the gamma match/road.

eham members Yaesu FT-857 and Yaesu FT-857D reviews

A live audio stream from the _Broadcastify_ platform provides real-time monitoring of public safety communications for Life Net-Air Methods West in Sioux City. This feed allows listeners to monitor emergency services, including air ambulance dispatch and operational traffic, which is crucial for situational awareness during critical incidents. The service offers a direct interface to listen to scanner audio, typically covering VHF/UHF frequencies used by emergency responders. Listeners can access the live feed directly through the web interface, with an option to upgrade to a premium service for ad-free listening and access to feed archives. The platform displays current listener counts and a history of archived audio segments, showing activity over the past 24 hours. This resource is particularly useful for those interested in local emergency response, providing immediate access to scanner traffic without needing a physical radio.

Gap Titan DX Antenna manual. This is an enhanced version of the common Gap Titan DX Manual document you can download from other sites. This manual is in PDF Format.

Plans and drawings of common amateur radio antennas, like jpoles, copper cactus, super jpole, omnidirectionals and quads

A pictorial guide to the basic ways of desoldering joints

F5DQK repairing and swr measurement tests of a Cushcraft R7 Antenna

Setting up a Raspberry Pi as a SDR Server with RTL-2832U USB dongle

by Adam M. Farson VA7OJ/AB4OJ

Slot antenna and complementary dipole

The page discusses Axial-Mode Helical Antennas, focusing on turning helical antennas over perfect ground and modeling helices in NEC-2 for optimized design. It covers topics such as high-gain performance, broadband, impedance matching, radiation pattern, feedline, balun, near field, far field, and DIY applications.

An interesting modification to improve the gain of your 5 element Tonna Yagi beam for 50 MHz by roughly 3 db!

Draws a world map centered on your QTH. Type in a DX station's call sign to get the beam aim azimuth and distance to the station.

There is considerable confusion as to what exactly a multiband vertical antenna is. The confusion concerns the method of feed, how much mismatch one can expect, how many radials are required, how the particular antenna is built for multiband use, plus some other points.

High gain, good pattern and acceptable bandwidth. These aims can be realized with a radiation-resistance of 25-35Ohms, because the 28-Ohm-feedpoint is very simple to match.

Investigates the gain characteristics of the **axial-mode helix antenna**, a widely used circularly-polarized antenna, by addressing conflicting claims in amateur literature regarding its performance. This article summarizes an extensive numerical modeling study using **NEC-2** to simulate approximately 10,000 different helical antenna configurations, systematically varying physical parameters like length and turn radius. The study consumed around 3,000 hours of compute cycles, with each antenna model utilizing between 600 and 1,400 segments for accuracy. The modeling data were rigorously compared against professional antenna literature, including experimental and theoretical work, revealing that the original Kraus formula for gain is often overly optimistic, predicting gains up to 4 or 5 dB higher than observed. Empirical expressions are provided for the maximum possible gain, Gmax(dB) = 10.25 + 1.22 L - 0.0726 L^2, and the optimum turn radius, Rmax = 0.2025 - 0.0079 L + 0.000515 L^2, both valid for antenna lengths (L) between 2 and 7 wavelengths. The research also notes that a half-lambda square groundplane performs nearly as well as an infinite groundplane, while radials incur a gain penalty of about 3.5 dB.

The Maik Uniform France website, established on March 27, 2000, serves as a central hub for French CB radio operators interested in DXing. It provides a platform for sharing DX news, logging contacts, and distributing relevant software tools. The resource caters to various CB DX groups, including Papa Alfa Tango, Wisconsin Michigan, Charly Tango, Oscar Sierra, Big Time Operators, WAC Club, Azteca DX, and TX&RX Group, fostering a community around long-distance CB communications. This online presence facilitates the exchange of operational information and resources among CB enthusiasts. While primarily in French, an English option is available. The site's content structure supports the practical application of CB DXing by centralizing information on recent DX activity and providing utilities, thereby assisting operators in improving their DXing capabilities and staying informed about the CB DX scene.

Drake Radio Repairs by Jeff WA8SAJ