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An Energy Analysis at an Impedance Discontinuity in an RF Transmission Line

An homebrew audio mixer for the ham shack by GW6ITJ

A simplified Guide to the FT8. Dxpedition mode. By Stefano IK2HKT – Rel. 2.0.0 - January 2019. This document explains how to configure WSJT to work on F/H mode DXPedtions, how to operate and make a call to a dxpedition calling CQ in FT8 Fox Mode.

Want to operate on 40 meters but only have a space a little over 16X16 ? Try this antenna.

An 80m transceiver using just 14 parts plus crystal and earpiece

The _ISS Detector_ Android application, with over 5 million downloads, offers precise predictions for visible passes of the International Space Station. It notifies users minutes before an overhead pass, integrating local weather conditions to ensure optimal viewing opportunities. The core functionality focuses on the ISS, but in-app purchases extend its capabilities to track other celestial and artificial objects. Optional extensions, available via in-app purchase, allow users to monitor dozens of amateur radio and weather satellites, providing real-time transmitter information and Doppler frequencies. Additional extensions cover _Starlink_ satellites, the _Hubble Space Telescope_, rocket stages, bright satellites, comets, and planets, expanding the scope beyond the ISS to a broader range of observable space phenomena. The app's interface is designed for ease of use, displaying pass times, directions, and elevation. It adapts predictions based on the user's GPS location, ensuring accurate local forecasts. The latest update, dated April 3, 2026, includes corrections for magnitude values and various speed and stability optimizations.

Article from 73 Amateur Radio Today about experimenting on ferrite loops transmitting loop antennas for 80 and 160 meters bands.

Hone your Morse code skills with this entry-level project. Article includes the full schematic of the CW Trainer, describes the sketch and how to operate the morse code trainer.

Digital voice on Amateur Radio - devoted to the discussion of digitized voice and data over analog emission modes.

An home made FETer QRP transceiver for the 80 meters band

Design and build a 6 meter 2-element Moxon antenna mostly from available aluminum tubing and angle stock.

There are many designs for building preamps each with their own advantages and disvantages. In this PDF Article author reviews several different types.

The author who works successfully via EME on this band wants to describe his own yagi design and give some of hints for the construction. by Heinrich F. Reckemeyer, DJ9YW

This document is a must read for anyone considering building a good low cost HF multi-band antenna system. The author combine in this document four important ingredients to produce simple but effective antenna system, like antennas of non resonant length, line attenuation, the transmatch and the balun

About Coax Traps, NC4FB examine the operation of coax traps through modeling.

A 160W linear amplifier for 4 meters band based on GI0GDP

How to run an SDR Receiver on the Android Google Nexus 7 using SDR Touch App and an RTL-SDR dongle, review and costs by IW5EDI

Cushcraft XM240 transformation into a Moxon antenna by W6NL

This is a schematic drawing of a project for the construction of a portable mast that can easily be made with PVC pipes.

A free PDF from NASA about cubesat. Basic Concepts and Processes for First-Time CubeSat Developers. A great introduction document dedicated to Cubseat developers.

Have you ever thought of setting up a portable HF station for an activity ?

Marshall G. Emm, N1FN, meticulously examines iambic keying, dissecting its historical introduction in the late 1950s with transistorized electronic keyers and its purported advantages. The resource defines keying systems, electronic keyers, and various paddle types, including single-lever and dual-lever paddles, clarifying the distinction between iambic keyers and the iambic sending technique itself. It details the two main types of squeeze keying: true squeeze for alternating dot-dash strings and character insertion for specific elements within a character. N1FN critically evaluates the actual efficiency gains of iambic keying, referencing Chuck Adams, K7QO's, keystroke analysis. While a straight key to bug transition yields a 34.1% reduction and a bug to non-iambic keyer offers 16.1%, iambic keying provides only an 11% theoretical improvement. However, considering typical QSO text and Morse code's inherent optimization for common letters, the practical efficiency gain is estimated at a modest 4-6%. The article also highlights how iambic keying's reliance on precise timing gates can impose a speed limit, making it less effective above 40 WPM, where many operators revert to non-iambic methods or single-lever paddles.

Adding 17 meter band to Mosley TA-33M yagi antenna

Introduction to WSPR beacons. Article describe WSPR2 and WSPR15 beaconing mode and include a frequency reference table for both WSPR modes

Getting started on RTTY contesting. A PDF by ED Muns, presented at CTU conterst university, about amateur radio RTTY Contesting

This is a QST Article published in January 1982 by W1FB D. Demaw and HH Beverage and is a complete review of the original article published in 1922, which updates and reivew the beverage antenna theory and developlment, explaining the antenna design of transformers and gives accurate reports on antenna general performance.

Technical supplement manual of the Yaesu FT-8800R in english

The ADIF Processor is an online application that visualizes amateur radio contacts from an ADIF log file using Google Earth. SOTA CSV log files can also be used. As well as allowing you to view and explore your contacts in Google Earth, you will be able to see a Markdown or text table of contacts, use the output ADIF file which contains QRZ.com data, accurate contact distances and fields populated from comments in the input file. Print QSL labels. One of the benefits of using the ADIF Processor before uploading/storing your ADIF file is detecting errors in callsigns and activity references (e.g. POTA or SOTA references).

The TransWorld Antennas TW4040 The Adventurer Monobander™ is a portable HF antenna designed for rapid deployment in field operations, including **SOTA** and **POTA** activations. This manual details the antenna's assembly, tuning procedures, and operational guidelines for optimal performance on the 40-meter band. It outlines the specific components, such as the telescoping whip and base unit, required for proper setup. Instructions cover mast erection, radial wire deployment, and impedance matching to achieve a low **VSWR** across the designated frequency segment. The document also provides guidance on antenna orientation and environmental considerations for portable use. It specifies the antenna's power handling capabilities and physical dimensions when fully deployed and collapsed for transport.

A presentation of the Yagi Antennas, and other interesting tid-bits by Brian Mileshosky. The document provides an in-depth exploration of the Yagi-Uda antenna, detailing its historical development, design principles, and performance characteristics. Originally described in the 1920s, the Yagi antenna features a driven element and parasitic elements, including reflectors and directors, which collectively determine its behavior. The document highlights how element lengths, diameters, and spacing influence gain, impedance, and directivity. It also discusses the antenna's reciprocal nature and presents data on typical gain values for various element configurations. Additionally, the text covers practical considerations, such as the construction of a "Tape Measure Yagi" for amateur use, and touches on related antenna types like dipoles and their application in Near Vertical Incident Skywave (NVIS) communication.

How can the current "flowing" out of the top of a mobile loading coil be greater than the current "flowing" into the bottom of the coil?

A distributed capacity coaxial dipole antenna. The antenna is very broadbanded with a very flat swr on all band when setup of the antenna is done at the proper lenght and height.

Manual of the BD-35 Dual Band VHF UHF RF power amplifier by Mirage Amp

A december 2003 QST article to Build a condenser microphone that will perform like the costly commercial units by KT4QW

A Chaotic Collection of Keys, Paddles, and Bugs

A multiband vertical antenna for HF bands with elevated ground radials slant down at 45 degrees and acting also as guy wires.

APRS-Webserver, that presents aprs-data and maps for free using Google Maps api. The position data is imported from aprs.org, winlink.org and echolink.org. The map data are partially commercial and free. This server is for amateur radio purposes only.

An interesting presentation of a real multiband Fan Dipole antenna, optimized for better DX operation performances, considering the terrain, position, DX destination path and other influencing factors

A homemade band pass filter for the 30 meter band based on the original VE7BPO design

When I tell friends that I enjoy amateur radio contesting, their reaction is usually a quizzical stare. "What's that?" It is hard to explain in the span of a cocktail conversation, so here is the answer.

How to make proper maintenance of your antenna. Fighting Antenna Corrosion is a QST article published in 1993 that helps on antenna maintenance works

How do two-wire reversible direction Beverages work, an excellent document that explains fundamentals of beverage antennas. This article details the design and performance of a reversible beverage antenna. Leveraging orthogonality between common mode and differential mode currents on a 2-wire line, this antenna facilitates independent reception from both ends. While common mode signals arrive and are summed on a transformer's secondary for common mode reception, differential mode signals induce anti-phase currents, providing individual reception. Various measurements explore impedance, transmission loss, and F/B ratio, highlighting the antenna's effectiveness and areas for improvement. Notably, increasing the antenna's height significantly improved performance.

Constructing a compact directional antenna for the 17-meter band, this resource details the build process for a Moxon rectangle, a two-element Yagi variant with folded-back elements. It covers the antenna's evolution from the _VK2ABQ beam_ and provides specific dimensions for a version built using fishing pole whips. The content includes a discussion of the antenna's radiation pattern, feedpoint impedance, and its inherent front-to-back ratio, which is often superior to a standard two-element Yagi. Practical considerations for element spacing and material choices are also addressed, alongside a visual representation of the antenna's physical layout. Performance data presented includes a comparison showing the Moxon rectangle's **2.5 dB gain** over a half-wave dipole and a front-to-back ratio of **20 dB**. The resource also touches upon the antenna's relatively wide bandwidth for a two-element beam and its suitability for portable operations due to its compact footprint. It offers insights into optimizing the design for specific operating conditions and discusses the advantages of its lower take-off angle compared to omnidirectional wire antennas, making it effective for DX contacts on the 17-meter band.

The dipole shown in this document is installed in an inverted Vee configuration, with two leg elements on each side held parallel to each other by 21cm spacers. The upper leg is for 40m and the lower leg for 20m. The spacers are made of 7mm plastic garden hose support for garden sprayers cut to 21cm.

30 meters beacon from UK. QRSS is a method of sending very slow morse code.

An open design exercise in interface archaeology, that decodes the input from a classic Morse key to send twitter messages

A 70 MHz QRP transverter project

10MHz WSPR and QRSS Transmitter Project

T2FD is a 600-900 ohms folded dipole, terminated with resistor. Feed impedance is coupled with 50/600 ohms voltage balun. It is a wide band antenna with rather low SWR over the full designed frequency range: antenna tuner is seldom needed.

Keyclicks and NB modifications for the Yaesu FT-1000MP Mark-V HF transceiver