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KD8KSB realization of the CJU satellite antenna that allow similar performance to the arrow antennas.

MFJ-264 dummy load restoration by VE3LNY

Study of the Coaxial Dipole: Just how does this thing work.

Technical Correspondence, QST, July 1990 - Why even "perfect" phased array element currents don't produce perfect patterns.

By Peter Kemp, KZ1Z

A 1:4 current balun made with 2 4C65 cores by PA1G in Dutch

Balanced feed with coaxial line by John F. Clemens W9ERN

The **Solarcon A99** vertical antenna, a half-wave over a quarter-wave variable mutual inductance design, primarily serves the 11-meter CB band but also finds use on 10 and 12 meters for amateur radio operators. Its simple construction, consisting of three fiberglass sections and a 16 AWG radiating element, makes it an accessible option for new operators or those seeking an easy-to-install base station antenna without complex mounting requirements. Despite claims of 9.9 dBi gain being widely considered exaggerated, and a manufacturer rating of 2000 watts power handling often viewed with skepticism (with 300 watts suggested as a practical limit), the A99 maintains popularity due to its low cost and ease of deployment. It typically tunes to a 1.2-1.3 SWR out of the box, requiring minimal adjustment via its two tuning rings. Its high angle of radiation allows for effective local communication even when mounted at low heights, such as 8-10 feet off the ground. However, the A99 is known for significant RF bleed-over issues, particularly when operated with higher power or mounted close to residential electronics. While its internal design is often described as cheap, the antenna exhibits remarkable durability, frequently lasting a decade or more in various weather conditions. Its affordability and straightforward setup continue to make it a go-to choice for many radio enthusiasts.

Wikipedia page dedicated to the T2FD antenna

Getting the most out of LowFER transmitting antennas, designing an efficient antenna for the 1750-meter band by K0LR

The florida contest group, is the first amateur (ham) radio contest club, organized in the state of florida.

The N3UJJ antenna project,parallel-cage dipole a multi-band horizontal antenna, without the need of an antenna tuner.

Web Site of Ukrainian Club Amateur Radio station from Vernadsky Research Station on Galindez island EM1U

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

A versatile hybrid synthesizer for UHF and Microwave Projects

This online WebSDR is located near Corinne, Utah, has coverage on all U.S. amateur HF, MF and LF bands, 2 meters, the bottom 1 MHz of 6 meters, and several shortwave broadcast bands.

Collecting and history of CRT tubes and physics instruments

AMSAT NA official web site.

Experiments on vertical antennas among the trees by ik2egl

This useful coax tester allows you to screw the PL-259 onto the tester to get a GO/NO GO status. When the LED lights up- you have a short circuit.

There are several reasons that can cause coax line radiation, most of them are related to wrong or missing use of a balun, but none can be imputed to load mismatch.

Presents the Holy Cluster, a contemporary DX cluster service offering real-time amateur radio spot data. This platform integrates a dynamic graphical map to visualize current contacts, enhancing situational awareness for DXers and contesters. Developed by an Israeli group of developers and supported by the Israeli Association of Radio Communication (IARC), the Holy Cluster aggregates DX spots from various sources, including traditional telnet clusters, the Reverse Beacon Network (RBN), and PSK Reporter, providing a comprehensive view of band activity. The cluster's design emphasizes a user-friendly interface for monitoring DX activity across multiple bands, including dedicated support for JOTA (Jamboree On The Air) operations. Its aggregation capabilities allow operators to quickly identify propagation openings and active stations, streamlining the process of making two-way radio contacts. The integration of RBN and PSK Reporter data offers insights into propagation conditions and station reception reports, which can be invaluable for optimizing antenna direction and operating strategies.

Win4K3Suite is an integrated control program for the entire Elecraft K-Line. It supports the K3, the KPA500, the KAT500 and the P3 Panadapter. Has a remote server mode as well, that supports P3 streaming video.

by Jim Stafford, W4QO appeared in QRP Quarterly, Fall, 2006

Demonstrates a specialized **DX cluster** designed to support the annual Jamboree On The Air (JOTA) event, facilitating real-time spotting for participating Scout stations. While its web interface has been discontinued due to security concerns, the cluster remains fully operational and accessible through standard cluster software. Operators can connect to the JOTA cluster by pointing their client to www.pi4raz.nl on port 7300. This setup allows for the exchange of **DX spots** and other operational information relevant to JOTA participants, ensuring that Scouts and their amateur radio mentors can continue to make contacts and log stations during the event.

Frequencies and location of every meteo radiosonde launching centres in Europe. Equipments, antennas, history, SondeMonitor and BalloonTrack tutorials

This is a presentation used at OVARC on the LindenBlad antenna construction. The presentation cover several topics about this antenna, from the basic antenna design, to the guide on how to contruct a custom lindenblad antenna for the 2 meters band and and 70 centimenters band.

This Radio Direction Finder Device Connects to an FM Receiver, Transceiver, or HT

SCRRBA is a volunteer organization providing coordination of a number of heavily utilized amateur radio frequency bands in Southern California.

KV5R review of the Icom 706MkIIG

Optimizing audio settings on the Kenwood TS-990 by AB4BJ

Comparing the ICOM IC-7600 and the Yaesu FTDX-3000

Projects you can build, an amplified shaped sine-wave oscillator

Article on an outdoor usage of the AH-4 antenna tuner

Taking the Raspberry Pi 2 for a Test Drive with GNU Radio. Installing GNU Radio and receiving aircraft radar with a USB TV tuner

A dual band delta loop antenna resonating on 30 and 40 meters band using a single wire for the top slopers on both 30 and 40 meters and does not need any balun

Basic guidelines for proper placement of an amateur radio mobile antenna

The mark 2 Crossfield Antenna was described in Sprat 76 by Alec, GD3HQR

An article on RFD antennas, resonant feed-line antennas

An end-fed-half-wave antenna matcher project based on a FT-82-43 core with a 100 pF and 45 pF capacitor in parallel

This article describe the principles of baluns when referred to devices used to balance unbalanced systems, like a coax cable and a dipole antenna

The m0xpd keyer project utilizes a PIC16F628A microcontroller, offering Iambic A and B modes, adjustable speed from 5 to 40 WPM, and variable weight control. It incorporates a sidetone generator with adjustable frequency and volume, along with a PTT output for transceiver control. The design includes a 16-pin DIL IC socket for the PIC, a 3.5mm stereo jack for the paddle, and a 3.5mm mono jack for the PTT output. Powering the keyer requires a 9V DC supply, which is regulated down to 5V for the PIC. The circuit board layout is designed for through-hole components, facilitating home construction. A detailed schematic and a parts list are provided, guiding builders through the assembly process. The project also discusses the firmware programming for the PIC16F628A, essential for the keyer's functionality. Construction details cover component placement and wiring, ensuring proper operation. The keyer's compact size makes it suitable for portable or shack use, providing a reliable CW interface.

The copper J-Pole antenna soldered in a couple of hours with an interesting method to setup the feeding point

FT-847 PA Mod, there is a better way, by G0MGX

Complete guide to receive weather satelite images with a RTL SDR dongle and free software

A source of knowledge for learning about and understanding antennas. The goal is to present a comprehensive tutorial on antennas.

Home for dutch speaking radioamateurs, wordwide. We also provide information about our hobby in english and other languages. Hamradio guide for visitor to Holland

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

The A QRP Club is a small group of Amateur Radio enthusiasts who enjoy building, operating and (mostly) talking about Low Power radio communications, equipment and systems.

Maintained by Larry Tree Tyree N6TR