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

Learn how to start using ham radio satellites for your DX contacts, PDF presentation by Dave Long

If you can program split-frequency memories in your dual-band radio, or your dual-band radio has two VFOs, you can work an FM satellite

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.

Assembling a Code-Practice Oscillator, a PDF by ARRL

In this PDF article Zack Lau describe how to homebrew a four element yagi beam antenna for 50 MHz band, including how to build mounting blocks and tubing clamps to hold elements.

A Compact and efficient multiband beam antenna based on a Modified W8JK Array by K5LJ

FREE ham radio newsletter The K9YA Telegraph is in full-color and delivered to your computer each month as a PDF.

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

ZS6YI modifications for the Icom IC7000

Article explain how create your own D-ATV station. By Ken W6HHC & Robbie KB6CJZ on RF Newsletter

The electrical characteristics of an antenna that are of interest to obtain by direct measurement are the frequency at which the antenna is tuned, the gain and radiation pattern

A pdf file with drawings and instruction to properly assembly and solder most popular coax cable connectors

QST Article on what you should know about matching networks for class C RF power amplifiers

Collection of various Dubus articles in PDF format

Limiting static surges on dipoles, verticals or end fed antennas

A document about Repeaters what are they and how to use them in a pdf file format

Many Hams suffer from a cruel obsessive-compulsive disorder. They're driven to achieve the lowest possible SWR even when it is not necessary by WB8IMY

A complete test report on Icom IC-7851 obtained with some lab tests, in a 21 pages pdf file.

An illustrated and printable introduction to PSK 31 by by Alan J. Gibbs, VK6PG

Download the Yaesu VX-8R Cheat Sheet PDF File

A new, simple way to build the Eggbeater Antenna. This document introduces a new, simpler way to build the Eggbeater antenna. It also introduces a technically proper way to construct the Eggbeater antenna in order to achieve the best result.

Sometimes we need a little more output filtering than traditional designs offer. Look at a new filter that can give you that extra boost. QST article by W3NQN

Project for DXers and experimenters alike. An old article publishes by 73 Amateur Radio magazine in PDF format, where all the components required to build your own HF spectrum analyzer may be found in a well-stocked junk box.

Third-order Cauer filters can boost performance of multi-transmitter, multi-operator contest stations to the next level. The filters are practical and you don’t need expensive test equipment to align them.

QST Magazine Product Reviews - Key Measurements Summary - HF-Transceivers or Receiver and Linear Amplifiers

Building a Windom HF Antenna. A PDF file presentation about homebrewing a windom antenna for the HF bands with formulas for 40 and 80 meters bands and step by step guide on making a 4:1 balun to feed the antenna.

Here is a simple, self-contained beacon which can run a few milliwatts or as much as a watt depending on choice of amplifier and supply voltage.

Article by N6LF on a top band vertical antenna array system

Improving measurement accuracy when low-power analyzers are used.

Get familiar with the basic operating procedures for using the JT65 mode of HF digital communications, a 35 pages PDF file.

An antenna project to obtain a bigger signal on the 80 Meter (3.5 to 3.8 MHz) amateur radio band

Loop Antenna Basics and Regulatory Compliance for Short-Range Radio

Fixing the IC-7000 noisy audio that can occur when IC-7000 audio output is connected to Hi-Fi earphones or external speaker.

Design for a dual-band CW transceiver using the AD9834 Direct Digital Synthesizer

HSMM Experiments on the 6M Amateur radio Band

A portable USB SO2R box made with Arduino

An ham radio contest log sheet in a PDF US letter printable format, can be used for portable operations, free to print and download.

As used on the new GB3VHF 144.43MHz Beacon

This manual is an edited version of the GAP supplied document, complete with diagrams, pictures and assembling notes by Mitch Baum AE2A. This is 29 pages document in PDF Format.

A amateur radio guide to RFI, ferrites, baluns, and audio interfacing by K9YC

Notes on using the QST propagation charts to determine propagation conditions

YAESU FT-1000MP Mark V ESSB Modifications pdf file

PDF File of the Kenwood TM-710A user manual

This is a concept paper, not a constuction article. There are too many variables to propose a one size fits all design. However, this paper should give you the basic idea how to do it

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

Kenwood TS 480 english manual in pdf format

A 200 kHz bandwidth digital transmission system for image transfer in the Amateur Service is under development, specifically targeting VHF allocations. John B. Stephensen, KD6OZH, leads this project under an FCC Special Temporary Authority (STA) valid until September 10, 2006, authorizing emissions up to 200 kHz bandwidth in the 50.3-50.8 MHz segment. Current regulations typically limit bandwidths to 20 kHz on VHF amateur bands, making this STA crucial for testing wideband digital modes. The modem, a modified **OFDM** (Orthogonal Frequency Division Multiplexed) unit, was initially tested on the 70-cm band. It splits a high-rate data stream into multiple low-rate subcarriers to mitigate multipath echoes. The system uses a DCP-1 card with a Xilinx XC3S400 FPGA and Oki Semiconductor ML67Q5003 microcontroller. The transmitter, located at 36d 46m 30s N, 119d 46m 22s W, generates 150 WPEP into an 8 dBi gain vertical antenna, while the mobile receiver uses a Ham-stick. Three data formats for 50, 100, and 200 kHz channels are being tested, with encoded data rates of 96, 192, and 384 kbps. Verilog code for the VHF OFDM modem is 95% simulated, with modifications from the UHF version including increased filter coefficient precision and a change from Ungerboeck **TCM** to BICM for improved performance over fading paths. Final tests will involve one-way over-the-air measurements of bit error rates and coverage area.

Building a Resonant Feed line Dipole for 2 Meters

G3SEK answers to some practical questions on builing the N2PK VNA Vector Network Analyser