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This is a description of how KO4BB built his tower. It is provided in the hope that it will be useful to anyone want to setup his own ham radio tower.

The page provides detailed information on a compact two-element yagi antenna, also known as the Moxon rectangle, specifically designed for the 17 meters band. It includes construction details, evolution history, performance data, and comparison with a 1/2 wave dipole antenna.

Build this noise reducing system to enhance audio of your speaker. A project by kg4jjh

A 70 MHz QRP transverter project

A collection of audio amplifier projects by N1HFX

Christoph Petermann DF9CY DRM demonstration receiver project including Circuit Diagram and component list

A synthesized 2.3 GHz Amateur Television (ATV) transmitter design, conceived by Ian G6TVJ, is presented, targeting broadcast-quality video performance on the 13cm band and extending up to 2.6 GHz. The core of the design utilizes a commercial Z-comm Voltage Controlled Oscillator (VCO) that tunes from 2.2-2.7 GHz, providing a +10 dBm output and simplifying RF alignment. This VCO's stability, originally intended for narrowband applications, readily accepts high-frequency video modulation, contributing to the transmitter's robust performance. The exciter stage, incorporating a Mini Circuits VNA 25 MMIC amplifier, boosts the signal to +16dBm, while a Plessey SP4982 prescaler divides the output frequency for the synthesizer. The synthesizer employs a Motorola MC145151 CMOS parallel IC, favored over the common Plessey SP5060 for its superior video modulation characteristics and ease of programming without microprocessors. This choice addresses issues like LF tilt and distorted field syncs often seen with SP5060 designs, particularly when operating through repeaters or over long distances. The MC145151 divides the signal further, enabling precise frequency stepping, with programming handled by EPROMs for channel selection and LED display. The loop filter network, critical for video integrity, was developed through experimentation to prevent the PLL from reacting to video modulation, ensuring a clean transmitted picture. The transmitter incorporates a Down East Microwave commercial power amplifier module, delivering approximately 1.6W output, driven by the exciter through a 3dB attenuator. Construction involves surface-mount SHF components on micro-strip lines etched onto double-sided fiberglass board, housed within a tinplate box. The design boasts no AC coupling in the video path, preserving low-frequency response, a common failing in other ATV transmitters. Performance tests with a 50Hz square wave revealed no LF distortion, and a calibrated "Pulse & Bar" signal showed a near 100% HF response, demonstrating its capability for high-quality ATV transmissions.

This circuit is very simple and has a fantastic range of potential uses.

Collection of ATV projects

N1HFX project to improve PL tone encoder providing a more stable frequency

The VersaBeacon is a frequency agile, modulation agile RF source using a DDS chip and minimal support circuitry. It covers a frequency span of 1MHz to 150MHz in 1 Hz steps and provides a variety of modulations

This article was first published in CQ-TV issue 208. Author try to explain digital television in layman's terms and without getting too involved in mathematics.

NHRC-2 Based Repeater Controller A perfect controller for a simple repeater or link, or portable/solar powered system.

A Tape Measure Beam Antenna for Radio Direction Finding based on WB2HOL design.

The CAT and audio interface version 3 project by PA5CA presents a comprehensive solution for integrating amateur radio transceivers with computer sound cards, facilitating digital mode operation and CAT control. It includes detailed schematics for the interface circuitry, illustrating the isolation transformers for audio paths and optocouplers for CAT data lines, ensuring robust electrical separation between radio and PC. The resource also provides PCB layouts, enabling constructors to fabricate their own boards for this specific design. The project outlines the component selection and assembly process, emphasizing the use of readily available parts to build a reliable interface. It addresses common challenges in sound card interfacing, such as ground loops and RF interference, through its isolated design. This construction guide offers practical insights into building a functional interface, making it suitable for hams interested in DIY radio accessories for digital modes like FT8, RTTY, and PSK31.

iota mapping project - a mapping resource for the IOTA (Islands On The Air) award program

A well documented Heathkit SB-200 restoration project by NT1K

Homebrewing a vhf bicone antenna with 8 clothes hangers and 4 feet of Sch40 non-metallic rigid conduit

Some techniques on homebrewing yagi antennas by VK5AJL

A simple VHF quarter wave antenna from PL25

A project for a vertical antenna for 60 to 20 meters by KV5R

MultiPig+ CW Transceiver Kit Construction

Battery-powered monitor designed to provide an audible indication of keying for those whose rigs lack a CW sidetone

Amateur projects to investigate radiowave propagation - G3PLX's chirp project, ionosonde database, and more

A stepper switch controller made with arduino by N3OX

A Picaxe Morse Code keyer project with source code and links to useful resources by K6ACJ

A really simple project to make a power meter measuring RF output powers from a few mW up to half a watt. A DIY amateur radio project for QRP enthusiasts

A home made project for an ATV RF power amplifier

Constructing a dip oscillator provides radio amateurs with a fundamental piece of test equipment for resonant circuit analysis. This particular design, adapted by VK3YE from a concept by _Drew Diamond VK3XU_, details a practical build using readily available components. The unit incorporates four plug-in coils, covering a frequency range from **2.6 MHz to 55 MHz**, mounted on 5-pin DIN plugs for versatility. A salvaged two-gang air dielectric variable capacitor, fitted with a vernier reduction drive, serves as the tuning mechanism, with the smaller gang optimizing bandspread at higher frequencies. In practical application, the dip oscillator is used by setting the meter needle to approximately two-thirds scale. When the instrument's coil is brought near a tuned circuit under test, a noticeable dip in the meter reading indicates resonance. This allows for precise measurement of resonant frequencies in antennas, filters, and other RF circuitry, proving invaluable for homebrewing and troubleshooting. The design emphasizes short wire runs for stable operation, particularly at the higher end of its operational range.

Adding a 20m band pass filter for the Icom IC-706MkII(G) by ON7EQ

Interfacing the Jabra 9450 flex wireless headset to the Icom IC 7300 ham radio trasceiver.

Add bands to your Hustler xBTV Series Vertical

Schematic of a fast charger for Gel Cell batteries

A PTT switch from Home Depot parts

Band filters for PA6Z made by PA9M, designed by W3NQN.

13cms and 23cms ATV my projects and builds. Also using wifi amps on 13cms, 13cms dish feeds using a Sky dish. GB3CZ

A shortwave radio listeners log book runs on Windows and MacOS Catalina and above. The KB6IBB SWL Logger is a program designed for the shortwave radio listener. It offers shortwave specific logging of stations, with most tasks handled automatically. The program also incorporates the use of EiBi shortwave database for logging and looking up various known shortwave stations world wide.

Details on projects by WA3TFS published in QST magazine over the past few years. Includes an online shop with several ham radio kits, circuit boards, simple SDR transceivers

Modifications to an Ameritron ALS 600 power amplifier by AF6SA

A simple RF probe diagram

Repairing and restoring a Tektronix 465 oscilloscope

Make your own battery clip by nj2x

Build a 7 Element 4M (70MHz) Beam By Paul M1CCZ

The N1HFX thermal cooling fan controller project details a practical circuit designed to manage cooling fan operation based on temperature, a common requirement for high-power amateur radio equipment. This build utilizes a **LM34** temperature sensor, providing a linear voltage output directly proportional to Fahrenheit degrees, simplifying the control logic. The circuit's core functionality involves a comparator that activates the fan when a preset temperature threshold is exceeded, ensuring efficient cooling and reducing unnecessary fan noise. This controller is particularly useful for amplifiers, power supplies, or transceivers that generate significant heat during operation. The design incorporates a _TIP120 Darlington transistor_ to drive the fan, capable of handling up to 5 amps, making it suitable for a range of fan sizes and current requirements. Field results indicate stable temperature regulation, preventing thermal runaway in enclosed environments. Construction involves readily available components, making it an accessible project for hams looking to optimize their station's thermal management.

Pro and cons of Digital ATV versus Analogue ATV

A trapped multi band end-fed-half-wave antenna for 40/30/20/17/15m.

A CW beacon keyer for 222 MHz by VA3NFA

A summary of common calling frequency for each digital mode on that band.

Switching Regulator Basics By Mike Martell N1HFX

Pictures of the restructuring of the ham shack starting from an existing garage. Changes includes isolation of walls and roof and rebuilding of the radio table.