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PDF files describing how to homebrew a 1:2.5 balun

The project details modifications to an ARK-40 QRP CW transceiver kit, specifically replacing its original thumbwheel frequency selectors with a **BASIC STAMP BS-II microcontroller** and an optical shaft encoder. The redesigned control circuitry outputs a BCD code to the ARK-40's synthesizer, enabling more convenient knob-type tuning. This modification significantly alters the user interface, moving from discrete frequency selection to continuous tuning. Operating frequency is presented on an LCD readout, offering two distinct display modes: a "bandspread dial" mode that simulates an analog dial scrolling across the display in 1 kHz increments, and a conventional digital readout with 100 Hz resolution. Pushing the main tuning knob toggles between these modes, providing both rapid band traversal and fine-tuning capabilities. The software for the BASIC Stamp is written in P-Basic, addressing the challenge of accurate analog dial simulation. Physical modifications include fabricating a custom PC Board for the STAMP, mounting it with an L-bracket to the optical encoder, and creating a new front panel. The front-mounted speaker was relocated to accommodate the new tuning knob and display, transforming the **ARK-40 transceiver** into a more user-friendly rig with its built-in CW keyer and 5 watts of power.

no tune SSB/CW transceiver for 1296, 2304, 5760 and 10368 MHz

An RF power supply for 144 MHz schematics and instructions

VU3NSH article on high current universal supply for rigs

Homebrewed transceiver for 20 meter originally born for 17 meters band

Article describing how to homebrew a yagi antenna for 50 MHz, includes plans for a four and five elements yagi beam and details how how match impedence with a gamma match

Practival project that contains two isolation transformers, one for AF from the tranciever to the line in on a soundcard, and one from the audio out of the soundcard back to the mic / data input of the radio. Both of which are variable inside the interface via two preset resistors.

An economical dipole for simple QRP HF homebrew rigs

A DIY Automatic Band Decoder (ABD) project, designed for dual-radio operation, addresses the common challenge of integrating band data with older transceivers lacking dedicated outputs. This particular build utilizes an AVR AT90S8515 microcontroller and a 16x2 Liquid Crystal Display (LCD) to provide band information, specifically targeting Kenwood rigs via a computer's LPT port. The design aims for cost-effectiveness while maintaining functionality, offering a solution for hams seeking to add automatic band switching capabilities to their station without significant expense. The project outlines the core components required, including the microcontroller, LCD, and an enclosure, noting that the Printed Circuit Board (PCB) fabrication and AVR programming might present challenges for some builders. It details the input requirements, such as a four-pin input and PTT for each radio, along with a 13.8V DC power supply. The decoder provides 2x6 outputs capable of sinking 500mA, suitable for controlling external devices like antenna switches or filters. Despite the original unit being damaged by a lightning strike in 2004, the author confirms its successful operation prior to the incident and mentions plans for a revised version. The resource includes a schematic in PDF format and images of the finished PCB and assembled unit, demonstrating the practical implementation of the design.

Ham radio Blog, focusing on homebrewing and testing antennas, rig mods and contesting.

This online project guide details the construction of a homebrew boom microphone system. It details the assembly of a microphone shell from a 3/4" PVC pipe section and an end cap, requiring a drilled hole for a snug fit of the electret or condenser mic element. The internal wiring schematic specifies a **2.2 K** resistor and a **47 uF** polar capacitor for signal conditioning, with a circuit diagram provided for integration with IC-706 series transceivers. The guide outlines the use of CAT-5 cable for internal connections, incorporating strain relief at the rear of the mic shell, and an inline 3.5 mm jack to facilitate an external _PTT_ line, designed for a foot-mounted switch. Further construction involves fabricating a microphone shock mount from a 2-inch PVC connector, detailing the creation of four "fingers" and the insertion of screw-eyes for attaching elastic bands, which are twisted 180 degrees for tensioning and vibration isolation. A foam wind screen is also incorporated into the microphone assembly, secured with adhesive. The boom arm itself is repurposed from an articulated architect lamp, with the original lamp assembly converted into a **60 watt** resistive load for testing power sources. Microphone cabling is secured to the boom arm using wire ties, ensuring sufficient slack at hinge points to maintain articulation. The boom base is mounted to a bookshelf, requiring specific positioning to achieve proper microphone placement in front of the operator. Performance evaluation of the microphone system is conducted through on-air audio signal reports from other amateur radio operators. DXZone Focus: Online Project Guide | Boom Microphone Construction | Electret Mic Element | PTT Line

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

Noise Canceller kit originally developed about 1989 by G4WMX and GW3DIX and improved by DK9NL and DG0KW.The VK5TM Noise Canceller is another version of the design, with the HF Vox circuit removed and a couple of other minor changes, including the use of SMD JFETs and a double-sided pcb.

A homebrew radio transmitter project, based and inspired by the original 30 Watts input on 80 50 and 15 meters band transmitter by W11CP

Documents the operational experiences and technical insights of amateur radio station VA3STL, offering a firsthand account of various on-air activities and equipment. The blog features a detailed narrative of a **QRP transatlantic QSO** on 12m SSB, achieving a 55 report with 10W to a mobile station in Italy using a homebrew 90ft doublet antenna. It also introduces the _Ten-Tec 539_ QRP HF transceiver, a 10W output rig covering 80m through 10m, designed for portable operations and featuring DSP and dual VFOs. The resource also delves into historical radio technology, specifically the "Gibson Girl" survival radio, an emergency transmitter operating on 500kHz (and later 8280/8364 kHz) with a hand-cranked generator and kite-deployed antenna. This section explores its origins from German designs and its use during World War II, including its distinctive curved shape for ergonomic hand-cranking. Further historical content includes a visit to Signal Hill in St. John's, Newfoundland, commemorating Marconi's reception of the first transatlantic radio signal in 1901. The post describes the Cabot Tower exhibit and the VO1AA station, highlighting the site's significance despite the thick fog during the visit. It also showcases a homebrewed _Marconi-style straight key_ by WB9LPU, crafted to celebrate the centenary of Marconi's achievement.

Homebrewing a UHF antenna to be used on a bicycle. This simple project gives you the right hints on how to build and setup and install a 70cm antenna on a bicycle.

The PAC-12 Antenna, a multi-band portable vertical, is meticulously detailed in this construction article by James Bennett, _KA5DVS_. The design emphasizes ease of homebrewing using readily available components from local hardware stores, including replaceable loading coils. It outlines the preparation of the 72-inch telescoping whip (originally from Radio Shack, with an alternate source now provided by _Pacific Antenna_), the construction of the loading coils from PVC risers, and the fabrication of the aluminum rod base sections. Specific instructions cover threading aluminum rod with a _1/4-20 threading die_ and assembling the feedpoint insulator with a BNC connector, along with recommendations for radial deployment. KA5DVS, an avid traveler and QRP enthusiast, developed the PAC-12 to address the bulkiness of random wire setups and the limitations of commercial portable antennas like the Outbacker or SuperAntennas MP1. His goal was a lightweight, packable antenna that disassembles into 12-inch sections, achieving an assembled length of approximately 8 feet. The design strategically places the loading coil away from the base for improved efficiency. The PAC-12 notably placed first in efficiency compared to a quarter-wavelength wire vertical at the HFPack antenna shootout during the Pacificon conference in October 2001, demonstrating its practical performance for field operations. Appendix C showcases various _NJQRP Club_ members' PAC-12 constructions, including a 20m beam made with multiple PAC-12 elements.

The 222 MHz Transverter project, based on Zack Lau's (W1VT) original July 1993 QEX magazine design, provides an IF of 28 MHz for both transmit and receive paths. Rick Bandla (VE3CVG) contributed supplemental notes and construction details, including modifications to achieve 10 mW output power from an initial 4 mW PEP. The design incorporates three distinct boards: a Local Oscillator (LO), a Transmitter (Tx), and a Receiver (Rx), with an estimated parts cost of just over $150 CDN, significantly less than commercial kits. Construction involves both through-hole and surface-mount components, with specific guidance on mounting MAV and MAR devices, grounding techniques, and component selection. The project details include parts lists, schematics for the LO, Tx, and Rx, and board layouts. Troubleshooting advice emphasizes sequential testing, starting with the LO, then Tx, and finally Rx, using a 194 MHz and 222.100 MHz capable FM handheld for signal tracing. Further enhancements are discussed, such as an optional Tx driver stage to boost output to 100 mW and the potential modification of a Motorola Maxor 80 PA for 222 MHz SSB/CW operation. The resource also covers practical aspects like power attenuation pads for IF radios (e.g., FT817) and considerations for enclosure design, including repurposing a Maxor 80 case. Performance reports indicate successful 70 km contacts with only 4 mW output.

The FT101ZD DDS VFO project replaces the original VFO in the Yaesu FT101Z/ZD rigs with an AD9850 DDS module, providing enhanced frequency control. It uses the original optical encoder and clarifier for compatibility, with a custom 6V power supply modification. The project includes selectable step sizes, a frequency save function, and works with both RX and TX modes. The design involves mechanical and electronic modifications, including SMD components and a custom PIC processor. Calibration ensures accurate frequency output, with further improvements under consideration.

This project outlines a simple Lead Acid/SLA battery monitor, designed to alert users when battery voltage falls below 10.6V. The monitor, based on a PIC16F1827 microcontroller, checks the voltage of up to five batteries and triggers an alarm if any drop too low. The system operates in various modes, including self-test, monitoring, and alarm. This updated version improves upon the original 1999 design, offering a more modern microcontroller and extended functionality for workshop use, with minimal impact on battery charge.

This article discusses a high performance, 7MHz, 5 watt SSB rig, the Daylight Radio, an all-analog radio design from the 1980s that includes a full circuit diagram, IMD NR60 calculations, QER crystal filter, bandpass filter, receiver portion, and more. The author explores the design, components, and functionality of this analog radio for hams interested in vintage or homebrew radio projects.

This guide by F4ANN (2014) explains replacing the backup battery in a YAESU FT-757 GX when stored frequencies reset on power-up. The original CR-1/3N lithium cell (3V, 160 mA) can be substituted with a CR2032 (170 mA), which is cheaper, widely available, and easier to replace. The process involves opening the transceiver, carefully desoldering the old battery from the PCB, and wiring in a holder for the CR2032. Extra care is required with screws, connectors, and soldering. The author also replaced backlights and serviced the cooling fan. Future battery replacements are simplified to four screws.