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Schematics plans by K9GDT and all infos to build a 600 Watt HF Amplifier. The amplifier uses four Motorola MRF150 50 volt TMOS power FETs configured in push-pull/parallel and biased for class AB linear operation.

Galaxy web site updates and additions with modifications, diagrams, and schematics for galaxy radios

Schema of a self made balun used to match randmon wire antennas, mainly for shortwave listening pourposes, in italian

Documents and schema on how to build a Magnetic Loop Antenna fo 80/30 mtrs

The project details a DIY SWR/Wattmeter designed around an _Arduino Uno_ shield, providing capabilities to measure RF power from 2 to **200 watts** and Standing Wave Ratio (SWR) for HF amateur radio bands. This construction features a compact design, integrating the measurement circuitry directly onto a custom PCB that interfaces with the Arduino Uno microcontroller. Key components include a directional coupler for sensing forward and reflected power, precision rectifiers, and analog-to-digital conversion for processing RF signals. The Arduino firmware handles calibration, calculations, and displays the results on an integrated LCD, offering real-time feedback on antenna system performance. The design prioritizes simplicity for homebrewers. Performance specifications indicate accurate readings within the **2-200W** power range, suitable for typical QRP to medium-power HF operations. The project provides schematics and a basic overview of the software logic.

Detailed plans of my homebrew receiver. Frequency coverage is from below 300kHz to 30MHz. Pictures, schematics, board layouts, parts lists and more can be found here.

Roy G4WPW has collected one of the most complete and interesting pages for microphone connections schemas and wiring. Includes Kenwood microphones schematics as well as Yaesu Icom Alinco Adonis Drake Heil JRC MFJ schematics

K9AY loop antenna installed at PA6Z Contest group. This is a receiving antennas for the low bands (160m, 80m and 40m). Include schematics and info on a building the control box, preamplifier and low-pass filter

VHF magnetic loop atenna by ON1DHT

813 Linear Amplifier Project includes many schematics, drawind and assembling construction

Specializes in antique radio schematics, circuit diagrams and service data for vintage tube radios. Carries information for American, Canadian and European antique radios.

To connect up your FT-817/857/897 to a PC you have a number of options. For the serial connection you can go ahead and obtain a CT-62 from YAESU. Alternatively you can make up your box with a level converter and cable using schematic in this page

ON6MU project for a vhf uhf preamplifier

50 MHz 1500 Watt Russian GS35B amplifier. Well documented. Complete construction details,pictures,schematics, and more.

Service information, modifications, diagrams, manuals and schematics, and technical files on Galaxy DX Radios.

Schematics for a VHF UHF duplexer

Dealer for Cb radios, Cb antenna & accessories Galaxy radio, Cobra cb radio, Ranger, Texas Star, Palomar. Police scanner, radar detector, GPS, GMRS, FRS, Wilson cellular amplifier & antennas. Owners manuals, schematics and links.

A 3 elements long yagi antenna for 6 meters band by ON6MU

Service information, manuals, diagrams pictures and schematics, and technical files on Cobra Radios

The _Astron RS35m Power Supply Schematic_ provides a detailed circuit diagram for this popular linear power supply, focusing on the rectifier and pass transistor stages. It presents the AC input and DC output sections, illustrating the component layout and interconnections critical for understanding its operation. The schematic is enhanced with specific annotations derived from the December 2005 QST "Hands-On Radio, Experiment #35 Power Supply Analysis." These notes offer insights into the circuit's functionality and potential analysis points, making the diagram more instructive than a bare schematic. The resource serves as a practical reference for hams interested in the internal workings or maintenance of the _Astron RS35m_ unit. This document specifically highlights the key components responsible for voltage regulation and current delivery.

Contain schematic diagram of many different radio, and some operations instructions.

Complete 144/50 MHz transverter with GaAs Fet LNA and 400 mW out. No printed circuit board. Schematics and images by Christoph Petermann DF9CY

WV7U YC156 and 3CPX800 amplifier projects. See pictures, schematics, test data, links, and more!

Based on Motorola MRF454, schematics and component list

Two types of home-brewed 12/20 Ampere 13,8volt power supplies, including detailed part lists by ON6MU

Schematics, mechanical drawings and picture of a Receiving loop antenna by N5ESE - N5FC

FT857 and FT897 Interface PCB and schematic

A 13,8v/5Amp 78H05 based power supply for portable use. In this example used to power up a Yaesu FT-817

A full wave 2-meter VHF omnidirectional antenna by ON6MU

This project uses a widely available IRF510 MOSFET, work on HF 80, 40, 30, 20 and 17 meter bands

Electronics service manual exchange, IC-706 service parts, schematics from ICOM official manual

Regenerative short wave radio schematic

UHF 3 element portable antenna with gamma match by ON6MU

This is a picture of a schematic diagram of a multifunctional interface for Yaesu FT-8x7 Series Transceivers. It will work for Yaesu radios like FT-897 FT-857 FT-817

Service Manuals & Schematics, supplied for most types of equipment, Audio, TV, Video, Test and Ham Radio

Simple eprom programmer for 27Cxx family , used in TNC and G3ruh modem, eprom tutorial, schematics and KissEprom software for windows by iz7ath

Schematics and plans to build a custom CAT and audio pc interface

Infomration schematics and pictures about various hf and vhf QRO linear amplifiers

HF/6M antenna tuner preselector and antenna switcher project by ON6MU

AM/FM/CW QRP RF Power Amplifier for the HF 10 or 11 meterband (28MHz/27MHz)

Italian page including pictures schematics diagrams of an home made linear amplifier using four EL509 in parallel. Output power is about 700W.

A 1:4 balun suitable for folded dipole antennas

Demonstrates the construction of a **homebrew spectrum analyzer** designed by Wes Hayward, W7ZOI, and Terry White, K7TAU, enabling radio amateurs to build a capable test instrument without significant expense. The resource details a _double-conversion superheterodyne_ circuit, employing intermediate frequencies of 110 MHz and 10 MHz, and covers essential blocks such as the time base, logarithmic amplifier, resolution filters, and local oscillators. It highlights the use of hybrid and monolithic ICs, including mixers, amplifiers, and VCOs, to simplify construction while maintaining performance. The design supports useful measurements in the 50 kHz to 70 MHz range, with methods outlined for extending capabilities into VHF and UHF. The authors emphasize that this analyzer, while simple to build, is intended for serious measurements, requiring careful control of signal levels to avoid spurious responses. It uses an oscilloscope for display, with specific instructions for calibration and adjustment of various stages, including the log amplifier and IF gain. The guide provides detailed schematics and component lists for each section, such as the 110 MHz triple-tuned band-pass filter, which achieved **90 dB** image rejection, a significant improvement over double-tuned circuits. Practical advice on alignment and troubleshooting is included, drawing on the authors' extensive experience in RF circuit design.

Magnetic longwire baluns 1:9 combined with ground, a 1:2 and 1:1 balun connections by ON6MU

TVI and BCI bandpass and bandstop filters in SMD technique. Schematics and images.

Yaesu FT-1000MP, FT-990 and FT-920 packet data port to pc sound card for psk 31 interface.

A delta loop antenna project for the 40 meters band, include dimensions 80 meters band, with construction details, schematic and tuning instructions

MC-50 microphone modification for high emphasis, connecto kenwood ts-50 to kenwood radios.

End-Fed Half-Wave Antennas (EFHWAs) are analyzed for their utility in portable QRP operations, emphasizing their simplicity, efficiency, and predictable radiation patterns compared to other portable antenna types. The discussion contrasts EFHWAs with vertical antennas, random length wires, and center-fed dipoles, highlighting the common pitfalls of each, such as ground system dependency for verticals and feedline issues for dipoles. The article details the electrical half-wavelength calculation using the formula L (Ft) = 468/F(MHz) and explains how EFHWAs can be resonant on harmonic frequencies, enabling multiband operation. Various deployment configurations are presented, including the inverted L, inverted Vee, sloping wire, and vertical setups, each with specific advantages for radiation angle and polarization. For instance, a vertical EFHWA offers a low angle of radiation suitable for DX contacts without requiring an extensive ground system. The resource also addresses the counterpoise requirements, suggesting a quarter-wavelength wire or connection to a metallic structure for decoupling. A schematic diagram for a simple parallel-tuned circuit tuner, based on the _Rainbow Bridge/Tuner_ design, is provided, detailing component values for 30 and 40 meters, including a 6 microhenry toroidal inductor and a 20-100 picofarad mica compression capacitor. The tuner's adjustment process for SWR matching is also outlined.

Details a practical QRP wattmeter construction, leveraging a simplified SWR meter design by JA6HIC. The project focuses on a forward-only power measurement circuit, providing a functional instrument for RF power levels from milliwatts up to 5 watts. It maintains a 50-ohm input and output impedance, suitable for typical QRP transceivers and antenna systems. The resource includes the schematic for the "VSW" (Very Simple Wattmeter) and outlines a six-step alignment procedure. This calibration process involves using a known RF source up to 5W, setting full-scale deflection, and marking power increments. It also addresses minimizing frequency effects on readings with a 100pF trimmer capacitor, noting that measurement error is highest at the lower end of the scale. Construction notes mention using a piece of RG-213 coaxial cable for the inductance and coupler, with the wattmeter assembled in early 2003. The author provides an example measurement showing 0.8W into a dummy load and 1W into a 3-element beam.