circuit specialists

Antentop: Loop Antennas - Article on radiation patterns of small loops, equivalent circuits of loop antenna, small loops as receiving antennas, ferrite loops

Building Coaxial Traps - This page describes the design and construction materials W8WWV used to build a coaxial cable trap. A coaxial cable trap is a parallel resonant circuit that is usually inserted in an antenna element to enable multiband operation.

Multi Band Antenna Traps - These devices are called Traps, but they are actually more like frequency sensitive switches. They are parallel resonant, high Q, tuned circuits which provide a very high impedance at their frequency of resonance.

Getting the most from your tuner - Here is how to adjust this popular tuner circuit so it transfers maximum power to your antenna without going snap

A remote antenna tuner - Interesting project to remotely control, using a servo control circuit, a common commercial antenna tuner by N30X

Emtech ZM-2 Antenna Tuner Kit - The Emtech ZM-2 Antenna Tuner is a nifty little portable transmatch for QRP (low power). It utilizes the well-known Z-match circuit, which is especially useful for balanced antennas (like dipoles and loops).

Fun With Tubes - A noncommercial site operated by Max Robinson and dedicated to passing on and preserving knowledge of vacuum tube circuits and techniques.

Antique Radio Schematics and Capacitors for Tube Radios - Specializes in antique radio schematics and capacitors. carries antique radio schematic diagrams and electronic circuit service information for american, canadian and european antique radios.

Canadian Antique Radios Schematics Diagrams Service - We specialize in canadian antique radio schematics for vintage tube radios made in canada. we carry lots of factory electronic circuit schematic diagrams as well as all rcc / radio college of canada service data 1920's - 70's.

E. H. Armstrong - Radio's premier inventor, Edwin H. Armstrong was responsible for the Regenerative Circuit (1912), the Superheterodyne Circuit (1918), the Superregenerative Circuit (1922) and the complete FM System (1933).

PSK31 Interfacing - PSK31 basics and radio to pc soundcard interface circuits, radio to soundcard, soundcard to radio and pc serial port to radio

Far Circuits - FAR Circuits is exclusively a manufacturer of Printed Circuit Boards for electronic projects that are used by the Amateur Radio and electronic hobby enthusiast.

ExpressPCB  ^updated - Free PCB software is a snap to learn and use. For the first time, designing circuit boards is simple for the beginner and efficient for the professional.

DesignWorks - Commercia, productive and easy-to-use electronic circuit schematic drawing tool Featuring full hierarchical design, standard and custom netlist formats, extensive symbol libraries, scripting and customization features and much more.

ViPEC Network Analyzer - This program intended for electronic circuit analysis (mainly for Linux). ViPEC is a powerful tool for the analysis of high frequency, linear electrical networks.

Qucs - Quite Universal Circuit Simulator Priority listing - Qucs, briefly for Quite Universal Circuit Simulator, is an integrated circuit simulator which means you are able to setup a circuit with a graphical user interface (GUI) and simulate the large-signal, small-signal and noise behaviour of the circuit. After that simulation has finished you can view the simulation results on a presentation page or window. Run on Linux.

AM-6154 FAA Amplifier circuit conversion - AM-6154 222MHz grid Conversion Information by N0UK

Medium Frequency Amplifier Circuits Compared - Mark Connelly, WA1ION article on Medium Frequency Amplifier Circuits in PDF format, include some RF amplifier schematics

Rotator Brake Delay and Protection Circuit - A rotator modification by W4ZT

Audio processor for SSB transceiver - This circuit consists of microphone amplifier and a high pass filter. Suitable to improve signal readability.

NiCad battery charger - A basic nicad battery charger using a single medium power transistor.

A low cost UHF/VHF duplexer - Duplexers for dual band radio are usually high pass filter and low pass filter combined in the same box. This circuit is a design within a cost of US$10.

A Power Supply on the Cheap - Need a variable power supply that is short circuit protected and over voltage protected; Here is a good one that can be built cheap by VE3IVJ

External Keypad for FT-817 - An external keypad for FT-817(ND), for the serious portable/field-day contester/operator. Homebrew it with the free firmware and public circuit diagram. The circuit is very simple and takes power supply from the ACC port of the radio

Universal QRP Transmitter - Here's the homebrew Universal QRP transmitter adapted from work by Wes Hayward - W7ZOI. The circuit originally appeared in QRP Classics published in 1980 by the ARRL