circuit cad

Active HF antenna - An active HF receiving antenna circuit by G7BCJ

LU9DPD Daniel - Homebrew, antenas, balunes, expediciones, circuitos, electrónica, torres, fotos y relatos, todo referente a radioafición, radioaficionados y radioamateur

Quad loop antenna for 10 meters - A 27-28 Mhz quad loop antenna by Bernard Mourot F6BCU in french

Radio Cadena Escolar

RACOM - Radio modems - RACOM is a Czech company specialized in design and production of radio modems and other devices for wireless data networks for radio channels from 140 to 900 MHz. RACOM radio data networks are suitable for data transfer in telemetry & SCADA applications, transaction networks, security systems, IP networks and firts of all mobile tracking and fleet management.

Low Power Radio Modules - Low power radio modules - supplying rf modules, rf transceivers, radiometrix transmitters receivers, low power radio modules, scada, frequency hopping, 900 mhz, wireless data transmission, data telemetry, gps modules & receivers and more

VLF-LF And the Loop Aerial - The article discusses the theory of loop aerials for receiving and how they reduce the level of local noise. A Loop Aerial is described suitable for use on the LF and VLF bands together with a circuit of an interface loop tuner and preamplifier. The discussion extends to the problems of amplifier noise and the advantages of tuning the loop.

Antenna Noise and Signal Cancelling at LF - The fact that the phasing between a wanted signal and an unwanted signal can be different on different antennas is put to advantage. With this condition, the unwanted signal can be cancelled out by controlling amplitude and phase. The heart of the system is some form of phase control circuitry.

Far circuits - Direction finding projects, useful tools for t-hunting operations

NiCad Lady - Radio Battery - The NiCd Lady Company has been in the business of assembly and distribution of batteries since 1994, supplying government, industry and retail with a wide variety of batteries, and production of assembled products.

The Battery Station - Lithium Lead NiMH NiCad Ion batteries

YagiCAD - A freeware software package for Yagi design. This webpage also contains many sample and standard antenna downloads for experimentation.

Smith Chart Software - SimSmith is a highly interactive, real time Smith chart graphing program. Circuits are constructed using drag-n-drop. Load files can be imported from the EZNEC and CocoaNEC antenna simulation software and from the AIM4170 and miniVNApro antenna analyzers. Circuits and load files can be of any size. Key Features: SimSmith is one of the few Smith chart packages which models transmission line losses. SimSmith also allows the description of circuit elements using algebraic equations. SimSmith has only one screen and allows the screen to be resized to increase workspace or readability.

TCube - TCUBE is a combination of a Spectrum Analyzer and a Two Tone Generator, with optional quadrature outputs. It can be used for measuring the intermodulation behavior of an audio circuit, and as a general purpose tool

Defpom's CB Radio Simulator - It is a application which can be used for troubleshooting CB radio faults, by giving a graphical display of the normal operating frequencies generated by various parts of the CB radios circuits, it can help you identify if a frequency is incorrect or even missing. Another good use for this software is simulating possible frequency expansions, as it allows you to choose any frequency that the PLL is capable of generating, so you can see what the radio will allow you to get !

Audio Preamp - Easy circuit that provide good gain to weak audio signals

OZ2M - Beacon Keyer - Circuit and software to build a beacon keyer, includes downloadable packages.

KB2LJJ Radio Mods Database  ^pop - The KB2LJJ radio mods database offers approximately 12,000 Radio Mod's, circuits and manuals.

DigChip IC database - DigChip is a provider of integrated circuits documentation search engine, it's also distributor agent between buyers and distributors excess inventory stock.

50MHz frequency counter, V-meter - Circuit schematic PCB and photo documentation on building a 50 Mhz frequency counter

Bowden's Hobby Circuits - A small collection of electronic circuits for the hobbyist or student. Site includes over 100 circuit diagrams, links to related sites, commercial kits and projects, newsgroups and educational areas. Most of the circuits can be built with common components available from Radio Shack or salvaged from scrap electronic equipment

Antenna Noise and Signal Cancelling at LF - By using the signals from two antennas, controlling their relative amplitudes and controlling the phase of one of them, unwanted signal or unwanted noise can be phased out. Circuitry is described which uses the signal from a wire antenna to provide selective cancelling against the signal output from an LF loop antenna.

Regenerative Radio Receiver Circuit - Useful and well thought out regenerative receiver design

WD5HOH Regenerative(Regen) Receiver - This web page describes a small, single tuned circuit regenerative receiver primarily for daylight reception in the 16, 19, 22 and 25 meter international shortwave broadcast bands.

Build A Vector Network Analyzer - The VNA (vector network analyzer) is an essential tool for measuring the complex impedance of a circuit at a given frequency. Article on how to build a Impedance analyzer.