circuit design

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

Yagi Element Mounting Considerations - One of the most important considerations when designing and building a Yagi antenna is the method used to attach the elements to a boom. This is true because the boom influences the electrical length of the elements. In this article JH Reisert explain with drawings techniques on mounting yagi antenna elements to a boom

Antennas for 136kHz - A very long and exaustive documentation on building antennas for 136 khz. Includes links to antenna design software for longwave

VHF/UHF Yagi Antenna Design  ^{updated  pop} - Design your vhf yagi antenna online, a JavaScript enhanced web page that implements the design of an antenna in the VHF, UHF by K7MEM

New HF antenna HB9ABX  ^{updated  pop} - A new, revolutionary design allows the construction of small HF antennas, which provide the same efficiency as large antennas. This antenna can be built for all HF bands, from 10 to 80 m.

DF3CB BV QSL Management and printing - DF3CB site, contesting, and software BV is a professional freeware software for the QSL Management and Label/QSL Printing under Windows developed and distributed by Bernd Koch, DF3CB, since 1989. It is mainly designed for the contester and QSL manager with high QSL quantities but useful for all other QSL'ing purposes as well. Includes logging features

K8ZT's Ham Radio Resources - K8ZT's Extensive Ham Radio Resources about QRP, Vanity Callsigns, Software, Maps, Kent State, Shack Design, Argonaut, Sommer, Log Analysis

Star Antenna  ^updated - Communication Electronic designs, manufactures and markets antennas for fixed wireless and mobile wireless applications in a wide range of frequency bands.

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.

CAP Wireless Amplifiers - Design and manufacture application specific microwave and RF amplifiers, upconverters, downconverters and multifunction assemblies.

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.

Space Weather Education - Special space weather course designed to teach individuals without any background how to predict space weather

Automatic Identification Systems (AIS) - Automatic identification systems (AISs) are designed to be capable of providing information about the ship to other ships and to coastal authorities automatically.

APRS-Beacon - The purpose of the APRS-Beacon is to provide simple APRS-compatible position beacons for up to three Objects. It is designed to 'stand alone' and does not monitor other traffic on the frequency. It can use a single-port TNC (in 'native' mode), a single- or dual-port TNC in Kiss mode or the AGW Packet Engine in order to transmit on up to four radio ports.(When running with AGWPE, APRS-Beacon will also work with Windows 2000)

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.

HamCalc v1.3  ^pop - By G4VWL, HamCalc is collection of calculators for radio amateurs: Antenna ERP calculations. Attenuators. Audio Filter design.Coil Winding. Decibels. Great Circles map and calculator HF Filters HF Traps Metric conversions OP Amps QRA Locator to Latitude/Longitude (and back) Radio Horizon calculator Resonance Satellite orbit calculator Timer calculations (555 timer)Zener Diode calculations

SmartSmith - A smarter version of the Smith Chart program. It allows you to dynamically generate impedance point plots as you configure each design element of an impedance matching network. Has an extensive Help file with a Wizard that tells you what steps to take in designing a matching network for a given load impedance. Complete Windows installation kit by w9dmk

Baudline signal analyzer - A Linux based FFT spectrum analyzer designed for time-frequency browsing and scientific data visualization. Oscilloscope waveform, statistical histogram, accumulated spectral trace,Weak Signal reception, continuos data logging, FFT Analyzer and specialized measurement windows.

Packet Terminal Interface - Simple Windows based TNC interface program Designed for ARES operation, simple operator interface to connect and perform communication functions, control operator programs screens before operations Both receive and transmit screens Simple Windows based TNC interface program Designed for ARES operation Simple operator interface to connect and perform communication functions Control operator programs screens before operations Both receive and transmit screens

Shortwave Log (SWLog) - Shortwave Log, SWLog is a comprehensive logging and radio control program. While designed for shortwave and mediumwave listening, the program is quite adept when listening to longwave, utility, or amateur radio. Support Icom Drake TenTec Yaesu JRC and lowe receivers.

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

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

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

QRM and noise reduction Priority listing - You will find on these pages my experiences and results on antennas and local/non-local QRM/noise reduction. Using a broadband vertical active magnetic loop and a home made / designed broadband amplifier. Two vertical magnetic Alford loops are used in an array. Analog and Digital Signal Processing and a dual phase coherent Software Defined Radio (SDR) are used. By PA0SIM

A 80/40m Direct Conversion HF Receiver with DDS VFO - Juha (OH2NLT) and Matti (OH7SV) have designed JUMA-RX1, an award winning 80/40m direct conversion HF receiver with highly accurate direct digital synthesis VFO. The receiver is very compact, because it constructed using surface mount components. No coils need to be wound to construct this receiver!