circuit design

A Collapsible 2-Element Delta Quad - This easy-to-build and inexpensive 2 meter antenna is also made to store easily. It's designed for hand held use, so it's great for fox hunting! By Charles Scharlau, NZŘI

The Little Stick Antenna  ^pop - The Little Stick antenna is an aluminium version of the Vertical Bazooka design which was made from coax.

C-Pole antenna calculator - Based on the original design by Brian Cake, KF2YN this online calculator let you find the correct dimensions for a cpole antenna

Small Transmitting Loop Antenna Calculator Priority listing - A free online calculator for making all of the calculations required to design and build small transmitting loop antennas, also known as magnetic loops by 66pacific.com

L Match ATU for QRP - The L match is designed for the matching of random and long wires and should not be mounted in a metallic box/case, i used a small plastic food container which was the most expensive part of the project.

Short Whip Antenna Tuner - Here is a circuit that will resonate a short whip antenna for the HF Bands.

Bicone antenna - This antenna is a simple double bowtie biconical dipole design. It was designed as a broadband scanner antenna resonant on the 2 meter ham band.

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).

160 80 40 Meter Vertical Array - A 6-element vertical array which is designed for 40 and 80 meter operation, and receive-only operation on 160 meters by W8WWV

SolarVolt Power - Solar power products for the true environmentalist Solar energy systems, design engineering Residential and Commercial

Alfiniti Aluminium products - Custom assemblies, complex products, versatile applications… no matter what your challenge, we can design a solution for it.

Cleveflex - Clevaflex is a manufacturer of flexible wound tubing that can be used in a variety of applications. our unique manufacturing process allows tubes to be designed and built with a multi-ply convoluted wall contour that creates a permanently bonded tube.

Is HF propagation reciprocal - Some test circuits using the ACE-HF System Simulation & Visualization software, about reciprocal propagation on HF bands by NW7US

Phase Noise. - This is perhaps the most important parameter in many oscillators and it deserves an in-depth discussion on what it is, how it affects a system and how it can be minimised in an oscillator design.

RF Circuit design basics - Ebook by Akira Matsuzawa Tokyo Institute of Technology, Building blocks in RF system and basic performances, Device characteristics in RF application , Low noise amplifier design, Mixer design and Oscillator design

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.

NBEMS - The Narrow Band Emergency Messaging System (NBEMS) for Windows is a suite of software programs designed for point-to-point, fast, error-free, emergency messaging up to or over 100 miles distant, and takes up a very minimum of frequency space on the ham bands, leaving more space for other ham activites.

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.

AA Battery Solar Charger - This almost trivial circuit may be used to charge a pair of AA or AAA sized rechargeable battery cells from sunlight.

Free Sun Power - Free basic and advanced system design tutorials for every component and aspect of solar power. Plus system sizing calculators, battery bank calculators and wire size calculators

TANKIT Priority listing - A free design aid for vacuum tube linear RF power amplifiers. Determine plate circuit operating parameters and design pi or pi-L tanks quickly and easily.

500 KHz Low Pass Filter - This article describes a shielded low pass filter with a cut off frequency of about 500 KHz. It is built with components suitable for receiving, and was designed to use in front of a low frequency receiver for LOWFER work.

FM Morse Code Keyer - A simple circuit which will generate a 700 Hz tone into any FM transceiver allowing an amateur to practice CW with another amateur on a 2 meter simplex frequency.

Signal Generation Solution - Build an inexpensive RF signal generator

A reliable VOX PTT circuit - This VOX PTT has been designed with Echolink in mind, but it will work equaly as well with repeaters