circuit design

Design your own dipoles - Formulas to design your own dipoles and inverted vees

Helical Antenna for WiFi - Improved Helical Antenna Design for 802.11b WLAN by PA0HOO

WLAN Helical Antenna - 23, 13, WLAN Helix antenna design

KGD - Reduced size antenna - A reduced size antenna made of two series resonant circuits with a radiant tube condenser in German

VHF UHF Slim Jim Antenna - A vertical monoband antenna design that can work from 6 meters to 70 cm by F5ZV in French

NP Technologies Inc - Design, develop, test and manufacture a wide range of Amplifier products including highly linear class A Broad Band, Cell Band, Pulse, AM & FM broadcast and Military VHF

EZE UK PCInterfaces - Digital mode interfaces are a speciality of EZE(UK). We are designers, agents, and manufacturers of both commercial, and ham radio interfaces together with programming units, and controllers.

80M Fox-Or-Test Transmitter - The 80 metre fox-or/test transmitter is a small low power transmitter which is designed to be used as an alignment aid for running up 80 metre foxhunt or ARDF receivers. It is also usable as a micro transmitter for fox-or-ing events.

The Microsniffer Project - The Microsniffer is a fully autoranging VHF or UHF sniffer which has been designed for those who are foxhunting on a budget.

ELSTAR OY - ELSTAR Oy, Ltd Radio & IT Communications Finland, dealer for Palstar, Ten Tec, ACOM, Alinco, Creative Design, AEA, LDG and SGC

International SWL Registry - Obtain a unique SWL Designator to use on your signal reports and QSL cards. Official certificates also issued.

International SWL Registry - Official SWL Designators & Certificates issued and Online SWL Directory.

Coil Inductance Calculator - Approximate Air Coil Inductance Calculator

Codec2 - Codec2 is a open source low bit rate speech codec designed for communications quality speech at around 2400 kbit/s. Applications include low bandwidth HF/VHF digital radio.

AktivFilter - Active filter design software for windows, AktivFilter 3 for the design of active filters tuned on the opamp type.

iSDR - iSDR is a software defined radio application compatible with the Apple iPhone, iPod touch and iPad™. iSDR is designed for experimenters, shortwave listeners, and amateur radio enthusiasts who would like a truly portable software-defined radio receiver.

1500 Watt Solid State HF Amplifier - This is a project to develop an Open Source reference design for a 1500 watt solid state linear amplifier for 10 through 160 meters by K6IF

Speech Intelligibility - Articles published by the Radio Society of Great Britain, basic principles, construction of a simple equaliser circuit

A Two Meter Duplexer - How to get a cheap-squeaky clean signal, a 2 meter duplexer designed by Leonard WB3AYW

1.5KW 6m Low Pass Filter - This filter is designed to follow a FULL legal limit, GS-35B, 6m linear amplifier. Designed and built by Bill Jones, K8CU

DRAKE TR7 Downloads - Circuit diagrams drake tr7, Schaltbilder Drake Tr7, antenna tuners, baluns, and home brew power supplies, dual tone ssb test generator, zweiton ssb test generator, zweiton testgenerator, dual tone test generator by DK4DDS

Multi-Four a VXO QRP Transmitter for HF bands - This transmitter has been designed for use on 20 30 40 and 80 m with 5W output

The Duet CW RTX - Design for a dual-band CW transceiver using the AD9834 Direct Digital Synthesizer

Signal Source for AO40 mode S - Signal source circuit for 2.4 GHz by sv1bsx

SARK100 Antenna Analyzer - The SARK100 Antenna Analyzer it is yet another antenna analyzer but available in kit form and designed to be easy to assemble and with an affordable pricing.