circuit design

Getting The Most Out Of LowFER Antenna - Getting the most out of LowFER transmitting antennas, designing an efficient antenna for the 1750-meter band by K0LR

10m Band 2 Element Loop - 2 elements horizontal high gain loop for 10 meter band

160m Band Mega Delta Loop Antenna - This antenna is great for the long haul QSO on 160m as it has a lovely low angle of radiation

160m Band 5 Element delta loop - The goal for this antenna project is to determine what sort of gain and radiation angle is possible on 160m using 5 delta loops with a max height of just 14m

Quad Maker - Quad maker designing and calculating quad dimension. Excel spreadsheet

VSWR Loss Calculator - This calculator is designed to give the efficiency loss of a given antenna, based on the input of VSWR (voltage standing wave ratio) and other subsequent factors

40/80 Trap Dipole Design - An home made trapped dipole antenna for 40 and 60 meters band by 2E0HTS

Distributing Receive antennas - Designing low-band receiving antennas By Eric L. Scace K3NA and George Cutsgeorge W2VJN

What is a loop antenna? - Article on loop antennas, size, properties and designing notes of loop antennas by David Jefferies

7MHz - 14MHz Slot Fed Skeketon Antenna - 40 to 20 meter band slot fed skeleton HF Antenna.

Microwave Slot Antennas - Slot Antenna Design by Stephen Bell, KB7TRZ

Free Yagi Antenna Designs by G0KSC - Free Yagi Antenna designs for many bands including stacking and EME information

Southeastern Asterisk Radio Networks - Interoperability solutions via Asterisk based RF Gateways - Southeastern Asterisk Radio Network (SEARN) and the Southeastern Asterisk Amateur Radio Netwok (SEAARN) are designed for the purpose of developing interoperability capabilities amongst diverse communications systems. Digital Amateur Radio Project Association - DARPA expanding the digital experience.

Solarcon Antennas - Solarcon custom designs and manufactures a wide range of standard and specialized antenna products, Patch Antennas, Loop Antennas, Helical Antennas, Yagi Antennas, Slot Antennas, UHF Antennas, VHF Antennas, Bluetooth antennas, Dipole antennas and many more.

Verdant - Designer and manufacture of Airborne Antenna & Radomes covering a range of applications. Products include vhf antenna ,uhf antenna,navigation antenna,comm antenna,blade antenna,vor/ils antenna ,L band antenna, direction finding antenna,DF antenna,vor,ils, IFF antenna on aircraft,aircraft antenna for airborne application.

marnic.org - F5VLB and EA4EOZ have designed a small but powerful system using satfinder and standard LNB to make radioastronomy. A step by step descritpion for the novice about radioastronomy, VLB and listening to echo of meteorite.

Transceiver to pc interface for echolink - with a hardware DTMF detector and galvanic isolation designed for SVXlink based Echolink gateway

Kenwood TS-50 IF-10D interface - Circuit of the Kenwood IF-10D interface for the TS-50 transceiver.

Microwave Antenna Design Calculator - Available to run on all major operating systems, this free calculator provides quick estimation of antenna size required for a given gain and frequency.

KComm - KComm is an amateur radio communication and logging program that has been designed specifically for Elecraft K2 and K3 transceivers. KComm has been developed using the cross platform development tool Lazarus. The program is developed and tested under Windows XP but it can be compiled under Linux. By G4ILO

Restoring an Harris RF-103 - These amps are designed to operate from 2.0 to 30MHz continuously, at an RF power output level of 1Kw, in any mode, no time limit.

Low-Pass Active Filter Designer - Javascript filter design page with introduction to low pass filters by k7mem

High-Pass Filter Design - Online high pass filter design page with introduction to high-pass filters by K7MEM

Tuna Tin 2 - The Tuna Tin 2 is a simple transmitter originally designed by the legendary author and experimenter Doug DeMaw, W1FB. The TT2 was first published in the May 1976 issue of QST.

NB6M 10 Homebrew Receiver and Keying - Schematic of a homebrew receiver and keying