Crystal Set Society
- http://www.midnightscience.com/
- Newsletter and several books about crystal receivers. Crystal set projects, tips for crystal radio design, and crystal radio / antique radio history.
K5BCQ Homebrew
- http://www.qsl.net/k5bcq/
- For radio enthusiasts interested in building and using the popular 1950s-60s era HBR receivers. Repair information for Heathkit SB-104, SB-101, and HW-101 Transceivers.
The thermionic device website
- http://www.thermionic.org/
- A website devoted to electronic thermionic devices known as 'tubes' or 'valves'. Includes information on a homebrew 1.8 MHz transmitter. By Andrew Burge in England.