Here is a collection of amateur radio links.
End fed half wave
- End Fed Half Wave (EFHW) antenna construction with links - https://www.nonstopsystems.com/radio/frank_radio_antenna_multiband_end-fed.htm (added 14/4/20)
- Filter design, Skin depth, Smith Charts etc - https://leleivre.com/rftools.html (added 14/4/20)
Class D/E Amplifiers
- Class E amplifier design and construction - http://www.classeradio.com/ (added 14/4/20)
- AMfone Class E forum - http://amfone.net/Amforum/index.php?board=76.0 (added 14/4/20)
- VK3HN’s website (links to the sites above and more) - https://vk3hn.wordpress.com/am/