He builds most of his sets as "crystal" radios but also adapts some of them to "tube" radios. He also builds "loop" antennas. This one I find particularly nice because he's adapted it to cover the 31-41-and 49 meter "shortwave" bands. Even the 12v tube version is "reasonable" to work with as the voltage is manageable. The biggest danger is handling the "hot" tube before its had time to "cool off".
The "crystal" version uses a "cat whisker", the next uses a tube.
I'm fascinated with these radios because I consider them "works of art" as much as "electronic" listening devices. They're beautiful to view and (I'm sure) a joy to listen to with a good set of earphones. Most are for the AM radio band.
These aren't toys. He uses advanced materials and techniques in his craft. You can view all his radios from the link on the right hand side on my blog. I've spent several hours exploring the site and find it VERY informative and inspiring.
Dave was gracious enough to allow me to use the above graphics in this post and to add a link to his "Dave's Homemade Radio" site.
Daves sez "The sweetest music comes from a radio you made!".
You can also view his page from here: N2DS-Daves Homemade Crystal Radio's