Specs for this radio can be found at:
http://www.clarion.org.au/crystalset/mystery.html
MATERIALS
Wood for the project included Cherry, Black Walnut, Wormy Chestnut and Pine. The coil form is a 4-inch PVC wastewater connector. On this is wrapped 45 turns of 20awg copper wire and 21 turns of 28awg Teflon coated silver wire in a bifilar arrangement.. Over this is 15 turns of 20awg copper wire wrapped on top of overhead projector film. The variable capacitor is a brass 23 vane ACME (the makers of whoopee cushions and Wiley Coyote's toys of destruction) 500pF from the 1920's. And I also used a true red, white and blue 1N34 American Diode
My twist on the design is the use of a Lazy Susan undercarriage. This permits the coil to be rotated. I had noticed on my first 2 Mystery Sets, that the coil acted like a loop antenna and I was always rotating the radio to better tune the set. So instead of turning the radio, lets turn the coil.
Performance
Like all Mystery Sets, the improved design still leaves one to scratch (fill in the blank) and wonder. My set works without either a ground or an antenna. In that mode I pick up three stations. With a ground, a few more and with an antenna, the stations are overwhelming. When I connect my Radio Shack amp speaker on the set, tuning the capacitor below 650AM, I started to pick up Japanese or Chinese broadcasts.
Crystal Set Building Contest
General Class – General Class
Mike Lee