Loop Antenna by Robert Tso

Crystal Radio With Loop antenna by Robert Tso

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Here is my Loop Radio #2, the design of which was formulated after many hours of "imagineering". Besides making a fully functional crystal radio, I wanted to create something unique, and interesting to look at. The coil is "Spiro-graphic", consisting of 13 turns of 12/30 Litz wire bought from you. The mitered frame is made from 1x3 red oak planks at 24" per side, held together using only Elmer's white glue. Each plank has 3/8" dowel pegs that are arranged diagonally along the plank, to make the coil pattern slightly non-planer. The oak base houses the rest of the radio and provides good stability for the slightly top heavy antenna frame.

The radio is designed to be modular, so that other loop antennas can be easily swapped in and compared. Two AOL CDs glued together with Gorilla glue form a stiffened, art-deco faceplate on which the 365pF tuning capacitor mounts. (I first had to tap some #4-40 threads). For matching to my hi-fi Sony headphones, I used a tiny matching transformer from Oceanstate electronics (#45-703). Minwax Polyshades urethane finishes the wood work with a nice color (pecan) and high gloss.