Emerald & Brass Crystal Radio

A single side for an archtop guitar without a mate was left over and I decided to build a crystal radio cabinet with it. Bending the side into an oval is not much different than bending it for a guitar and this one was just long enough to make a 5 ¼” diameter circle. Not a great deal of room but with the help of some precision timing belts and timing pulleys it was just enough for the radio.

The cabinet was not deep enough for a traditional vernier drive so another approach was necessary. A 1 to 1 pulley ratio for the antenna tuning capacitor was used and a 2 to 1 match was good for the main tuning capacitor which provided the vernier reduction needed. A polished steel idler post with a brass sleeve was used to take care of slack in the main tuning belt while keeping the control knobs at equal distances from the variable capacitors.

The detector stand is a model I saw on one of Mike Starcher’s crystal sets and this one is my rendition of it. It is the best detector I have ever used. Placing the tip of the cat’s whisker is precise, easy and quick. I am surprised that I have not seen more of these. It is more involved to build but the performance is more than worth the effort. A spring located in the vertical post creates great action of the cat’s whisker shaft in rolling and moving back and forth. The ¼” set screw in the top of the post adjusts pressure on the spring to give just the right amount of firmness needed. The post pivots to move the whisker from side to side. The brass cup holds galena or pyrite and the other brass post selects a diode for detection.

The binding posts on the front panel are for antenna, ground and phones.

All wood for this set is tiger maple and the lacquer shades are created here in my shop. Finish is nitrocellulous lacquer.