Green Felt Crystal Radio

Crystal Radio with amplifier

This radio is called Green Felt because the speaker cloth is green felt and there is green felt cushioning the base of the cabinet. The cabinet is made from a tiger maple archtop guitar side and was bent to this cathedral shape as art deco styling. It is 5 ¼” wide, 4 1/5” deep and stands 13” tall. The three knobs were also hand made of tiger maple and include brass cores and set screws. The lacquer shading is done in my shop and is then finished with clear nitrocellulose lacquer.

The tuning dial is covered with a 3 ¼” convex glass crystal and the pointer was hand made of solid brass. Tuning is done via special “O” rings and brass pulleys. The horizontal cat’s whisker was also hand made here and includes an argentiferous galena crystal. This crystal can be selected for detecting or a diode may be chosen using the special switch that I painstakingly made of solid brass just for this set.

Circuitry was borrowed from one of Dave Schmarder’s schematics and features a double tuned design and includes a low voltage amplifier which drives the speaker or it can be listened to with a headset. The little amp is surprisingly loud but volume and the on and off function are controlled by one of the three knobs. I wound the HoneyComb coil with 180-44 Litz wire with the tank made up with a 365pf variable capacitor. Antenna tuning is also accomplished with a matching 365. Power for the little amplifier comes from a 9 volt battery accessible on the back panel where binding posts for antenna, ground and the headphone plug are located.

This is by far the very best performing set I have ever been able to build. The selectivity is beyond anything I’ve ever accomplished whether crystal or tube circuit. There are two religious ‘blow torches’ in my area and neither have any influence on this radio. I am simply amazed.

Crystal Radio with amplifier front view

Crystal Radio with amplifier battery compartment

Crystal Radio with amplifier back view