The device that holds, and makes the electrical connection to, the galena crystal
consists of a small home-made spring, a bolt and a set of washers and nuts.
The crystal should be positioned so that one of its faces can make contact
with a fine, coiled wire attached to connector A. Move the free end of this
wire around on the crystal's surface to get the best signal. This is
very much trial and error, and requires a lot of patience.
galena crystal and its holder