The Bogen T725 Audio Transformer is an excellent audio matching transformer for your crystal radio. This allows you to use lower impedance headphones with your crystal radio set.
This Bogen T725 has 3 black wires. The outer two black wires are 8 ohms. The inner black wire is the common (ground) connection.
Bogen T725 Specs:
|Far left black to far right black 8 ohms|