Base Detector. The antenna goes to the top of the primary, pin 3 of the antenna coil, P-C70-A. The bottom of the primary, pin 4 connects to circuit common and earth ground. The top of the secondary, pin 1, goes to the stator of the variable capacitor. Pin 1 of the coil also goes to the base of the transistor, 2N3904. The bottom of the antenna coil secondary, pin 2, connects to the rotor of the variable capacitor which is insulated from the chassis. Pin 2 also goes tot the positive end of a 1 mike 25 volt cap. The negative end is grounded. Pin 2 also goes to the wiper of a 10 k pot. The bottom of the pot is grounded. The top goes through a 100 k ohm resistor to plus 12 volts. The emitter of the transistor is grounded. The collector goes through a 22 k ohm resistor to plus 12 volts. The collector also goes through a 100 pf cap to ground. The collector also goes to the positive end of a 1 mike 25 volt cap. The negative end goes to the center contact of a phono jack. The shield contact of the jack is grounded. There is a drawing showing the lead connections of the transistor. Holding it with the flat side up and the leads toward you the order left to right is, emitter, base, collector. End verbal description.