Ferrite Loopstick Crystal Radio

Here's my version of a ferrite loopstick crystal radio.

Parts used are a moulded inductor, a 2200pf capacitor, a MW loopstick antenna, a PVC gang condenser and a germanium diode. The enclosure is a 3" x 3" x 1½" electrical bakelite box.

Ferrite Loopstick Crystal Radio
Ferrite Loopstick Crystal Radio - Schematic
Screw terminals are provided on the rear of the enclosure for connecting the antenna, earthand headphones. Headphones used are of the sensitive, balanced-armature type.

Inside the Ferrite Loopstick Crystal Radio
The loopstick is 125 turns of Litz wire close-wound on a 2" length of ferrite rod with a tap at 25 turns. The number of turns may vary depending on the diameter of the ferrite rod and its relative permeability.

The primary series-tuned circuit consists of the 200μH moulded inductor, the 2200 pf capacitor and the capacitance of the 60' wire antenna. The secondary is parallel-tuned.        

Reception of the local 612 kHz, 200 kW AM broadcast station is quite good. Headphone current, measured using a 1mA FSD 60 Ω meter, is 300 μA.

Reception is as good without an external antenna and earth, when the radio is held close to a CATV cable running over the shack and working as a passive radiator. Signal strength is maximum when the ferrite rod is laterally oriented with respect to it.

Related: Permeability-tuned Crystal Radio