Another Loop Antenna Crystal Radio

A heavy 2 m x 2 m floor-standing wooden showcase in the shack appeared to be suitable as a
frame for a crystal radio loop antenna. As luck would have it, the lone 20 km distant 612 kHz,
200 kW AM broadcast station being in the end-on position by default, there would be no need
to move the unit. The counter top would make it quite convenient to sit down and carry out
the testing.

The 5 turn loop was easily wound using about 42 m of ordinary hook-up wire.

The shack is relatively quite small to get a photo of the actual unit.

Here's a representation of the same.

Makeshift 2 m x 2 m Square Loop Antenna
The series-tuned circuit was wired first using a 500 pF variable capacitor and a MBR 1060 Schottky rectifier found in the the junk box.

Series-tuned Loop Antenna Crystal Radio - Schematic
The local station came in real loud through the balanced armature phones. Headphone current, measured using a 1mA FSD 60 Ω meter, was 200 μA.

Next the parallel-tuned circuit was tried out.  

Parallel-tuned Loop Antenna Crystal Radio - Schematic
Reception was quite good, with the OA 79 diode delivering a headphone current of 100 μA.
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