Portable AM Crystal Radio |
M0UKD's 'Loaded Quarter Wave Antenna Inductance Calculator' gave a loading coil inductance of the order of 10 mH at 612 kHz (the frequency of the 200 kW AM station located 20 km away). Hence two 4.7 mH moulded inductors were connected in series at the feed point, to resonate the 0.75 m long telescopic antenna at that frequency.
Portable AM Crystal Radio - Schematic |
Portable AM Crystal Radio - final version |
Related post: A Tuned Passive Radiator
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