Another Series-tuned, Shunt-fed Crystal Radio

Discussion in 'Wireless & RF Design' started by vu2nan, Oct 12, 2015.

  1. vu2nan

    Thread Starter Member

    Sep 11, 2014
    This shunt-fed crystal radio is housed in a plastic pencil box.

    Series-tuned, Shunt-fed Crystal Radio

    It has 2 windings of 30 SWG enamelled copper wire on a 6" long, 3/8 " diameter ferrite rod. The primary has 10 turns and the secondary 90, both close-wound.

    Series-tuned, Shunt-fed Crystal Radio - Schematic

    The primary series-tuned circuit, which includes the 200μH moulded inductor and the capacitance of the 60' short- wire antenna, is resonant at 612 kHz (the frequency of the local 200 kW station located 20km away. The secondary is also series-tuned using a 500pf PVC variable capacitor. The detector, a germanium transistor with its base and emitter connected, shunt-feeds sensitive balanced-armature phones.

    Series-tuned, Shunt-fed Crystal Radio - Inside view

    Reception of the local station is quite good with headphone current being 400 μA (measured using a 1mA FSD 60 Ω meter).


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