Another Crystal Radio with Air Core Coil

Discussion in 'Wireless & RF Design' started by vu2nan, Aug 7, 2015.

  1. vu2nan

    Thread Starter Member

    Sep 11, 2014
    43
    10
    This is an improved version of my Crystal Radio with Air Core Coil.

    [​IMG]

    The coil is 75turns of hook-up wire, close-wound on a 2 ⅝" diameter plastic bottle, with a tap at 35 turns.

    The 35 turn primary series-tunes the capacitive 60' random wire antenna to resonance at 612kHz (frequency of the lone 200kW local AM broadcast station). The secondary is parallel-tuned using a 500+500 pF PVC gang condenser.

    [​IMG]

    The plastic bottle serves as the coil former cum enclosure. A screw-type terminal strip is used to connect antenna, earth and headphones.

    Reception, using sensitive balanced-armature headphones, is quite good.

    Regards,

    Nandu.
     
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    Last edited: Aug 10, 2015
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