Quote:
Originally Posted by radio nut
I watched the video, if I saw it correctly there is not an ant. connection to the main coil.....how does that work?
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The antenna tuning coil is inductively (magnetically) coupled to the main coil. Since the antenna coil is lower inductance, it is affected less by the antenna capacitance. Then the transformer coupling to the higher inductance means that the main coil sees, in effect, a higher impedance (lower capacitance) antenna load, and because of the turns ratio, also outputs a hgher voltage to the diode and earphone.
You could use a lower inductance main coil in the first place to make the antenna capacitance less of a problem, but that would reduce the voltage output to the diode and earphone.