HIMNL9
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- May 26, 2009
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As far as i remember from my (very very very) old experiments, it looks as a "galena" radio tuning assembly ..... i mean, the holder on the back have a galena (lead sulfide) crystal hooked in it, and the knob must be a "baffle" or thin steel wire with a fine point at the end ..... you had to search for sintony touching the galena crystal with the point in different position, til you find a spot that work as a diode, for detect and reveal the radio emission, and hear them directly in a high impedance headphone ..... good old times