MR> JE> I can still remember the first radio I built:
MR> JE> Wound a coil myself, used a lead crystal for a diode and a pair of
MR> JE> headsets. Of course this was just recently - in 1942!

MR> WC> I built one of those.
MR> WC> Quaker oatmeal box coil form.
MR> WC> Real solderable tin foil peeled from gum wrappers
MR> WC> for the capacitor.
MR> WC> Enamaled wire coil on the form with one band stripped of insulation
MR> WC> and tuned by a sliding contact.
MR> WC> Crystal holder made of some small piece of rearranged copper
MR> WC> tubing and gallina Xtal.
MR> WC> Early 60's in the Boy Scouts.

MR>The toughest part to find these days is the high impedance headphones
MR>or crystal earphones. The galena used to be substituted in the early
MR>20's by some specific brand of safety razor blade. Apparently the
MR>razor blade metal manufacturing underwent a "bluing"
process that made
MR>it an ideal rectifier. Probably some type of oxide, in other words a
MR>metal/oxide rectifier. Those had a pretty low junction voltage just as
MR>germanium. The easiest is still to simply use a 1N60A or 1N34 but then
MR>they didn't have those in the 20's.

Nor in the 30s or 40s - and IIRC the early 50s. We used a galena and a
"cat whisker" - small thin piece of wire. Depending upon where the wire
touched the galena determined the station brought in. Sometimes it was
quite hit or miss.

Jay
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