-=> MIKE ROSS wrote to WAYNE CHIRNSIDE <=-

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

 No doubt.
 I recall those old uncomfortable bakalite high impedence monsters
 with somethng less than fondness.

 MR> 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.

Popular Electronics ran a circuit of a modified Xtal
reciever where the signal diode was biased into it's active region
by a common carbon - zinc battery with the bias voltage adjustable to
just above the barrier voltage with a center tapped 1.5
Meg ohm potentiometer IIRC.
Never built the critter but it looked good on paper.

Perhaps my favorite receiver was something put out for a time
by Radio Shack in their P-Box series of kits.
A regenerative two FET all band receiver where you manually
swapped tuning coils for different bands.
Cost 7 dollars at the time and got nearly every signal my expensive
all band receiver could manage :-)
 
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