"amdx" wrote in
:

....
Connecting the antenna to taps on the coil is common, I don't believe
this
method transfers maximum energy into the tank circuit, But I am open
to more info about that.

Well, you have to move beyond "believing" and do some analysis.

Broadly, adjusting the tap point, and retuning for maximum output is
finding the point of maximum power transfer for the given components and
source impedance.

I am quite skeptical (that is like "don't belive") that your scheme for
headphones is going to deliver what you suggest.

When I was a kid, these things here ALL used a crystal (or piezo)
earpiece, which has an impedance that looks like extreme R and a very
small shunt C, in all a very high impedance at audio frequencies of
interest.

Look at http://www.jaycar.com.au/productView.asp?ID=AS3305
&keywords=earpiece&form=KEYWORD for an example. (You probably will need
to fix the split URL. They also have a simple crystal radio kit in the
catalogue, no doubt suppliers in your country do also.

Traditionally, these were used with improvised smallish antennas, eg bed
iron, and that brought in too many stations. To obtain benefit from
enhanced sensitivity, you might need to be in a very quiet location, and
have extreme selectivity... both are practical issues.

Owen