Trouble tuning am radio
The way you connected your coil - well it is wrong; instead of singling out the desired frequency, it suppresses it. It has to be connected parallel to the the amplifiers input, through a germanium diode (you may potentially use a silicone one, but you'll need to add a DC shift circuit). 

This is what you want: 

http://www.mikroe.com/old/books/rrbook/chapter3/21a.gif

Ignore the extra output from the the coil, just connect the diode parallel to the coil.