This was my first crystal radio project. It started out as a WWII foxhole radio which uses a burnt rusty razor blade, safety pin with pencil lead attached as the detector. It worked and let me hear 2 local AM stations.
Then I removed the razor blade detector and tried the 1N34a diode and the volume nearly doubled, but still only 2 stations and one which was close to me nearly wiped out the other. I knew I needed more improvements.
Next, I built a wave trap. This really helped and completely eliminated the local blow torch that was close to me. But, I could still only hear 2 stations.
Here is the complete set as it is now. I'm learning so much and want to built a new set with better parts, like better coil material, better wire "LITZ" and a better detector diode, maybe a FO-215?
After some more modifications this set now picks up stations over 1000 miles away.
These coils have a decent Q - 840 at 800khz. Follow this link for more info on these type coils - TheRadioBoard
Update: A friend came over and tested my coils with his Q meter. The Q ranged from 820 to 1000 across the MW band.
Another benefit of using ferrite coils is less space needed for coupling. Mine nearly touch end to end.
This set uses 176/46 Litz wire ferrite coils, SEC, Tuggle Front End, 200k:32ohm Ming Transformer and FO-215 Diode.
More upgrades Jan 2014. Swapped out old air variable caps with better silver ceramic types. Removed the SEC circuit. Substantial increase in performance!