The HamBone

Ok. I have a soft spot for the humble and no-so-humble crystal radio. As a kid, it taught me about selectivity -or lack of it, antenna matching, diodes and some concept of impedance. Also I had a lot of fun.

Here's a new take on old thoughts.
More details are at https://www.aliexpress.us/item/3256803973124719.html . The link has many different designs, mostly just asking to be tinkered with.

This site refers to this kind of receiver as Ore Radios, or Mineral Radios, only occasionally as Crystal Radios.

How could this radio be improved? Maybe 10:1 antenna coupling? band-pass tuning? More diode choices to include your own minerals and different metals for the "whisker"?

Any thoughts?

Well, here's another one, same source. Take a close look at it. First thing is the variometer tuning. Changing the inductance of a LC tuned circuit changes the resonant frequency, as seen in permeability tuners often with sliding cores to effect tuning.
There's no circuit shown with the ad, but i suspect that the capacitor for the LC tuning must be under the board, because there is a switch on the right and the set 'boasts' two ranges, AM broadcast as well as a shortwave. Maybe windings of the variometer are switched?
All very unusual. I have never tried a shortwave xtal receiver because i thought the SW antenna signal strength would be too low and a single LC tuner would have nothing like sufficient selectivity. Anyone going to risk buying one? It's tempting....
There's a classic "cat's whisker" detector, which is fun if you have time to fiddle with it, but I guess one could always bridge it with a Ge diode if you lose patience.

Any thoughts about this odd animal?