As radio amateurs, we are often after new challenges. One such is DXing with crystal sets. In the past, there have been some remarkable designs.
Remember that all the power is provided by the TX station (no batteries, no solar cells etc.), so people struggle to get the strongest signals with decent selectivity.
Amateur DX is possible, and on 80m I have copied SSB signals at some distance. Of course, this was just envelope detection and I had to use other means to ID the station with certainty. On bands like 10m, it should be possible, at times, to copy DX stations, especially with Es on a crystal set. Signals need to be in the low mVs to be received.
In the days when AM was common on 160m I have copied stations at some distance on a crystal set. Patience is required. People regularly copy 80m AM nets in the USA.
See https://crystalradio.net/crystalplans/index.shtml
See https://sites.google.com/site/g3xbmqrp3/hf/crystalset. As this page is quite old, some of the links may not work. At some point I really must check and delete any that no longer work.
Remember that old pages, now closed, can often be found on the Wayback Machine.