Under FCC rules, unlicensed individuals are permitted to transmit up to one watt of power into an antenna up to 50 feet long. This combination is very inefficient, and normally the maximum range would be less than a mile. However, with careful attention to antenna design, grounding, and propagation factors, much longer distances can be attained. In fact, one such station in California was heard in Hawaii!
The Longwave Club of America has an excellent WWW page here, which includes lists of longwave beacons, experimenters, and a Message Board which is updated almost daily. Check it out!
At this site, I keep an archive of the "LF Notebook" column of the Lowdown, the monthly LWCA publication. Here you will find all the latest news on the experimental front, reception reports, beacon updates, propagation reports and much more.
Here are some pictures of the RI Lowfer beacon. You can see the schematic for a simple IC preamp for longwave listening. Can be used with E-field probes, loops, etc.
Also on this site are some other files related to longwave radio. For aeronautical beacon hunters, there is a database of all the Canadian NDB's. Have fun!
73,
Pierre Thomson, KA2QPG