The Wikipedia page doesn't elaborate, but these weren't separate, dedicated stations, just existing AM stations that retuned their transmitters to 640 or 1240 (or maybe some had an dedicated Conelrad transmitter?), and operated in a round-robin sequence to prevent homing in on a transmitter signal. See, for example, http://www.oldradio.com/current/bc_conel.htm - scroll down to Phil Alexander's story for a description of the frequency change.WLYNgm said:Conelrad consisted of high-power regional stations, on specific frequencies,
that would be the only ones on the air, during a declared emergency. This
was during the days of the "Cold War" era. Check it out on the internet.
Interesting reading!
Most of the Google search results are just versions of the Wikipedia page, but a transistor radio project in Boys' Life (January 1956) has a good explanation of how the system worked (though I doubt that the system intended stations as far apart as New York and Kansas City to be part of the same rotation):
http://books.google.com/books?id=biVS179K0A0C&pg=PA43&lpg=PA43#v=onepage&q&f=false