And every other man you met on the street buttonholed you to tell you how he had sat up until two o'clock the night before, with earphones clamped to his head, and had actually heard Havana! - Frederick Lewis Allen, on the great DX Boom of 1922, in Only Yesterday
Perhaps you grew up in a small town, where there was no local rock-'n'-roll radio station. In that case, it is quite likely that every night you waited until after sunset, got your transistor radio, and tuned in WLS out of Chicago or WLAC out of Nashville, or half a dozen other stations in the big cities that played rock-'n'-roll. (All of them-almost without exception-also played Count Basie and Mitch Miller, too, often in the same time slot, but that's another story for another web page.) You didn't know it, but you were DXing, which is what radio heads call the practice of receiving distant signals.
Things have changed a bit since the 'fifties and 'sixties, but you can still hear distant AM stations almost any night of the week. The quality of some AM radio sections of AM/FM radios is no longer good enough for this, but most AM radios will still receive at least a few distant stations. If you live on one of the Coasts, you might even hear overseas stations! Stations in some parts of the world use 9 kHz channel spacing, as opposed to the 10 kHz spacing we use in the United States. This results in heterodynes, audio-frequency tones whose pitch is determined by the difference in frequency between two AM carrier waves. So, if you hear a constant tone in the background, especially if it seems to fade in and out, tune around; you may get an overseas broadcast.
But, if you want to try AM DXing, don't wait too long. Radio broadcasters, unwilling to use AM radio for reaching distant audiences (which is the most natural use for it) have decided to push In Band On Channel (or IBOC) digital radio onto the AM band. Digital technology is notoriously useless for weak-signal broadcast work (although hams, using modes like PSK31 and WSJT, have at long last found digital modes that work better than old-fashioned Morse code for point-to-point weak signal text transmission) so my advice would be gather ye rosebuds while ye may, tempus fugit, and all that.AM radio propagates by groundwave during the day and skywave at night. Thus, DX during the day generally means significantly shorter distances than DX at night.
During the day, 500 miles is good near the low end of the AM band, where groundwave performance is significantly better, while 250 miles is good near 1700 KHz at the upper end. One of my biggest daytime catches was hearing KTSA 550 out of San Antonio in broad daylight just below Engineer's Pass in the San Juan mountains of Colorado, a distance of over 800 miles! We were using the standard AM radio in a Ford Bronco (you need four-wheel-drive to cross Engineer's Pass), and were in an ideal position on the eastern slope, which meant we were very high in elevation facing San Antonio. I've long wanted to repeat the experience, but sadly, I haven't seen Engineer's Pass for some twenty-five years now. I also had the pleasure recently of calling in to a sports talk show on WWLS 640 out of Oklahoma City to defend my beloved Texas Longhorns. The show's host couldn't believe I was hearing him all the way down in Austin, Texas (WWLS AM does not webcast), but I proved it to him on the air by recapping some previous calls!
At night, using skywave signals which bounce off the ionosphere, AM stations can travel up to halfway around the world, but they are usually drowned out by much closer stations. 1500 miles is a good long hop at night.
You probably already know from personal experience that many summer nights, the AM band deteriorates into a mass of lightning static (known as QRN to hams and DXers). In addition, much more of the Northern Hemisphere is in darkness on a winter night. So, conditions are generally better in the winter. Nonetheless, just the other night I listened to the Astros on KTRH, then switched to KMOX to catch the end of a Cardinals game, then over to KOA for the end of a Rockies - Reds contest. AM DXing is possible in summer!
Not really, but not all AM radios "hear" DX equally well. Naturally, hearing a station two thousand miles distant is more difficult than hearing one two miles distant. Some radio manufacturers inexplicably spend more time and money on building and aligning the AM circuits in their radios than others. For many years, the best AM radio I had for DXing was a Panosonic AM/FM cassette. It was sensitive (heard weak stations well) and selective (separated stations that were close together well). Older, tube-type radios, if you can find one in working order, are also almost always superior performers when it comes to hearing distant stations (most consumers expected an AM radio to receive distant stations well in 1940).
Another thing that helps is a loop antenna. Perhaps you've notice that most AM receivers are directional; rotate them ninety degrees and the station you're listening to gets louder or quieter. This is because of the directional qualities of the ferrite rod antenna, which most modern AM radio manufacturers use (older AM radios often have air core loops, which work in much the same way). It is a common assumption that the best way to use such an antenna is to rotate the radio until the station you want to hear comes in the loudest. This means the node, or part of the directional antenna pattern that has the loudest reception is pointed toward the station you wish to hear. Actually, most ferrite rod antennas have a fairly broad node, which means they receive well from a broad arc of the compass without rotating. They do, however, have a sharp null, or place where the signals are minimized. Hence, what you can do is point the null in the direction of any station interfering with your desired station. As long as the two stations are not located either in the same direction from you, or in 180 degree opposite directions, odds are you can use the null to minimize interference, while the broad node allows you to continue receiving the desired station. (The reason for the caveat about stations in 180 degree opposition to each other is due to the fact that loop antennas are bi-directional; they "hear" equally well in two directions.)
Until about 1980, several spots on the AM dial were set aside as "clear" channels. The FCC allowed only one station to operate after dark on that frequency (why after dark? As noted above, that's when AM radio signals propagate thousands of miles instead of hundreds). During the Reagan era, the National Association of Broadcasters armtwisted the FCC into abandoning true "clear" channels for "protected" ones, which means that while smaller, weaker stations are allowed to operate on the same frequency as the "clear" channel ones, they are supposed to take steps to minimize interference. Very quickly, the number of AM stations went from about 900 to about 2000. Even today, though, the AM stations that are easiest to DX are the ones that were true "clear channel" broadcasters in the old days. Some of the ones that come quickest to mind are 650, WSM, Nashville (where you can hear the Grand Ol' Opry on Friday and Saturday nights); 740, KTRH, Houston (flagship station of the Houston Astros Baseball team); 820, WBAP, Dallas-Ft.Worth; 850, KOA, Denver; 870, WWL, New Orleans; 900, XEW, Distrito Federale, Mexico; 940, XEQ; 1050, XEC, Monterrey, Mexico; 1110, KFAB, Omaha; 1120, KMOX, St. Louis (flagship of the St. Louis Cardinals); 1130, KWKH, Shreveport; 1200, WOAI, San Antonio; and the aforementioned 1510, WLAC, Nashville.
As you might guess, the easier a station is to hear, the less interest it holds for the hard-core DXer, but everyone has to start somewhere, and besides, I think the stations listed above also tend to have more interesting programming than many less prominent AM stations.
The premier source of information about AM DXing are the publications of the National Radio Club. They offer everything from station lists to help you get started to plans for rather complicated devices like noise cancellers. In addition, more information can be found at DXing.com. And, as always, the dxzone.com can give you more links than you have time to visit!
All radio stations are required by FCC regulations to identify twice each hour, once on the hour and once at half-past; but radio broadcasters more and more see FCC regulations as quaint reminders of a day when broadcasters were still burdened some sense of responsibility. They want people to think of their stations as Radio Disney, or Sports Talk 1100 The Zone, so they are reluctant to give their call signs in their I.D.s and tend to have the announcers blurt them out quickly and indistinctly with no warning, or even neglect the call sign completely! Fortunately, the FCC has a service called the AM Radio Query to help you identify a station when you know only the frequency and city or if the call letters are "haarrumphed" out by the announcer so quickly you don't catch them. You always know what frequency your receiver is on, and most stations still carry local ads which clue you in to their general region; with this information AM Query can help you find the exact call and location.
