Most of us already know this, but for those just getting started in DX’ing, here are the AM and FM frequencies used by broadcasters in the United States. If you hear a station operating outside of these frequencies, it may be a foreign station or even a pirate (unlicensed) broadcaster!
Amplitude Modulation – AM – Stations utilize 10Khz spacing in both North America and South America. In some other parts of the world, stations use 9Khz spacing. This allows more stations but compromises bandwidth and, by extension, signal and audio quality. Licensed power outputs range from 250 watts to 50,000 watts, depending on the frequency being used. Here are the legal AM broadcast frequencies used by broadcasters in the United States in kilohertz:
540 550 560 570 580 590 600 610 620 630 640 650 660 670 680 690 700 710 720 730 740 750 760 770 780 790 800 810 820 830 840 850 860 870 880 890 900 910 920 930 940 950 960 970 980 990 1000 1010 1020 1030 1040 1050 1060 1070 1080 1090 1100 1110 1120 1130 1140 1150 1160 1170 1180 1190 1200 1210 1220 1230 1240 1250 1260 1270 1280 1290 1300 1310 1320 1330 1340 1350 1360 1370 1380 1390 1400 1410 1420 1430 1440 1450 1460 1470 1480 1490 1500 1510 1520 1530 1540 1550 1560 1570 1580 1590 1600 1620 1630 1640 1650 1660 1670 1680 1690 1700
Note: 1610Khz is NOT a legal frequency for commercial broadcasters. It is used by Travelers Information Radio Stations (TIS.) Typically, these stations relay highway and road information to motorists located in the immediate area. Power is limited to 10 watts output using inefficient loaded whip antennas. However, DX’ers have received these stations from distances of several hundreds of miles during nighttime hours when AM skywave reception is possible. On the low end of the band, 530Khz is also used by TIS stations in some areas.
The frequencies 1620-1700Khz are known as the “AM Expanded Band.” These channels were opened up for commercial broadcasters in the mid-1990s by extending the upper end of the AM band from 1600 to 1700Khz. Originally, only existing daytime stations with restricted directional antenna patterns and/or operations which were causing significant interference to other stations were allowed to “migrate” to the extended band. Their old facilities were then turned off and dismantled, reducing interference with remaining stations. Recently, though, this rule has been loosened somewhat.
Frequency Modulation – FM – Stations utilize 200Khz spacing in both North and South America. Stations may broadcast in monaural or (usually) stereo multiplex. Licensed power outputs range from 10 watt LPFM stations to 100,000 watt regional powerhouses. Output is measured as ERP, or effective radiated power from the antenna. Here are the legal FM broadcast frequencies used by broadcasters in the United States in megahertz:
88.1 88.3 88.5 88.7 88.9 89.1 89.3 89.5 89.7 89.9 90.1 90.3 90.5 90.7 90.9 91.1 91.3 91.5 91.7 91.9 92.1 92.3 92.5 92.7 92.9 93.1 93.3 93.5 93.7 93.9 94.1 94.3 94.5 94.7 94.9 95.1 95.3 95.5 95.7 95.9 96.1 96.3 96.5 96.7 96.9 97.1 97.3 97.5 97.7 97.9 98.1 98.3 98.5 98.7 98.9 99.1 99.3 99.5 99.7 99.9 100.1 100.3 100.5 100.7 100.9 101.1 101.3 101.5 101.7 101.9 102.1 102.3 102.5 102.7 102.9 103.1 103.3 103.5 103.7 103.9 104.1 104.3 104.5 104.7 104.9 105.1 105.3 105.5 105.7 105.9 106.1 106.3 106.5 106.7 106.9 107.1 107.3 107.5 107.7 107.9
The frequencies 88.1-91.9 are reserved for non-commercial FM stations. Originally, these were NCE or Non-Commercial Educational stations. These days, religious broadcasters and other non-commercial entities are also allowed to use these channels.
You will occasonally come across an FM station transmitting on 87.7 or 87.9Mhz. These have become favorites of unlicensed broadcasters in recent years. The audio portion of TV Channel 6 used to be located on 87.75Mhz. Because of this, many FM radios were and are able to tune as low as 87.7. In 2009, all TV stations in the U.S. converted from analog to digital transmission. Because digital signals generally propagate poorly on the low VHF channels, nearly all former Channel 6 telecasters have moved to either the high VHF or (usually) to the UHF band. Faced with today’s crowded band conditions in most markets, FM pirates have taken to “squatting” on 87.7 and especially 87.9 in recent years. Personally, I don’t believe this is a very smart practice. Since these frequencies are not used by licensed stations, an 87.7 or 87.9 broadcaster sticks out like a sore thumb to FCC enforcement personnel and to commercial broadcasters who are likely to report such unauthorized broadcasts. It is perfectly legal to listen, however, and the unlicensed broadcasts heard on these frequencies are often quite interesting and entertaining.
Since a station’s Legal ID (call letters followed immediately by city of license) are only required once per hour, most stations use a moniker as their primary identifier. Typically, this is a combination of their format and dial position or a portion of their call letters and dial position. News Radio 990, Sports Radio 107.1, News Talk 1230, Hot Talk 100.3, etc., are common identifiers for news/sports/talk stations. Music stations used to commonly use one letter and either round up or round down their frequency. KXEZ-FM 94.7 became “Z-95.” In today’s world of digital tuners and closely spaced stations, most broadcasters will now disclose their complete frequency in their on-air monikers: Q-102.1, Hot Hits 96.9, Sunny 630, Bull Country 103.3, Oldies 1340, Hot Rockin’ 104.1, Super Hits 99.9, and so on and so forth. With the advent of the Internet, it has become easier for DX’ers to identify these “non-ID” stations since they can usually be tracked down using the search engines. In the world before computers, it was frustrating since these stations only used their Legal ID once an hour and it seemed the signal would always fade out or incur interference during those few seconds!
Hopefully, this list of AM & FM broadcast frequencies in the United States and related info will help you ID those elusive signals that are fading in and out of your radios. Happy DX’ing!