AM RADIO
Radio channels that operated in the relatively low 500–to 1,600-kilohertz range; home of the Packers and Rush Limbaugh, I-95, and Jesus.
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AM stations, if you can tune them in at all, are so often realms of pontificating jockeys, bummer health news, and scintillating traffic analysis that it's easy for many of us to just completely ignore that entire spectrum of the dial. Not long ago, however, AM-short for amplitude modulation-was the only option for radio users.
For the bulk of its ninety-plus-year lifetime, the AM dial played mostly music and had a kind of magic ability to span great distances. While its ground-wave signal only reached locally during the day, at night it would bounce off the atmosphere and the water, enabling it to travel thousands of miles. This meant that the strongest signals gave people glimpses of lives in parts of the country they might never see. Grand Ole Opry, which, as of this writing, is still broadcasting on 650 AM WSM in Nashville, Tennessee, started blasting country music into homes in Maine and California in 1925-and was likely Woody Guthrie's first introduction to the genre when he was growing up in Oklahoma; New York's 77 AM WABC brought a taste of big city life to people living in shacks in Wyoming. Yes, there was often crackling during the day caused by the waves' wrestling matches with storms and sunspots, but this only added to the organic, ephemeral nature of the listening experience: The sound, delicate and prone to disturbance, was fighting its way across land and sea all so you could hear Casey Kasem's dulcet tones. If you had to play with your radio's knob or the antenna in order to get the least static-y sound, it only made the end listening experience feel all the more earned.
Frequency modulation radio, a.k.a. FM, was in development since before World War II, but it didn't amass a loyal following until the late 1970s; it was in the 60s, however, that it became a way for counterculture music lovers to get on the radio when the FCC had already handed out most of the frequencies in the AM band. FM, which operated at much higher frequencies that were less prone to natural interference, had about ten times AM's range. This extra space meant that the sound waves could carry more information. With all that additional room to play with, FM broadcasters put out their signals in stereo, so that people with FM receivers could get a sound much fuller than the tinny one that AM listeners were accustomed to-that thin, old-telephone sound today sometimes used as an effect in modern pop songs.
College radio DJs and the non-mainstream music aficionados broadcasting on the FM airwaves shirked the tight formulas that had become de rigueur on the AM band-the Top 40 countdowns and the same songs in rotation every hour, each one bookended by ten-minute commercials. Instead, they used the stations to play experimental music and embraced offbeat talk programs. The content could afford to be esoteric, if only because the people who owned FM receivers were few and far between. If you were listening to FM in the 60s, you were considered to be kind of weird. But you were probably proud of that fact.
In 1962, according to the FCC, there were only 983 commercially operated FM stations; by 1975, there were close to four thousand. The shift happened when FM operators began embracing some of AM's formatted ways, and people started to catch on that music sounded way better in stereo. There was also the fact that manufacturers began selling affordable radios that could pick up both bands. Once listeners had a choice between hearing something full and rich or something flat and tinny, they sought out music on the FM channels, leaving AM stations to pick up sports and talk shows-programs where sound quality wasn't so important. In 1979, the New York disco station WKTU FM made news for bumping the AM channel WABC from its long-held #1 slot.
By the time that the FCC approved some of the AM stations to also broadcast in stereo in 1982, listeners had already made the switch and had little reason to go back to their old ways. AM's future was further complicated by the fact that you had to have the right equipment in order to hear the richer AM stereo tones. This required going out and buying a new, often expensive receiver that had to correspond with whichever of the handful of transmitter systems your favorite station used. There was no AM transmitter/receiver standardization until 1993 in the US, by which point there was little point to hearing AM in stereo unless the thing that bothered you most about Don Imus was his timbre.
Today, many MP3 devices with radio components don't offer AM stations at all, largely because the AM signal requires a transmitter that's bulkier than FM's, and the signal tends to receive interference from nearby MP3 circuitry.
That doesn't mean that old AM transistors don't have any use in modern times. When Bill Schweber of Electronic Engineering Times took one of his old ones for a trip around his home in 2008, he found it was unexpectedly useful-despite the fact that he couldn't actually tune in to any stations.
"What really struck me were the specific sounds I heard," he writes. "There was the whine from the electric motor of a nearby service cart; you could judge its RPM by the pitch. There were loud snaps from switches in nearby heavy machinery. PC power supplies and display oscillators added their own noise to the mix. I could have decided to toss the radio… but in today's world, it's all about spin and repositioning your assets and attributes. I took out my Brother electronic labeler, made up an 18-point-size label that clearly announced '500-to 1,600kHz RF Sniffer,' and felt I had done the radio justice."
