Christmas Eve and the Radio Skywave
Any editor who’s been in the business for a few decades has certainly accumulated their share of oddball anecdotes and knowledge tied to techniques and processes lost to history. I’m no exception. And so, I’ve decided to start posting a few of these. However, I’ll start this first one in the land of AM radio.
My first official job in media was as a part-time disk jockey during my senior year of high school. It was a small central Florida 1,000 watt AM radio station that covered a range of musical programming – country in the morning, MOR (middle of the road) midday, Top 40 early in the evening, and more album cuts at the end of the night. That last part, 10PM-midnight (our sign-off time), was my shift.
AM radio, like shortwave radio, transmits a signal that bounces between land and the ionosphere. Sunlight during the daytime excites the atoms of the ionosphere, which blocks the penetration of the radio signal, thus limiting its distance. As a result during the day a 1,000 watt AM station signal can’t be heard too far past the county line. Stations in different cities are able to occupy the same frequency without interference.
With the sun gone at night, the ionosphere is now less excited. The radio signal can punch through to a higher level and ricochet a greater distance, thanks to a phenomena called skywave, aka skip. If the transmitter continues to operate at full power, the signal will then travel far enough to interfere with any radio station on that same frequency in another city. To mitigate this effect and reduce interference, the FCC requires most AM radio stations to reduce power at sundown – down to 250 watts in our case.
The exceptions are clear channel stations, which are allowed to operate at full power – typically 50,000 watts. These stations are assigned a frequency that is not also allocated in another market and, therefore, won’t create interference. In central Florida, we routinely picked up a station from Nashville at night. Such stations in the US and Mexico play a key part of rock ‘n roll history and radio lore – think Wolfman Jack, American Graffiti, and ZZ Top.
At our little station, one of the DJ’s responsibilities during morning or evening shifts was to raise transmitter power at 6AM sign-on and lower it at sundown. During the holidays, shifts were re-arranged to accommodate Christmas and New Year programming. So on Christmas Eve, I was on the late afternoon shift and got off right at the time of the power change. On this night, our country music morning DJ, who was a bit of a local celebrity, was on until midnight doing his annual special Christmas Eve program. He was a rather jolly old elf who arrived for his shift ready for the night – a tray of brownies, a loaf of bread and cold cuts, and some libations.
On schedule, I reduced the transmitter power to 250 watts, did my end-of-shift paperwork, and prepared to turn things over. On my way out the door I reminded my colleague that I’d already taken care of the power shift. “That’s OK, I’ve got it,” he replied. To my surprise, he walked back to the transmitter and switched it back up to full power. A nice, strong signal for his Christmas Eve special, I suppose!
The rest of this story is second hand. As I understand it, the station GM was driving around later that evening and realized the station had a much stronger signal than usual. He immediately knew what must have happened. The conversation went something like this (insert your own expletives to taste):
GM: “What are you doing! They must be able to hear us clear up to Georgia!”
DJ: “I have no idea what you’re talking about.”
GM: “Yes you do! Bring the power down right now before we get into serious trouble.”
As far as I know that’s what happened. Just one of those experiences that point to the fact that the radio business is (or at least was) a truly crazy place.
©2022 Oliver Peters