The Whittier Daily News says the La Mirada planning commission has recommended approval of KFI’s request to rebuild the station’s tower, which was knocked down by a small airplane in 2004. For old radio freaks like me, this is interesting. KFI’s signal is as big as they get in the U.S. Like lots of other big AM stations, KFI is 50,ooo watts. Unlike most big stations, it sits on a relatively “clear” channel (one where there aren’t others sharing the channel), has a low dial position, a non-directional signal, and radiates from a single tower just under half a wavelength high (175.4 degrees; half is 180 degrees). Thanks to all those advantages, KFI’s daytime signal reached from Mexico to Fresno and Las Vegas, while standing like a skyscraper on the dial in Los Angeles, its home city. At night KFI reached across the whole U.S., thanks to the reflective qualities of the ionosphere.
The approved replacement tower would be shorter: 648 feet. I see in the KFI’s construction permit that the tower will be sectionalized (divided into more than one radiating section) and “top loaded”, giving it the electrical equivalent of a half-wavelength tower. Technically, it would be 181.4 degrees. The old one was 175.7. The predicted signal would be “RMS Theoretical: 374.98 mV/meter (per kW) or 2651.51 mV/meter at 50 k”, which is identical to the old tower.
The nearby Fullerton Airport wants KFI to build the tower at 500 feet or less. From the story:
“It’s not a matter of if another aircraft will run into the antenna, it is only a matter of when another aircraft will run into it,” said Rod Probst, airport manager.
But Commissioner David De Boer said two accidents isn’t that bad.
“You can only imagine the air traffic,” De Boer said. “When you’ve only had two collisions that’s pretty good odds.”
Probst contends the tower shouldn’t be higher than 500 feet, but KFI officials say that won’t give them the power they need.
Greg Ashlock, acting general manager of KFI, said a 684-foot-tall antenna is needed to allow it to increase its signal and meet its responsibility to provide emergency information.
Without the tower, KFI’s signal – now using a 204-foot-tall auxiliary tower on the same property – only goes out to 11.2 million people, Ashlock said. With it, it would go out to 16.2 million people.
“We’re one of a handful of stations designated as civil defense stations,” he said.
Back during the height of the Cold War, in the 50s and early 60s, all radios were marked with a two little triangles in circles, at 640 and 1240 on the dial, indicating that these were the dial postitions to which citizens must tune in the event of a dire emergency, such as a nuclear attack. This was the CONELRAD system. With CONELRAD, all stations in the country would suddenly switch their transmitters to 640 or 1240 and broadcast the same emergency information — or no audio — at low power, confusing any incoming missles that might be listening to one big AM station, such as KFI.
I gather KFI is still grandfathered as a big daddy civil defense station. Makes sense, because it’s the biggest signal around.
As for the danger posed by a full-size tower, KFI’s had been standing there for 57 years before a plane hit it. I think it might even predate the Fullerton airport.
As for the actual effect of the tower loss on KFI’s signal, the station’s ratings numbers have been unaffected, as I recall, even though it’s broadcasting from a much shorter tower in the same location. It’s still a big signal.
As a kid I used to listen to KFI at night in New Jersey. That’s how clear channels worked in those days. They really were clear. I could turn my transistor radio so it would null out a competing signal from Cuba, and there KFI would be… weak, but quite audible. That’s no longer possible. The FCC has gradually allowed more and more signals on all the old clear channels, and the AM radio dial at night is a mess.
Now with the Internet, radio happens through podcasts, cell phones, laptops and other devices., making traditional radio more and more antique. This is especially so with AM (or MW elsewhere) — a band that has been all but abandoned in some other parts of the world.
But for old farts like me, it’s a sentimental thing. Also, cars still come with AM receivers, and that’s still where all the ball games are. So I’m guessing AM will still outlive me.
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