Today on Geerling Engineering, my Dad and I toured the tower site for WSDZ-AM, located in Belleville, IL. It's a 20kW AM radio station broadcasting with an array of eight individual towers:
How does one get a single coherent signal out of an eight-tower array? Enter the phasor:
That's phasor with an o, not phaser with an e, so Trekkies need not fret about a misspelling.
...except it was a beef frank. Make your wurst jokes in the comments.
What you see above is the remains of a hot dog after it has been applied to an AM radio tower operating in its daytime pattern, at around 6 kW.
A couple months ago, soon after we posted our If I touch this tower, I die video, a few commenters mentioned you likely wouldn't die after touching a high-power AM tower—rather, you'd have serious RF burns.
I was trying to figure out a way to somewhat safely test the scenario: what would happen if someone walked up and touched the tower, while standing on the ground?
If reading's not your thing, check out the short video we posted on Geerling Engineering:
Nearing it's centennial, KMOX-AM (1120 kHz) is a 50,000-watt clear-channel AM radio station with studios located in downtown St. Louis, MO, USA.
But their broadcast tower is located about 10 miles northeast, in Pontoon Beach, IL. My Dad was the director of engineering overseeing the tower and studios for about 20 years, and though he's no longer there, he and I got permission from Audacy and the St. Louis engineers (thanks!) to tour the site, and learn a bit about how they broadcast their AM signal—which reaches all the way into Canada and Mexico at night!
In this blog post, I'll write a bit about KMOX's tower system (AM towers are a lot different than FM, like the FM Supertower we toured last year), the transmitter, and the some of the history found at that tower site.
...that was the question I asked my Dad, a radio engineer for many decades, who worked at the biggest AM station in St. Louis, KMOX. The station is approaching its centennial in 2025, as are—some YouTube commenters argue—its primary audience!
I recorded that video during my convalescence at my parents' house (I am feeling much better now, thank you!), and my Dad discussed a few reasons why AM radio—at least in the US—is not dead. But it is suffering.
In the video, I pointed out the current dichotomy:
Last year I spent a lot of time in the hospital. Between multiple surgeries and outpatient visits and follow-ups (either intentional or through an unexpected ER visit), I probably spent at least a month or two in a hospital room. For a time, you could see the exact date ranges I was checked in by the holes in my GitHub contribution graph! Such is the life of an open source developer.
Despite appearances, this was not a very fun recovery!