When I was driving up to watch the eclipse, I naturally (for me) took an interest in what was happening on radio along the way. I have way too much to report on that (and I probably never will report most of it), but I'll unpack one small discovery for the few (or none) of you who might be interested. It's from notes I took en route but didn't post because there was no connection.
Among the stations we heard heading through northeast Utah and southwest Wyoming was a collection of ten huge signals, all Class C (the biggest allowed, with 100,000 watts at 2000 feet above average terrain), most radiating on channels called Class A (107.1, 102.3, 103.1... ) which are normally reserved for local signals (max of 6000 watts at 300 feet), though the rules got more lax about that in recent years.
The site they transmit from, I discovered, is Humpy Peak in the Uintah mountains (far east of Salt Lake). They share a Shively 6016 panel antenna stacked 20 high (good sale for Shively), to maximize gain toward the horizon. All the stations put out 89,000 watts at 2,123 feet, which is equivalent to 100,000 at 2,000 feet, and they do it with transmitters that are just 7,900 watts eacj. While that's a good way to save watts, it's highly unusual. Almost... insincere.
What are they really up to with this? I wondered. Is it just so all these signals can reach Evanston, Wyoming, population 12,000, 43 miles away and the only population center to which these giant signals have a clear shot? (FM stations want to be high up because FM is mostly a line-of-sight band.)
Here's the reason, and I'd love to know who thought it up.
See, while the signals of all these stations are terrain-shadowed in the Salt Lake market by the Wasatch Mountains, the site is close enough to put the predicted signals' primary service area over the Salt Lake metro, but far enough from Farnsworth Peak (home of all the big Salt Lake FMs) to allow Class C signals to drop in on second-adjacent channels, which are mostly those Class A's. That way all the Humpy Peak FMs can put up boosters, some with powers up to 20,000 watts, at elevated locations on the east side of Salt Lake, Provo and Ogden, to fill in that shadowed terrain, which is full of people and business.
I just read that one of those stations was just sold for $1.1 million. What the new owner got was those boosters. Not the giant place-holder signal serving mountain goats in the wilderness.