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Exploring a 1 Million Watt Broadcast Tower

Joe and Jeff Geerling are a friendly pair of YouTube hosts

The father and son team of Joe and Jeff Geerling have teamed up on radio-related projects before. 

Joe is a broadcast engineer, working into his fifth decade in the St. Louis market. He was market chief for CBS Radio for 20 years and today is the director of engineering for Covenant Network. 

His son Jeff has spent nearly 15 years as a software architect and developer. He founded Midwestern Mac LLC and is active in many open-source software communities. Jeff recalls that one of his first web programming projects in the late 1990s was to construct an interface to display the current song on 98.1 KYKY(FM)’s initial website for his dad. 

Last February, Joe appeared on a video on Jeff’s YouTube channel to install a Raspberry Pi IP KVM in a Covenant Network studio. That collaboration went so well that commenters on Jeff’s videos began clamoring for more appearances by the senior Geerling. 

Over a family vacation, Joe and Jeff came to the realization that the iconic Crestwood Master Tower in Shrewsbury, Mo. — nicknamed by its original engineering community as “the Supertower” — would make for a perfect showcase for a new Geerling Engineering YouTube channel. 

Given Joe’s expertise with the site, the idea for a video was a natural. In fact they ended up making two. 

The Supertower.

Ten Class C FMs and more

The father and son duo has a history with the structure, which was built in 1986. 

That year, Joe started working with EZ Communications, the broadcast company that had the tower built, doing contract projects and working on remotes. He later was brought on full-time and soon became its corporate engineer. The company was later sold to American Radio, which was in turn purchased by CBS in 1998. 

Starting when Jeff was around 6, Joe took the boy on numerous visits. Well into his teens, Jeff would tag along when Joe did weekend checkups on newly installed gear or responded to an emergency. Jeff himself was hired for some networking and computer work at the site as he got older. 

“It was always fascinating to see such a well-maintained facility, especially in comparison to more rural tower sites, and one with so much activity,” Jeff said. “It seemed there was often a new tenant, or some equipment being replaced.” 

The location of the tower, just west of the city of St. Louis, provides optimal market coverage. 

“When the master antenna was built, it was extremely close to the center of the population of the St. Louis Metro,” Joe said. “The metro population has shifted a bit west, but the site still has the greatest population count advantage of any site.” 

The 1,030-foot Stainless G-74 model tower has three faces, each 7 feet in width. The site is owned by American Tower and was originally completed by Lodestar Networks.

Ten Class C FM signals are served by an eight-bay Dielectric TAV-8FN/24U-2 antenna that was installed in 2006.

They are Audacy’s 96.3, 98.1 and 102.5; iHeartMedia’s 93.7, 103.3 and 107.7; Hubbard’s 94.7 and 106.5; Gateway Creative’s 99.1; and Bott Radio Network’s 91.5. 

The 16-year-old Dielectric master FM antenna is seen on the Supertower in this drone-based photo.


Thanks to the cooperation of engineers at Audacy, Joe and Jeff had access to the Supertower on a sparkling November morning to film both the immediate exterior of the site and the interior transmitter rooms. 

The duo pulled up to the tower through the neighboring Resurrection Cemetery — “Nobody has ever complained about nearfield radiation here,” Joe quips in the second video.

With the sheer number of cables running into the facility, one might wonder if the condition of the transmitter rooms inside resembles a disorderly rat’s nest. Nothing could be farther from the truth. 

The rooms in the videos appear immaculate. To Chris Nixon, site manager from American Tower, the Supertower’s condition is a credit to the quality and cooperation of the engineers that have been present in the Gateway to the West.

“Of our 85 sites I manage in the central U.S., it is among the busiest,” Nixon said. 

“The engineers who represent the broadcast interests in St. Louis act so professionally. There’s an appreciation for the other tenants, as they never know when it might be their own equipment that requires the site to undergo downtime.” 

Joe cited some of his mentors in the market, including Ed Bench (SBE Fellow), who helped guide engineers in using an FM combiner system at the tower, and Mike Waldman (CPBE, CBNT), who oversaw several special projects at the site related to emergency power and shutdown. 

Jeff and Joe in the FM Combiner room.

If the cleanliness of the transmitter rooms doesn’t hold your attention, the easy-to-understand explanations of the multitude of equipment choreographed by the Geerlings will. 

In the first video, Joe details how it is possible to combine 10 FM signals via the custom Dielectric combiner. Nine of the 10 FM stations also run separate HD Radio signals through the antenna, and four of those use increased –14 dBc injection levels. 

Five additional FMs — full-powers 104.9 of iHeartMedia and Emmis’ 105.7, and translators on 95.9, 101.9 and 103.7 — use a side-mounted antenna on the tower, and there are five TV stations, two cellular companies and several public safety and two-way communication entities up there. 

All told, just under 1 Megawatt of effective radiated power emanates from the tower.

It makes for a handy attention-grabbing video title, but the claim is far from clickbait. In around 18 minutes, Joe and Jeff explain cable management, a GatesAir liquid-cooled FM transmitter, the gain factor of 4 that exists for the master antenna, and the RF lockout system employed for safety when tower work is necessary. 

Joe explains a liquid-cooled GatesAir transmitter.

The two have a great camaraderie and their videos are free of jargon or overly technical language, making it easy for both newcomer and veteran engineer to understand. 

“I compiled a list of questions I thought people would have visiting the site, and we ran through that list on the day of the filming,” Jeff said. 

“My dad and I try to include a little more of the father-son banter because I think it can make the videos a little more approachable, especially if we’re discussing topics that tend to be a bit dry on their own.”

Family plan

The cherry on top are visuals of the majestic tower from a DJI Mavic Pro drone. It was a gift from Joe’s son Joel. In addition to the views, as Joe explains, it makes for an excellent tower inspection tool. 

“I could go on and on about drones and their uses,” Joe exclaimed, hinting to Jeff of a possible future video topic. 

The November Supertower YouTube video had 440,000 views as of February. It sparked so many questions in the comments that Jeff and Joe decided to return for a followup, just prior to when Jeff was scheduled to undergo a surgical procedure. 

Some of the queries they addressed in the second video include delving into the concept of ERP further, RF radiation concerns even just being at the base of the tower, and the incandescent safety lighting used on the tower (as opposed to LEDs). The second video was released in early December and has 219,000 views. 

Joe standing at the tower base.

“For both my main channel and Geerling Engineering, I try to make videos that I know I want to watch, and also try to make them approachable to as wide an audience as possible,” Jeff said.

The Supertower lives on as one of the more unusual master antenna setups in the country, a list that also includes the Empire State Building’s master antenna and the taller Senior Road Tower serving Houston. Many tenants have come and gone, “dreams that have started big and failed, but some dreams that have come true,” as Joe summarized in the videos. 

Jeff, following a successful recovery, and Joe have their sights set on additional father-and-son tower site videos in 2023, including at least two AM towers, helping to showcase the differences from FM with aspects such as grounding. Joe’s Covenant Network station antenna sites would surely make for more enthralling video content as well. 

Check out part 1 of the Supertower videos below. Find the rest by searching for “GeerlingEngineering” on YouTube.