Exploring a 1 MILLION Watt FM Tower

My Dad and I took a road trip to tour the 1 MW FM community tower in Crestwood, MO, serving the entire St. Louis metro area combining 10 FM radio signals into two antenna systems.

Special thanks to the Audacy engineers who allowed us to take a peek at their (very clean!) transmitter rooms and equipment!

#Radio #Transmitter #Engineering

Contents:

00:00 - The Supertower
01:52 - Grounding and Guy-Wires
03:11 - Tower-scale cable management
04:13 - Transmitter Room
05:49 - 400A power and backup power
07:09 - 50kW Dummy load, switching, and 30kW water cooling!
09:16 - MARTI filter cans and cable loss
10:37 - In the basement - from 30 to 300 kW
12:47 - Giant coax with explosive arcing potential
14:00 - Tower safety: RF lockout
15:01 - Power, Aux services, Comms, and Lights
16:41 - One tower, many stories

[NathanTallack]

Your dad is a legend! You must be so proud of him!

[Jofacup]

Your dad is an excellent presenter. He made it easy for the non-broadcast engineer to understand by not using commonly used terms likee Line, STL, RPU, Vault, and Tenant. Once again thanks for the great videos.

[wientz]

I am not an engineer but I am an electrician...Let me tell you, your dad does an amazing job of explaining how things work in real life...very practical without ever trying to seem smart. Just a lot of knowledge with an amazing ability to simply explain how things work.

[rcflyboynj]

As a telecom engineer I loved seeing all of this. Thanks to both you and your dad for this amazing walkthrough!

[DJ-Daz]

Now I've watched the video, it's amazing.
Who ever gets to see all the work involved in engineering to get a radio tower signal? Makes me really appreciate my radio even more.

[mikefromflorida]

Your dad is a wonderful engineer and a fantastic presenter of information. An absolute joy to hear. Thank you both.

[cuttinchops]

It’s crazy how TV and radio TX’s have evolved. A once entire room, now just one air cooled rack with a bunch of small solid state amps can push quite a few KW, mindblowing compared to what it all was.
On behalf of us broadcast nerds, thanks for the production work and upload! Always fun to see.

[RossT]

Hi from Australia. I was a broadcast technical officer during the 70s and 80s. Retired (changed professions) just as solid state was taking over. Loved the walk through. I felt right at home.

[NomenNescio]

I'm halfway through the video and I just had to pause and leave a comment about how awesome this video is.

[--Zook--]

as someone who is closer to your dads age than you I really appreciated this video. I wish I would have had any dad to teach me about anything. I tried to make a huge effort to teach my daughter everything I learned as I never was fortunate enough to get a son. She turned out better than I could ever imagine. Anyway enough of a pity party, I loved this video, and we need more of dad.

[michaelterrell]

I worked at a 5 MW EIRP UHF TV station in Florida. Our antenna was at the top of the 1700 foot tower. We had a eight input FM antenna at the 1200 foot level and another TV station was added at around 1400 feet. This was in the Orlando market. We had five FM stations on the tower, and a Trunking radio system which predates affordable Cell service. There were also leased two way radios for things like the Forestry Service.
We had two microwave STL systems. One from or original transmitter site that was fed from a former CARS link when the station transitioned from local access cable TV to OTA. the second STL came from our new studio just North of Orlando. The Comark TV transmitter used three 65KW EEV Klystrons, and large rectangular waveguide after the Diplexer.

I moved and rebuilt a RCA TTU25B transmitter in 1990 that had been at our old transmitter site. It was then used on Ch 58 in Destin Florida. It was 25 KW Visual, and 12.5 KW maximum Aural. The Aural section was a modified FM Broadcast transmitter that tripled the output frequency before it went to the final amplifier. That transmitter was released from final test at RCA on the day that I was born. 😁

M first job as a Broadcast Engineer was in 1973, at a US Army radio and TV station, in Alaska. The TV station was on Channel eight, and monochrome but I managed to transmit our station ID in color with no color equipment just to prove what an idiot the Information Officer was.
The radio station was on 980KHz, and the only AM station that I ever saw that used a center tapped horizontal dioole antenna.

I was allowed to tour both the now closed VOA station at Bethany Ohio in 1969, and the WLW site with the legendary 500KW 700KHz transmitter.
The VOA station was being upgraded from the original Crosley transmitters to new transmitters. These used servos to auto tune each stage, so they were more agile than the original Crosley units. There were ten identical new 50 KW transmitters that could be paralleled and the huge East/West curtain antenna aimed towards Europe. A new control room for the site was being built as well. It was fed by microwave from Washington DC, and it was to be the secondary master control site in case the DC studios were down or were destroyed. This was in the days that the TV networks were fed by AT&T microwave links from city to city.
I later worked at Microdyne which supplied a lot of Microwave equipment to Cable TV and Broadcast stations.
I was repairing C-band sat equipment in the '90s in my shop. I built a C-band signal generator from a highly modified tunable down converter.

[radscientist]

Takes me back to being a kid when my grandfather was an engineer for a local station and would take me with him to their AM transmitter.

[dgolfer]

I remember when they started moving the stations in St. Louis to that tower. To say I was drooling is an understatement. Seeing all that Heliax and all that wiring is amazing. It was definitely an engineering masterpiece to get all of those stations on one tower. I know at least one Amateur Radio repeater has a remote receive site on there (I think the K9HAM repeater out of Alton). Your Dad definitely gave a fantastic explanation of how that all works. I was nodding my head on a lot of stuff he was taking about. Especially gain on the antennas. Power on FM systems is considered ERP (effective radiated power) which is a what is being pushed up the coax and then combined with the gain of the antenna system.

Thanks again to your Dad and you for putting this video together. I know I appreciated it.

[TheSoundmanPete]

Being a broadcast engineer.... this brought back good memories. Great job recording and editing. Thanks.

[turboltr]

As a guy that volunteers to climb towers for ham radio sites, I don't really get to see broadcast FM stuff. That basement was awesome!

[TheSeanUhTron]

16:00 - As an IT guy, I can relate to that issue. People plugging in stuff to your UPS and ruining the battery up time! I had to start doing the same as that fiber installer did, place labels over the receptacles.

[RadioChief]

Great tour Mr. Geerling. Radio engineering gets in your blood. I've been at it for over 45 years now and everyday is as exciting and unpredictable as the day before.

[scottb]

A fascinating series of insights into modern RF transmission. Large diameter coax with solid inner and outer cores. Never seen that before. Jeff's Dad is cool.

[mpokoraa]

Your dad seems like a genuinely nice guy. Big kudos to him!

[Murdoch]

I remember seeing this tower, and it was interesting that it was in the middle of a cemetery.
I remember when I used to live in Mehlville as a kid, and a friend and I visited that same cemetery. I thought it was super interesting that there was a gigantic tower in the middle, and I always wondered what it was for, but know I know! Pretty awesome, and greatly appreciated, especially considering K-SHEE was one of the stations I listened to a lot.

Thank you for sharing this with us!