A Dangerous Demonstration Of The Power Of Radio

Terrestrial radio may be a dying medium, but there are still plenty of listeners out there. What would a commute to or from work be without a check of “Traffic on the Eights” to see if you need to alter your route, or an update of the scores from yesterday’s games? Getting that signal out to as many listeners as possible takes a lot of power, and this dangerous yet fascinating demo shows just how much power there is on some radio towers.

Coming to us by way of a reddit post, the short video clips show a crew working on a 15,000-Watt AM radio tower. They appear to be preparing to do tower maintenance, which means de-energizing the antenna. As the engineer explains, antennas for AM radio stations in the medium-wave band are generally the entire tower structure, as opposed to the towers for FM and TV stations, which generally just loft the antenna as high as possible above the landscape. The fun starts when the crew disconnects a jumper and an arc forms across the clamp and the antenna feed. The resulting ball of plasma acts like a speaker, letting us clearly hear the programming on the station. It’s like one of the plasma speakers we’ve seen before, albeit exceptionally more dangerous.

It’s an impressive display of the power coursing through broadcast towers, and a vivid reminder to not mess with them. Such warnings often go unheeded, sadly, with the young and foolish paying the price. There’s a reason they put fences up around radio towers, after all.

49 thoughts on “A Dangerous Demonstration Of The Power Of Radio

  1. I recall one or two videos regarding RF burns over the years on Youtube. This one and watching to about 2:05 is like one of the earliest that surprised me. https://www.youtube.com/watch?v=L50x35df2nI&feature=youtu.be&t=85

    Makes me wonder about carrier methods to transmit electrophysiological modalities related signals via wireless heterodyne, pulse train and other CW modulation methods highly focused from remote sources transmitted to cause similar not only RF burn effect. Not fun with beam forming and duty cycles… and especially beyond target hacking, coagulation, cauterization and well… ablating effect. More reason for a DEW Defense network scheme.

      1. How so? There are clearly medical procedures that use RF to create changes in the human body, from electrocautery to RF cardiac ablation to correct arrhythmias like PVCs and atrial fibrillation.

      2. All the Standard Operating Procedures (SOP’s) I revised, developed and validated in my U.S. and a few other countries regulated industry career, always included a Glossary section to make sure everyone understood the definitions of the words used in the procedure.

        Here are some references to enlighten for starters… you can google search or use a library for more references to read into:
        https://en.wikipedia.org/wiki/Electrophysiology#Electrographic_modalities_by_body_part
        https://en.wikipedia.org/wiki/Heterodyne_(disambiguation)
        https://en.wikipedia.org/wiki/Pulse_(signal_processing)
        https://hackaday.com/2019/02/01/those-voices-in-your-head-might-be-lasers/
        https://hackaday.com/2019/02/14/creating-coherent-sound-beams-easily/

        Researching the methods used for acoustic hailing sheds some insight to at least three methods used.

        Interestingly, I see there is an updated reference to the laser microphone now including Theremin as I’ve wondered about him, Lebedew, A.G. Bell and J.C. Bose having ever worked on prior to what was disclosed as a more modern invention. https://en.wikipedia.org/wiki/Laser_microphone

        The technology I intentionally blanket statement referenced briefly isn’t all classified either, though the potential uses might be something to consider when you have one of the best NSA whistleblowers describing abuses of power… on the 700 Club now even:
        https://www.youtube.com/watch?v=xF_VYNtDgN8

        Also, interesting to consider: https://youtu.be/HaNKCeA10ek?t=2074 (watch until 35:53)

      1. No, tubes can safely be turned off for maintenance. In some cases they may leave the filaments running, but anode voltage is always turned off when the TX is not in use.

    1. I’ve had some experience with these AM towers. The tower is not directly energized by a transmitter. He could not short it out as shown if it were without tripping the transmitter off. Instead the tower is part of a directional array of two or more towers. At the moment another tower or towers are connected to the transmitter. Though this tower is not, it still receives a lot of energy since it is close. They’re doing work on the tower like changing the light bulbs or painting. Shorting it out shunts that received energy to ground to you can touch it.

      1. Ah, that makes more sense. I was wondering what they were doing. I’ve seen antenna farms with towers like these and always assumed they were linked together for beam-forming or something like that. Very interesting.

        I think that actually makes this all the more impressive, since the energy we see being discharged in the video is *received* RF energy rather than from the transmitter. Just, wow…

      1. What is the purpose of this antenna if there is one nearby that can be picked up? Are they grounding it because of this nearby antenna or would they still have to if there were no antennas at all nearby?

        Where is a good place (or book or youtube channel or something) to learn more about the theory and basics of this stuff because it is fascinating.

      2. That’s what i thought first, but the arc length seems a bit long. I assume the TX is running at night time power, and this is done to demonstrate that the whole tower is at a high RF voltage.
        Modern digitally controlled transmitters can handle a shorted output just fine.

    2. Well that transmitter is burning up money at a fairly brisk rate.
      Cycling the power on an AM, FM, or TV transmitter is a less than simple process, even for a solid state transmitter. it takes time, time is money. AM stations are not making a lot of money these days; so for every minute the transmitter is shut off is lost profits.

      1. No, that energy is just what is picked up by the antenna structure itself. There is a charge coming from the radio signals that are hitting it as well as an electrostatic charge that builds by the wind flowing around the structure and the electromagnetic effect of the tower itself. All of that energy is free but it is a lot like free static electricity, not that useful

    3. YES, if that was the actual energized tower. That would have dropped out the transmitter overloads of it was the only tower and tuned to match the 50 ohm coax coming from the transmitter. When I had to do actual work on the live antenna parts, such as the tuning unit or tower light circuits, it was Midnight Sunday Night when we were Off The Air and the transmitter was powered down. I’d drop the breakers in case someone at the studio decided to mess with the remote control.
      Someone else suggested this was a tower in a directional array, when the station was operating non-directional on one tower of the array. Possible (video is in daylight) but the detuning caused by that grounded tower would affect the local signal distribution.
      Changing tower light bulbs and tower painting were done in daytime with the worker jumping off the ground and onto the tower or (my well-known approach) using a nice dry wooden stepladder.

      Got my first RF burn off the South tower at WELI, New Haven CT. about 1946. My Dad, the Chief Engineer, showed me the big ceramic insulators, and said “Don’t touch the tower, you’ll get burned.!” So, as he was busy in the tuning house, I carefully touched the insulator. Nothing. At the top of the insulator there was what looked like caulk at the joint to the steel tower leg. So I touched that. Ouch!! (It was a lead seal).. Slight RF burn, not even any burned skin smell. I did put my finger in the mud of the brook, though. Many years later as a working Broadcast Engineer, I got a couple more good burns working on tower base tuning units and directional phasor cabinets. They DID smell… No feeling of electrical shock, of course…

      1. OK, this is weird. My dad grew up in New Haven in the 40s. He related a story about dropping by the transmitter for a radio station – maybe WELI – and having the engineer amuse them by pulling a fluorescent tube out of a fixture and having it light up all by itself. Wonder if it was your dad goofing on my dad?

  2. Somewhere on the Internetz I found a page that listed unlikely radio detection, someone got a pot on the stove in a transmitter complex to act as a diode detector, someone else had a mirror make sound due to the cupper/silver layers on the back acting as a diode…
    I don’t remember the details, it was a long time ago, but now I will search for it again
    Also there is a youtube of a guy using a plant against a tower to detect the radio…

    1. My father grew up near WLW in the ’30s when they were running 500KW for a few years. He said that you could hear the station clearly from a metal fence near his house which must have had a connection that acted as a semiconductor.

    2. Have you seen the Mythbusters episode with the one about Lucille Ball having claimed to have picked up radio transmissions in her tooth fillings? They went on and on about the possibility of two different metals making a point contact diode that might pick up radio waves.

      Then when they did the test using a real human jawbone, they put the two different metals on *opposite sides* of the jaw, nowhere near to touching each other. Without any contact there can be no possibility of making a point contact diode.

      1. Except that your saliva is conductive so yes you could make a semiconductor in your mouth under just the right conditions. You would have two metals separated by a less conductive liquid (or potentially human tissue). Doubt you would get a radio signal but your whole body is a semiconductor which is why you can get electrical burns and why a defibulator works.

  3. Used to be a BBC transmitter engineer. I’ve seen similar hair-raising phenomena several times on 250KW shortwave feeders and aerials. Bottom line, dont mess with this stuff because you’ll only get it wrong once.

  4. What this guy did is extremely dangerous and can cause instant death or medical issues that won’t show up for decades. The FCC and OSHA have mandatory requirements for anyone inside the fence or with access to restricted areas to have rf radiation training. What is in this video is a reportable incident with shared responsibility of the tower owner the broadcast licensee and the tower maintenance company if that is where the worker is employed. This is very stupid. There is very little protection the worker has with the insulation in his glove and the automotive jumper cables he is using to ground the tower and there could be significant near field radiation from that jumper as well. Even if this is a directional element it will be powered through a matching network with significant power and power reflection into the transmitter.
    The explanation that it is powered off and has coupled power from another broadcast station isn’t correct with the size of the arc on the video. Wouldn’t happen. This tower crew would be fired on the spot and banned from all of my sites and I would immediately report it.

    1. Without knowing the actual reactive volume of this antenna structure or it’s RF field exposure, or what other safing and grounding processes have already been accomplished, etc. Blanket statements as to “how large the arc” is are only an opinion, informed or not. The arc is not really visible but the indicator of iron/steel particles being blasted off of the contact area and oxidizing as sparks in air is indicative of the energy level… similar to what might occur discharging a fairly large capacitor. While I share the opinion this is pretty “roughneck” (he should at least be wearing an RF dissipating face shield) we have to presume these folk are experienced, practical workers in the industry and the employer would certainly not expose himself to the obvious non-compliance risks. No one has mentioned nominal atmospheric phenomena that would create a significant potential to exist on this tower just because it is “sticking up in the air”. I would suggest that what is seen here is the act of discharging/shunting the electrostatic charge as well as any induced RF charges. Take a look at as an example for the “atmospheric” part…

      1. You’re kidding, right?
        Personnel safety isn’t optional on the worksite.
        OHSA requires lockout tagout on any equipment that can cause injury to employees.
        Bullshitting and cowboying around high powered broadcast sites gets people killed.
        I’ve known 5 people killed on broadcast sites by this sort of thing and one who is permanently disabled by using a homemade insulator rod to force a klystrode supply switch. All of them were doing things that were hurry-ups or short cuts or showing off and fully preventable by following safety standards. I’m a ham too and the difference between ham radio and a 15 KW broadcast site is night and day. You might get bit by your Yeasu, have a conical cauterized burn mark and not have problems. At 15KW you can die. Oh by the way. There is absolutely no way the arc is caused by anything other than an active transmitter connected to the tower.

        1. Fine. Him and the crew taking the pictures are all dead now. If this tower is radiating, what in the heck are these guys doing inside the fence in the first place?… did they just happen to be driving by the tower and decide they wanted to hop the fence and play Russian Roulette on an active tower ? Per OSHA / Tag out/lock out why would the Station Manager not be aware some yahoos were throwing arcs to ground on his expensive finals? The guy throws the arc long enough to generally trip the transmitter off-line or at least bias out as if it were a lightning strike if it is a fed tower. Most modern tower installs have perimeter alarms and interlocks anyway. What station is this ? what is the power level ? What is the electrical design of the antenna ? (base feed current loop, etc.) … Whatever… It is all moot as there is not enough info to determine clearly what is illustrated, but thanks for the safety thoughts; there is no substitute for step by step procedures that if followed will generally make you as safe as it is going to get for areas and work that are intrinsically hazardous. Feynman’s piece on atmospheric potential gradients https://www.feynmanlectures.caltech.edu/II_09.html …was deleted from my other post.

          1. I agree with you that it appears to be a contracted service company. Also I agree that there must be some knowledge by the radio station that they are on the site.
            The root cause analysis is clearly a management and training failure.
            The steps for risk management for both personell and equipment hazard is to immediately remove the people exhibiting unsafe behavior from the site and to re-secure the site to restore safety.
            Once they’re removed from the risk, initiate remedial project review consisting of management and training reviews and determine next steps. If the tower crew was supplied by a contractor, determine why an untrained crew was sent to a broadcast site and if they can supply a qualified crew.
            My personal standard would be to fire them immediately and replace them with a competent company.
            I’ve never had problems contracting NATE certified tower crews who have extensive training with the RF radiation hazards, ANSI, OSHA, and all the fall protection and rescue requirements that are required for safe operation.
            The crew demonstrates insufficient training and knowledge and should be prohibited access to broadcast sites without remedial training.
            High powered broadcast sites don’t have to be dangerous at all if proper professionalism knowledge and safety standards are used.
            Remember, it’s a job and everyone goes home every day.

    2. If the transmitter is not energized I dont see the problem with what he did. This very well could be the charge built up from atmospheric. I am also a tower technician. Showing something like this is useful to illustrate what could happen to you the same way using a hotdog to demonstrate electrocution is acceptable. Under controlled circumstance it is perfectly acceptable to demonstrator like this.

      1. 1. Electrostatic discharge from a vertical conductor. Drop a wire over the side of a 4 story building and see if you can get an ‘electrostatic’ arc of the type demonstrated. Or fly a kite or touch a flagpole.
        2. If you were on my site drawing an arc off of my transmitter to show someone how you can hear the modulated audio in the arc and I had a telephone, that would be the last time you would work in the industry. Full stop.

  5. I once spoke with an ex-Army engineer who did radio work in the service. They would cut the signal to an antenna long enough for the man to climb onto it, then re-energize. Because the man had no ground contact it was “safe”. Not sure what frequencies this was at, because obviously some freqs would cook you like an egg.

    1. From actual experience I can tell you that a WOODEN stepladder works fine for grabbing and climbing the tower. (At least at 5KW ). Almost all the guys we hired to replace the tower light bulbs all just jumped up and grabbed the tower. One did accept my offer of the ladder.

  6. RF is weird stuff! When you get to high enough frequencies it goes down tubes which need to be tuned. And if you don’t tune them right it will bite you! In early 1970, as a junior trainee engineer at the BBC my group of newby’s were taken on a visit to the Crystal Palace UHF transmitter in South London. At the time this broadcast 3 channels, BBC 1 & 2 and ITV (there were only 3 channels back then!). In a corner of one of the equipment rooms was a large piece of “plumbing”, beautifully machined and polished, bit looking a bit melted! This we were told was the original combiner for the 3 transmitters. It took the output of the 3 transmitters, which were somewhere around 240MHz, and connected to the single antenna feed. the story was that it one of the tuning stubs had been fitted incorrectly, and when the 3rd transmitter was turned on the power went into the stub instead of up the antenna feed! About 4MW! Of course it got a bit hot and all 3 channels tripped out. It looked like a piece of modern sculpture.

  7. Nice demonstration of sensible work habits. No, this tower is not directly energized by a transmitter. A dead short like that would activate the VSWR overloads on any functioning well designed transmitter. These guys are inside the fence. Fence locks would have been unlocked by the site manager who would also have reduced power on this specific tower to a safe level per OEB 65, possibly all the way to zero. Even though the worker says 15 KW, I would bet this is a 50 KW site for three reasons. The controlled area within the fence is too large for a 15 KW site, but looks about right for a 50 KW site. Our 15 KW radio station uses fenced areas about 20 feet square, which is sufficient to meet uncontrolled exposure limits. The arc in the video is too small for a 15 KW arc. And third, the base insulator looks oversized for a 15 KW station. As others have said, the likely explanation is that the radio station employs multiple towers for beamforming. When you work on one tower, you reconfigure the parameters to maintain energy into the remaining tower(s) and short out the one you are climbing. Because the inactive tower remains in a very strong field, it intercepts substantial energy. That’s the whole idea of radio communications, some antennas radiate, other antennas capture. Safety dictates you short the tower that is not directly connected to a transmitter to dissipate the intercepted energy. I’d estimate there’s about 20-100 watts of RF being turned into heat in the video, not 50 KW or even 15 KW or even 1 KW. The tower is passive and is intercepting RF from it’s brothers on the same site. The workers are properly grounding the tower so they don’t get hurt when they contact it with their hands.

    1. “Nice demonstration of sensible work habits.”
      Wow.
      I wonder if OSHA would share the same sentiment. Or an FCC FOB inspector.
      OET 65 completely stops when the tower hand approaches the tower with a car jumper cable.
      You can’t determine transmitter power by fence size. In a lot of cases fence dimensions may exceed the minimums as the builder sees fit.
      I understand how people might want to ‘splain away bad behavior for all sorts of reasons but there is no way this constitutes “sensible work habits”.
      Workplace employee safety is not optional.

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