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 Post subject: The Tower Could Not Be Grounded Very Good
PostPosted: Nov Mon 18, 2019 3:04 am 
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https://www.youtube.com/watch?v=vn60LwuUteg

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 Post subject: Re: The Tower Could Not Be Grounded Very Good
PostPosted: Nov Mon 18, 2019 3:06 am 
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The Arc was playing the transmission.

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 Post subject: Re: The Tower Could Not Be Grounded Very Good
PostPosted: Nov Mon 18, 2019 3:13 am 
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simplex1040 wrote:
The Arc was playing the transmission.


Yes it was.

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 Post subject: Re: The Tower Could Not Be Grounded Very Good
PostPosted: Nov Mon 18, 2019 3:14 am 
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Wow, that's crazy. The fidelity wasn't even that bad.


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 Post subject: Re: The Tower Could Not Be Grounded Very Good
PostPosted: Nov Mon 18, 2019 4:11 am 
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Nah, I think rf was getting into the camera. Thats why you heard it.


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 Post subject: Re: The Tower Could Not Be Grounded Very Good
PostPosted: Nov Mon 18, 2019 5:59 am 
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Yes you can create music with RF arcs.
https://www.youtube.com/watch?v=-f6GijQXaBI

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 Post subject: Re: The Tower Could Not Be Grounded Very Good
PostPosted: Nov Mon 18, 2019 2:53 pm 
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I'm still not convinced. The transformers used to produce the sparks could be modulated by the music through regular means. Kind of like the old color organs we built as kids. I'm open to the possibility of the arcs are producing the sound but I would have to do more research before I believe it.


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 Post subject: Re: The Tower Could Not Be Grounded Very Good
PostPosted: Nov Mon 18, 2019 4:39 pm 
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Either Popular Electronics or ELectronics Illustrated had an article on building an arc speaker using a flyback to generate the arc.


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 Post subject: Re: The Tower Could Not Be Grounded Very Good
PostPosted: Nov Mon 18, 2019 6:47 pm 
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forumuser wrote:
I'm still not convinced. The transformers used to produce the sparks could be modulated by the music through regular means. Kind of like the old color organs we built as kids. I'm open to the possibility of the arcs are producing the sound but I would have to do more research before I believe it.


What transformers? Unless I'm completely misreading the video the RF energy supplied to the antenna is what's causing the arc. The arc is modulated by the transmitter. That's why it's not a good idea to touch any high power antenna.

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 Post subject: Re: The Tower Could Not Be Grounded Very Good
PostPosted: Nov Tue 19, 2019 12:08 am 
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Devilsmist linked to a video in the post above mine. Thats what I answered to.


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 Post subject: Re: The Tower Could Not Be Grounded Very Good
PostPosted: Nov Tue 19, 2019 12:09 am 
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forumuser wrote:
Devilsmist linked to a video in the post above mine. Thats what I answered to.


Nevermind.

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 Post subject: Re: The Tower Could Not Be Grounded Very Good
PostPosted: Nov Tue 19, 2019 3:12 am 
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If the tower was grounded, there wouldn't be any reason for the double doughnut
isolation transformer to power the lights on it.

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 Post subject: Re: The Tower Could Not Be Grounded Very Good
PostPosted: Nov Tue 19, 2019 5:59 am 
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I’m confused.if this is a bottom(end fed)Marconi antennae, the feed point should have maximum RF current and minimum voltage? I guess it would produce an arc to ground, if a path is provided as illustrated. Why would someone purposely attach a ground, trying to produce an arc. Wouldn’t this damage the feedlines and/or the transmitter components.

I could see grounding in order to do maintenance, but you would, Kill the transmitter first.

I question the validity of the video. Judging the length of arc,and fact that 1000 volts only can jump 1/1000bof an inch, I don’t think the gloves and insulation on the ground clamp is insufficient. Something seems amiss.
Or am I missing something.


Last edited by Y2KEDDIE on Nov Tue 19, 2019 6:26 am, edited 1 time in total.

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 Post subject: Re: The Tower Could Not Be Grounded Very Good
PostPosted: Nov Tue 19, 2019 6:12 am 
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radiotechnician wrote:
If the tower was grounded, there wouldn't be any reason for the double doughnut
isolation transformer to power the lights on it.

I believe the linked torroids are to act as an RF choke to keep RF off the tower lighting.

The whole video needs further explanation.

I once saw an antique spark gap transmitter with a rotating spark gap. The rotation speed determinesd the audio modulation.

I believe an auto mobile mechanical distributor can modulate the spark noise, Varying with rotation.


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 Post subject: Re: The Tower Could Not Be Grounded Very Good
PostPosted: Nov Tue 19, 2019 6:25 am 
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after further review of the video, the worker says,’”...the tower is the feed horn for the parabolic dish...” Just doesn’t make sense. A 50 kw, microwave AM broadcast?


I’ve seen 1/4 wave vertical AM broadcast band attenaes Insulated at the base, but not ghz dishes. ( with exception of high power pulsed radar).


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 Post subject: Re: The Tower Could Not Be Grounded Very Good
PostPosted: Nov Tue 19, 2019 2:59 pm 
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Reminds me of the time I was working on a giant jet and there was a short to the airframe with 120 Volts from equipment on the plane thru extension cords. People were getting shocks touching the plane. I investigated and found the ground between the plane and the ground rod in the floor was disconnected. Tried to connect to ground the plane and got big blue arcs like that. The equipment had a short to the case and the extension cord had the ground pin removed.

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 Post subject: Re: The Tower Could Not Be Grounded Very Good
PostPosted: Nov Tue 19, 2019 4:15 pm 
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Greetings to Y2KEDDIE and the Forum:

The two torroidal windings in the video are a 1:1 transformer for 120 volt tower lighting. The tower lighting wiring is part of the radiator and cannot be directly connected to either ground, neutral or hot AC mains circuits without introducing RF into the power lines and ruining the tower feed point impedance.

The transformer design allows fairly efficient coupling of the AC line without inductively or capacitively coupling the lighting circuit RF to the AC mains.

I'm not sure what those guys were doing; I couldn't see what they were connecting to well enough to tell where it was electrically.... but if they were shorting the tower base to ground, they were certainly playing havoc with the antenna VSWR and were risking dumping the station off the air.

On the other hand, I have heard of jumper cables and even vice-grips being used in an emergency to replace burned up RF connections, so maybe that's why the jumper cable was there.

As far as the arc size is concerned, bear in mind that this is RF, not DC. Also, bear in mind that many broadcast towers are not 1/4 wave in length, and that the feed point impedance can be quite high. Most AM broadcast antennas have antenna tuning "huts" at their bases where the impedance is transformed into 50 ohms to make the transmitter and feed line happy.

One of the people I used to work with back at KCBS spent some time at the KNX AM transmitter site. This is also a 50 KW station at 1070 KHz. One day, he decided to try an experiment. He took a 10 foot length of EMT (1/2" steel conduit) and attached it to a wooden stake. He added a coil with large wire that could be contacted with an alligator clip. He then constructed a clip lead out of fairly heavy gauge wire and took the whole thing out to near the base of the KNX antenna in the near field. He drove the stake into the ground, connected the clip lead to the antenna ground system and proceed to tap up the coil. He got a few sparks from the alligator clip as he moved it up the coil until he hit the magic resonance point... at which time an arc formed from the tip of the EMT to the ground near him like a giant Tesla coil.

He crawled away to escape the arc, wondering what to do now? How to dismantle the thing? Finally, he placed his trust in theory, and walked erect up to the gadget, disconnected the clip lead and took the apparatus away. He reasoned, correctly, that his body capacitance would de-tune the system sufficiently to quench the arc.

A word to the wise... don't try this at home... or at your friendly local 50 KW AM station either. :D

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 Post subject: Re: The Tower Could Not Be Grounded Very Good
PostPosted: Nov Wed 20, 2019 1:04 am 
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Jthorusen wrote:
Greetings to Y2KEDDIE and the Forum:

The two torroidal windings in the video are a 1:1 transformer for 120 volt tower lighting. The tower lighting wiring is part of the radiator and cannot be directly connected to either ground, neutral or hot AC mains circuits without introducing RF into the power lines and ruining the tower feed point impedance.

The transformer design allows fairly efficient coupling of the AC line without inductively or capacitively coupling the lighting circuit RF to the AC mains.

I'm not sure what those guys were doing; I couldn't see what they were connecting to well enough to tell where it was electrically.... but if they were shorting the tower base to ground, they were certainly playing havoc with the antenna VSWR and were risking dumping the station off the air.

On the other hand, I have heard of jumper cables and even vice-grips being used in an emergency to replace burned up RF connections, so maybe that's why the jumper cable was there.

As far as the arc size is concerned, bear in mind that this is RF, not DC. Also, bear in mind that many broadcast towers are not 1/4 wave in length, and that the feed point impedance can be quite high. Most AM broadcast antennas have antenna tuning "huts" at their bases where the impedance is transformed into 50 ohms to make the transmitter and feed line happy.

One of the people I used to work with back at KCBS spent some time at the KNX AM transmitter site. This is also a 50 KW station at 1070 KHz. One day, he decided to try an experiment. He took a 10 foot length of EMT (1/2" steel conduit) and attached it to a wooden stake. He added a coil with large wire that could be contacted with an alligator clip. He then constructed a clip lead out of fairly heavy gauge wire and took the whole thing out to near the base of the KNX antenna in the near field. He drove the stake into the ground, connected the clip lead to the antenna ground system and proceed to tap up the coil. He got a few sparks from the alligator clip as he moved it up the coil until he hit the magic resonance point... at which time an arc formed from the tip of the EMT to the ground near him like a giant Tesla coil.

He crawled away to escape the arc, wondering what to do now? How to dismantle the thing? Finally, he placed his trust in theory, and walked erect up to the gadget, disconnected the clip lead and took the apparatus away. He reasoned, correctly, that his body capacitance would de-tune the system sufficiently to quench the arc.

A word to the wise... don't try this at home... or at your friendly local 50 KW AM station either. :D

Regards,

I agree with what you said. Different wavelenght height would change the feed point resistance. Even odd wavelength antennas are typically feed at the lowest impeadance point. Even at 50 Kw, and several thousand ohms the RF voltage produced would not be 3-4 inch in length in air. As I said in my latest post, They said the “tower” was used as the “feed” for the parabolic dish. The tower appeared to be around 10 feet tall. I know of no AM broadcast station using such a tower.

In cursory examination it appears they are using a short section from a discarded end fed AM broadcast antenna, used as a tower/support for a microwave parabolic dish. The audio, does appear to be that of an AM broadcast, but from a microwave dish?

The arc is flame ionization, which can be modulated. Being non linear can cause rectification/detection.
The physical dimensions of the feed horn on the dish does not appear to be high power.

Hoax? Still ambigous!

PS:; I once made an RF choke for tower lighting isolation by making a coil /several turns/of ridged conduit and then fed the lighting conductors thru the coiled conduit.


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 Post subject: Re: The Tower Could Not Be Grounded Very Good
PostPosted: Nov Wed 20, 2019 1:26 am 
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With regards to WLW broadcasting at 500KW I recall the following quote:

"Many reports have surfaced over the years of the power fluctuations from those who lived near the 500 kilowatt transmitter. Residents would see their lights flicker in time to the modulation peaks of the transmitter. It was widely reported that the signal was so overpowering some people picked up WLW radio on the metal coils of mattress and boxed bedsprings, similar to KDKA-AM in Pittsburgh, Pennsylvania. Arcing often occurred near the transmission site."

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 Post subject: Re: The Tower Could Not Be Grounded Very Good
PostPosted: Nov Wed 20, 2019 3:34 am 
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Y2KEDDIE wrote:
Jthorusen wrote:
Greetings to Y2KEDDIE and the Forum:

The two torroidal windings in the video are a 1:1 transformer for 120 volt tower lighting. The tower lighting wiring is part of the radiator and cannot be directly connected to either ground, neutral or hot AC mains circuits without introducing RF into the power lines and ruining the tower feed point impedance.

The transformer design allows fairly efficient coupling of the AC line without inductively or capacitively coupling the lighting circuit RF to the AC mains.

I'm not sure what those guys were doing; I couldn't see what they were connecting to well enough to tell where it was electrically.... but if they were shorting the tower base to ground, they were certainly playing havoc with the antenna VSWR and were risking dumping the station off the air.

On the other hand, I have heard of jumper cables and even vice-grips being used in an emergency to replace burned up RF connections, so maybe that's why the jumper cable was there.

As far as the arc size is concerned, bear in mind that this is RF, not DC. Also, bear in mind that many broadcast towers are not 1/4 wave in length, and that the feed point impedance can be quite high. Most AM broadcast antennas have antenna tuning "huts" at their bases where the impedance is transformed into 50 ohms to make the transmitter and feed line happy.

One of the people I used to work with back at KCBS spent some time at the KNX AM transmitter site. This is also a 50 KW station at 1070 KHz. One day, he decided to try an experiment. He took a 10 foot length of EMT (1/2" steel conduit) and attached it to a wooden stake. He added a coil with large wire that could be contacted with an alligator clip. He then constructed a clip lead out of fairly heavy gauge wire and took the whole thing out to near the base of the KNX antenna in the near field. He drove the stake into the ground, connected the clip lead to the antenna ground system and proceed to tap up the coil. He got a few sparks from the alligator clip as he moved it up the coil until he hit the magic resonance point... at which time an arc formed from the tip of the EMT to the ground near him like a giant Tesla coil.

He crawled away to escape the arc, wondering what to do now? How to dismantle the thing? Finally, he placed his trust in theory, and walked erect up to the gadget, disconnected the clip lead and took the apparatus away. He reasoned, correctly, that his body capacitance would de-tune the system sufficiently to quench the arc.

A word to the wise... don't try this at home... or at your friendly local 50 KW AM station either. :D

Regards,

I agree with what you said. Different wavelenght height would change the feed point resistance. Even odd wavelength antennas are typically feed at the lowest impeadance point. Even at 50 Kw, and several thousand ohms the RF voltage produced would not be 3-4 inch in length in air. As I said in my latest post, They said the “tower” was used as the “feed” for the parabolic dish. The tower appeared to be around 10 feet tall. I know of no AM broadcast station using such a tower.

In cursory examination it appears they are using a short section from a discarded end fed AM broadcast antenna, used as a tower/support for a microwave parabolic dish. The audio, does appear to be that of an AM broadcast, but from a microwave dish?

The arc is flame ionization, which can be modulated. Being non linear can cause rectification/detection.
The physical dimensions of the feed horn on the dish does not appear to be high power.

Hoax? Still ambigous!

PS:; I once made an RF choke for tower lighting isolation by making a coil /several turns/of ridged conduit and then fed the lighting conductors thru the coiled conduit.




That is a larger tower than 10 ft , he said the hole in the ground is the "dish" and the tower is the "feed horn". they state it is an AM tower not microwave. That is prob a STL dish you see in the shot.

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