high power arc

[picobyte]

That arc looks nice,and as long as it burns at least the transmitter can dump its power somewhere.

[gppms]

The protection of the VSWR of the transmiters didn't work?

[envisionelec]

echo...echo....echo....

[m0eme]

Hope you got a nice tan.

[BenHutchinson1]

Singing arc, on a HUGE scale. And also I'm just as worried (due to the arc) that you would be fried by the UV rays just as much as by the radio waves. And where were the welding gogles? NOWHERE! This guy was a COMPLETE MORON!

[DragonFlyback256]

Ladies & Gentlemen, High Power Plasma Arc Speaker. ;D

[DrMR2000]

All this having been said, if you are standing in frontof it, you will be cook and not even know it right away!!

[DrMR2000]

What is dangerous is specifically ionizing radiation which can come in the form of high-energy particle radiation. Ionizing electromagnetic radiation starts with ultraviolet on up through x-rays and gamma rays. Below these frequency are the visible spectrum, then infrared and then below that microwaves and then lower frequency radio bands such as UHF,VHF, HF (shortwave & AM commercial broadcasts) down to LF and VLF and ULF which covers the 60Hz e-m noise from your AC power lines and such.

[drradio2003]

no way, wanna see vidioes of my WMIN arc experance, thats scarry expically with an antique RCA BTA-50, thats impressive good video tho!.

[RyuDarragh]

They're lucky for two reasons. One, the frequencies used are not close enough to produce much thermionic heating (2.54GHz and they'd feel the burn) and the faraday cage would catch any E-field arcs (conducted RF is excruciatingly dangerous). But, the fact is, radio is like light. If you can see the arc, the brightness of the radio field is probably thousands of times brighter. They weren't hurt because they are transparent at those frequencies.

[rwefdfgdg]

@RyuDarragh:

The dangerous thing there was the heat of the arc!

Not much of the RF Power was radiated, for its frequency is much too low....

I really wonder if you know how an antenna works ;)

in that case, the power was burned in that arc!

so it doesn't even matter, that their bodies are transparent at those frequency....

[RyuDarragh]

@rwefdfgdg:

Well, of course the heat is also dangerous. That goes without saying. And I've worked in RF at extreme power so I'm summat familiar with antennas :P

The thing you're forgetting is the impedances. Under the wrong conditions, you can get easily burned by RF fields, arc or no arc. Every object has a different imepdance at different frequencies based on what its made of and an arc can generate some crazy harmonics. The danger is real at microwave freqs, but not so much at 100+MHz.

[rwefdfgdg]

@RyuDarragh:

Im not forgetting the impedances... the impedances are exactly what i've meant.

Thats a shortwave station, isn't it?

There absolutely no matching to the free space impedance (the thing that is normaly done by the antenna), which is the reason why theres not much radiation.

You are right, microwaves are indeed dangerous. I'm a microwave engineer ;)

But that was shortwave radio and without an appropriate antenna to radiate it, it won't be radiated so easily.

[rwefdfgdg]

I did not mean to offend you, I just wanted to make clear, that such low frequencies cannot be compared to microwaves.

Another point is, that you said, RF is like light: if this would be true, you could never get around the whole world at shortwave frequencies ;)

it's only true for higher frequencies

[RyuDarragh]

Actually, at all frequencies. There's no special change due to frequencies beyond the easiest way to propigate the photons. At 500K to 15M, the ionosphere can reflect them over the horizon. At 10GHz some plumbing of the right diameter suits. And low frequencies (WWCR uses 3MHz to 16MHz for their shortwave broadcasts) are close to those used by medical diathermy machines (30-200MHz). It's all in the perspective. At 1.1THz you can image things with details as sharp as any IR camera, after all :)

[rwefdfgdg]

You are right, in principle there is no difference between high and low frequencies.

But it's still wrong to compare a shortwave arc to a radiating microwave source ;)

the effect behind it are very different!

[rwefdfgdg]

regarding shortwave diathermy for medical use:

these devices use a quite strong coupling to the patients body.

Either magneticaly, using coils that are positioned close to the body, or electricaly, using metal plates....

And to achieve a result, they still need up to a few hundred watts!

I don't see where that strong coupling should come from in the situation that can be seen in the video....

[RyuDarragh]

You're right. I wasn't comparing them to each other that way as microwave frequencies can propagate very differently. That's what I was saying by mentioning that flesh is pretty much transparent at those frequencies (less than ~30MHz). At each frequency from DC to Cosmic Ray, different coupling effects, impedances and so forth take over as you go up in frequency. Always wondered what our world would look like if we had eyes that could see in radio wavelengths without being 10s of meters accross.

[DragonFlyback256]

@RyuDarragh

Radio wavelength "vision" would be very blurry and full of interference patterns i guess.

[douro20]

100kW...I'm thinking that they are 20kW final tubes, and if I am right, each one costs about $25,000.

[imfree707]

Spectacular arcing, but I have a disturbing feeling that this video could win a citation from the FCC. IMHO