ICP coil first test

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steve_rb
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ICP coil first test

Post by steve_rb » Sat Apr 10, 2010 7:11 am

13.56 MHZ Rf generator and impedance matcher (automatic and manual 2.5 KW) are ready and I am about to do my first RF test experiment. Water is connected to both generator and matcher. Coil has made from copper and connected to match box with water flowing inside it. For the first test I intended to insert a flour cent lamp inside the coil and increase Rf power gradually and watch reflected power on bird wattmeter until plasma generation starts. What I need to do is only increase power gradually. Since match box is automatic I wound need to do matching myself. If I saw reflected power is high and matcher is unable to match the impedance then I will know impedance matcher needs tap increase or decrease from inside (need opening the matcher cover and decrease or increase the tap). Since I will start with low powers wouldn't worry about safety issues (only will stay about 3 meters away from the coil).

Since this is my first experience with RF equipments please welcome to comment or advice if you thing anything necessary

Linda Haile
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Re: ICP coil first test

Post by Linda Haile » Sat Apr 10, 2010 10:18 am

Are you certain about safety? RF burns are an issue here. The coil should be shielded.

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Chris Bradley
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Re: ICP coil first test

Post by Chris Bradley » Sat Apr 10, 2010 10:30 am

As I have commented before, my advice is not to proceed.

I would be comforted if you were to state clearly that this experiment of yours is done independently of any encouragement (indirect or otherwise) or advice this forum has given.

Have you, even, got an electrosmog meter or something similar to measure wideband field levels?

If this is your first experience of RF and you are proposing to play around with >kW generator into a non-standard feed, the advice is simple: STOP. DO NOT OPERATE.

Linda Haile
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Re: ICP coil first test

Post by Linda Haile » Sat Apr 10, 2010 10:42 am

Chris and I agree here. Is the unit not covered with warning labels ie DANGER RF RADIATION?

Linda Haile
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Re: ICP coil first test

Post by Linda Haile » Sat Apr 10, 2010 10:59 am

If you ignore these warnings you risk permanent blindness and worse, even death.

Dustinit
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Re: ICP coil first test

Post by Dustinit » Mon Apr 12, 2010 12:14 am

I think blindness is a bit far fetched at 11Mhz. Magnetron 2.4Ghz possibly but not 11 or 12mhz. I think a test into a dummy would be wise to ensure resistive match and power is at a level you expect. Efficient radiation at these wavelengths requires an antenna of huge dimensions so emissions at low power would be of little concern.
Remember that the electric field is maximum at 1/4 wavelength which is about 6 metres at this frequency compared to about 3cm at 2.45Mhz. The heating effect is due to dissipation factor of the dielectric which is essentially mechanical vibrations from bond stretching and rotations creating heat. This effect is greater at higher frequencies due to the higher electric field from the shorter wavelength and the sheer number /sec of field reversals. Lets keep things in perspective.
Dustin.

John Futter
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Re: ICP coil first test

Post by John Futter » Mon Apr 12, 2010 9:44 am

Dustan is right
no big danger to the eyes @ 11 MHz but an RF burn at these power levels will burn deep and will take nearly forever to heal.
take it easy and keep your body parts away, the worst that can happen is your generator will pack a sad.
Keep an eye and ear on the TV and or radio (am) these will show up "blocking" if you are radiating too much --you don't need the FCC at this point --they may call up less sympathetic agencies

adrian.f.h
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Re: ICP coil first test

Post by adrian.f.h » Mon Apr 12, 2010 1:14 pm

Hi
I did some little tests with tube based hf oscillators (plasma tweeter style).
One can be seen here: http://www.adrian-homelab.de/hfgu29.html
I will improve it in the next 2 weeks and I already began building an oscillator using high power transmitting tubes (between 1 kW and 2 kW output).

Even with this little poorly conceived device on my website I made some interesting/alarming observations. If a finger is held close to the coil you can feel the warmth. I was quite surprised about this and became really careful. Also radios (not connected to the main antenna of this house) are badly influenced. You can't hear anything than the 50 hz humming (bad filters).

I have a lot of respect for hf sources even at those wavelengths and low power levels. Good shielding is advisable but I don't think I need to tell you since I'm no expert. At least if you don't want to disturb your neighbour. Don't run the device during a football match or something like that

Adrian

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Chris Bradley
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Re: ICP coil first test

Post by Chris Bradley » Mon Apr 12, 2010 2:15 pm

My concerns are less radiated power but more coupled conducted power. We're potentially talking peak voltages of 1000V RF here, if it flows into a low impedance sink, like *you*... and it is the kind of RF 1000V that will pay no heed to your rubber gloves and boots and that may feel like no more of a tingle.

RF can get up to a few crazy tricks in this power range and frequency band. Cable shielding and well-designed connector shells are useful for safety as well as reducing emissions! The first you may know of an issue is a smell not dissimilar to frying bacon. At that point, turn off the power (if you still have sufficient command over your muscles) and look for smouldering finger tips and toes.

Hey, maybe I'm overly risk-averse and blowing it out of proportion, sure, but in the scenario of using a kW supply in one's "first RF experience" then I feel it is entirely appropriate to over-, rather than under-, emphasise the risks.

I confess to taking some similar risks, but it's on my head and no-one has encouraged me to think it's OK to do.

steve_rb
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Re: ICP coil first test

Post by steve_rb » Mon Apr 12, 2010 2:19 pm

Coil is ready. Hardly glass man could build a copper inside a pyrex coil but he finally did a good job. I will not start test yet. I have to get more about saftey issues.
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