ICP coil first test

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steve_rb
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ICP coil first test

Post by steve_rb »

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 »

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 »

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.
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Re: ICP coil first test

Post by Linda Haile »

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 »

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 »

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.
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Re: ICP coil first test

Post by John Futter »

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 »

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 »

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 »

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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Richard Hull
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Re: ICP coil first test

Post by Richard Hull »

Having run unshielded 15kw in copper coils in Tesla coils, the LF stuff is no worry. More interesting and probably more likley is heating nearby junk inductively that you would not normally think about like bolts, etc.

I was stunned about the eye warnings. Just not an issue, of course. More likely is roasting your belly button or being branded as your closed loop belt buckle heats in the near field of the coil.

Richard Hull
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Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Carl Willis
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Re: ICP coil first test

Post by Carl Willis »

That copper-in-glass coil certainly is unusual...and probably cost a fortune. Would have been fun to see the glassblower at work on that. What was the rationale behind this construction?

Your test plan looks fine. It's good that you plan to start at low power. As you've been advised before, put a long piece of cable between the rf generator and the matchbox to help protect the rf generator. Watch your fingers near the coil or you'll get flamed.

-Carl
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Linda Haile
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Re: ICP coil first test

Post by Linda Haile »

Fair enough, Dustin, but these multi-killowatt RF generators can still cause RF burns.
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Re: ICP coil first test

Post by Linda Haile »

These multi'killowatt units will still 'boil your head' if it gets too close.

I was erring on the safe side when I mentioned blindness as no-one else was posting at the time.

Safety was the issue. How about a FAQ on RF generators?
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Carl Willis
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Re: ICP coil first test

Post by Carl Willis »

Steve's plan makes it clear that at most he'll have no more than a few dozen watts of delivered power (enough to light a fluorescent bulb).

Unlike earlier ideas that implied multi-kilowatt testing with the supply at full excitation, this is a logical and safe place to start. Nobody's head will be "boiled," nor will any of the other fairy-tale consequences trotted out at the beginning of the thread be realized. Just to put things in perspective, the old diathermy machines for home use developed 100-200W in the HF or low VHF bands (and besides heating flesh, will light fluorescent bulbs in spectacular fashion). Sun-Kraft lamps develop a few dozen watts at 18 MHz with a tube oscillator in the base; touching the open feeders at the UV bulb will brand your hide but otherwise is of little concern.

-Carl
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Linda Haile
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Re: ICP coil first test

Post by Linda Haile »

But what about a multi-killowatt unit running at peak power, Carl?

I'm as interested as everybody else. Are you saying it won't 'boil my head'?
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Carl Willis
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Re: ICP coil first test

Post by Carl Willis »

I'm not commenting on the possibility of boiling one's head in circumstances outside of what Steve described, which was a low-power test that carries the risk of minor RF burns and that's about it.

Realism ought to temper and inform the cautionary lecturing or it loses its relevance. Commenters hung up on boiled heads and whatnot in this thread should read Steve's plan over again and consider whether such response is apropos to the real situation, or whether it is a fanciful cautionary tale a la Struwwelpeter. Also, the preferred responses relate to direct experience rather than received "folk wisdom," which is what I think this stuff about blindness and boiled heads is likely to be.

Rf (and its hazards) are well-understood by hobbyists. The amateur radio hobby is replete with knowledgeable people, useful online and printed expert resources, forums, list servers, and so on. I don't think rf generators merit a FAQ. If the level of experience and interest rises, there might be a reason for the experienced parties to write one. But right now I think that endeavor would just be an instance of hot air.

-Carl
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AllenWallace
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Re: ICP coil first test

Post by AllenWallace »

A quick google search shows that to keep below the FCC radiation limit you should keep 9 feet away from a 14 Mhz dipole transmitting 1 KW.
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Richard Hull
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Re: ICP coil first test

Post by Richard Hull »

All such government radiation limits are set based on rather continuous exposure or at least long term exposure. You will not become a piece of bacon at 1KW even right up next to the coil so long as you are out of arc range. Just watch out for metal stuff on your body or metal stuff in the vacinity that you might touch or lean up against. More much ado about nothing.

If you get cooked you are stupid. If you don't read or have prior knowledge about what you are doing then you deserve the RF burn, exploded head, or loss of life and limb.
It is nature's way of thinning the herd of nebishes and the non-fleet of foot.

We are not thought or activity police here. Simple advisories are OK, but dire, out of the realm portents of impending doom are enough to put you off marriage, eating, or having a bit of fun. The world used to be a wonderful place when I was a kid....Full of endless enjoyments and possibilities. Now I have to worry about lead in paints, toys choking children, asbestos, metals in my water, an unlimited number of cancers due to consuming the wrong foods, mercury in fish, asteroids and meteors ending the world, the ozone layer depletion, the magnetic poles disappearing, global warming, global cooling, nuclear winters, terrorists, religious zealots, run away Toyota hybrids, skyrocketing energy costs, run away inflation, collapse of global finanical markets, my job, and the list goes on ad infinitum.

Have fun......If you dare.

Richard Hull
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Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Linda Haile
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Re: ICP coil first test

Post by Linda Haile »

Carl, these multi-killowatt units do have suffieient power to 'boil your head'. Steve had said he would start on low power, and turn it up. He now has a greater understanding of what he is dealing with.

RF and microwave radiation heat up the soft tissues in the body. The lenses in your eyes are soft tissue and cannot dissipate the heat. There is a risk of impaired vision even with RF if you are close enough to it or the power is high enough.

There is no such thing as a 'minor' RF burn and accidents do happen even to experienced RF technicians.

At least Steve is safe,

We should be getting one of these units next week. While they are a lot safer than magnetrons they still pose risks to health, especially the multi-killowatt units.

I stand by what I said. (Better safe than sorry).
steve_rb
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Re: ICP coil first test

Post by steve_rb »

Carl Willis wrote:

> Your test plan looks fine. It's good that you plan to start at low power. As you've been advised before, put a long piece of cable between the rf generator and the matchbox to help protect the rf generator. Watch your fingers near the coil or you'll get flamed.

>


Unit comes with a 5 meter RG 213/U cable. Is this cable long enough and appropriate or do I need longer cable for pretecting the rf generator?
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Re: ICP coil first test

Post by John Futter »

Steve
RG213 cable loss is 2.4dB for 100m
I have said it before use a whole roll of this to protect your RF generator this then equals 4.8dB return loss or SWR of 3.7:1 which the RF gen should handle at all loads presented ie from open circuit to short circuit.
50m of RG 213 would give an swr max of around 8:1 which will be outside the protection inbuilt into the RF devices of your RF gen.
Also if using the auto match you may find it beneficial to off tune it one way so that it finds the tuning point without hunting. We do this on our ICP-OES so that it doesn't blow the 63 amp HRC fuses on the three phase supply. This is an argon in air ioniser with 1.6kW RF in the discharge @11.56MHz and yes this is a tube type generator all the solid state ones blew up.
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Chris Bradley
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Re: ICP coil first test

Post by Chris Bradley »

Carl Willis wrote:
> Realism ought to temper and inform the cautionary lecturing or it loses its relevance. Commenters hung up on boiled heads and whatnot in this thread should read Steve's plan over again and consider whether such response is apropos to the real situation, or whether it is a fanciful cautionary tale a la Struwwelpeter.

I do not know of the allegorical references that you use, but what I can say is that I have re-read Steve's plan - all such posts - and it is clear that he is intent on dumping RF power into a plasma in the mistaken belief that plasma + a load of power will lead him to fusion.

It should be clear that if he doesn't get fusion, then he's gonna crank up the power, without understanding the difference between power input and the specific energy of an ion necessary for fusion.

Should he 'muck about' with some RF so as to see what'll happen? Sure, he can if he likes... In the meantime, if you find out that Steve is actually a 10 year old, or in some other way not able to formulate legal responsibility, and he writes in his journal "Carl Willis and Richard Hull say it's OK to run this experiment now" and bad things happen, then much as *you* may think this is all a bit of a lark and it's his responsibility, others may not agree with you.

We know nothing about Steve Robinson, he has not described his experiment except at the most cursory and high-level, and he has not taken me up on my invitation to him to make it clear that he's pursuing this experiment of his own volition.

There are responses I read on this forum that I would consider to be 'beyond comments' and that have become 'encouragements' and there are *now* legal implications associated with that that may not have been the case in times gone by, whether we like it or not. But those times *have gone by*.

Steve, I am not trying to insult your level of competence, whatever that may be, I just have a concern that you are doing potentially injurious or deadly things and not demonstrating a sufficiently deep understanding of electricity and RF, whilst responding in a way which suggests you are gaining succor from the input of others. Please seek co-operation/supervision at your location by someone who knows enough about these things to spot dangers.

Whether you think Lyn's response is an over exaggeration, or my own, or anyone else's, once the safety concern is raised it is for *Steve* to show that he understands it is not a risk - it's not for *you* to show that you know it's not a risk.
steve_rb
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Re: ICP coil first test

Post by steve_rb »

John Futter wrote:

> RG213 cable loss is 2.4dB for 100m
> I have said it before use a whole roll of this to protect your RF generator this then equals 4.8dB return loss or SWR of 3.7:1 which the RF gen should handle at all loads presented ie from open circuit to short circuit.
> 50m of RG 213 would give an swr max of around 8:1 which will be outside the protection inbuilt into the RF devices of your RF gen.


OK. Already ordered a roll of 250 meter BDA RG213 cable. (too expensive but better than ending up with damaged RF generator)


> Also if using the auto match you may find it beneficial to off tune it one way so that it finds the tuning point without hunting. We do this on our ICP-OES so that it doesn't blow the 63 amp HRC fuses on the three phase supply. This is an argon in air ioniser with 1.6kW RF in the discharge @11.56MHz and yes this is a tube type generator all the solid state ones blew up.

I have no experience with off tunning. Could you please give some detailes on how to do this?

Auto match manual says "in case the reflect power does not approach to 0W or there is no plasma generation inside the chamber a matching point can be adjusted by changing the Tune Coil TAP".

Do you mean by "off tune" changing Tune Coil TAP?

Also manual under the "Coil matching for the inductive match network" says " The Ashern L50 matchbox must be adjusted to each coil type. Refer to the technical data of your coil.Your coil type belongs to one of the three categories:
Low-Z (j30~j60 ohm)
Medium-Z (j50~j170 ohm)
High-Z (j160-j600 ohm) "


I also don't know how to find out which category my own made coil is belong to since I don't have any equipment for measuring Z. Only have normal ohm meter for measuring R.
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Re: ICP coil first test

Post by John Futter »

Steve
My guess is that your coil is lowZ the j notation = 2 x Pi x L (in Henries) x F in Hertz

There are free coil calculators on the net ie turns diameter and wire diameter will give a fairly good approx in uHenries then use the above to get j Ohms.

by off tuning I meant to start with the tuning cap offset from the tune point. One way will be much faster to get tune.

good luck
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