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Current through coils
Cecil Moore wrote:
Roy Lewallen wrote: It'll be easy enough to show that's false. If I set up a simple measurement with a piece of Air-Dux in series with a resistor, a couple of calibrated current probes, and a dual-channel scope, will you believe the results? Or would you rather have someone else make the measurement or do it yourself? Sorry for the double posting, but I just thought of an experiment that will settle everything. Take W8JI's 100 uH coil. Keep the spacing between coil 1 and coil 100 the same at one foot. Get rid of all the other coils leaving only coil 1 and coil 100 separated by one foot of air. Use coil 1 as the primary coil and measure the coupling from coil 1 to coil 100. If it is 100%, you will have made believers out of everyone and we can stop this silly argument. The lumped circuit theory says that all the flux in coil 1 links to coil 100 one foot away just as if they were both tightly wrapped around a toroid. So there's the challenge. Simply prove that 2" dia coils one foot apart in air transfer all the energy from one coil to the other. Piece of cake. What lumped circuit theory? It's a simplification and everyone knows it. Don't set up any more straw men than you have to, Cecil. 73, Tom Donaly, KA6RUH |
Current through coils
Tom Donaly wrote:
Cecil Moore wrote: So there's the challenge. Simply prove that 2" dia coils one foot apart in air transfer all the energy from one coil to the other. Piece of cake. What lumped circuit theory? It's a simplification and everyone knows it. Don't set up any more straw men than you have to, Cecil. It's not a straw man if someone actually believes it. We have a 2" dia. x 12" long coil. That's a length to diameter ratio of 6/1. There's no way coil 1 links all its flux to coil 100. Yet the *measured* delay through that coil was 3 nS. EZNEC says the delay through a better linked 70 uH coil is 6.22 nS. Have you noticed that the coils having instantaneous propagation times have been getting smaller and smaller and more conceptual rather than real? -- 73, Cecil http://www.qsl.net/w5dxp |
Current through coils
Cecil Moore wrote: It's not a straw man if someone actually believes it. We have a 2" dia. x 12" long coil. That's a length to diameter ratio of 6/1. There's no way coil 1 links all its flux to coil 100. Cecil sure is selective in presenting data. He alters dimensions and anything else that gets in his way. He dismisses EZNEC when it disagrees with him (he did that just a dozen or two posts ago), he uses it when it suits him. What a character! |
Current through coils
Tom Donaly wrote:
What lumped circuit theory? It's a simplification and everyone knows it. Don't set up any more straw men than you have to, Cecil. It's a simplification of any real-life coil - but loading by pure-and-simple lumped inductance is also a vital test case. This form of loading is the simplest imaginable. If a theory about the behaviour of loaded antennas fails to give correct results for this very simplest test case, it cannot be valid... and all the further elaborations about real-life coils will not be valid either. Cecil's theory does work for this test case, because it requires that basic electrical properties like current and inductance switch into a different kind of behaviour in what he calls a "standing wave environment". But it is an absolutely basic fact that the physical world does NOT change its behaviour according to the way we choose to think about it. If any theory requires that, it's an absolute proof that such theory is false. For the avoidance of doubt (as they say in Scottish legal documents): It certainly IS possible to analyse and predict the behaviour of coil-loaded antennas in terms of travelling and standing waves. My objection is specifically against Cecil's method, which is provably incorrect. (Away now to the GMDX Convention, so no replies till Monday.) -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Current through coils
On Sat, 01 Apr 2006 00:25:48 GMT, Cecil Moore
wrote: But apparently, it has been forgotten in the past half-century. Classic 5th sign of bogus science being offered. 5. The discoverer says a belief is credible because it has endured for centuries ... our ancestors possessed miraculous remedies that modern science cannot understand. Hi Tom, How could I possibly find this boring? It isn't every day that you find someone channeling Ramtha from the antediluvian 1950s to design antennas. OK, so it is a cheesy sort of K-Mart channeling. 73's Richard Clark, KB7QHC |
Current through coils
Ian White GM3SEK wrote:
It's a simplification of any real-life coil - but loading by pure-and-simple lumped inductance is also a vital test case. It only tests the validity of the lumped-circuit model. It does NOT test the validity of the real world. Testing the validity of the real world is best left to metaphysicians, not engineers. This form of loading is the simplest imaginable. If a theory about the behaviour of loaded antennas fails to give correct results for this very simplest test case, it cannot be valid... and all the further elaborations about real-life coils will not be valid either. Whoa there, Ian. You are confusing cause and effect. If the lumped inductance fails to give correct real-world results, then it must be abandoned in favor of a more powerful model, e.g. the distributed network model. You are making my argument for me. Do you really believe a 2" dia x 12 inch coil has 100% flux linkage between coil 1 and coil 100? But it is an absolutely basic fact that the physical world does NOT change its behaviour according to the way we choose to think about it. Exactly! Choosing to think about an inductance as "lumped" does NOT change the behavior of the coil. The behavior of the coil is what it is. Choosing to think about it as "lumped" is often an over-simplification, a fantasy existing only in someone's mind. For the avoidance of doubt (as they say in Scottish legal documents): It certainly IS possible to analyse and predict the behaviour of coil-loaded antennas in terms of travelling and standing waves. My objection is specifically against Cecil's method, which is provably incorrect. The distributed network model, a superset of the lumped circuit model, is "provably incorrect" after being accepted and tested for more than a century??? By all means, please prove it incorrect. That should be very interesting - overturning a century of acceptance. -- 73, Cecil http://www.qsl.net/w5dxp |
Current through coils
Cecil Moore wrote: The distributed network model, a superset of the lumped circuit model, is "provably incorrect" after being accepted and tested for more than a century??? By all means, please prove it incorrect. That should be very interesting - overturning a century of acceptance. Ian, It seems to me Cecil now agrees the system can be modeled as a lumped components and loads and we do not need to use standing waves. At least that's what it sounds to me like what he is saying now. 73 Tom |
Current through coils
Cecil,
That's quite remarkable. You issued a "challenge" to design and report on a loading coil for 4 MHz, with a whip of 8 feet. I responded with a solution that used a whip length of 10 feet. I did not "alter" anything, and I told you exactly what I did. What came back in return? Three separate times you altered my file and reported back here that something was incorrectly designed, illegal, or just plain different. You did not acknowledge the changes you made until I complained. (EZNEC did not change the coil pitch or connect the bottom of the coil to the top of the coil.) I don't have a copy of the IEEE Dictionary, but I believe the correct descriptive word for your action is dishonesty. -73 Gene W4SZ Cecil Moore wrote: wrote: He alters dimensions ... I don't remember the exact dimensions of your coil so you might refresh my memory. Was it 100 turns at 8 TPI? I have the same coil stock in a 50 uH version. As far as the EZNEC files go, I created them. Gene altered they away from the agreed upon length specifications. I altered them back and corrected a mistake I made in the traveling wave configuration. |
Current through coils
Gene Fuller wrote:
Cecil, That's quite remarkable. You issued a "challenge" to design and report on a loading coil for 4 MHz, with a whip of 8 feet. I responded with a solution that used a whip length of 10 feet. I did not "alter" anything, and I told you exactly what I did. What came back in return? Three separate times you altered my file and reported back here that something was incorrectly designed, illegal, or just plain different. You did not acknowledge the changes you made until I complained. (EZNEC did not change the coil pitch or connect the bottom of the coil to the top of the coil.) I don't have a copy of the IEEE Dictionary, but I believe the correct descriptive word for your action is dishonesty. I wasn't complaining about Cecil altering your coil's dimensions Gene. I was complaining about him altering the coil I measured and altering the context of what I say. What you say about him altering your data is true, but I want you to know that *I'm first*. .... woops.....I'm not first! I just remembered this: http://www.w8ji.com/agreeing_measurements.htm Roy's first. You're way down the list Gene. Get back in line. 73 Tom |
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