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#231
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Ian White, G3SEK wrote:
Cecil Moore wrote: Ian, I apologize if my humor offended you. It wasn't the "humor" (which was too feeble to offend anyone) but your talent for turning any technical discussion into a total waste of time. Imaginary circuits impossible to achieve in reality are not a waste of time? What is the agenda for diverting the discussion away from reality to something that cannot possibly exist in reality? I may be wrong, but it seems to me that agenda simply seeks to avoid the truths that will be uncovered by limiting the discussion to things that are possible. Since lumped inductors are impossible to achieve in reality, one might assert that they can sit up and spit cider in your eye. (From an old Dean Martin movie) How could you ever prove otherwise since the assertion cannot be tested? -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
#232
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Richard Harrison wrote:
Cecil, W5DXP wrote: "Until someone can explain exactly how a lumped inductor causes a 45-degree phase shift in the current, I`m going to assume that a lumped inductor is incapable of that feat." There are base loading coils in shielded boxes which don`t radiate but do have significant inductance which make too-short antennas seem long enough for impedance matching purposes. But the point is, those loading coils in shielded boxes are NOT *lumped inductors*. We have been told that lumped inductors have zero phase shift. Apparently, a 45-degree phase shift in the current through a lumped inductor would violate the rules of usage for lumped inductors. I have no doubt that real-world inductors provide a phase shift in the current. My statement was limited entirely to lumped inductors, a purely imaginary conceptual model. Sorry if that wasn't clear. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
#233
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KB7QHC wirtes:
As this is your party, the burden of proof is upon you. I supplied you with a litany of trip-points and you in fact responded to none. I appreciate your points, some are valid, I know about them, some were off target, some are in the area of nitpicking, when we are overlooking bigger picture. I explained that your previous posting was based on wrong assumptions (not reading carefully the threads?) - the 100mA on 8A meter, measurement techniques, etc. I will do my tests and measurements, first I will do that on my Radiomobile, to test the real life typical mobile situation. Next it would be to replicate W9UCW setup with radials. I keep getting "arguments" that are nitpicking in the .01 area of significance vs. 50% and the facts. I presented 7 points of proof and asked if anyone can debunk them, prove wrong, so far not a single "overthrow". Let me try to summarize again briefly: The temperature test, feeling or thermal strips prove that there is not .1 difference in current accross the loading coil but around 50%. W9UCW measured it and showed 40 - 60% differences. W5DXO explained mechanics of the effect. Are the FACTS in the way of coil "must" have the same current theory? This is not enough proof that current is significantly different at both ends of the coil rather than miniscule, hardly measureable? That IS the argument. As has been demonstrated, there is a camp that believes the current is the same. We know it is not and are bringing it to their attention in hope that it will set the record and knowledge straight. If they choose not to believe it, then let them be happy with their calculated world. Anyone measured it yet? Yuri, K3BU.us |
#234
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Yuri Blanarovich wrote:
Are the FACTS in the way of coil "must" have the same current theory? This is not enough proof that current is significantly different at both ends of the coil rather than miniscule, hardly measureable? That IS the argument. As has been demonstrated, there is a camp that believes the current is the same. We know it is not and are bringing it to their attention in hope that it will set the record and knowledge straight. One more data point. Assuming a 102 inch base-loaded mobile antenna on 75m, the impedance looking into the whip is around 0.5-j2000. If we assume a current of 1.5 amp into the bottom of the coil and also out of the top of the coil, the voltage at the top of the coil will be around 3000 volts. With a base loaded 75m antenna, the voltage at the top of the coil should not be extremely difficult to measure and could be viewed with an oscilloscope. This is an experiment that I can do at reduced power. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
#235
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Cecil Moore wrote:
We have been told that lumped inductors have zero phase shift. I think the claim is that there is zero current differential in magnitude across a lumped inductor. It's certainly true of a pure inductor. Presumably, one in which radiation is not a factor, and for which the electrical length is short compared to wavelength. 73, Jim AC6XG |
#236
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Cecil, W5DXP wrote:
"My statement was limited entirely to lumped inductors, a purely imaginary conceptual model." Sorry I didn`t get the picture. An inductor that provides no phase shift is similar to a capacitor that holds no charge. Inductors and capacitors store energies in their magnetic and electric fields. Current lags in the inductor and leads in the capacitor. Pure reactances have a 90-degree phase shift between applied voltage and resulting current by definition. An inductor sans phase shift is salt without savor or sugar without sweetness. Lumped inductance means coiled in place of straight wire, to me. Reference to toroidal coils in this thread implied to me an absence of external field, for which I chose a shielded coil with a straight-axis for my example. I agree with Cecil that a 90-degree antenna which includes only a 45-degree length of wire needs another 45-degree phase-shift in its length to reach the full 90-degrees. As the coil is in series with a resistance, and the resistance the coil experiences depends upon its position between drivepoint (low-resistance) and far end (high resistance) at the end of the element, the inductance required to produce the same required phase shift, varies with its position in the element. Where the resistance is low, so is the required inductance. Where the resistance is high, so is the required inductance, and it is all for the same number of degrees that the antenna is short. Best regards, Richard Harrison, KB5WZI |
#237
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Cecil Moore wrote:
If a loading coil has no effect on the current or the electrical length of the antenna, exactly what effect does it have? Apparently the correct answer is "loading". 73, Jim AC6XG |
#238
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#239
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Yuri, K3BU wrote:
"Are the FACTS in the way of coil "must" have the same current theory?" Sure. Power traveling along a radiator is absorbed in resistance, both loss and radiation resistance, so it is diminished by the time it gets to a reflection point, the tip of the antenna. This is not like a coil without an opportunity to radiate or which is small in terms of wavelength. Often an extreme example is more impressive than the mediocre. For instance, complete reflections on a lossless line make clearer examples of phase patterns than slight mismatches on a lossy line. For a coil, use the example of the "normal helix antenna". At one of the radio broadcast stations where I worked in 1949, was an operator, James L. Davis, W5LIT who wrapped a bamboo fishing pole completely from end to end with wire in the form af a solenoid, using it as his rear bumper mounted 75-meter phone mobile antenna. When he modulated, the corona at its tip echoed his voice. Obviously, there was a huge difference in the drivepoint current (high) of this antenna, a continuous coil, and the current at the tip (low). The voltage was the reverse of its end currents, being high where the current was low and being low where the current was high. J.L. Davis was very pleased with his mobile operation. Best regards, Richard Harrison, KB5WZI |
#240
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Jim Kelley wrote:
Cecil Moore wrote: We have been told that lumped inductors have zero phase shift. I think the claim is that there is zero current differential in magnitude across a lumped inductor. It's certainly true of a pure inductor. Presumably, one in which radiation is not a factor, and for which the electrical length is short compared to wavelength. For a lumped inductance, the electrical length is zero. Presumably, that has a zero effect on the current. Assuming that only the voltage is affected, the phase relationship between the voltage and current is blown compared to an unloaded antenna. But the relationship is somehow (magically?) restored by the time the end of the antenna is encountered. Exactly how is that relationship restored? -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
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