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#121
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Revisiting the Power Explanation
On Sun, 25 Mar 2007 22:20:25 GMT, Walter Maxwell
wrote: Richard, assume a mismatched load has produced both voltage and current refleftions on the line that result in a particular reactive impedance at the line input. The line input is connected to the output of the transceiver that has a pi-network output coupling circuit. I call this condition 1. It exhibits a mismatch and it exhibits the probability of the reflected energy being absorbed by the source to the degree of the phase relationships. When the network has been adjusted to deliver all the available power into the line the output source impedance is the complex conjugate of the line input impedance. I call this condition 2. It exhibits just what you describe: In this condition the reflected voltage and current waves are totally re-reflected back into the line, while adding in phase to the voltage and current waves from the source, respectively. Consequently, the reflected waves do not pass rearward through the network to be incident on the plate. Only if the network is mistuned, such as being connected to the reactive input of the line without being retuned to resonance, in which case the excessive plate current due to being mistuned will result in an inordinate amount of heating of the plate. It seems to me that in your initial post in the original thread (that was largely ignored for comment) you made mention of injecting a signal from an external source into the mouth of the dragon for the purposes of measuring the source Z. Am I wrong? Yes, you are wrong here, because I made no mention of the 'mouth of a dragon'. That comment must have come from another poster, twarn't I. From March 14: "2. The amplifier is now powered down and the load resistance RL is measured across the input terminals of the resonant pi-network tank circuit (from plate to ground) with an HP-4815 Vector Impedance Meter." Richard, try this on for size and then determine whether you believe RF understands the function of the phasing in impedance matching: .... Now, when adjusting the output network of a tube-type transceiver to deliver all the available power into a line having reflections, the adjustment of the network accomplishes the same function as the stub on the line in the above discussion. Consequently, this is the reason why the reflected power is totally re-reflected at the output terminals of the network, and is never seen at the plate of the amp to cause heating. If you follow my separation of arguments above, you will find it demands that the source MUST have the intervention of an outside agent to resolve its probability of facing destructive energy. In the arts, this is called Deus ex Machina. In the world of science, we would have to say that the source is extremely non-linear when its internal state of Z (a distinctly non-Thevenin characteristic) changes to follow the load. In short, of course no energy finds its way in, we twisted knobs to make that a self-fulfilling prophecy. Without this intervention reflected energies present the real probability of destruction by heat. This is the concept I believe Richard Fry is not appreciating. If I'm wrong on this I hope he'll straighten me out. I will let him speak for himself. 73's Richard Clark, KB7QHC |
#122
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Revisiting the Power Explanation
On Mon, 26 Mar 2007 00:35:46 GMT, Cecil Moore
wrote: Richard Clark wrote: Correct but "disputed." Hmmm. i.e. 92% correct. Correct but "debatable." Hmmm. i.e. 85% correct. This is from someone who's experience an orgasm in the 80 percentile? Now we venture into almost pregnancies. |
#123
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Revisiting the Power Explanation
Gene Fuller wrote:
Cecil Moore wrote: *** 1 *** If reflected energy is not dissipated, it undergoes destructive interference and is redirected back toward the load as constructive interference instead of being incident upon the source. Why are you having difficulty with that concept from page 388 of "Optics", by Hecht, 4th edition? *** 2 *** Again, reflected power doesn't flow so it doesn't go anywhere. Until you understand that simple fact of physics, further discussion is unlikely to yield valid results. "Reflected power that goes" is only one of your many conceptual flaws. So your first logical step would be proving that reflected power actually flows. After you do that, we can continue to your other conceptual flaws. Paragraphs 1 and 2 appear to declare exactly the opposite behavior for energy (power). Paragraph 1 is about energy and doesn't mention power at all. Paragraph 2 is about power and doesn't mention energy at all. Energy is as different from power as length is different from velocity. Do you also get length and velocity confused? Is there some subtle re-definition going on to allow "redirected back toward the load" and "it doesn't go anywhere" in the same message? Here's a quote from my web page: "The term "power flow" has been avoided in favor of "energy flow". Power is a measure of that energy flow per unit time through a plane." The dimensions of power flow would be watts/sec. I'm not sure what quantity watts/sec would represent or where it would go. -- 73, Cecil http://www.w5dxp.com |
#124
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Revisiting the Power Explanation
Richard Clark wrote:
This is from someone who's experience an orgasm in the 80 percentile? At my age, I wish it was up to 80%. :-) -- 73, Cecil http://www.w5dxp.com |
#125
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Revisiting the Power Explanation
Cecil Moore wrote in
: Owen Duffy wrote: Considering only the attenuator case, you suggest in such a general statement that reflected power always increases the dissipation in a real source that includes an attenuator for the purpose of constraining the equivalent source impedance. Owen, why do you feel compelled to lie about what I said? You are not being paranoid here are you Cecil? If the reflected energy is dissipated within the source, it increases the dissipation. If the reflected energy is not dissipated within the source, it does not increase the dissipation. Why is that so hard for you to understand? Cecil, I can understand the above paragraph ok, it is self defining though so I don't consider it to be any great advance of the art. Whilst I can understand the paragraph, the content is so trivial I can't understand why you felt it necessary to state it. Owen |
#126
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Revisiting the Power Explanation
Owen Duffy wrote:
You are not being paranoid here are you Cecil? The word would be inebriated to the point of poor judgment. It was a rough day loading and unloading a full 6x12 U-Haul trailer all by myself. I apologize. If the reflected energy is dissipated within the source, it increases the dissipation. If the reflected energy is not dissipated within the source, it does not increase the dissipation. Why is that so hard for you to understand? Cecil, I can understand the above paragraph ok, it is self defining though so I don't consider it to be any great advance of the art. Didn't say it was an advance. It is my position that you questioned and it really seems obvious to me. Whilst I can understand the paragraph, the content is so trivial I can't understand why you felt it necessary to state it. It was apparently necessary to get you to understand my position. Wherever the circulator load resistor is located is where the dissipation of the energy in the reflected wave will occur. It can be either inside the source box or outside the source box. -- 73, Cecil http://www.w5dxp.com |
#127
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Revisiting the Power Explanation
Cecil Moore wrote:
Gene Fuller wrote: Cecil Moore wrote: *** 1 *** If reflected energy is not dissipated, it undergoes destructive interference and is redirected back toward the load as constructive interference instead of being incident upon the source. Why are you having difficulty with that concept from page 388 of "Optics", by Hecht, 4th edition? *** 2 *** Again, reflected power doesn't flow so it doesn't go anywhere. Until you understand that simple fact of physics, further discussion is unlikely to yield valid results. "Reflected power that goes" is only one of your many conceptual flaws. So your first logical step would be proving that reflected power actually flows. After you do that, we can continue to your other conceptual flaws. Paragraphs 1 and 2 appear to declare exactly the opposite behavior for energy (power). Paragraph 1 is about energy and doesn't mention power at all. Paragraph 2 is about power and doesn't mention energy at all. Energy is as different from power as length is different from velocity. Do you also get length and velocity confused? Is there some subtle re-definition going on to allow "redirected back toward the load" and "it doesn't go anywhere" in the same message? Here's a quote from my web page: "The term "power flow" has been avoided in favor of "energy flow". Power is a measure of that energy flow per unit time through a plane." The dimensions of power flow would be watts/sec. I'm not sure what quantity watts/sec would represent or where it would go. Cecil, I understand the physics quite well, thank you. What I neglected to fully pick up was the silly semantic game you were playing. We all know that "power flow" is a bit of an oxymoron, but it still is widely used as an equivalent to "energy flow". I was just trying to understand the phase of the moon in Texas for this particular thread. 73, Gene W4SZ |
#128
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Revisiting the Power Explanation
On Mar 25, 3:48 am, Ian White GM3SEK wrote:
Ian Jackson wrote: In message , Cecil Moore writes Richard Clark wrote: Cecil Moore wrote: your analysis is correct but moot Is he stealing your style? "Moot" is an interesting word, Richard. From Webster's - "moot - 1. a: debatable, b: disputed" Have a look here. http://en.wikipedia.org/wiki/Moot_hall I remember 'Moot Hall' from my days at primary school (some 60 years ago), learning about the Anglo-Saxons. I guess the word may possibly be associated with 'meet', ie a meeting hall where things were debated. However, my Anglo-Saxon is a bit rusty (not much call for it these days). Cecil was using "moot" in its legal sense: that a point had become irrelevant, or no longer needed to be decided because of a change in circumstances. Or at least, Cecil tried to claim that a point made by Keith had become moot. But Keith disputed that... and so it rumbles on. -- 73 from Ian GM3SEK Rumbles, yes indeed. But does it retain any entertainment value, or has it simply gotten painful to watch? Cheers, Tom |
#129
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Revisiting the Power Explanation
Gene Fuller wrote:
We all know that "power flow" is a bit of an oxymoron, but it still is widely used as an equivalent to "energy flow". From your last posting it was not readily apparent that you knew the difference between energy and power. There is no reflected power wave but there is a reflected RF energy traveling wave, the power of which can be measured at a fixed point. A Bird directional wattmeter indirectly senses the reflected power at the fixed location of the Bird. -- 73, Cecil http://www.w5dxp.com |
#130
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Revisiting the Power Explanation
On Sun, 25 Mar 2007 19:14:07 -0800, Richard Clark wrote:
On Sun, 25 Mar 2007 22:20:25 GMT, Walter Maxwell wrote: Richard, assume a mismatched load has produced both voltage and current refleftions on the line that result in a particular reactive impedance at the line input. The line input is connected to the output of the transceiver that has a pi-network output coupling circuit. I call this condition 1. It exhibits a mismatch and it exhibits the probability of the reflected energy being absorbed by the source to the degree of the phase relationships. Richard, although it exhibits a mismatch, and thus detunes the source, the probability of the reflected energy being absorbed by the source is zero. The additional power dissipated in the source is due to lowered impedance of the network resulting from off-resonance operation, thus increasing the plate current. The reflected energy does not enter the network, but only results in a decrease in the power delivered relative to that when the reactance in the load is cancelled by correct retuning of the source network. When the network has been adjusted to deliver all the available power into the line the output source impedance is the complex conjugate of the line input impedance. I call this condition 2. It exhibits just what you describe: In this condition the reflected voltage and current waves are totally re-reflected back into the line, while adding in phase to the voltage and current waves from the source, respectively. Consequently, the reflected waves do not pass rearward through the network to be incident on the plate. Only if the network is mistuned, such as being connected to the reactive input of the line without being retuned to resonance, in which case the excessive plate current due to being mistuned will result in an inordinate amount of heating of the plate. It seems to me that in your initial post in the original thread (that was largely ignored for comment) you made mention of injecting a signal from an external source into the mouth of the dragon for the purposes of measuring the source Z. Am I wrong? Yes, you are wrong here, because I made no mention of the 'mouth of a dragon'. That comment must have come from another poster, twarn't I. From March 14: "2. The amplifier is now powered down and the load resistance RL is measured across the input terminals of the resonant pi-network tank circuit (from plate to ground) with an HP-4815 Vector Impedance Meter." Richard, try this on for size and then determine whether you believe RF understands the function of the phasing in impedance matching: ... Now, when adjusting the output network of a tube-type transceiver to deliver all the available power into a line having reflections, the adjustment of the network accomplishes the same function as the stub on the line in the above discussion. Consequently, this is the reason why the reflected power is totally re-reflected at the output terminals of the network, and is never seen at the plate of the amp to cause heating. If you follow my separation of arguments above, you will find it demands that the source MUST have the intervention of an outside agent to resolve its probability of facing destructive energy. In the arts, this is called Deus ex Machina. In the world of science, we would have to say that the source is extremely non-linear when its internal state of Z (a distinctly non-Thevenin characteristic) changes to follow the load. In short, of course no energy finds its way in, we twisted knobs to make that a self-fulfilling prophecy. Without this intervention reflected energies present the real probability of destruction by heat. Twisting the knobs is what adjusts the output impedance of the network to the complex conjugate of the load. But without this intervention the real probability of destruction by heat is not resulting from the reflected energy reaching the plate--it is only that the reflected energy detuned the network, causing the plate current to rise because the network is off resonance. This is the concept I believe Richard Fry is not appreciating. If I'm wrong on this I hope he'll straighten me out. I will let him speak for himself. OK, Richard F, speak up. 73's Richard Clark, KB7QHC |
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