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#71
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Roy Lewallen wrote:
We are not going to get anywhere until you admit there is 68 joules/sec in the feedline that haven't yet made it to the load. Once you admit that fact, everything else will be moot. Let's try again. The source is providing 40 watts, 32 watts of which is delivered to the transmission line. The transmission line is transferring this 32 watts of power to the load. In the transmission line, we can calculate that there's 50 watts of "forward power", and 18 watts of "reverse power". And it is easy to prove that the source has generated 50+18=68 watts that have not been delivered to the load. So I ask you: Where are those 68 joules/sec located during steady-state if not in the forward and reflected power waves? Why will 68 joules/sec be dissipated in the system *after* the source power is turned off? If those 68 joules/sec that have been generated by the source but not delivered to the load are not in the forward and reflected power waves, exactly where are they located? There's really no sense in continuing this discussion until you answer that question. Everything else is just a side argument. The answer to that question will expose the errors in your premises. You are apparently assuming there is not enough energy in the system during steady-state to support the forward and reflected power waves. But that exact amount of energy was supplied during the power-on transient state and will be dissipated during the power-off transient state. If it's not in the forward and reflected power waves, you are going to have to store it somewhere else. Where is that somewhere else? The source has supplied 68 joules/sec that has not reached the load. The forward and reflected power waves require 68 joules/sec. That you don't see the logical connection between those two equal energy values is amazing. But I will get you started on an understanding of the component powers using an S-parameter analysis. How much of that 18 watts of reverse power is going through the source resistor to reach the source to "engage in destructive interference"? reference the S-parameter equation: b1 = s11*a1 + s12*a2 I calculate 11.52 watts. (s12*a2)^2 = 11.52 watts The other 6.48 watts are in (s22*a2)^2 where |a2|^2 = 18 watts What does it interfere with? From the S-parameter equation above, it obviously interferes with s11*a1 . Please reference HP App Note 95-1, available on the web. It should answer most of your questions, in particular pages 16 & 17. |a1|^2 = Power incident on the input of the network |a2|^2 = Power incident on the output of the network |b1|^2 = Power reflected from the input port of the network |b2|^2 = Power reflected from the output port of the network -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
#72
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Cecil,
You completely ducked the question. How did those waves get there in the first place? Hint: there are no laws for conservation of waves or continuity of waves. It is easy to set up a problem with physically unrealizable inputs. It is pointless to try to solve such a problem, however. We've been around this track a couple of times before. Neither of us has changed. Bye. 73, Gene W4SZ Cecil Moore wrote: Gene Fuller wrote: Cecil, Nice try. You first. Describe how you set up this coherent wave/anti-wave pair that happily travel together for some indeterminate distance. Then I will describe what happens when at some arbitrary point and time they decide to annihilate. Sure, here's the two coherent reflected waves that cancel at a Z0-matched impedance discontinuity in a transmission line. b1 = s11*a1 + s12*a2 = 0 I'm sure you recognize the S-parameter equation for the reflected voltage flowing toward the source which is the phasor sum of two other reflected voltages. They don't travel together for some indeterminate distance. They are cancelled within the first dl and dt. And they don't annihilate. They simply cancel in the rearward direction. Incidentally, if you square both sides of the equation you get b1^2 = s11^2*a1^2 + s12^2*a2^2 + 2*s11*a1*s12*a2 Pref1 = rho^2*Pfor1 + (1-rho^2)*Pref2 + interference The forward voltage equation toward the load is b2 = s21*a1 + s22*a2 |
#73
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Richard
Thanks for your explanation, I'm still thinking it over since its been 40 years since I've studied any tube theory. .. I recall many years ago watching a guy trying to fix an old radio. IIRC it had an 80 rectifier and right after the radio was turned on and started to warm up a blue cloud could be seen in the tube as the plates started to turn redder and redder. He would turn it off, change a part and check it again. I don't think he fixed it before the 80 went south. Later I figured out that he probably had a shorted filter cap. In this case the diode's plate dissipation rating was exceeded and it melted. The electrons slamming into the plate have a lot of kinetic energy to transfer. and heat up the plate. This results in lower efficiency as this power isn't delivered to the load. Now the diodes resistance can be easily calculated but I'm not sure how to visualize it. Is this where your term cathode resistance enters the picture? tnx -- 73 Hank WD5JFR "Richard Clark" wrote in message ... On Mon, 06 Jun 2005 20:52:52 GMT, "Henry Kolesnik" wrote: But in any event for something to melt we need dissipation and only resistance can do that! Hi Hank, Unfortunately as much as you and I agree on that bedrock principle, others with Simpson Ohmmeter in hand would glare goggle eyed at us and say that plate has no resistance to speak of and that no amount of current through its Ohmic resistance could ever bring about enough heat to produce the effects so obviously witnessed. One of the most enraging questions I've asked "If it is not the value I've offered, what value is it?" Well, I've never been given a quantitative answer, however I've seen enough carefully crafted mathematical proofs in this group to replace substantive results so easily seen. There is some irrefutable logic in circulation that clearly reveals that what we've experienced just couldn't be. Glasses will be need to be readjusted for such extreme myopic aberrations. There are two principles involved in what is called Plate Resistance, and the first and foremost is not even related to the plate at all. It is called the work function of the cathode emissivity. So, in fact it is more proper to refer to this usual loss as Cathode Resistance, not Plate Resistance. The cathode is the fundamental limit on power generated. What Plate Resistance is, is the ill termed substitution for Plate dissipation. If folks want to work their Simpson, they would blow an aneurysm trying to measure the resistance from cathode (filaments have the same work function issue too) to plate. In fact, the hobby horse argument of it is not resistance at all, but some figurative charting artifice called a "load line" usually appears in the last gasp. Plate Dissipation is resistance clear and simple in spite of the failure of conventional tools to measure a common physical property. Newton would have recognized it, it is called inertia. Once the work function is overcome (the job of the grid), then Plate voltage dominates through the acceleration of charge beyond the grid, toward the plate. That stream of electrons (and there is no doubt about actual current flow in easily counted, significant populations of electrons) is elevated to 90% the speed of light. This current flow is entirely different from what current flows in the remainder of the Plate load. That is also known as displacement current and electrons are shuffling along at a placid meter per second rate. Plate current and displacement current are equal in amplitude and phase, but not in motion nor kinetics. NOW. When that same stream encounters the Plate - WHAM! If anyone here has walked into the wall, and NOT encountered resistance, then we will call you Casper. Inertia reveals that to slow a mass in a distance results in acceleration (negative in this instance) and that property is called Force. Force over time expends calories and is expressed in any number of systems and units - Watts is one, Degrees is another. We could abstract to Horsepower and Candelas (the plate glows too). We know the speed, not many here would give it much though, but none would know the length interval of going at that speed to going zero (0). It is roughly two atoms distance into the metal of the plate. I will leave those calculations of Force to the student to compute or I can provide it from notes of correspondence with Walt Maxwell and Richard Harrison from a round robin discussion several years ago. Hank, does this fulfill your earlier question as to "what" is happening? I first gave you many examples, I hope this segue into real physics fills in their actuality. Too many correspondents demand that I open the source and point at a 50 Ohm carbon composition resistor that is the "source resistance." 73's Richard Clark, KB7QHC |
#74
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Gene Fuller wrote:
You completely ducked the question. How did those waves get there in the first place? Hint: there are no laws for conservation of waves or continuity of waves. I answered the question in another posting. The waves got there during the power-on transient state. Conservation of energy is assumed. Hope you don't disagree with that principle. If we make Roy's lossless 50 ohm feedline one second long (an integer number of wavelengths), during steady-state, the source will have supplied 68 joules of energy that has not reached the load. That will continue throughout steady state. The 68 joules of energy will be dissipated by the system during the power-off transient state. What you guys are trying to do is hide 68 joules of energy that cannot be destroyed. Where can you hide it in a transmission line to prove that it is not there in the forward and reflected waves? What is your agenda in trying to deny/hide/disguise/ignore that 68 joules of energy? In the one second example, the forward and reflected waves require 68 joules of energy for their existence in the feedline. The source has supplied 68 joules of energy that has not yet reached the load so it must necessarily still be in the feedline. Wonder where the energy in the forward and reflected waves came from? Shirley, you jest! Incidentally, QEX wants to publish my article. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
#75
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Please reference HP App Note 95-1, available on the web.
There's only one in every half a million of radio amateurs who have a copy of this document, or have ever heard of its existence, let alone having any chance of finding a readable copy of it within the next dozen years. By which time they will have changed their hobby to keeping tropical fish or making Newtonian telescopes. Or just died. In all likelihood they won't be able to make any sense out of it anyway. Cec, why do you bother to mention it? (smiley) ---- Reg. |
#76
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Reg Edwards wrote:
W5DXP wrote: Please reference HP App Note 95-1, available on the web. There's only one in every half a million of radio amateurs who have a copy of this document, or have ever heard of its existence, let alone having any chance of finding a readable copy of it within the next dozen years. Give me a break, Reg. Download it for free and enjoy from: http://www.sss-mag.com/pdf/hpan95-1.pdf In all likelihood they won't be able to make any sense out of it anyway. My dog isn't able to make sense of it either - poor dog. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#77
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Cecil Moore wrote:
Roy Lewallen wrote: [No, I didn't. Cecil wrote the following paragraph.] We are not going to get anywhere until you admit there is 68 joules/sec in the feedline that haven't yet made it to the load. Once you admit that fact, everything else will be moot. I never said a word about how much energy is stored in the feedline; it's irrelevant. It's stored there during the initial charging to the steady state condition, and the same amount remains there until the steady state condition no longer exists. It's exactly like the DC charge on a capacitor or a DC current through an inductor (which, in fact, is exactly what the feedline stored energy consists of) -- it doesn't have any effect on an AC analysis. [I did write this one.] Let's try again. The source is providing 40 watts, 32 watts of which is delivered to the transmission line. The transmission line is transferring this 32 watts of power to the load. In the transmission line, we can calculate that there's 50 watts of "forward power", and 18 watts of "reverse power". And it is easy to prove that the source has generated 50+18=68 watts that have not been delivered to the load. Surely even you can do the basic circuit analysis which shows that the source is continuously generating 40 watts, not 60. 32 of those are delivered to the load and 8 to the source resistor. I guess you mean 68 joules -- but as I said, it's irrelevant. So I ask you: Where are those 68 joules/sec located during steady-state if not in the forward and reflected power waves? Why will 68 joules/sec be dissipated in the system *after* the source power is turned off? The line's stored energy will be dissipated in either the source or load resistor or both when the source power is turned off. But we're doing a steady state analysis here. If those 68 joules/sec that have been generated by the source but not delivered to the load are not in the forward and reflected power waves, exactly where are they located? There's really no sense in continuing this discussion until you answer that question. Everything else is just a side argument. You tell me -- they can be anywhere you'd like. Just answer the simple questions about the power "waves". The answer to that question will expose the errors in your premises. What exactly is my premise, please? All I've done is to give the currents and powers at significant points in the circuit. Are any of the values incorrect? It's you who has the premise, not me. You are apparently assuming there is not enough energy in the system during steady-state to support the forward and reflected power waves. I'm making no such assumption. I'm questioning the existence of traveling waves of average power, and so far you've failed to give any evidence to convince me otherwise. But that exact amount of energy was supplied during the power-on transient state and will be dissipated during the power-off transient state. If it's not in the forward and reflected power waves, you are going to have to store it somewhere else. Where is that somewhere else? You tell me. My analysis doesn't need to consider the stored energy at all. Apparently yours does, so have at it. The source has supplied 68 joules/sec that has not reached the load. I think you mean 68 joules. The forward and reflected power waves require 68 joules/sec. The "forward power" is 50 watts. The "reverse power" is 18 watts. It requires 32 watts to sustain this. That's the amount of power flowing through the transmission line, from source to load. That's 32 joules/second, not 68. If the line were open circuited, the forward and reverse powers would be equal, and it would take no power to sustain them. That you don't see the logical connection between those two equal energy values is amazing. But I will get you started on an understanding of the component powers using an S-parameter analysis. Where will you find to put those all-important 68 joules in an s-parameter analysis? That's a steady state analysis. How much of that 18 watts of reverse power is going through the source resistor to reach the source to "engage in destructive interference"? reference the S-parameter equation: b1 = s11*a1 + s12*a2 I calculate 11.52 watts. (s12*a2)^2 = 11.52 watts Finally, an actual answer. So of the 18 watts of "reverse power", 11.52 watts is making it to the source to "engage in constructive interference". Does any of it get dissipated in the source resistor, or does it just slide through unscathed? The other 6.48 watts are in (s22*a2)^2 where |a2|^2 = 18 watts What's (s22*a2)^2? The forward power wave? The reverse power wave? If it's something else, does it have a name? Where does it go? Is it getting dissipated in the source resistor, reflected at the transmission line/resistor interface, reflected at the source/resistor interface, get radiated, or what? What does it interfere with? From the S-parameter equation above, it obviously interferes with s11*a1 . What's s11*a1? It must be something inside the source. The source is just that, a source. It has (AC) voltage and current, 100 volts of voltage and 0.4 amps of current. Does s11*a1 reside inside every source, or only some special ones? Apparently 11.52 watts of this s11*a1 gets cancelled by the reverse power wave. How much of it is left over? Please reference HP App Note 95-1, available on the web. It should answer most of your questions, in particular pages 16 & 17. |a1|^2 = Power incident on the input of the network |a2|^2 = Power incident on the output of the network |b1|^2 = Power reflected from the input port of the network |b2|^2 = Power reflected from the output port of the network Nope. Enough hand waving and evasion, we've been here before. [Of all the questions, the sole quantitative answer was "(s12*a2)^2 = 11.52 watts".] I'll leave you to the folks who regard this kind of gobbledegook as convincing evidence. Have fun -- I've got actual work to do while you take care of the visionary leadership part. Roy Lewallen, W7EL |
#78
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On Tue, 07 Jun 2005 15:01:26 GMT, "Henry Kolesnik"
wrote: Now the diodes resistance can be easily calculated but I'm not sure how to visualize it. Is this where your term cathode resistance enters the picture? Hi Hank, Getting electrons to "boil" off the cathode (or filament, same thing) is not a simple task otherwise there would be no filaments needed. Even with filaments, Edison current is not very considerable unless you add a monomolecular layer of metal to the surface of either the filament, or the cathode. You may note that some tubes are described as having "Thoriated" filaments. This is that monomolecular addition. Its purpose is to lower the W, the work function of the interface. It is far from odd how physics demonstrates at every stage and in every discipline that interfaces where there is mismatch, there is difficulty in transfering power. When an electron from the interior of the metal crystal approaches the surface, it is repelled by that interface due to the potential of the work function, and is attracted by the bulk material behind it. The Thoriated surface offers a matching mechanism between the bulk metal and the free space beyond the surface. In classic Optics this is known as Index Matching. To give examples as to how well a monomolecular addition performs: A Tungsten filament (no treatment) offers a current density of ½A/cM² This makes for a baseline. A Thoriated Tungsten filament offers a current density of 4A/cM² Then we step back to a cylindrical cathode employing Barium. Such a cathode offers a current density of ½A/cM² That seems rather regressive to use a cathode, but temperatures are telling. The simple Tungsten filament is operating at 2500° K and the cathode needs only to simmer along at 1000° K. This gives considerably longer life and more efficiency (most of the power for heating is lost through radiation). Needless to say, cathodes find more application in low power circuits, or their surfaces are treated with other low work function metals for greater emission. Now, when you add a potential gradient, you also lower the work function of the surface (but it is always an advantage to have it lowered going into this game). This is called the Schottky effect. One might be tempted to simply ask, why don't we up the voltage and discard the filament? This device would be called a Cold Cathode but the potential gradient then rises to the level where you run the risk of secondary emission. When that electron stream strikes the plate and raises the temperature, it is just short enough power to present this secondary emission. But if we were to run at 17KV or so, then the electron stream would be so aggressive as to produce high energy effects such as X-Ray emission. So, to return to the resistance of this all, we have physical impositions of cathode surface area (probably offering the prospect of being greater than filament surface area), current density, and potential difference. Discarding all the extraneous surface units (cM²) and employing the proper division (E/I) we have a resistor that glows in the dark under extremes of operation. How this fails to be source resistance is strictly handwaving and the schematic symbolic mysticism of demanding a carbon composition resistor. 73's Richard Clark, KB7QHC |
#79
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On Tue, 07 Jun 2005 11:44:29 -0700, Richard Clark
wrote: When that electron stream strikes the plate and raises the temperature, it is just short enough power to present this secondary emission. But if we were to run at 17KV or so, then the electron stream would be so aggressive as to produce high energy effects such as X-Ray emission. Something felt wrong here. I should have said: ...just short enough energy to present this secondary emission. |
#80
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Roy Lewallen wrote:
Cecil Moore wrote: We are not going to get anywhere until you admit there is 68 joules/sec in the feedline that haven't yet made it to the load. Once you admit that fact, everything else will be moot. I never said a word about how much energy is stored in the feedline; it's irrelevant. Do you think it is random coincidence that the amount of energy stored in the feedline is *EXACTLY* the amount of energy required by the forward and reflected waves???? The fact that you think it is irrelevant is simply a flight into a wet dream fantasy. It's stored there during the initial charging to the steady state condition, and the same amount remains there until the steady state condition no longer exists. It's exactly like the DC charge on a capacitor ... What a coincidence! It's *EXACTLY* the amount of energy required by the forward and reflected waves that you say don't exist - and it's RF photons, not DC, so it must travel at the speed of light! You cannot store photons in a capacitor. Surely even you can do the basic circuit analysis which shows that the source is continuously generating 40 watts, ... Of course, but during the power-on transient period, 68 watts is NOT delivered to the load. Please don't make me waste my time calculating the forward and reflected power during the power-on transient period. When you actually do those calculations, you will agree with me that, during the power-on transient phase, 68 watts of power has been stored in the feedline and remains there until the power-off transient phase. It is *EXACTLY* the amount of power required by the forward and reflected waves. The line's stored energy will be dissipated in either the source or load resistor or both when the source power is turned off. But we're doing a steady state analysis here. Which must necessarily include the energy stored in the feedline during the power-on transient condition because it is *still there during steady-state*. Ignoring the energy stored in the feedline during the power-on transient phase is both irrational and illogical. It could even be bad for your mental health. What exactly is my premise, please? from my earlier posting: You are apparently assuming there is not enough energy in the system during steady-state to support the forward and reflected power waves. I'm making no such assumption. I'm sorry, Roy, but that is just BS! Either you admit there is enough energy to support the steady-state forward and reflected waves or you don't. My analysis doesn't need to consider the stored energy at all. And that is exactly why your analysis is wrong. You have, once again, been seduced by the steady-state model and are spreading old wives' tales as a result. Hopefully, you don't really want to do that. The source has supplied 68 joules/sec that has not reached the load. I think you mean 68 joules. 68 joules/sec in your original example. 68 joules in my one-second- long feedline example. Where will you find to put those all-important 68 joules in an s-parameter analysis? That's a steady state analysis. The 68 joules were stored in the feedline during the power-on transient phase. They are still there during steady-state. An S-parameter analysis yields the correct results because it includes the reflected power, |a2|^2, as an energy source, something you deny. Wonder what the S-parameter analysis folk know that you don't choose to admit? Finally, an actual answer. So of the 18 watts of "reverse power", 11.52 watts is making it to the source to "engage in constructive interference". Does any of it get dissipated in the source resistor, or does it just slide through unscathed? It never encounters the source resistor as it is re-reflected by wave cancellation, not by an impedance discontinuity. I have a QEX article coming soon that will explain the details. Stand by. With an unprejudiced open mind, you might actually learn something. What's (s22*a2)^2? Same as (1-rho^2)*Pref2 in ham terms. Reflected power from the load that is re-reflected back toward the load by an impedance discontinuity. What's s11*a1? Same as Vfor1*rho in ham terms. Forward voltage that is reflected back toward the source by an impedance discontinuity. I'll leave you to the folks who regard this kind of gobbledegook as convincing evidence. Do you realize what intellectual shape you would be in if you had adopted that attitude when you were one year old? :-) -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
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