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On Tue, 14 Jun 2011 14:18:53 -0700 (PDT), walt wrote:
Thanks again Richard, for your insightful response. And goodness no, Richard, you won't hurt my feelings. I like being correct, but if I'm not I surely want to be told about it. This situation is no different. However, if you're not following me on the 'non-dissipative' path, I'd like you to review the last portion of the TS-830S experiment, and follow the numbers. If you don't have that material in front of you, you can find it again on my web page at www.w2du.com. Click on 'Preview Chapters from Reflections 3', and then click on Chapter 19A, which is a part of Chapter 19 in the 3rd edition. Observe that when the load impedance is changed from 50+j0 to the complex impedance 17.98 + j8.77 ohms, the plate current rose expectedly from 260ma to 290ma. This change occurred because the amp is now mismatched, and the pi-network is also detuned from resonance. The unwashed would conclude that the reflected power caused the increase in plate current. However, one will also observe that after the pi-network has been retuned and adjusted to again deliver all the available power into the otherwise 'mismatched' load (which is now matched to the source), the plate current went back to it's original value, 260ma. In addition, the amp returned to deliver 100w into the complex impedance at the line input, with the 30.6w of reflected power in the line, and adding to the 100w of source power, making 130.6w incident on the mismatched load, absorbing 100w and reflecting 30.6w. Hi Walt, There is absolutely NOTHING that I can dispute in your numbers or method. However, as to "dissipation" this says nothing. As for what it says about the reflection coefficient, I would agree with you. However, the math and the math experts you speak of - they are not answering the model we are examining above. You distracted them with stubs and reflecting waves. If you cast this agreement in the reflection coefficient back into effects purported to exist in the matching with stubs model, we may yet argue. IMHO, these data prove beyond doubt that the pi-network not only didn't absorb any of the reflected power, but totally re-reflected it. In my book this says the pi-network reflection coefficient rho = 1.0. How can anyone disagree with this? *** Nothing further useful about the topic is to be found below *** There is a curious side bar to this found at: http://www.w5big.com/purchase4170c.htm Observe the second data screen that purports to examine a mismatch through a length of both RG58 and RG59 terminated with 100 Ohms. Of particular note is the distinct transition from the Zc of 50 Ohms to the Zc of 75 Ohms and the similarly distinct transition from the Zc of 75 Ohms to the termination R of 100 Ohms. Note that the transitions both span a distance of 2 feet. 2 feet is not insubstantial compared to connection technology that spans, probably, no more than one tenth that distance. Whence the extra 11 inches on both sides of the connection plane of either connection? In the physics I've been studying for the past 10 years, near fields, this would not be unusual. In fact it would be expected. There is a transition zone (in waveguide design, there would be a taper or a sweep section to anticipate this and they would be physically large in terms of wavelength) not a transition cliff. Similarly, at the connector to your TS-830S, there is a zone that surrounds it that only approximates the 50 Ohm which occurs (in the terms of this link's demonstration) some distance away, deep inside your TS-830S. To me, dissipation inhabits this zone (certainly large enough for the tube and tank to occupy) and embraces the match with a complex addition of phases that could result in loss or even gain. This is also to say that I do not subscribe to dissipation being all about loss - especially when the hand of man is on the tuning knob instead of letting the chips fall where they may. 73's Richard Clark, KB7QHC |
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