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On May 24, 7:30*am, Keith Dysart wrote:
On May 23, 4:31*am, Owen Duffy wrote: Owen Duffy wrote in news:Xns9D81BC11E3183nonenowhere@ 61.9.191.5: "Sven Lundbech" wrote in . dk: ... As mentioned earlier, most of the stuff is old hat to me - but I really look forward to dig into the chapters concerning tx output impedance. A highly controversial subject for decades. Here is a simple little test for the hypothesis that Zs=50+j0 that uses equipment found in many if not most HF ham shacks. Oh, the URL:http://vk1od.net/blog/?p=1028. Owen While the analysis of transmitter output impedance in Reflections is flawed, experiments (claimed to be repeatable) described in Reflections appear to support the conclusions of the flawed analysis. It would be highly valuable if the results of these experiments could be explained in a manner that aligns with established understandings. Such an explanation might start by describing the circuit conditions that result from following the manufacturer’s tuning procedures. After all, these usually depend on measuring currents and voltages so are only indirectly related to power. Perhaps the resulting conditions are not as they are usually assumed to be. Try as I might, I have not been able to derive a mechanism to explain the observations in Reflections. But the explanations offered in Reflections require large chunks of linear circuit theory to be discarded, so this does not seem to be an appropriate path. ...Keith Keith, would you please elaborate on why you believe my analysis of transmitter output impedance is flawed? And what is the basis for your belief that my explanations in Reflections require large chunks of linear circuit theory to be discarded. Could it be because you consider the source resistance in the transmitter to be dissipative, as in the classical generator? If so, you must be made to realize that the source resistance of the transmitter is non-dissipative, which is the reason that its efficiency can exceed 50%. Or are you considering the output characteristic of the transmitter to be non-linear? This is not the case, because the effect of energy storage in the tank circuit isolates the non-linear input from the output circuit, which is linear as evidenced by the almost perfect sine wave appearing at the output of the tank. One last question: Are you basing your dissatisfaction of Reflections from reviewing the 2nd or 3rd edition? Chapter 19 has been expanded in the 3rd edition, in which I presented additional proof of my position on the subject that you should be aware of. If you haven't yet seen the addition that appears in the 3rd ed, please let me know so that I can send you a copy of the addition. Also include your email address so I can send it. Keith, you are the only person I know of who appears to have found flaws in my presentation on this subject. Which is why I'm anxious to know exactly why you believe my presentation is flawed. Walt Maxwell, W2DU |
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