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On Jun 12, 1:13*pm, Richard Fry wrote:
It has been theorized that a circuit consisting of a Class C vacuum- tube r-f amplifier using a tuned tank circuit in its output network provides an operational “non-dissipative source resistance” of 50 ohms for energy present at the output connector of the transmitter. However the information and measured data provided in the text excerpts below is not very supportive of that theory. yeah, lots of words that say things kind of related, but more confusing than useful for what is really being discussed. what is so hard about stating: 1. tubes and transistors are non-linear devices 2. tank circuits and other output matching systems TRY to make them appear more linear to the outside world, but are not perfect. any circuit that has non-linear characteristics will have a response that is not like a simple resistance. such systems must be modeled using appropriate non-linear techniques to get the full and proper response characteristics. An APPROXIMATION may be used in many systems that allows an equivalent simple impedance representation, but often only over SMALL ranges of voltage/current or frequency. The problem appears to be in this discussion that some people have used this small signal approximation to derive results in a domain where it is not applicable and are drawing the wrong conclusions. |
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