Averagesupernova
Science Advisor
Gold Member
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the_emi_guy, you are causing the output of the transmitter to see a 10 ohm load correct? Looking into the LC network? If this is your aim, here is what happens which gets up back to what sophie and I are saying is something to avoid:
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Take a transmitter with Zout of 10 ohms as you described. Feed it into a 50 ohm load. We will say there is a voltage across the load of 10 VAC. Thevenize and you will find the thevenin voltage is 12 VAC. The load is dissipating 2 watts, the Zout of the transmitter dissipates .4 watts. Use an impedance matching network and now the Zout of the transmitter dissipates 3.6 watts. From the thevenin voltage you find this to be the case, and assuming a lossless matching network the power dissipated in the load will also be 3.6 watts. This kind of power dissipated in the output stage is considerably higher than the .4 watts when driving the load 'mismatched' which is exactly what sophie was saying is to be avoided in the first place.
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Take a transmitter with Zout of 10 ohms as you described. Feed it into a 50 ohm load. We will say there is a voltage across the load of 10 VAC. Thevenize and you will find the thevenin voltage is 12 VAC. The load is dissipating 2 watts, the Zout of the transmitter dissipates .4 watts. Use an impedance matching network and now the Zout of the transmitter dissipates 3.6 watts. From the thevenin voltage you find this to be the case, and assuming a lossless matching network the power dissipated in the load will also be 3.6 watts. This kind of power dissipated in the output stage is considerably higher than the .4 watts when driving the load 'mismatched' which is exactly what sophie was saying is to be avoided in the first place.