Circuit VR: Measuring with LTSpice

Usually, with Circuit VR we look at some circuit in detail with simulation — usually LTSpice. This one will be a little meta because I wanted to look at a capability in LTSpice which ironically is very useful, but not often used. Along the way, though, we’ll look at why you get maximum power transfer when your source impedance matches your load impedance. This is something you probably already know about, but it is interesting to look at in simulation if you know how to coax LTSpice — no pun intended — into showing you a meaningful graph.

The circuit is super simple. An AC source and a 50-ohm resistor stand-in for a 40-meter ham transmitter. With 100 volts into a 50-ohm load. So far, so good.

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