Low Power Broadcasting with Carrier Current
One item not covered earlier was the amplifier needed for effective carrier current transmission. Experimenters who might have a Part 15 compliant AM transmitter won't get much range in carrier current without a low power booster amplifier able to push a watt or two of RF down the power lines.
Basic theory for an external final amp is to first match the 50 Ohm output of the transmitter to the input impedance of the amplifying transistor. You do a little power management and then you match the output to the 50 Ohms for a typical transmitter output. Included here for your review are four amplifiers from two designers, ranging from 1 Watt to three Watts of additional power. These circuits are fairly simple and reasonably tolerant of various approaches but do have the onerous component of winding several coils.