The tesla coil has fascinated many people but had little actual use in the manner Tesla had in mind. Namely, the transmission of power over long distances. The following is quoted from the booklet TESLA COIL, by George Trinkaus, copyright 1986, 1987 & 1989 as:

"The tesla coil is a special transformer that takes power from a wall socket or battery and boosts it to a rapidly vibrating half million volts and up. This is not just a boost in voltage at the expense of amperage as in a conventional transformer. It is a real gain in power." -- Page 1.

Also is quoted from the same booklet:

"Tesla used a souped-up version called a magnifying transmitter to light up wirelessly 10,000 watts worth of bulbs 26 miles away. Other lights or "loads" on such a circuit presents no additional drain to the tesla coil any more than a radio broadcast is affected by the number of receivers tuned to it." -- Also page 1.

This suggests to me that the power gain may come from the influence of gravity (over the horizontal distance) from the source coil on the standing waves of energy generated by the tesla coil. (Standing waves are also sometimes called scalar waves.)

Careful analysis of a quarter-wave shorted load transmission line reveals that as the source impedance is changed from capacitive to inductive, the field mass related to the reactive current changes sign from minus to plus. I envision the gravitational field as interfacing with the reactive standing waves of the tesla coil and alternately pushing and pulling on the wave such that the energy is increased each time the standing wave changes polarity. This would be the horizontal version of an earthbound photon's frequency raising due to the action of gravity increasing its kinetic energy as it travels towards the Earth. The photon velocity does not increase so the frequency raises since E = hf requires that the frequency increases in proportion to the increase in energy.

Finally, it occurred to me that the possibility exists for using the boosted power received to power the sending tesla coil transmitter by shipping the received power back to the transmitter over conventional power lines. (Possible because of the power gain feature.) Thus gravitational energy is tapped into by means of the standing wave energy increase over distance as demonstrated by Tesla early in the 1900's.  -- Jerry E. Bayles.

The booklet quoted from above is published by:
High Voltage Press
4326 S. E. Woodstock, #489
Portland, OR    97206