Better than a Hartley oscillator ...https://is.gd/halleluyah
An oscillating tank circuit of a few mega amps and giga volts initiated by less than 100 pico amps using a momentary surge from a snap switch.
Not only do the oscillations of this circuit never die, but they continue to escalate at a pace so small, that it would take a lot of patience to discern the change. Merely a momentary snap of the switch located near the antenna A/C source on the far left is required to get it going. But you could also hold the switch closed for too long and the outcome will remain the same. You'd just be wasting power.
This is a non-trapezoidally approximated simulation tied to a 1 second time frame for some weird reason. There's not much, if any, wiggle room for varying the values of any of its components. In other words, it's precisely tuned.