Rapid communication: cleaning up a Hartley oscillator.

In a programme to understand, and learn to control, radiofrequency interference from neurological prostheses, it was discovered that a harmless-looking Hartley oscillator (one type of harmonic oscillator) generated a forest of harmonics extending to 1 GHz. These harmonics were not difficult to eliminate. The point of this paper is to emphasize that, given the selection of instruments used by most development engineers, the harmonics would probably have been missed.