ABSTRACT
The magnetron oscillator generated no great love for itself at GEMA. It was easy enough to fabricate. In principle it was just a diode with an anode split into two cylindrically shaped halves with a tungsten filament concentrically centred. The electrodes were contained in a glass envelope with the anode connections passing out of the top and connected to a Lecher-wire resonant circuit. The key to its operation was, of course, a magnetic field parallel to the filament. An electric field that results from a potential being applied between anode and filament is at right angles to the magnetic field, and the values of these two fields are critical in determining if and how oscillations occur. A variation in the strength of one or the other of these two fields causes an undesired change in the frequency, a deficiency that had frequently provoked von Willisen and had disrupted a number of experiments.
