Egbert von Lepel and the Invention of the Spark-Gap Transmitter

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Abstract. On 29 October 1923, radio broadcasting or “Rundfunk” was officially opened in the Voxhaus in Berlin and thus the new communication medium was now also available in Germany, but later than in other countries such as the US and the UK. However, first experiments with wireless telephony, which is the technical basis of this medium, were carried out more than ten years earlier (Pungs, 1922; Mathis, 2019; Titze and Mathis, 2020; Mathis and Titze, 2021). One of the pioneers of this technology was the German Egbert von Lepel, who developed in 1907 a new concept of wireless transmitters that was also suitable for use in wireless telephony. The concept later became known as the quenched spark-gap transmitter (“Löschfunkensender”) or ”Singing Spark” transmitter where a specific variant was developed by the Gesellschaft für Drahtlose Telegraphie (GDT: “Wireless Telegraph Society”), System Telefunken. This article discusses the history of this type of transmitter using new historical sources from national and international archives. It turns out that contrary to what is known on this subject from almost all publications on the history of early wireless technology, the German Imperial Patent Office decided in January 1911 that Lepel's patent was granted as the most fundamental for quenched spark-gap transmitters. With the disclosure of this important historical source, the question of the origin of the invention of the quenched spark-gap transmitter must be reassessed.