Tesla coils do not use a primary spark gap. A/s are possible with a spark gap. One side of the spark gap was directly connected to the antenna. Thus arcing in the spark gap starts "before" lasing. His receiver was a loop antenna with a micrometer spark gap between the elements. They consist of a spark gap and sometimes a series inductor. Powerful spark gap pulse generators are still used to simulate EMPs. First the spark gap and the capacitor are charged. Lifeboats were equipped with spark gap transmitters such as the Marconi Type 241, c. 1920. A spark plug uses a spark gap to initiate combustion. The Tesla coil primary winding, spark gap and tank capacitor are connected in series. Connecting the antenna directly to the spark gap produced only a heavily damped pulse train.