A part of the high tension vault. On the right side at bottom, the power supply capacitors, and on the middle the ignitron tube, which was warm maintained with the infrared lamp. The ignitron tube shorted the high tension if there was a problem mainly with the final stage or modulator section, in order to protect them. In fact, this photo was not taken in Pals, it was scanned from the book which came with the transmitter, due the lack of Marconi's photos.