WWI Trenches Marconi Radio Transmitter Pictured here is a spark transmitter used in World War I. It was discovered with a Marconi trenches receiver. Although the receiver was manufactured by Marconi in London, the two sets were found in Italy. With the top screwed on all that is seen on the outside of the drab green wood box is a coil of wire that goes to the battery, two large posts which are A for antenna and E for ground (earth), and the knob of the key. On the inside photo you can see the key, tuning inductance coil, spark coil, spark gap, and a round brown glass condenser. What is remarkable is that after cleaning the set up and resoldering one connection, I attached a battery, pressed the key and the transmitter immediately worked.