The first radio transmitters used a loud spark gap to generate radio waves, and so were often housed in a separate outbuilding or shed. When radio was first adopted by the U.S. Navy, a small, wooden structure placed on deck to house the ship's radio equipment became known as the "radio shack".
The early radio transmitters used spark gaps to generate radio waves and were often housed in separate structures like sheds or outbuildings. The adoption of radio by the U.S. Navy led to a small wooden structure being placed on deck, designated as the "radio shack" for housing their equipment.