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. When the U.S. Navy adopted radio technology, a small wooden structure placed on deck was designated as the "radio shack" for housing their equipment.