This item is given to you during the quest Eyesight to the Blind. You must attach the transmitter to one of the consoles in the radio control room at Black Mountain. You can also find Tabitha here. Once you have installed the transmitter you have to report back to Elder McNamara and end the quest.
pc ps3 After the quest is completed, the remote signal transmitter remains in the player's inventory, and is marked as a quest object. It can be fixed by using command setquestobject 001638f1 0. [verified]