This item is given to the Courier during the quest Eyesight to the Blind. They must attach the transmitter to one of the consoles in the radio control room at Black Mountain. Tabitha can be found there. Once the transmitter is installed it has to be reported back to Elder McNamara, in order to 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]