Abstract: An antenna coupling adapter device is disclosed of a type designed to connect an antenna to the output antenna jack of portable radio transmitter-receivers such as Citizens Band units. The adapter is comprised of a first coupling mating with the antenna output jack provided on the transmitter unit, a second coupling adapted to mate with the antenna coupling and the adapter also including a switch and a dummy resistive load comprised of an indicator lamp. The antenna coupling, when installed, actuates an operating plunger to operate the switch by seating and unseating of the antenna coupling to cause the switch to electrically connect either the antenna or the indicator lamp, respectively, to the transmitter output stage via the first coupling means so as to cause the indicator lamp to be automatically switched in as a dummy resistive load.