A fixture for holding electrical components on an external support structure protects the components from weather, dust, condensation, and mechanical impact. An example fixture includes a shell having an open bottom side; a base configured for sliding engagement with the bottom side of the shell, a first electrical connector held in a selected rotational orientation in the base; and a support frame configured for sliding engagement with the shell. The support frame includes a first component holder; a second component holder rotatably connected to the first component holder; and a third component holder rotatably connected to the second component holder and removably connected to the first component holder. An optional connector on the shell allows the fixture to be installed between a host connector and any previously-installed legacy equipment.