Tom, Hold the Ctrl key while using the Move key on the first instance of the component you are copying. Move the copy the desired distance. Either drag the copy to a reference point intersection of construction lines for example or let go of the mouse and Ctrl key and type the distance. Either way hit Enter after moving. Then type * followed by the number of copies you want to make and hit Enter again.
You can also move the first copy to the opposite end of the array, hit Emter, type / followed by the number of copies and Enter. This gets you the copies equally spaced between the ends.
Hope it works for you.