I thought the standard fit on T11s was Rebecca 8 with two obvious dipoles on each outer upper wing, sometimes mounted underneath. Its gubbins was in a black box located in a hatch behind the left hand pilots seat. It was the size of two loaves. Just switch on, dial and watch the single meter on the central control panel.
Rebecca 4 was a previous generation it was much larger and needed a dedicated operator to watch and interpret a CRT display. I never saw it on T11s.