"Realistic Navigation" - yellow light

[Pfeil]

It's likely the beacons from Lorenz are included with the AN/MRN-1 to allow non-US aircraft to use the hayrake transmitter.

The relevant information is given in the wikipedia article:

Two small radio beacons were also used with Lorenz, one 300 m off the end of runway, the HEZ, and another 3 km away, the VEZ, also broadcast on 38 MHz and modulated at 1700 and 700 Hz, respectively. These signals were broadcast directly upward, and would be heard briefly as the aircraft flew over them. To approach the runway, the aircraft would fly to a published altitude and then use the main directional signals to line up with the runway and started flying toward it. When they flew over the VEZ they would start descending on a standard glide slope, continuing to land or abort at the HEZ depending on whether or not they could see the runway.

In order to ease the workload, Lorenz later introduced a cockpit indicator that could listen to the signals and display the direction to the runway centerline as an arrow telling the pilot which direction to turn. The indicator also included neon lamp to indicate when the aircraft crossed over the marker beacons.