THE 516F-2 POWER SUPPLY
Whereas the 75S series of receivers had their own internal power supplies, the 32S transmitters and the KWM-2 transceivers required a separate power supply. This provided two high voltage rails and a variable bias supply. The earlier models were 110/120V AC only but the later ones had provision to change the wiring for 220/240V AC.
This is an early 110/120V power supply bearing the winged emblem
This is a much later model with the Rockwell Collins emblem, with the dual voltage mains supply option. The four extra screws indicate that a loudspeaker has been retro-fitted. None were manufactured like this, but it was convenient for space saving, and also eliminated the necessity to buy a separate 312B-3 speaker or 312B-4 speaker/control unit.
The four thumbnails above show from left to right the 516F-2 underchassis RC emblem, WE emblem, then the top RC and WE. As can be seen, over probably ten years little changed, the transformers still bear the same Collins part number.