de WB2CPN I'm late, but the SCS-51 I maintained in Berlin, starting in late 1946, had only the Localizer. No Glide Slope. It did have three 75 MHz marker beacons, (mounted on Jeeps). Downs maybe has the book. It modulated by using choppers and capacitive bridges. Back then one didn't expect a lot of accuracy, just get the airplane down without wrinkles. 73 Clete