Inside the Type 72X masthead installation

The 1947 paper describes the Type 72X as a roughly 30-watt system operating between 206.5 and 218.5 megahertz, with an NT52 magnetron feeding a half-wave vertical aerial. A solid parabolic reflector swept the narrow beam around the aerial, while the transmitter and aerial assembly occupied a canvas-and-plywood hut at the top of the foremast. Power supplies and a control table sat near the mast's base, where a precision chronometer regulated the reflector's rotation and compensated for changes in the ship's course. The equipment worked as a radio lighthouse, deriving its operational value from a straightforward rotating beam. Its mechanical simplicity contrasts with a difficult history: secrecy, sparse Royal Navy documentation, and rapidly changing variants leave a gap between the theoretical description and surviving accounts of actual use. This passage supplies the physical arrangement and evidential caveat behind the earlier watch-and-bearing explanation.