[1] The first version of this radar, Type 79X, was mounted on the RN Signal School's tender, the minesweeper HMS Saltburn, in October 1936.
They detected an aircraft at an altitude of 500 feet (150 m) and a range of 17 nautical miles (31 km; 20 mi) during tests in July 1937.
The first set was installed in September 1938 aboard the light cruiser HMS Sheffield and gave detection ranges up to 53 nautical miles (98 km; 61 mi) for an aircraft at 10,000 feet (3,050 m).
[2][3] Type 79B consolidated the transmitting and receiving antennae into one and its detection range was increased to 90 nautical miles (170 km; 100 mi) for an aircraft at 20,000 feet (6,100 m).
The radar also had a secondary ability to track a surface target at ranges from 2–6 nautical miles (3.7–11.1 km; 2.3–6.9 mi).