Beacon Hill Fort (RDF) Radar Tower is one of the earliest WWII Radar stations. Built in Feb 1941 and manned by the navy. It was (RDF) radar type 287 and was used, among its other uses, to detect German E-Boats.

Radar (RDF) was developed at Bawdsey Manor on the River Debon from the mid - 1930's and this was a very early development of it.

Built quickly in Feb 1941 as a top secret development but it only had a life of about one year because it was replaced by a later development at Landguard Fort, Felixstowe.

This later model was connected to the tower by a land line and the Felixstowe scanner signals were fed into Cathode Ray Tubes in Harwich. This led to experiments between the Navy and Army on radar fire control for the nearby six - inch guns.

Originally it was planned that the army would equip and operate the early radar stations, but as the army wanted to give priority to covering possible invasion beaches in the UK, the Navy agreed to establish and operate this radar station to protect the approaches to their important destroyer and minesweeper base at Harwich (HMS Badger). So here we have a naval Radar Station situated inside an Army fort.

The tower was fitted with 50cm Radar for surveillance of the Harwich harbour approaches.

It had a range of 28,000 yards (15 miles). This installation pre-dated the magnetron and the generator was set to run at 2,000 cycles per second DC for Radar operation - the same engine and the same output as used for searchlights.

It had a peak output of 25kw . The original generator for the Naval Radar Station was set up by personnel from the nearby Beacon Hill Searchlight unit.

The set is sufficiently early (and primitive) to require two sets of scanners, one to send and one to receive. Later improvements allowed one scanner only to both send and receive. Each scanner is 21 foot long - 2" X 6" aperture with 24 dipoles each.

The radar scanners do not rotate in the modern manner but were manually rotated through an arc covering the sea approaches. By this means the threat of E boat attacks on ships entering or leaving Harwich were combated.
The E boats could pick up radar signals which they learned to avoid.

No personnel were allowed near the scanners when the radar was in use because of the danger of radiation. The radio pulse from and to the scanners passes through the brickwork just as domestic radios receive their signals through the walls of a house.