Northam Chain Home Radar Station

Northam Chain Home Radar Station

A Second World War radar station built in 1941 and ceased operating in 1944. The site is dispersed over approximately 24 hectares and comprises two transmitter blocks, two receiver blocks, receiver tower bases, transmitter mast bases, a substation, and structures associated with either an Advance or an Intermediate Chain Home.

The two receiver towers were wooden, self-supporting structures standing 240 feet (73.15 metres) tall, but have since been demolished. Aerial photographs from 1945 and 1946 show them in situ. Four tapering concrete anchor blocks or feet, embedded with metal struts, remain in position and mark where the two towers stood. At the centre between each set of four blocks is a cable junction box constructed with four brick corner piers and a concrete cap, from which metalwork protrudes.

The two Type C receiver blocks are rectangular structures measuring approximately 14 metres north-south by 10 metres west-east, built of reinforced concrete sealed with a thick bitumen-type layer. They were originally surrounded by an earth mound or traverse for blast protection; the traverse to the west receiver block has been removed. Each block has entrances to the west and north elevations protected by concrete blast or wing walls. A tall concrete ventilator protrudes from the roof of the west block; that to the east is obscured by vegetation. Interiors are divided into a number of rooms, some with brick walls. The layout followed a standardised Air Ministry design and includes a receiver room, rooms for air filtration equipment, a telephone exchange, storage and a WC. The original yellow and green paint scheme survives in the east receiver block, along with simple wooden architrave and part of the original air conditioning arrangements. The air conditioning system allowed air to circulate around the building for temperature modification whilst preventing debris entering in the event of external blasts.

The four transmitter masts (AMES type 1) were constructed in a line of steel lattice and paired. They were supported by steel guy ropes and therefore are technically masts rather than towers. The bases for the masts survive and mark their locations. Each was held in position by aerial halyards anchored to large concrete blocks set into the ground; there are four pairs of blocks for each mast. Other surviving features include a winch base and concrete halyard balance weights which counterbalanced the weight of the aerial curtains suspended between each pair of masts.

The two Type C transmitter blocks housed the transmitter equipment which delivered pulses of high frequency energy from antenna erected on the four steel transmitter masts. They are roughly square structures measuring some 9 metres west-east and 10 metres north-south, built of reinforced concrete sealed with thick bitumen-type material and encased by an earth mound or traverse for blast protection. Each building has two entrances protected by concrete blast wing-walls and two concrete ventilators on top of the mound. The west transmitter block has heavy timber-clad steel doors to its main entrance with the transformer room adjacent. A second entrance opens to the north elevation. Internally, the central area housed the transmitter with air filtration plant in the adjacent room. Metal fittings to the ceiling of the plant room and some ventilation trunking survive. The east transmitter block was not inspected internally.

To the south-west of the west transmitter block is the substation, a flat-roofed building constructed of reinforced concrete retaining some bitumen-type covering; its earth traverse has been removed. It has three entrances to the north-west, south-west and south-east elevations, each leading to a separate room which do not interconnect.

Four brick structures are probably the remains of either an Advance or an Intermediate Chain Home erected and operated while the permanent buildings were under construction. The two largest structures are blast or retaining walls which have lost much of their protective earth mounds, and within each is a central concrete base, probably for a temporary wooden hut. Abutting one of the larger structures is a large concrete base and two plinths which may be the remains of a generator house. The smaller two buildings have flat concrete roofs and may have been a sentry or lookout post and a shelter.

The modern stable structure erected against the south side of the west receiver block, the animal shelter on the east side of the east receiver block and the stable partitions within the east receiver block are not included in the listing.