Site Records

Site Name: RAF Dunkirk - Chain Home Radar Station

Courtenay Road
OS Grid Ref: TR076595

Sub Brit site visit November 1996 & September 2004

[Source: Nick Catford]

Following the development of radar at Orfordness and at the Bawdsey Research Station in Suffolk during the mid 1930's, the Air Ministry established a programme of building radar stations around the British coast to provide warning of air attack on Great Britain. A survey was undertaken to assess the suitability of the local terrain for Air Defence Radar operations with the first of these new stations coming on line by the end of 1937. This network formed the basis of a chain of radar stations called CHAIN HOME (CH).

These original five East Coast stations (later extended to 20) were augmented by a new design of 'West Coast' stations. The East Coast stations were similar in design to the experimental station set up at Bawdsey in 1936. In their final form these stations were designed to have equipment housed in protected buildings with transmitter aerials suspended from 350' steel towers and receiver aerials mounted on 240' timber towerks.

Photo:The transmitter aerials seen from Boughton Hill
Photo received from Andy Rook

The West Coast stations differed in layout and relied on dispersal instead of protected buildings for defence. Thus the West Coast stations had two transmitter and receiver blocks with duplicate equipment in each. Transmitter aerials were mounted on 325' guyed steel masts with the receiver aerial mounted on 240' timber towers.

The majority of Chain Home stations were also provided with reserve equipment, either buried or remote. Buried reserves consisted of underground transmitter and receiver blocks, each with three entrance hatches (two for plant and one for personnel) set on steel rollers. Nearby were the emergency exit hatch, ventilation shafts and 120' wooden tower carrying the aerials. On some stations the transmitter and receiver buried reserves were together on an adjoining site (often the next field).At others the two buried reserves were separate but located close to their respective above ground building. Many of the West Coast stations had remote reserves some distance from the main station but utilising similar above ground transmitter and receiver blocks.

Photo:The receiver block
Photo by Nick Catford

Most stations were powered from the National Grid but they were also provided with generators to cover interruptions in the mains electricity supply. These were located in another protected building known as a stand-by set house. These were similar in design to the transmitter and receiver block although smaller and were of brick construction and surrounded by a traverse (earth banks) for blast protection.

The surviving Chain Home transmitter mast
Photo by Nick Catford
On completion of the experimental station at Bawdsey, Dunkirk was the third 'East Coast' Chain Home station to be constructed after 1937 (after Swingate at Dover) to provide long range early warning for the Thames estuary and the south eastern approaches to London. The site was controlled by No 11 Group Fighter Command and the area covered by the site was some 30 acres. Initially there were four steel 360' high transmitting towers spaced 180' apart and four 240' timber receiver towers in a rhombic pattern around the receiver block.In 1944 a fifth wooden tower was added and collectively they were known by locals as 'The Nine Sisters'.

As a result of bombing during the Battle of Britain the original wooden operations buildings were replaced by new protected technical blocks which were built on the surface of brick with a six foot thick shingle cap for added roof protection and surrounded by an earth traverse.

The strength of the establishment was 150 living in the domestic camp located on the north side of the technical site. RAF Dunkirk took part in the pre-war exercises by Fighter Command, having been handed over in July 1937.

In 1938 RAF Dunkirk went onto the alert-during the Munich crisis and was kept at readiness right up to the outbreak of war. For stores and victualing, Dunkirk care 'under RAF Manston, the nearest RAF station and this led to an amusing incident during the early part of the war.

On 9th August Dunkirk radar station was attacked by a formation of twelve bomb-carrying Me110's, escorted by a formation of Bf 109's. The fighter-bombers were from Test Group 210, an experimental unit, led by Hauptman Walter Rubendorffer. Their 250kg. bombs hit Dunkirk, the masts were shaken and near misses damaged the operations block. Three days later there was another attack, when two huts in the compound were destroyed and a 500 kg. bomb exploded near the transmitter block, moving it bodily several inches.

Another attack on 31st Aug damaged the station, but like Dover, only electricity power supply failure put it off the air.

Plan of the technical site
Drawn by Bob Jenner

Following the installation if the Chain Home network, continuous research and experimentation was taking place to improve the quality and type of radars that were available, During this process it became necessary to monitor and record enemy radar transmissions with a view to overcome possible jamming by the Germans and to facilitate our own jamming. This all resulted in the establishment of 100 Group equipped with both ground radar jammers as well as aircraft fitted jammers. The investigation part of the service was known as the 'J Watch'; their task was to identify geographical location of the source. They were required to monitor every frequency from 20 MHz to 3000 MHz. In May 1944 J watch control moved from Garston to RAF Dunkirk; this required the use of a fifth 240' wooden tower close to the main entrance to the station.

No 4 tower was also used to provide a base for the Type 55 CHEL radar which was located on the 200 foot platform with the technical block located in a wooden hut surrounded by a brick blast wall at the base of the tower.

Photo:Transmitter towers being demolished in January 1959. The transmitter block can be seen in the background with the Type 55 technical block infront of it.

The bases for the four transmitter towers are in a straight line, two on each side of the transmitter block. There is rectangular brick blast wall with a blast proof entrance on two sides standing between the remaining concrete supports for No. 4 tower. This was almost certainly the control room for the Type 55 radar that was located on the 200' platform on No. 4 tower

After the war Dunkirk radar was placed on care and maintenance and in the early 1950's RAF Dunkirk was one of 15 stations selected under the ROTOR programme as a 'readiness chain home'. The existing Type 1 radar was re-engineered, as part of the first phase of the rotor programme. (Code TDE). With introduction of Type 80 radar in 1955 RAF Dunkirk was redundant and closed. Three of the transmitter towers were demolished and sold for scrap in 1959. The wooden receiver towers were dismantled and sold for reuse elsewhere. The remaining transmitter tower remained in RAF hands and is currently used for microwave communications by the US Airforce so RAF Dunkirk is still an operational station.

For further information and pictures of RAF Dunkirk click here

[Source: Nick Catford]

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Last updated: 04 01 2011
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