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Early Days

Page history last edited by Alan Hartley-Smith 2 years ago





For the Committee for the Scientific Survey of Air Defence Robert Watson-Watt, Superintendent of the Radio Research Laboratory, produced a paper “Detection and Location of Aircraft by Radio Methods”. A practical test followed, on 26 February, in which a |Heyford bomber, flying through the short-wave radiations of the BBC’s Empire station at Daventry, was detected on a cathode ray tube oscilloscope display
 1935  Experimental work carried out at Orfordness and then Bawdsey Manor resulted in a decision to build five RDF stations to cover the approach to London via the Thames estuary, the Chain Home (CH) stations. Marconi involvement for array study.
1937   The success of the first five CH stations  promoted the ordering of twenty more, and for all of these the Marconi Company provided the transmitter ‘curtain’ arrays, and subsequently for the West Coast and other chains.
 1939  By the outbreak of war Britain was ringed with a chain of CH stations
   Dr. JT Randall and HAH Boot of Birmingham University constructed the first cavity magnetron for the generation of high-power centimetric waves.




 1940  To combat low-flying bombers the Chain Home Low (CHL) station was devised comprising a power-turned, five-bay, four-stacked array mounted either on a 20ft gantry or 185ft tower.

Baddow Laboratories taken over by Air Ministry, Admiralty and also became an operational RAF station.


Instrument Section plus Eckersley Group became the Kemp Group


The Vacuum Laboratories take over magnetron development and production


The Company was involved in the fitting of RDF for early warning against air attack to Navy capital ships. Modified Air-to-Surface metric equipment fitted to smaller ships. A crash programme to develop a small set also capable of detecting surfaced submarines was delivered in 1941. An improved form of aircraft warning system was the Type 281


Two senior engineers NE Davis and OE Keall were seconded to the Admiralty to devise counter-measures to the German radars sited along the coast of France...


 Following improvements to the magnetron the Chelmsford factory produced amplifier units for a new naval radar Type 271 There was also a new centimetric ASV for the RAF.


Magnetron production was moved to a new building at Waterhouse Lane enabling a delivery rate of several hundred per month.

 1943  Baddow in 1943 - a personal diary

Marconi designed, developed and manufactured at Writtle from research carried out by the TRE an airborne system, code named Bagful, to intercept and record the frequency and approximate positions of enemy radar stations, which was for large-scale operation prior to an invasion to build up a dossier.


One of the first applications of plated crystals, a Company speciality, was for this system, used by US and British aircraft to detect enemy radar stations and pin-point them for destruction on the eve of D-day. It was essentially a recording receiver with 8 m/cs reference points. Providing these reference points was an 8 m/cs plated crystal which in the early stages gave difficulty in operation. F.C. Lunnon. then in charge of Writtle activities, passed over an improved type of crystal to the Development Engineers concerned with the request “Try this in your Bagful. Trump". Immediately after the war °Bagful" received mention by President Roosevelt.

In addition on June 6th a multiplicity of jamming stations, in an operation code named Carpet paralysed the German radar networks.


Also for the invasion Marconi Marine provided servicing for all radio, echo sounding and radar equipments. 






Comments (2)

Ian Gillis said

at 6:06 pm on Feb 9, 2016

Page checked - dead link fixed

Ian Gillis said

at 5:33 pm on Aug 31, 2017

1 Typo "speciallity"
2 Is °Bagful" a typo - should be "Bagful"?

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