Mr. W. G. Pye once worked at the Cavendish Laboratory, and consequently Pye Ltd retained close links with the university. During the late 1930s a number of the government senior scientific advisers were ex-Cambridge University. From 1936 the government recruited scientists and physicists from the universities to work on the fundamental principles, techniques and components for radar transmission and reception, before the resulting information was passed for system design to other teams asigned to the three armed services. These teams in turn liaised with industry over product design, development and manufacture. The individual government teams knew very little about one another and what the others were working on. It was all top secret.
Due to Pye’s close links with Cambridge University Cavendish Lab the word was passed around government circles about their capabilities in scientific research, wireless, television and cathode ray tubes. It was therefore not by chance that they were involved in radar at a very early stage and from 1938 Pye worked for both the Army and the RAF teams on early radar, in parallel, in complete secrecy. EKCO soon followed Pye on airborne radar. Later, EKCO, Cossor, TMC, TGC and Dynatron took over the volume production of the radar equipment and Pye concentrated on the land warfare sets for the Army. This experience gained in land warfare and mobile radio led to the formation of Pye Telecom in Feb 1944.
Professor J. Cockroft (who joined the War Office from the Cavendish Lab) appears to have been particularly instrumental in involving Pye Ltd on the 200 MHz Coastal Defence (CD) radar project in 1938, going so far as to transport the prototype to Cambridge for Pye to re-engineer and manufacture. The first order was for 24 coastal defence radar stations, later increased to 52, renamed Chain Home Low (CHL) and added to the RAF early warning Chain Home radar stations around the coast. From 1940 this design of medium power 200 MHz radar was also adapted as mobile stations for airfield early warning and later developed into Ground Controlled Intercept (GCI) radar for the direct of RAF fighters to their target. Units were also sent abroad.
In 1939 Pye, followed later by EKCO, started working on airborne interception (AI) radar with the teams at Bawdsey and RAF Martlesham, but by 1940 when the German U-boats played havoc with the merchant shipping crossing the Atlantic, the priority was switched to air-to-surface-vessel radar (ASV) for submarine hunting. When the priority later returned to AI, Pye had moved on to the land warfare equipment and EKCO and Cossor etc took over the supply. The quantities of the early radar supplied by Pye and EKCO is summarised in the memoirs or E. Bowen, Sir Bernard Lovell etc.
- Coastal Defence (CD) & Chain Home Low (CHL) Radar (part involvement)
- Air Interception (AI) Radar (part involvement in 200MHz versions)
- Air-to-Surface-Vessel Radar (ASV) (part involvement in 200 MHz versions)
From 1939 onwards, Pye Ltd made an important contribution to the early airborne radar receivers by supplying amplifying units based on an existing 45 MHz TRF television chassis which used the revolutionary new Philips/Mullard EF50 valve designed by NV Philips in Eindhoven.
Work by the Government on airborne radar had started well before Britain joined the second world war and followed the design of the ground based Chain Home system. Pye had designed a high gain TRF television receiver to receive the prewar London TV station which broadcast on 45MHz. This was based on the Philips EF50 valve supplied by Mullard, the Philips UK subsidiary. The Pye 45MHz TV receiver circuit was found to be an excellent basis for the Intermediate Frequency (IF) amplifier and detector stages of Airborne Interception radar receivers, due to the gain, bandwidth and selectivity characteristics. Pye and Ekco supplied the early radar receivers before Ekco and AC Cossor became the main suppliers and Pye concentrated on land warfare equipment such as WS18, WS19, WS22 etc.
According to the memoirs of E.G. Bowen, Pye supplied over 12,000 of the 200 MHz radar receiver units for the 200 MHz radar systems AI MKI, AI MKII, AI MKIII, AI MKIV and ASV MKI, ASV MKII and ASV MKIII.
- Time scales:1939-1945
- Standard frequency range:Radar receivers Type R3039, R3041 etc. 176 - 200 MHz, Receiving Unit Type 153 45MHz ± 2MHz
- Transmitter RF output:N/A
- Primary model variants:Various AI and ASV receivers
(see http:/home.btconnect.com/gmb/ari.htm) Receiving Unit
Type 153A (10DB/8465) or the circuit configuration was built into other equipment platforms
- Technical manual extract:Manual not produced by Pye
An important innovation from this time was the "Pye plug" coaxial connector, conceived for the early AI and ASV radar equipments by Donald (Bo) Jackson and designed by mechanical designer George Baguley. The objective was to provide quickly detachable coaxial cables between the modules of the early airborne radar equipment and avoid the problem of poor high-frequency impedance matching (poor return loss and reflected signals) in cables which would otherwise have been terminated in a simple 'pig-tail' soldered connection.
The initial Pye connector was a right-angle elbow type with a range of different size co-ax cable entry clamps, but was expanded to include straight , T-piece and back-to-back connectors. The design was subsequently used in the majority of British RF equipment during the war. Illustrated above left are the Pye plug and socket and T-piece.
The connector design was also used by Pye Telecom commercially on all of the radio-telephone equipment from 1946 until the end of the Ranger series of mobiles and base stations in 1964.
- Time scales:1939 to 1969 in Military service
Between September 1939 and 1942, at the request of Sir John Cockroft of the Ministry of Supply, the radar team at Pye Ltd carried our pioneering experimental work on radio proximity fuzes for anti-aircraft artillery shells. This work included the design, in-house manufacture and testing of suitable miniature thermionic valves.
The proximity fuze was a miniature radio transmitter and receiver fitted in the nose of an anti-aircraft shell, which detonated when close to the aircraft. This required components which could withstand the shock of the shell being fired from the gun.
Later, details of the early work on proximity fuzes were handed over to the USA by the Tizard Mission, along with the secrets of the Magnetron Radar valve and the Jet engine. Production implementation of the proximity fuze concept was finally achieved by the Americans near the end of the war. See image of USA MK45 radio proximity fuze below right. This operated at approx 225 MHz.
- Time Scales:1939-1942
- Standard frequency range:TBA
- Transmitter RF output:TBA
- Primary model variants:TBA
- Technical manual extract:Technical details not in PTL Historic Collection