From as early as 1925, Pye Radio Ltd had taken a keen interest in television, and in 1930, started developing TV sets and cathode ray tubes (CRT).
By 1936, when the BBC began the worlds’ first high-definition (405-line) television broadcasts, Pye had already been making TV sets with a 9 inch cathode ray tube screen for over a year. The high point of Pye’s pre World War 2 development came with the introduction of the Model 915 TV. This was a high-gain receiver intended for reception of TV signals on the fringes of the Alexander Palace transmitter coverage area. By early 1939, a production line had been set up in Cambridge and sample equipment produced.
Interestingly, the Pye Ltd Model 915 TV receiver was a "straight" or "tuned radio frequency" (TRF) receiver design (not a super-sonic heterodyne type), centered on the BBC London TV carrier frequency of 45MHz. This receiver used what, at the time, was a revolutionary new Pentode radio valve of exceptionally high performance (high gain and low inter-electrode capacitance). This valve was the famous type EF50, developed by N.V. Philips at Eindhoven, The Netherlands, later to be manufactured by its UK subsidiary company, Mullard Ltd.
When World War 2 began on 3rd September 1939, UK TV broadcasting soon came to an end, as did the production of the Pye Model 915 45 MHz fringe TV receiver, and Pye was switched over to the design and production of radar and wireless communications equipment for the British Military.
Between 1935 and 1939, before the start of the Second World War, scientists and engineers at Bawdsey Manor, on the East Coast of England were working on various radio direction finding (Radar) equipment for future airborne and land-based operation.
For the airborne radar receivers they needed a compact, high gain (and stable) broadband intermediate frequency (IF) amplifier with a gain of about 80 to 100deciBels (dB). The scientists included Dr. ‘E.G. Taffy’ Bowen, (who later became known as the "father of airborne radar"). In May 1939 the airborne radar development team were searching for a suitable 45 MHz receiver to replace their single prototype (based on an EMI TV design) and were made aware of the developments at Pye in Cambridge.
At the suggestion of Professor Edward Appleton, in May 1939 Dr. Bowen visited Pye Ltd Radio Works in Cambridge. Edward Appleton (later Sir Edward Appleton), had previously been his professor at King’ss College, London and by then was the Jacksonian Professor of Physics at Cambridge University.
At Pye Ltd, Bowen saw the Model 915 television receiver chassis, which, as a TRF type receiver, was essentially a high gain, broadband 45 MHz amplifier based on the Mullard/Philips EF50 valve, and most suitable for use by the team at Bawdsey. With help from B. J. Edwards, then the Technical Director of Pye Radio Ltd, Bowen left Cambridge with samples of the Pye TV chassis. The cathode ray tubes developed by Pye were also found to be suitable for other radar display applications.
This meeting between Edwards and Bowen led to further co-operation between Pye and other Government telecommunications research establishments. The final outcome of Bowen’s visit was that the Pye design, using the Mullard/Philips EF50 valves was adopted as the standard IF amplifier for most of the British VHF radar equipment during the War.
From this introduction to radar Pye went on to work with Bawdsey Manor to engineer the prototype receivers and CRT indicator units for airborne interception (AI) and air-to-surface vessel (ASV) into production-worthy items. Many thousands of the early airborne radar systems were manufactured by Pye, EKCO, EMI and Metropolitan-Vickers. The Pye co-axial connector was developed at this time to allow convenient RF interconnections to be made between the different modules of the airborne radar systems.
In parallel with work at Bawdsey Manor on airborne radar for the RAF, studies into other applications of radar were being conducted by a Navy team and an Army team. In 1938 work started on a ground based radar for coastal defence (CD) and coastal artillery fire control (CA) led by W. S. Butement. This work progressed well and by mid 1939 the team was preparing to transfer the prototype 200 MHz radar information to the TV group at Pye Ltd to be engineered into a producible system.
However when war began, the Navy became concerned about the activities of German submarines around the Orkneys and Shetland Isles and a team of scientists from the Cavendish Lab in Cambridge, led by Professor J.D. Cockroft was recruited to urgently reproduce three (later four) examples of the prototype CD radar and install them in the North of Scotland. This radar was designated CDU. To speed things up, Cockroft and his team physically removed the prototype radar station from Bawdsey and transported it themselves to Pye Ltd in Cambridge to begin the re-engineering process for the anti-submarine version.
It had already been discovered that the low frequency, long-range Chain Home (CH) coastal radar (which saved us in the Battle of Britain) could not detect low-flying aircraft, but that the VHF CD type radar performed this task well, being designed to detect shipping. As a result Pye Radio Ltd was contracted to manufacture and install for the RAF 24 examples (later a total of 52) of this 200 MHz ground based radar station originally designed for coastal shipping defence, but now pressed into use with the Chain Home air defence network to detect low-flying aircraft, and designated Air Ministry Experimental Station Type 2 (AMES 2), otherwise known as Chain Home Low (CHL).
In August 1939, Pye Ltd was asked to quote for the manufacture of an Army man-pack radio transmitter/receiver for the Infantry, which had been designed by the Government Signals Experimental Establishment Department (SEE).
After careful consideration, Pye declined to quote for the manufacture of the set as initially designed, because the Company considered it too costly to manufacture and too heavy for the application. However within 6 weeks Pye offered prototypes of two alternative configurations to the Ministry of Supply
Eventually, after successful field trials in France, orders were placed for one of these alternative designs and the equipment was designated Wireless Set No.18. This set was developed by a small team, which included Donald Hughes and William Pannell.
A small quantity (about 250) of the original SEE designed sets were manufactured by Murphy Radio and called Wireless Set No.8, however Royal Signals figures show that by the end of hostilities, 76,000 of the improved Wireless Set No.18 design had been made by Pye and other manufacturers (Invicta Radio - another Stanley family company, Murphy Radio, Bush Radio and EKCO).
Donald Hughes was also the principal designer of the famous Pye Wireless Sets No.19, which soon became the standard UK radio set for armoured fighting vehicles used by the British Army and also in many other vehicles and ground station applications. The MK I version of this equipment design was created in three months of intensive work in order to equip the British Army for the North Africa campaign.
Wireless Sets No.19 contained three different communications systems in one case - two separate transmitter-receivers and an intercommunications amplifier for the tank crew. The main ‘A’ set, which was used for medium and long range communications covered the frequency range 2.5 to 8.0 MHz in two bands. The ‘B’ set operated between 229 to 241 MHz for short range communication between tank commanders in a squadron. The ‘B’ set (which fulfilled part of the specification of Wireless Set No. 24) could be claimed as the first ever Very High Frequency (VHF) mobile radio that was built in quantity by Pye.
For a time Pye Ltd was the only manufacturer of WS 19, but as a company of limited size eventually three other British companies and six others in the United States, Canada and Australia were also contracted to manufacture the MKII and MKIII Wireless Sets No.19. Some of these later sets produced under the Lend-Lease scheme had dual English/Russian front panel and dial markings, although little used by the Russians. A total of 115,000 WS19 sets were manufactured during the war by the various companies involved.
It is not generally known that early in the war, Pye also designed a VHF hand-held radiotelephone for infantry soldiers to use for communication with the WS19 ‘B’ set in tanks. This was intended to fulfill part of the specification of Wireless Set No. 24, and was proposed to the Government in a secret report dated 9 November 1942.
It is believed that samples of this hand-held radio were sent to the USA with the Tizard Mission, and shared with the Canadians. Just after the war, in 1946 this Pye hand-held two-way radio was featured in a cinema newsreel film to demonstrate how such advanced communications concepts could be utilised in the future by the general public for personal radio communications.
Between 1941 and 1942 Pye designed the Wireless Set No. 22, a general purpose low-powered radio compatible with WS19, for non-armoured vehicles. This could also be used as a man-pack or as an animal-pack set. W.M. Pannell also led the design of this set. Pye Ltd and the Mitcham Works factory of Philips Lamps Ltd manufactured a total of 55,000 of this equipment during the war.
An add-on linear amplifier called Amplifier RF No 2 was also designed by Pye to boost the transmit power output of the WS19 and WS22 equipment.
Another military wireless set developed and manufactured (only) by Pye during World War 2, was the Wireless Set No. 62, intended as a waterproof replacement for WS22. This was a lightweight, low-power (0.5 to 1.5 Watt), high frequency, mobile transceiver covering the frequency range 1.6 to 10.0 MHz in two bands. It was constructed mainly of aluminium and was designed to withstand immersion in water for up to 5 minutes. The British Army adopted this as a vehicle mounted station for un-armoured vehicles, as a man-pack station for use by airborne troops, and also as a portable animal-pack station. W.M. Pannell was again the principal designer and started work on the design in early 1944. First prototypes were demonstrated at RAF Leeming Bar in Yorkshire in June 1944, and shortly after this Pye was given the go-ahead for quantity manufacture. In February 1945, about 200 equipments had been delivered, and at the end of the war Pye had manufactured 7,350 WS62 units.
After the war, Pye continued to supply the WS62 to various armed forces and later sold the WS62 commercially as a rugged HF transceiver. Production of this remarkable set was re-started for the Korean War and continued in volume production until it was finally removed from the Company product catalogue in 1965.
In early 1944 Pye finalised the drawings of a light-weight portable communications receiver type PCR which covered long, medium and short wave bands. This equipment was based on the receiver section of the Wireless Set No.19 ‘A’ set, together with an internal loudspeaker and external PSU. This receiver is often erroneously described as a forces entertainment receiver, which became one of its later post-war roles. However, according to wartime Pye employees, it was intended to be used for reception of Army broadcasts by the 21st Army Group in Operation Overlord, the invasion of Europe, and was also air-dropped to Resistance Groups in Norway, Holland and France. Pye was contracted to produce 17,000 of these receivers, and Philips Lamps and Invicta Radio also manufactured the design. Donald H. Hughes has now been identified as the design authority for the PCR receiver family.
Pye also designed and produced the receiver and power supply section of the first 8 channel transportable microwave radio relay link, Wireless Set No. 10. GEC were responsible for the transmitters and TMC the multiplex filtering. This advanced equipment was the world’s first multi-channel Time Division Multiplex (TDM) microwave radio relay link, and operated in the 4GHz frequency band. WS10 was used by the British Army following the D-Day invasion to maintain voice and teleprinter communications back across Europe and over the English Channel to Jersey and then by land-line to London. Pye was initially contracted to produce 400 of these units, and the design was shared with USA companies who subsequently pioneered commercial microwave links after the war.
During the War, Pye Limited expressed great dissatisfaction with the Ministry of Supply procurement system, which led to other companies being given contracts to manufacture larger quantities of the Pye designs than Pye itself. Questions were asked in Parliament about Pye’s complaints. This situation led to an increasing reluctance by the Company to accept military design contracts (as opposed to military manufacturing contracts). As a result, the design of Wireless Set No.62 was privately funded by Pye Ltd, and subsequently only manufactured by Pye and its associated companies during its 20 year production life.
Following the War, Pye Ltd largely (but not completely) withdrew from the military communications supply field to concentrate on commercial two-way radio (trading as Pye Telecom), scientific instruments, industrial electronics and domestic radio and TV.
Sources: 1. Mr. D. B. Delanoy 2003, 2. The Story of Pye, Pye Limited, 1956 3. Bowen E. G., Radar Days, 1987, Adam Hilger, Bristol, 4. RAF Air Publication AP2544A Vol.1 ASV MK II