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A Mullard TDD4 valve. The gold spray coating served no purpose other than to hide the blackened interior, as Mullard valves were still manufactured using the azide process, long abandoned by other makers.[1]

Key Information

A Mullard EL34 power pentode
An EL84 valve made in Russia in the 21st century

Mullard Limited was a British manufacturer of electronic components. The Mullard Radio Valve Co. Ltd. of Southfields, London, was founded in 1920 by Captain Stanley R. Mullard, who had previously designed thermionic valves (US term: vacuum tube) for the Admiralty before becoming managing director of the Z Electric Lamp Co.[2] The company soon moved to Hammersmith, London and then in 1923 to Balham, London. The head office in later years was Mullard House at 1–19 Torrington Place, Bloomsbury, now part of University College London.

Start-up

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In 1921, the directors were Sir Ralph Ashton (chairman), Basil Binyon of the Radio Communication Co, C.F. Elwell and S.R. Mullard (managing director).[3]

Partnership with Philips

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In 1923, to meet the technical demands of the newly formed BBC, Mullard formed a partnership with the Dutch manufacturer Philips. The valves (vacuum tubes) produced in this period were named with the prefix PM, for Philips-Mullard, beginning with the PM3 and PM4 in 1926. Mullard finally sold all its shares to Philips in 1927. In 1928, the company introduced the first pentode valve to the British market.

Factories

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Mitcham

[edit]

Mullard opened a new manufacturing plant at the end of New Road, Mitcham, Surrey in 1929. A second building was added in 1936. Both buildings had a very distinctive flat roof construction and were very similar to those at Philips' headquarters in Eindhoven, Netherlands. Co-sited with the Mullard buildings was the manufacturing complex for Philips Radios. Mitcham was also home to the Mullard Application Laboratory.

Blackburn

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In the late 1930s Philips opened a plant in Blackburn, Lancashire, and during the Second World War some operations were moved there from Mitcham; by the end of the war, nearly 3,000 were employed. Tungsten and molybdenum wire were produced on-site from 1954, and a glass factory was built in 1955. In 1962 over 6,200 were employed and Mullard described the Blackburn works as "the largest valve manufacturing plant in Europe".[4]

By 1949 Mullard had produced a number of television sets, such as the MTS-521 and MTS-684. In 1951 Mullard was producing the LSD series of photographic flash tubes.

Others

[edit]

Mullard had factories in Southport and Simonstone, both in Lancashire. The latter closed in 2004. There was also a sister factory at Belmont in Durham (closed in June 2005).[5][6][7][8] Other factories included those at Fleetwood (closed in 1979) and Lytham St. Annes (closed in 1972). A feeder factory at Haydock closed in 1981. A small factory in Hove closed in the early 1970s.

Teletext

[edit]
Main article: SAA5050

In the early 1980s, Mullard manufactured the SAA5050, one of the first teletext character generator modules made in the UK.[9]

Semiconductors

[edit]
Mullard transistors of the 1960s, showing the variety of SO-2 packages used:
  • OC200, silicon PNP transistor in an aluminium can.
  • Germanium OC45 in a black-painted glass package.
  • OC45 in a clear glass and blue putty package, with rubber sleeve

Mullard owned semiconductor factories in Southampton and Hazel Grove, Stockport, Cheshire.

Southampton (Millbrook Trading Estate) was a purpose-built plant, opened in 1957 for the manufacture of semiconductors. Production of germanium alloy transistors was transferred from Mitcham. At the same time the plant started the research, development and production of electro optical devices. Fabrication of planar devices on a mass production basis did not begin until 1966, when germanium sales were decreasing. 1967 saw the start of the development and production of integrated circuits. The plant was planned to be the biggest semiconductor facility in Europe, employing 3,000 people including 200 scientists and engineers.

In 1962 Associated Semiconductor Manufacturers (ASM) Ltd was formed by Mullard and GEC to combine the semiconductor development and production facilities of the two companies; Mullard owned two-thirds of the company and included the Southampton plant; GEC contributed their small factory in School Street, Hazel Grove, producing thyristors, rectifiers and power diodes. GEC pulled out of ASM Ltd in 1969. In 1972 production was moved to a newly constructed factory nearby on Bramhall Moor Lane.

Both sites were later owned by NXP Semiconductors (formerly Philips Semiconductors). The Southampton site is now closed. The one in Hazel Grove, Stockport specialises in power semiconductor devices and is now Nexperia Manchester.

The first transistors produced by Mullard were the OC50 and OC51 point-contact types in 1952, which were not widely used. In 1953 Mullard moved to junction transistors, beginning with the plastic-cased OC10 series. These were followed by the glass-encapsulated OC43...47,[10] OC70/71, (released in 1957) and OC80 series (the output devices were metal encapsulated to facilitate heatsinking), which were produced in large numbers and copied by other companies, such as Valvo (another Philips subsidiary) and Siemens in Germany, and Amperex (another Philips subsidiary) in the USA. RF transistors were the OC170 and OC171. All these were germanium PNP transistors. Mullard's first silicon transistors were the OC201 to OC207, PNP alloy types using the standard SO-2 metal-over-glass construction such as the OC200 shown. From about 1960 Mullard switched to using the BC prefix for silicon, and AC for germanium, eliminating the confusion of part numbers. in the mid-1960s the first plastic packages were introduced. In 1964 the company produced a prototype electronic desktop calculator as a technology demonstrator for its transistors and cold cathode indicator tubes.

Space science and astronomy

[edit]

In 1957 Philips-Mullard helped to set up the Mullard Radio Astronomy Observatory (MRAO) at the University of Cambridge. In 1966 the Mullard Space Science Laboratory (MSSL) was opened near Dorking, Surrey as part of University College London. The Royal Society Mullard Award for "those who have an outstanding academic record in any area of natural science, engineering or technology and to individuals or teams whose work has the potential to make a contribution to national prosperity", previously for young researchers[11] but as of 2025 with no restrictions on career stage, has been awarded annually from 1967.[12]

Mullard brand name

[edit]

Philips continued to use the brand name "Mullard" in the UK until 1988. Mullard Research Laboratories in Redhill, Surrey then became Philips Research Laboratories. As of 2007, the Mullard brand was used by Sovtek for valves[13] sold as ECC83, EL34 (European type numbers used by Mullard and many others), etc.

Z Electric Lamp Company

[edit]

The Z Electric Lamp Co. continued business into the 1970s operating from premises in Thornton Heath, southern Greater London, manufacturing lamps of specialised design. However, it closed due to the recession in the mid-1970s.

50th Anniversary in 1970

[edit]

To mark the 50th anniversary of the founding of the company, Mullard management decided to have a rose named after the company. Mullard's quest was simple, they wanted a world-beater, nothing less, so they contacted the renowned grower Sam McGredy IV in Northern Ireland.[14] The naming fee of £10,000/$24,000 was a lot of money in 1970 and established a record fee for a new rose: Mullard Jubilee "Electron". To mark the occasion every employee received a "Mullard Jubilee" rose bush.

See also

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References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Mullard

View on Grokipedia
from Grokipedia
Mullard Limited was a leading British electronics company specializing in the manufacture of vacuum tubes, semiconductors, tubes, and other components essential to radio, television, and early computing technologies. Founded in as the Mullard Radio Company by Stanley R. Mullard in , , it quickly became a major player in the burgeoning radio industry, producing high-power transmitting valves initially for the British Admiralty and maritime communications. The company's early success stemmed from its focus on innovative valve designs, such as the PM3 and PM4 series introduced in 1926, and the development of the valve in 1928, which improved amplification for radio receivers. By 1924, Mullard had sold half its shares to the Dutch firm N.V. , leading to full acquisition by in 1927, after which it expanded production facilities to sites like and . Under ownership, Mullard diversified into cathode ray tubes starting in 1936 for broadcasts and entered the era in the 1950s with products like the OC50 and OC51 germanium transistors. Post-World War II, Mullard established the Mullard Research Laboratories in 1946, fostering advancements in semiconductors—by 1960, it produced 75% of all British semiconductors by volume—and infrared detectors introduced in 1956. The company also acquired E.K. Cole's thermionic in 1938 and took over British Tungsram in the , bolstering its market dominance. Notable contributions included support for the Mullard Observatory in 1957 and the Mullard Space Science Laboratory in 1966, which advanced scientific instrumentation. Facing industry shifts toward integrated circuits, Mullard underwent restructuring in the and , with factory closures and the research lab renamed Philips Research Laboratory in 1977; the Mullard name was phased out in 1988 when Philips rebranded to Components Limited. Despite these changes, Mullard's legacy endures in vintage electronics, particularly its high-quality valves prized by audiophiles and in historical innovations that shaped 20th-century electronics, and the brand was revived in 2007 by for certain products such as the and ECC83.

History

Founding and Early Operations

Captain Stanley R. Mullard, who had designed thermionic valves for the British Admiralty during , founded the Mullard Radio Valve Co. Ltd. in 1920 in , . The company was financed by the Radio Communication Co. Ltd., which sought to compete with Marconi in marine radio applications. Initial operations began at the premises of the Z Electric Lamp Works, where Mullard had served as managing director since , before he broke away to establish his independent venture, contributing to the lamp company's eventual demise. The early focus was on manufacturing high-power transmitting valves for the British Admiralty, building directly on Mullard's wartime expertise in valve development. As production ramped up, the company introduced early designs such as variations of the 'R' type , alongside other transmitting tailored for radio communication needs. Due to growing demand, operations relocated in 1921 to larger facilities in , , and then in 1923 to , , to accommodate expanded manufacturing. To handle the surge in commercial interest for its valves, a second company, the Mullard Wireless Service Co., was formed around 1923 specifically for marketing and sales activities. This period of independent growth culminated in a pivotal financing and technical partnership with in 1924, enabling further innovation in valve production.

Philips Partnership and Acquisition

In , facing the need for additional capital and technical expertise to support rapid expansion amid growing demand for radio valves from the newly established , the Mullard Radio Valve Company entered into a technical and financial partnership with the Dutch firm N.V. ' Gloeilampenfabrieken. This collaboration provided Mullard with access to Philips' advanced manufacturing techniques and resources, enabling the joint development of shared valve designs, including the PM-series valves such as the PM3 and PM4 introduced in 1926, which were specifically engineered for improved performance in British broadcasting applications. By 1927, had acquired the remaining shares in Mullard, fully integrating it as a and solidifying the into complete ownership. This acquisition allowed for immediate technological synergies, culminating in 1928 with the introduction of the first British-made , a significant advancement in amplification technology influenced directly by ' innovations in multi-grid tube design. Under this structure, Mullard's production capabilities grew substantially, achieving approximately 40% of the British market by the late through enhanced efficiency and scale. In a related expansion move the same year, Mullard acquired all shares in the Electron Company, a valve producer known for its SDI to SDCTY branded products, and restructured it as the Six-Sixty Radio Co. Ltd. to focus on specialized radio component manufacturing. This operated until 1935, when it was sold to Ever Ready (GB) Ltd., allowing Mullard to streamline its core operations while retaining focus on high-volume production under ' oversight.

Post-War Expansion and 50th Anniversary

During , Mullard played a significant role in the British war effort by producing valves essential for military applications, particularly the EF50 , which was widely used in receivers and communications equipment due to its high-frequency performance capabilities; production of the EF50 was halted in after a V1 hit the factory. The EF50, originally developed by and manufactured at scale by Mullard in facilities like , enabled sensitive (IF) amplification at 45 MHz, contributing to airborne systems such as those in night fighters and air-to-surface vessel detection. This production ramp-up was facilitated by urgent shipments of components from in the in 1940, ensuring continuity amid the German invasion, and Mullard ultimately supplied approximately 40% of Britain's radio valves during the conflict. The period saw rapid expansion enabled by the earlier Philips acquisition, which provided capital and technical resources for scaling operations. In the , Mullard diversified into , notably entering the burgeoning television market with models like the MTS-521 and MTS-634, which catered to the demand for home entertainment and featured 12-inch screens. Under ' influence, Mullard also began producing equivalents to American valves, such as adaptations of types like the 6C5 and 6SK7, to meet international standards and facilitate exports while maintaining compatibility with U.S. designs. By the 1960s, Mullard's growth reached its zenith, with the Blackburn facility employing over 6,200 staff in 1962 and operating as Europe's largest manufacturing plant, producing millions of units annually for radios, televisions, and industrial uses. This era marked early diversification beyond valves, as Mullard invested in semiconductor research starting in 1952 at the Redhill-based Mullard Research Laboratories (founded 1946), leading to initial production (such as the OC50 and OC51) in 1952 and ongoing development of solid-state devices. In 1970, Mullard celebrated its 50th anniversary with notable events, including the commissioning of a named the Mullard Jubilee , bred by McGredy IV and registered for a record fee of £10,000 to symbolize the company's enduring innovation in . This milestone highlighted Mullard's evolution from wartime producer to a diversified leader, with the 's deep blooms evoking the vibrancy of flow in valves and semiconductors.

Manufacturing

Mitcham Facility

The Mitcham facility, located in , (specifically in the Hackbridge area), opened in 1929 as Mullard's principal manufacturing site for electronic components, particularly vacuum tubes or valves. This plant marked a significant expansion from the company's earlier operations in , , enabling larger-scale production to meet growing demand in the radio industry. From the 1930s through the 1950s, the facility specialized in radio receiving valves and high-power transmitting valves, becoming a cornerstone of Britain's early electronics sector under the influence of ' technical standards following their 1927 . Wartime demands during led to substantial production ramp-ups for defense applications, with valve manufacturing classified as essential war work by the British government; in 1944 alone, the site output 5 million valves despite disruptions from bombings, including strikes that temporarily halted operations. In the , as Mullard pivoted toward solid-state technologies, the facility began assembling early , such as the OC10 series junction transistors introduced in 1953, before much of this work shifted to dedicated sites like and . The plant continued operations into the semiconductor era but ultimately closed in 1993 amid broader Philips-led rationalization and centralization of production.

Blackburn Facility

The Blackburn facility, located in , , was established in 1938 as a key production site for Mullard, focusing on the assembly of vacuum tubes and electronic components. This northern plant complemented earlier operations in the south, enabling the company to scale up manufacturing to meet growing demand for radio and early television valves during the pre-war period. Post-World War II, the facility experienced major expansion, with employment reaching 3,000 workers by 1945 amid reconstruction efforts and increased orders for consumer electronics. In 1955, a significant addition came with the construction of a dedicated television tube factory at nearby Simonstone, funded by the Board of Trade, which boosted capacity for cathode-ray tube production. By the late 1960s, further expansions solidified its role as a high-volume hub, covering over 46 acres and supporting large-scale output of specialized components. The 1960s marked the peak of operations, when the plant employed over 6,200 staff—including assemblers, technicians, chemists, and engineers—and became Europe's largest factory, producing millions of units annually. It specialized in high-quality valves such as the , widely used in audio amplifiers and receivers for their reliability and performance. Emphasis was placed on precision processes, from and to rigorous , ensuring consistency in output for domestic and export markets. The rise of transistor technology in the 1970s led to a sharp decline in vacuum tube demand, reducing the workforce from over 5,000 to fewer than a hundred by the early as production shifted toward semiconductors. The facility closed in 1982, ending an era of valve manufacturing amid broader industry changes. A legacy of its operations is preserved in the 1962 documentary film The Blackburn Story, produced by Mullard to illustrate the factory's sophisticated techniques and workforce.

Other Production Sites

In addition to the core facilities at and , Mullard established several specialized production sites across the to support its growing operations, particularly in semiconductors and components. The facility at Millbrook Trading Estate, opened in 1957, was a purpose-built dedicated to semiconductor production, including germanium alloy transistors such as the OC50 and related OC series devices. This site employed around 3,000 people and focused on diodes, transistors, and later detectors before its eventual closure amid industry shifts. Mullard operated component production sites in and Durham, both in , to supply sub-assemblies and specialized parts like electrodes and passive components for and assembly. The works, acquired from Vulcan Motor and Engineering Co. in 1955, housed custom tooling, mills, presses, and kilns for precision electronic parts manufacturing. These northern sites followed the expansion model pioneered at , enabling efficient scaling of production for . The Durham facility at Belmont, a sister plant to , specialized in similar component work until its closure in 2005 as part of broader operational consolidations. Further legacy continued at the Manchester-area site in , , established in the period and evolving into a key hub for power devices after the . Now operated as Nexperia Manchester, it represents Mullard's enduring contribution to discrete semiconductors, producing diodes and transistors for automotive and industrial applications. Many of these sites faced closures during Philips' restructuring in the and 2000s, driven by global competition, technological transitions from valves to integrated circuits, and cost rationalization, reducing the UK footprint from over a dozen facilities to a few specialized operations.

Products and Technologies

Vacuum Tubes and Valves

Mullard Radio Valve Company, founded in 1920 by Captain Stanley R. Mullard, a former Admiralty engineer, began producing vacuum tubes following a from the British Admiralty for 250 high-power silica-envelope transmitting valves at £66 each, which provided the initial capital for operations. This agreement stemmed from Mullard's wartime research on valves for military radio equipment, including work in a special laboratory at Imperial College established in 1916, leading to practical high-power transmitting valves by 1919. By 1924, annual production had reached 2.5 million valves, focusing on reliable designs for radio transmission. Following ' acquisition of full control in 1927, Mullard advanced valve technology through the Philips-Mullard (PM) series, which featured directly heated filaments initially produced via the process in collaboration with . From the mid-1930s, the series transitioned to oxide-coated filaments, with PM types often adapting designs for British production. A key innovation was the introduction of the first British , the PM24, in 1928, patented by and integrated into the 'Shoebox' AC mains radio, enabling improved amplification with a suppressor grid to reduce secondary emission effects. Among Mullard's iconic products, the EL34 power pentode, introduced in the 1950s, became renowned for its high output and tonal qualities in audio applications. Derived from earlier Philips designs like the EL37, the EL34 delivered up to 50 watts in push-pull configurations and was first detailed in a 1955 Wireless World article for hi-fi amplifiers, later adopted in guitar amplifiers such as the Marshall JTM45 from 1965, shaping the British rock sound. Similarly, the EF86, a high-transconductance sharp-cutoff pentode, served as a low-noise preamplifier valve in hi-fi systems, prized for its clarity in early-stage audio voltage amplification. By the late , Mullard had established itself as a dominant force in the UK market, producing 6.5 million units annually at facilities like the Blackburn plant opened in 1938. During , the company contributed significantly to technology, manufacturing the EF50 all-glass —a remote-cutoff design introduced in —for intermediate-frequency amplifiers in British military receivers, including those in RAF aircraft. This 's rugged, vibration-resistant construction was critical for wartime applications, with Mullard/ EF50 strips standardized in Pye equipment. The rise of in the 1960s led to a sharp decline in demand, with Mullard's valve production waning through the 1970s as transistors offered greater reliability and for consumer and devices. By the decade's end, the shift had rendered tube manufacturing unviable for most applications, though Mullard valves retained a legacy in high-fidelity and amplification.

Semiconductors

Mullard entered the field in 1952 with the production of its first transistors, the OC50 and OC51 point-contact types, which were designed as equivalents to early American devices like those from Bell Laboratories. These -based transistors marked Mullard's initial foray into solid-state technology, building on its established expertise in vacuum tubes as a precursor to more reliable electronic components. By the mid-1950s, Mullard expanded its lineup with alloy-junction transistors, including the OC44 for radio-frequency applications introduced around 1956. In the late , Mullard introduced the OC70 series, comprising audio-frequency transistors such as the OC70, OC71, and OC72, which utilized innovative glass encapsulation for improved durability and performance in . Transitioning to in the , the company released the OC201-OC206 series, with equivalents in the international 2N numbering system to facilitate compatibility in global designs; these planar transistors offered higher stability and power handling compared to earlier types. Semiconductor production became centralized at Mullard's purpose-built facility in , established in 1957 on the Millbrook Trading Estate, which grew to become the largest such plant in the by the early . This site focused on high-volume manufacturing of transistors and diodes, integrating seamlessly into Philips' global following the Dutch company's full acquisition of Mullard in 1927 and subsequent technological synergies. Mullard's semiconductors found widespread use in televisions, radios, and early computers through the , powering amplification circuits and in devices like radios and domestic TV receivers. For instance, the OC44 and OC70 series were staples in audio and RF stages of portable radios, while 2N-compatible transistors supported logic and switching functions in nascent applications. Through licensing agreements with American firms, such as those facilitating access to ' transistor patents via , Mullard enabled exports across and beyond, significantly bolstering the 's position in the postwar sector. By the , Mullard held nearly 60% of the British thermionic and solid-state component market, fostering domestic innovation and .

Teletext Systems

In the early 1970s, engineers at , as part of Research Laboratories in the UK, pioneered the development of , a broadcast data system designed to deliver text-based information and simple graphics to television viewers. John , working at Mullard Central Application Laboratories, proposed a method to transmit compressed pages of data using the vertical blanking interval of analog TV signals, enabling on-demand access to news, weather, and subtitles without interfering with the video broadcast. This innovation, initially aimed at providing for the hearing impaired, evolved into a versatile information service and marked an early step toward interactive . Building on their expertise, Mullard introduced the SAA5050 series in 1976, a key character generator chip that rendered characters using a 6x10 font, facilitating affordable on-screen displays. This was followed in 1977 by a four-chip decoder set, which became the industry standard for integration and was incorporated into the Mullard VM6101 decoder module for easy retrofitting into existing TVs. These components were seamlessly integrated into televisions, powering the UK's service launched by the in 1974 and the commercial system on ITV from 1978, where they enabled features like page selection and basic color graphics for millions of users. Mullard's technology was exported across Europe, contributing to the harmonization of standards under the (WST) specification established in 1976 and refined in 1983, which supported multilingual displays and enhanced data transmission for 625-line systems. Adopted in over 35 countries, WST influenced by providing a robust framework for embedded data services, with Mullard chips enabling widespread compatibility in European TV manufacturing and fostering innovations like Fast Text navigation. The rise of digital television in the 1990s, coupled with the advent of the , led to the decline of analog systems, as broadcasters shifted to more advanced digital subtitles and on-demand online content, rendering dedicated Teletext decoders obsolete by the early 2000s.

Scientific and Research Contributions

Space Science Initiatives

In 1966, Ltd, a leading British manufacturer of electronic components and a subsidiary of , supported the establishment of the Mullard Space Science Laboratory (MSSL) at (UCL) in Holmbury St. Mary, , with the facility becoming operational on 1 September 1966 and formally opened on 3 May 1967 by F.E. Jones, Managing Director of Mullard Ltd. The laboratory was founded under the leadership of Robert Lewis Fullarton Boyd, who served as its first director from 1965 to 1983 and set high standards for university-supplied instruments, drawing on his prior work in experiments. Funding came primarily from the Science Research Council (SRC), established in 1965 to coordinate , providing core support alongside project-specific grants and an initial £12,000 loan to address startup challenges. Although named after and initially backed by Mullard Ltd, MSSL operated independently under UCL's governance, free from direct Philips control, enabling focused academic pursuits in space science. MSSL's early contributions centered on developing instruments and components for UK-led space programs, including the provision of electronic valves and semiconductors from Mullard Ltd for sounding rockets and satellites in the 1960s. The laboratory participated in over 99 Skylark rocket flights between 1957 and 1978, supplying stabilized platforms and detectors, and contributed to the Ariel satellite series through UK-US collaborations. A landmark achievement was MSSL's role in the Ariel 5 satellite, launched on 15 October 1974, where it designed and built two key X-ray detectors: Experiment A for sky surveys in the 0.3-30 keV range and Experiment C for spectral analysis in the 2-30 keV range, advancing X-ray astronomy by enabling the detection of over 200 cosmic X-ray sources during the mission's five-year operation. MSSL extended its expertise to international missions, notably leading the development of plasma instrumentation for the European Space Agency's (ESA) Giotto spacecraft, launched on 2 July 1985 to study Halley's Comet. The laboratory provided electron and ion sensors for the Low Energy Plasma Analyser (LEPA), along with the three-dimensional positive ion analyser to measure solar wind-comet interactions, contributing critical data on cometary plasma environments during the close flyby. Following Mullard Ltd's integration into Philips and the laboratory's full transition to SRC (later SERC) funding, MSSL maintained an ongoing role in ESA programs, developing instruments for missions such as Exosat (1983), AMPTE (1984), and ROSAT (1990), and continuing to support contemporary efforts in X-ray and plasma science. As of 2025, MSSL continues its legacy with contributions to missions such as the ESA's Juice (launched 2023) and the upcoming SMILE (planned for 2025), focusing on planetary and magnetospheric science.

Astronomy Developments

The Mullard Radio Astronomy Observatory (MRAO) was established in 1957 at Lord's Bridge, approximately eight kilometers southwest of , , through a £100,000 donation from Mullard Ltd. to the University of Cambridge's . This funding, combined with support from the Science Research Council, enabled the construction of facilities for advanced research, with the observatory officially opened on 27 July 1957 by Sir Edward Victor Appleton. The site quickly became a center for the Cavendish Astrophysics Group, focusing on aperture synthesis techniques to map celestial radio sources. Mullard's technological expertise facilitated the development of several landmark radio at MRAO during the 1960s and 1970s. The One-Mile Telescope, completed in 1964, featured three 18-meter-diameter, 120-ton antennae arranged in an east-west baseline, employing Earth-rotation to produce the first detailed radio maps of Galactic and extragalactic structures, including contributions to the 5C radio source catalogue. The Half-Mile Telescope, operational by the late 1960s, introduced spectral and achieved the first imaging of neutral emission at the 21-cm , enhancing observations of spiral and irregular galaxies. These instruments exemplified Mullard's role in providing for high-resolution . Additionally, MRAO's facilities formed a core component of the (Multi-Element Radio Linked Interferometer Network) array, launched in the , with the site's 32-meter dish enabling long-baseline observations that rival resolutions for studying compact radio sources. A pivotal achievement at MRAO was the 1967 discovery of the first , CP 1919, by and using a 4.5-acre interplanetary scintillation , which revealed rapid pulsations from a rotating and revolutionized understanding of . This breakthrough relied on Mullard's and technologies, which were critical for low-noise receivers in the –, providing low-noise amplification essential for detecting faint cosmic signals amid terrestrial interference. By the , operational control and funding of MRAO transitioned fully to the , solidifying its integration into academic research and ensuring sustained contributions to astronomy, including the 1974 awarded to and for foundational radio work at the site. The observatory's innovations in radio detection techniques also influenced space-based applications, such as plasma wave instruments on missions like .

Legacy

Brand Evolution and Usage

The Mullard brand emerged in the early 1920s with the founding of the Mullard Radio Valve Company in 1920, initially focusing on vacuum tubes for radio applications, and gained prominence under Philips ownership after the company acquired full control in 1927. Throughout the mid-20th century, Mullard became synonymous with high-quality electron tubes used in consumer electronics, broadcasting, and military equipment, expanding into semiconductors by the 1950s with products like transistors, and later integrated circuits in the 1960s, produced at facilities in the UK and Europe. By the 1970s, the brand marked its 50th anniversary, representing a peak in its recognition for reliable components in audio and telecommunications sectors. In 1988, Philips discontinued the Mullard brand as part of a broader corporate restructuring to streamline operations and consolidate subsidiaries, renaming the UK entity to Philips Components Limited. The semiconductor assets, originally developed under Mullard, were integrated into , which was later spun off in 2006 to form , though the Mullard name was not retained by the new entity. Post-discontinuation, the Mullard for vacuum tubes was acquired by New Sensor Corporation, an American firm, in the late , leading to revivals through of reissue tubes manufactured in at the Saratov factory. This included partnerships with brands like , which began producing Mullard-branded audio tubes in the early 2000s to meet demand in the and hi-fi markets. The brand's legacy endures in hi-fi audio and collector communities, where vintage Mullard tubes from the Philips era are prized for their tonal qualities and durability, commanding premium prices in restoration projects. No active manufacturing occurs under the original Mullard entity, which ceased operations decades ago. As of 2025, trademarks for Mullard tubes remain with New Sensor Corporation, enabling occasional reissues, while Philips successors like NXP hold no association with the brand's consumer applications. Mullard originated from the Z Electric Lamp and Supplies Company, where Captain Stanley R. Mullard joined as a director in 1919 following his demobilization from military service. The Z company, based in , , initially produced electric lamps but transitioned to manufacturing receiving and transmitting for entities such as the Admiralty, , and during . This premises served as the starting point for Mullard's valve production venture after the Z company's collapse in 1919, marking a shift from lamp manufacturing to technology. A key related entity was Mullard Equipment Ltd. (MEL), established in 1935 as a subsidiary in the and operating until 1997. Separate from Mullard's core consumer components division, MEL specialized in applications, including systems, electronic warfare, communications, and cryptographic equipment from the 1930s through the . Notable products included the PRC-319 radio and the BA-1304 crypto/message unit developed under contracts in the late and early . In 1989, acquired MEL, integrating its and communications operations. The Mullard Award, established by a gift from Mullard Ltd.'s Board of Directors to the Royal Society, recognizes individuals or teams in the UK for contributions to physical sciences or applied sciences that advance national prosperity. First awarded in 1967, it has been presented annually since, often to multiple recipients for collaborative work, and includes a silver gilt medal with a £2,000 prize. In 2025, Professor Jason Hallett of Imperial College London's Department of Chemical Engineering received the award for pioneering ionic liquids as solvents in biorefining and the circular economy. Mullard's operations faced decline in the 1980s amid falling demand for vacuum tubes and semiconductors, leading to multiple factory closures. The Blackburn valve plant shut down in 1982, ending production after decades of operation. Philips, which had acquired full control of Mullard by 1927 and retained the brand until 1988, integrated its facilities more deeply by 1990, transferring semiconductor production to Philips Semiconductors (later NXP). The Simonstone TV glass factory closed in 2004, and the Durham cathode ray tube plant, operated as LG Philips Displays, shut in June 2005, resulting in 761 job losses. These closures marked the end of Mullard's independent manufacturing era under Philips.

References

  1. https://www.gracesguide.co.uk/Mullard
  2. https://collection.sciencemuseumgroup.org.uk/people/ap8736/mullard-limited
  3. https://www.r-type.org/static/makemull.htm
  4. https://collection.sciencemuseumgroup.org.uk/people/cp1121/mullard-limited
  5. https://www.gracesguide.co.uk/Mullard_Radio_Valve_Co
  6. https://www.r-type.org/static/makemul2.htm
  7. https://www.bvws.org.uk/publications/bulletins/pdf/BVWS_Bulletin_03_3.pdf
  8. https://collection.sciencemuseumgroup.org.uk/objects/co30777/four-ef50-valves-one-complete-and-three-dissected-1939
  9. https://www.r-type.org/exhib/aaa0582.htm
  10. https://www.dos4ever.com/EF50/EF50.html
  11. https://www.dos4ever.com/EF50/Jonker_full.pdf
  12. https://collection.sciencemuseumgroup.org.uk/objects/co203224/mullard-radio-television-receiver-1949
  13. https://www.radiomuseum.org/r/mullard_mts521.html
  14. https://www.worldradiohistory.com/UK/Bernards-And-Babani/Babani/Babani-144-Radio-TV-Valve-Equivalents-At-a-Glance.pdf
  15. https://www.effectrode.com/knowledge-base/speed-efficiency-perfection-aims-that-have-built-a-mammoth-factory-in-16-years/
  16. https://pepa-online.org.uk/wp-content/uploads/2017/07/MRL-PRL-History-book.pdf
  17. https://ietarchivesblog.org/2016/04/12/mullard-research-laboratories-newly-discovered-oral-histories/
  18. https://www.effectrode.com/news/mullards-centenary/
  19. https://www.helpmefind.com/rose/pl.php?n=11116
  20. http://www.wylie.org.uk/technology/semics/Mullard/Mullard.htm
  21. https://mullard.org/blogs/news/mullard-during-wartime
  22. https://www.facebook.com/groups/I.grew.up.on.the.St.Helier.Estate/posts/10161343502144770/
  23. https://creativeaudioworks.com/history/mullard-the-blackburn-vacuum-tubes-factory/
  24. https://www.lancashiretelegraph.co.uk/news/16091609.nostalgia-end-production-line-mullard-blackburn/
  25. https://www.worldradiohistory.com/Archive-All-Audio/Archive-Vacuum-Tube-Valley/Vacuum-Tube-Valley-Issue-16.pdf
  26. https://swling.com/blog/2016/05/tubes-and-valves-dans-research-uncovers-three-vintage-films/
  27. https://www.effectrode.com/knowledge-base/mullards-empire-of-rust/
  28. https://www.vintage-radio.net/forum/showthread.php?t=64707
  29. https://www.nexperia.com/about/company-timeline
  30. https://www.effectrode.com/news/mullard-southport-factory-visit/
  31. https://www.radiomuseum.org/dsp_hersteller_detail.cfm?company_id=687
  32. https://www.r-type.org/addtext/add017.htm
  33. http://www.r-type.org/exhib/aai0113.htm
  34. http://www.pyetelecomhistory.org/comphist/3-ww2.html
  35. https://sites.google.com/site/transistorhistory/Home/european-semiconductor-manufacturers/philips
  36. https://www.electronics-notes.com/articles/component-data/transistors/OC44.php
  37. https://frank.pocnet.net/other/Mullard/Mullard_PreferredTypes_ValveTubesSemiconductors_1965.pdf
  38. https://oro.open.ac.uk/57445/1/DX184765.pdf
  39. https://www.historyofinformation.com/detail.php?id=3801
  40. https://www.cpcwiki.eu/imgs/9/9e/Mullard_SAA5050_datasheet.pdf
  41. https://www.worldradiohistory.com/UK/Practical-Television/70s/Television-Servicing-UK-1979-10.pdf
  42. https://www.worldradiohistory.com/Archive-Company-Publications/Philips-Technical-Review/Electronic-Compoinents/Electronic-Components-&-Apps-Vol-10-No%203.pdf
  43. https://theconversation.com/teletext-was-slow-but-it-paved-the-way-for-the-super-fast-world-of-the-internet-124118
  44. https://www.ucl.ac.uk/mathematical-physical-sciences/mssl/about-department/our-heritage
  45. https://www.ucl.ac.uk/mathematical-physical-sciences/sites/mathematical_physical_sciences/files/dorling-book.pdf
  46. https://royalsocietypublishing.org/doi/10.1098/rsbm.2024.0029
  47. https://ntrs.nasa.gov/citations/19870059371
  48. https://www.ucl.ac.uk/mathematical-physical-sciences/mssl/missions
  49. https://www.astro.phy.cam.ac.uk/about/history
  50. https://www.cam.ac.uk/news/professor-john-baldwin-frs-1931-2010
  51. https://sam.hooke.me/post/2025/01/map-of-mrao-and-telescopes/
  52. https://www.aanda.org/articles/aa/full_html/2020/10/aa36214-19/aa36214-19.html
  53. https://blog.thetubestore.com/history-of-mullard-tubes/
  54. https://www.effectrode.com/knowledge-base/mullard-ecc83-12ax7-reissue-vs-original-an-electrical-comparison/
  55. https://www.tubedepot.com/t/brands/mullard
  56. https://www.thetubestore.com/tube-brands/mullard
  57. https://www.gracesguide.co.uk/Z_Electric_Lamp_and_Supplies_Co
  58. https://www.radiomuseum.org/dsp_hersteller_detail.cfm?company_id=6628
  59. https://www.gracesguide.co.uk/M._E._L._Equipment_Co
  60. https://www.cryptomuseum.com/manuf/mel/index.htm
  61. https://royalsociety.org/medals-and-prizes/mullard-award/
  62. https://blogs.bournemouth.ac.uk/research/2012/12/17/royal-society-mullard-award/
  63. https://www.imperial.ac.uk/news/267953/imperial-chemeng-professor-wins-royal-society
  64. https://www.lancashiretelegraph.co.uk/news/5846522.end-line-mullards/
  65. https://www.theguardian.com/business/2005/mar/02/17
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