Thermionic Products Ltd.
Pratt Walk, Lambeth, London SE 11. (1948)
Morris House, Jermyn Street, Haymarket, London (1949)
Shore Road, Hythe, Southampton. (1955)

Thermionic Products (Electronics) Ltd.
Shore Road, Hythe, Southampton.     (1958)

Racal-Thermionic Ltd.
Shore Road, Hythe, Southampton.  (1969)

Brands:  Recordon : Soundmirror

Thermionic Products pioneered magnetic recording, starting with the photographic Mega-Flash. They evolved from dictation machines Recordon to the revolutionary Soundmirror tape recorder. They excelled in specialized recording (air traffic control) and became Racal-Thermionic in 1969, ushering in the ICR communication recorder and digital era.

Thermionic Products Ltd.: A Pioneering Journey in Magnetic Recording (1944-1974)

From Wartime Expertise to Audio Innovation (1944-1949):

Thermionic Products Ltd. emerged in 1944, founded by Alfred Colley and Edward Angold. Their background in piezo-electric devices and wartime communications equipment fuelled their interest in the burgeoning field of electronic recording. Inspired by advancements in the US, particularly at the Brush Development Company, they secured a license for their Mail-a-Voice recorder.

While magnetic recording would become their defining legacy, Thermionic Products' first foray into the consumer market was with a different kind of flash: the Mega-Flash. This electronic flashgun, launched in the wake of World War II, was a testament to their ability to adapt their expertise to new applications. The Mega-Flash likely appealed to a growing market of amateur and professional photographers seeking portable and reliable lighting solutions.

In 1948, Thermionic Products launched their first commercial product related to magnetic recording – the Recordon TP503 dictation machine. This portable device, designed for office use, offered a novel approach to audio recording. Utilizing a 9-inch magnetic oxide-coated paper disc, it provided a recording time of approximately 3 minutes. The discs, a unique feature, could be folded into thirds for easy mailing after recording, catering to the needs of a communication-hungry post-war world. However, one drawback was the need to allocate recording space for essential details like addresses and reference numbers – a limitation addressed with later accessories.

Introducing the Soundmirror: A Leap Forward in Technology (1949):

Thermionic Products' vision extended beyond dictation machines. In 1949, they unveiled the revolutionary Soundmirror magnetic tape recorder. This versatile machine marked a significant leap in recording technology. Unlike the Recordon's limited capacity, the Soundmirror offered a generous 30 minutes of high-fidelity recording on reels of magnetic tape. The ability to playback recordings, combined with the permanence of the medium, made it a valuable tool for capturing and preserving audio. Additionally, the Soundmirror allowed for editing and erasing of unwanted sections, paving the way for a more dynamic recording experience.

Evolution and Expansion: Mastering the Recording Landscape (1950-1957):

Thermionic Products continued to refine the Recordon dictation machine throughout the 1950s. User-friendly features like press-button control for starting and stopping recording, and an automatic erasure function enhanced its functionality. Trade show advertisements showcased these advancements, solidifying Recordon's position as a reliable and innovative office tool.

Beyond office equipment, Thermionic Products demonstrated their expertise in specialized recording applications. In 1953, they unveiled a groundbreaking 14-channel airport recorder. This complex system, designed for air traffic communications, recorded conversations on a 0.7-inch wide tape at 3.75 inches per second. It boasted automatic switching for continuity and a fail-safe mechanism that transferred recording to a standby unit in case of any system malfunctions. Additionally, coded time signals ensured accurate message tracking. This project showcased Thermionic Products' capability to cater to sophisticated recording needs beyond the office environment.

The company actively expanded its product range throughout this period. In 1955, they acquired the exclusive distribution rights for Kelly Acoustics' innovative ribbon loudspeaker, demonstrating their interest in diversifying beyond recording equipment. They further ventured into the burgeoning FM radio market with the prototype TP100 FM tuner in 1957. This model, with its unique design features, aimed to eliminate the need for tuning indicators and automatic frequency control systems.

Around 1956, Thermionic Products became a subsidiary of Pena Industries.

Challenges and Transformation: Embracing the Future (1958-1963):

In December 1958, Pena Industries went into liquidation. Subsidiaries like Thermionic Products and Peto Scott were placed in receivership. Both companies survived the crash and were reconstituted. Thermionic Products (Electronics) Ltd. was formed to take over the goodwill and market the products of the original company.
Emerging from this period with a renewed focus, they recognized the changing market landscape and discontinued the production of domestic tape recorders and dictation machines. Instead, the company concentrated on specialized multi-channel recorders catering to specific applications like airport communications and data logging.[2][3]

Their expertise was evident at trade shows throughout the early 1960s. In 1963, they showcased the TDR4 four-speed tape transport and the TLS2 loop store, further solidifying their reputation as a leader in innovative recording technology.

Acquisition and the Digital Shift: A New Era (1969-1973)

Thermionic Products (Electronics) Ltd. entered a new chapter in 1969 when it became part of the Racal Group. This acquisition led to a name change – Racal-Thermionic Ltd. – and marked a pivotal point in the company's history, ushering in the era of digital technology.

Introducing the ICR: A Technological Leap (1972):

Racal-Thermionic continued to excel in communication recording solutions. A prime example was the ICR (International Communications Recorder), unveiled in 1972 at the Airports Exhibition. This revolutionary system boasted several advancements:

• High Channel Capacity on Minimal Tape Width: The ICR could record a significant number of channels on a narrower tape, maximizing recording efficiency.
• 24-Hour Continuous Recording: A single spool of tape offered a substantial 24 hours of uninterrupted recording, ideal for demanding applications.
• Compact Size and Competitive Pricing: Despite its advanced features, the ICR maintained a smaller footprint and remained cost-effective compared to similar systems.

The ICR's innovative design garnered significant interest. The UK Civil Aviation Authority quickly adopted the system for their air traffic control centers and major airports. International customers from France, Italy, Singapore, and numerous other countries followed suit, utilizing the ICR for various communication recording needs beyond aviation.

Beyond Communications Recording (1974):

Racal-Thermionic's expertise extended far beyond communication recording. They were also a leader in:

• Instrumentation Recording Systems: The company offered a comprehensive range of magnetic tape and direct writing devices, catering to the needs of medical institutes, industrial facilities, and scientific research establishments worldwide.
• Computer Peripherals: Racal-Thermionic designed high-quality and reliable computer peripherals, including magnetic tape systems and innovative digital data recording using cassettes, a relatively new technology at the time. [4]

Embracing Change and Looking Ahead (1974):

Due to its rapid growth, Racal-Thermionic planned to relocate to a larger, custom-built facility in 1974. This move would accommodate their expanding operations and solidify their position as a frontrunner in various recording technologies.

Racal was purchased by Thomson-CSF (now Thales Group) in 2000.

[1] Brenell tape-recorders website by Barry M Jones, accessed April 2024.
[2] London Gazette Sep 26, 1958, Page 5915.
[3] Wireless World Dec 1958, Page 578.
[4] The Controller, IFATCA Journal 1974, pages 47 & 47.