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The full story of Thermionic Products and Racal-Thermionics is told in A Truvox Product
Founded in 1944 by Alfred Colley and Edward Angold, their first product was Britain's first electronic flash-gun, the 'Mega-Flash'.
They already held patents for cinematographic sound recording which undoubtedly led to their patented improvements to the
Brush "Mail-a-Voice" disc recorder of 1946.
By 1948 they had secured the licence to build the "Mail-a-Voice" in the UK, launching it as the "Recordon
TP503", (right) built in London. This was marketed as an office dictating machine and operated very
much like a gramophone, recording onto a 9" magnetic oxide coated paper disc which could be folded into three and posted
to another office. It proved a most successful product and allowed the company to take up offices in Jermyn Street, London.
It was later produced at Hythe as the improved TP504 along with a deluxe 'Diplomat' version (below)
until 1953.
The Recordon's resounding success allowed Thermionic Products to secure the licence to build the Brush 'Soundmirror'
(lower left) in late 1948. It was the first British-built domestic tape-recorder, whereas the first British
built-and-designed tape recorder was the Wright & Weaire, which appeared a few weeks later (see Terry Martini's superb
history, Built like a Battleship). Production began in autumn 1948 but the quality of
the paper tape meant it shedded oxide too readily and clogged the heads! While this was being sorted out, Colley made
a fortune producing the drinking-duck novelty solar toys! The Soundmirror was a single speed machine and one of
the first to use a swinging arm pinch wheel operation. It employed a cross-over belt drive with joy-stick control and 'pop-up'
permanent magnet erase head - the full track head used only the central 2/3rds of the tape. The spools of paper-tape
were driven by flanges on the spool turntable - not the more usual off-set pin or DIN drive seen later. They were sold in
a superbly made walnut veneered cabinet as a piece of domestic furniture at £69.
Production moved to Hythe, Hampshire in 1950. It is said that their Chief Engineer elected to stay in London and
joined Scophony-Baird to help design their first tape recorder, the Scophony-Baird 'Soundmaster'; this 2-motor design
is quite different from the Soundmirror and used an oxide-out spooling and electromagnetic erase and play/record
heads. This model remainded on offer until 1955. However no proof of this move to Baird has been found. The T-P Soundmirror
was joined in 1951 by a portable model in a wooden case, finished in a yellow/brown fabric, (right). This
had provision for extra spools of tape, a large ACOS microphone and cables - and is surprisingly light! It sold for £79.
Production of the Soundmirrors continued to late 1954 by which time Thermionic Products had moved entirely over to multi-track
airfield voice loggers.
A new post-war Convention on International Civil Aviation brought forth a legal demand from 1951 for logging all
Air Traffic Control to pilot communications. This required multi-track machines which Thermionic Products pioneered in the
UK 1950 - they soon became world leaders, but that story is told in A Truvox Product. In the late 1950s,
T-P were pinning their hopes on a major contract for London Heathrow, but it went to the British Communications Corporation
- a young company owned by Dan Prenn of Truvox fame. The failure to win the contract soon pushed Thermionic Products into
receivership; they were bought by Prenn in 1958 and production of airfield voice-loggers continued at Hythe under T-P while
BCC concentrated on military and police radio communications. T-P were once again world leaders in multi-track recorders and
with expertise gained through Epsylon and Vectron engineers, expanded into instrumentation recorders and digital technology.
In 1967, Dan Prenn made his Truvox audio business a subsidiary of Thermionic Products and Truvox production moved to
Hythe. T-P's expertise in military contracts soon transformed the quality of Truvox's domestic tape recorders. Indeed the
Truvox Series 100 was chosen by T-P for their first portable instrumentation and seismic recorder - the T-P T3000,
(left). This had four speed operation and advanced electronic pcb circuitry. It was superceded by the Series
200 deck and alone survived as the Racal-Thermionic T3000 when Thermionic Products and Racal merged in 1969.
In addition to their multi-channel communication recorders, Racal-Thermionic developed an incredibly versatile and truly
advanced portable instrumentation recorder, the Store 4, which replaced the T3000. This offered optional speed ranges from
15/640ips (for seismic work) to 60ips in 4, 7 and 14 channel formats. Highly regarded for its delicate and accurate tape transport,
it was the machine of choice for replaying fragile aircraft "Black-box" tapes for analysis.
In 1971 Racal bought the Zonal (formerly Ilford-Zonal) magnetic tape business but sold it in the 1980s; Zonal are still
in business.
By 1977 the company had become Racal-Recorders and further developed specialist communications and instrumentation recorders,
but these are beyond the scope of this audio web-site! The full story is recorded in A Truvox Product.
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