At the outbreak of WW2, the typical airborne communications equipment aboard RAF bombers such as the Wellington, Whitley, and Hampden, to name just three, was the R1082/T1083 combination manufactured by STC. This setup was already more or less obsolete with the majority of domestic receivers of the day being of a more sophisticated design. The R1082 was a basic regenerative design, and required the operator to change two coils in the set each time he wanted to change frequency range. Not only was this inconvenient and not exactly conducive to battle conditions, the type was also renowned for its unreliability. Like the R1082, the T1083, matching transmitter required the operator to swap out complete modules when changing frequency ranges. The photograph on the left looks to me like the inside of a Wellington. The W/O is sitting on the left with the R1082 just visible in front of him. Above it is the T1083 with the two swapable modules, the unit with the two knobs on the left and the one with the single knob on the right. In effect, most of the transmitter was changed every time the operator changed band!. Whereas the receiver was entirely battery operated, the T1083 was powered from a dynamotor.

A contract was duly granted to Marconi to develop a new airborne communications package under the nomenclature T1154/R1155. The rest is history, ... as they say. Legend has it that Cockerell wrote the Air Ministry requirements on the back of an envelope.

As early as 1930, Marconi had already developed the world’s first airborne transmitter based around a variable frequency master oscillator, the AD18. This type was subsequently refined over the ensuing years. Thus Marconi was well suited to the task at hand. Development of the new T1154 transmitter, based on the AD67 and AD77 transmitters was carried out by Marconi, whilst work on the R1155 receiver, developed from the AD68-72 receivers was jointly carried out by Marconi and E.K. Cole Ltd. (Ekco).

By January 1940, prototypes of both units had been successfully tested in flight trials and the new kit was being installed in all bomber command aircraft by June that year. This was a truly amazing engineering achievement.

The photograph on the left gives an example of the new T1154 (top) and R1155 (bottom) configuration in a Lancaster. The iconic ‘Bathtub’ key is on the right of the W/O’s desk. This photograph clearly isn’t of an early installation since the R1155 sports the later Type 35 tuning mechanism, and a J-Switch antenna selector is clearly visible just to the bottom left of the T1154. Note also the unmistakable ‘pistol grip’ in the foreground, to the left of the receiver.  This is a flare pistol which fired vertically downwards through a hole in the fuselage in times of emergency.

Transmitter Type T1154M, a restoration.

By October 1939, after several disastrous raids which incurred massive losses, bomber command had come to realise that communications between aircraft and base, as well as that between individual aircraft were much in need of an upgrade. With this in mind, a representative of the Air Ministry was dispatched to The Marconi Wireless Company. Marconi’s representative at this meeting was one of their senior design engineers, Christopher Cockerell, who would later go on to invent the hovercraft.  

The STC R1082