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Why the French R valve?

by Gerald Garratt G5CS from Radio Communication February, 1981.
    
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A genuine Grammont 'Fotos' R valve.

The author bought his first R valve in September 1920 from Leslie McMichael (2MI) who was then running an ex-government disposals outfit-one could not give it the dignity of calling it a shop in the yard of a defunct garage off the Quex Road in West Hampstead. The author was only 13 at the time, and Leslie's store was for him an Aladdin's Cave of priceless treasure-what happy days! This was, of course, several years before Leslie started up as a serious manufacturer as McMichael & Co Ltd-as other old-timers may remember.

For the benefit of those too young to remember, the French R valve was a bright-emitter triode whose filament took about 1A at 4V. They were the valves nearly all of us used from 1920 to 1922, when the Mullard ORA arrived. But why were they called French R valves when everyone knew they had been made in England-by BTH at Rugby, by Ediswans at Ponders End, and by the Osram-Robertson Works at Harnmersmith (later to be known as Marconi-Osram)?

No-one was ever able to answer the question. One presumed, of course, that the design had first been produced in France during the first world war-but how had the French 'got in on the act'? They certainly had no history of being involved before the war in what we now call electronics, and so it remained a mystery. The story has only quite recently come to light. Involving an element of 'cloak and dagger', it is a story so fascinating in human interest and technical history that it deserves to be more widely known.

Fleming Oscillation Valve

We all know, of course, that it was Ambrose Fleming who invented the 'oscillation valve' in 1904, and that it was Lee de Forest who invented the three-electrode Audion in 1907. But the early Audions were poor performers, erratic and unstable, and de Forest did not properly understand how they worked and did not realize the potential value of his invention. In 1912 he sold the patent rights in the Audion, for all purposes other than wireless, for a mere $50,000 to the Western Electric Company who were looking for a good amplifier for use as a repeater on long-distance telephone lines.

Dr Harold D Arnold of Western Electric realized the potential value of the Audion, but he also realized that it would take a long and sustained programme of research and development to convert it into a device suitable for practical use in the telephone service. At an early stage Dr Arnold realized that the presence of gas in the bulb-which de Forest believed to be essential to its operation, was, in reality, a liability rather than an asset. He firmly believed, that in order to make an Audion which would operate consistently it was essential that the vacuum should be as perfect as possible, and by 1914 the Western Electric Audions were working well as amplifiers. But by this time the clouds of war were gathering in Europe, and it was at this stage that fate played a joker.

During the summer of 1914, a certain Paul Pichon had been touring the USA on an assignment from his employers, the Telefunken Company of Germany, to gather samples of all the latest wireless equipment he could find and to return to Germany with his samples for assessment. In the course of his tour he visited the Western Electric Company, and was given samples of the latest high-vacuum Audions together with full information on their use.

Pichon was a Frenchman, but he had deserted from the French Army in 1900 and, emigrating to Germany, he had earned his living teaching French. Among his pupils were the children of Count von Arco, one of the founders of the Telefunken Company, by whom he was subsequently recruited as a technical representative.

On his way back to Germany at the end of his American tour he travelled by Atlantic liner to Southampton and he found himself in London on 3 August 1914, the very day upon which Germany declared war on France. The poor chap was in a fix, a French deserter yet an alien in Germany; what was he to do? In his hesitation, he called on Godfrey Isaacs, the managing director of Marconi's, to seek his advice. He explained that he was still a French subject but that he would face immediate arrest if he returned to France. Whether or not Isaacs regarded him as a 'hot potato' is not clear; what is certain is that Isaacs failed to appreciate the importance of the samples Pichon carried in his baggage and which thus lay virtually within his grasp. He advised Pichon to return to France and offer his services to the French authorities.

Pichon crossed to Calais where he was promptly arrested. Protesting that he had brought back vital samples and information from America, he persuaded the authorities to communicate with the commandant of the French Military Telegraphic Service, Colonel Gustav Ferrie, who ordered that Pichon be immediately brought before him with all his baggage and papers.

Convinced of the reliability of Pichon's information, Colonel Ferrie immediately submitted the samples to a panel of eminent physicists for further assessment and, simultaneously, he ordered arrangements to be put in hand for manufacture at the works of Messrs E. C. & A. Grammont at Lyons. The design was substantially modified by French engineers, Michel Peri and Jacques Biguet, but within 12 months valve production was in full swing at the Grammont works. Known as the Type TM in France, samples were sent by the French to the Admiralty in London and to the Royal Naval Signal School at Portsmouth early in 1916, and it very quickly became evident that these French valves were vastly superior in every way to the soft-vacuum Round valves and the earlier model Audions in use hitherto.

A Round Type N

Arrangements were begun almost immediately for valves of similar design to be produced in this country by BTH, Ediswan and Osram- Robertson, but it was late in 1916 before significant production commenced of what was to become generally known as the French R valve. And that was how the French R valve got its name!

Even today, (1981) British-made R valves manufactured between 1917 and 1920 are not so very uncommon. Genuine French-manufactured valves, however, are decidedly rare but they can be identified by their markings. Those made by the Grammont Company are marked 'TM Fotos', while those made by the second producers, the Compagnie General des Lampes, are marked 'TM Metal'.

A Fotos Horned Valve

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