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Fotos valves were made by E C & A Grammont in France. Production commenced in France during WWI to make the then new hard valve. There valve was the TM.
The other company making the hard valve in France at this time was Compagne des Lampes who used the brand name Metal.
In the UK from 1929 Fotos valves were sold by Concertron Radio & Electrical Ltd.
References: 1043, Why the French R Valve & About the French TM Valve.
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