Société La Radiotechnique 'RadioMicro' Triodes

Bright and dull emitter triodes

Société La Radiotechnique 'RadioMicro' Triodes

These two early French triodes, probably made by Société La Radiotechnique and branded 'Radio Micro', while almost identical in external appearance are quite different. The first has a classic horizontal tubular 'R' type anode and with a cold filament resistance of 1 ohm, was probably a bright emitter. The second has a horizontal oval box anode and, with a cold filament resistance of 2.5 ohms was probably a dull emitter. Neither valve has any detectable markings.

The picture below shows one of these valves with an earlier 'RadioMicro' metal based triode and a later 'Spécial' from the same Société La Radiotechnique company. Notice the close similarity of the bases of the last two.