▼ Menu

TM

Sensibly equivalent to:
R. TM-Metal
See also:
Why the French R Valve - About the French TM Valve
    
Extras ▼

 

The Fotos TM was the original hard triode produced in France during WWI.
Grammont was the company and Fotos their trade mark. When demand outstripped their capacity another lamp manufacturer, Compagnie Generale des Lamps, became involved, their trade mark was Metal and the valve TM Metal. There are differences in the construction that can help to distinguish the different makes. In particular the Fotos spherical envelope touches the base whereas the Metal made valves have a short stem before the spherical part of the glass. See R Type for style.
The Fotos logo in better condition than on TM.
The etched maker name A Grammont under the Fotos trade mark.
Thanks to Joe Gruber for sending the images.
The balloon envelope is 55 mm in diameter, and excluding the B4 base pins is 88 mm tall.
References: 1047 & 1003. Type TM was first introduced in 1916.

 

Pin Connections
B4
1
2
3
4
a
g1
f
f

 

Absolute Maximum Operating Conditions
Triode
Vh
Ah
Va
4.0
0.65
120
Updated July 06, 2021.
Return to Main Index