4.3.1 - The transmission valve
Among its main groups, the reception and transmission valve, basically they are different considering only its operational principle. In this way hence in the former its most important factor is the amplification without distorsion, in the latter it is its output power. Therefore, the transmission valve is just a kind of reception valve converted to handle high output power and so operating with high plate voltage. Its evolution is related with several advances in the thermionic art such as: better getter technics, as well as improved anode radiation's dissipation.

Illustration of some types of transmission valves:

A = Valve 801A, power triode type used toried tungsten filament as amplifying of high frequency, oscilltor and power amplifying for radio frequency.

B = Valve type VT 154