Magnetron TAM 1,5/100_Philips

For special signalling systems, the frequency band above 300 Mhz is important, i.e. the wave band below 1 m. Single-grid and multi-grid valves are hardly suitable for these purposes since they can never furnish more than a few watts useful output in this frequency band irrespective of the circuit employed. On the other hand, a satisfactor.y efficiency can be obtained at these low wave-lengths by using valves in which the electrons are deflected during their passage through the axial field of a magnet which may be either an electromagnet or a permanent magnet. These valves are called magnetron valves.

Two magnetron valves of this type are shown in Fig. 8, viz., the TAM M with two anodes and TAM 1.5/100 with four anodes which are connected crosswise in pairs. At a frequency of 600Mhz the latter valve has, for instance, an output of 50 to 60 W, with an efficiency of approximately 40 per cent. The first-named valve can still be run effectively at a frequency of 1200 Mhz, having then an output of 7 Wand a 10 per cent efficiency. The magnetic field intensity in this case is approximately 1000 Oersted. These special transmitting valves are being steadily developed towards higher outputs and higher frequencies