Radio to a Submarine

Radio Record, Volume VI, Issue 25, 30 December 1932, Page 24

Radio to a Submarine

A New Invention

FTER months of experimenting with a special triode valye of 150 kilowatts and a co-operating pilot valve, two engineers have succeeded in making possible perfect transmissions of radio messages to a deeply-immersed submarine, To date the new 150-kilo-. watt valve, just completed at the Berlin Works, Malmaison, France, is the‘ only one in the world, the most powerful of its kind ever constructed, and the only one which has made possible perfect transmission between the earth and undersea vessels. It is designed to work on a wave-length of 10,000 metres. This valve, however, is only one unit in a very intricate and delicate set of co-operating apparatus. The 150 kilowatt valve only amplifies waves created by another valve of similar construction, but with a power of 40 kilowatts. The chief aim of the engineers was to perfect a system of valves that could quickly and easily be taken apart in order to verify that the electrodes were in good condition and working properly. ; For this the "vacuum" of the valve has to be maintained to a suitable degree. To make this taking apart possible required perfection in the arrangement of the joints. The upkeep of the vacuum is obtained by the oyrmanent use of a "molecular" pump.,! ; The assisting "pilot" valve of 40 watts keeps up the oscillations of the circuit, and keying is effected in the circuit of the amplifying valve, which feeds directly into the aerial. Seven thousand five hundred volts is applied to the plates of the triodes by a continuous current supply by dynamos or by mereury rectifying apparatus. The power arriving at the aerial slightly exceeds 100 kilowatts. Starting the gear at a maximum power takes 50 §' minutes (the same time required to produce the vacuum in the tube from the starting point of atmospheric pressure). If the lamp should be momentarily stopped, one or two minutes is sufficient to start it again if the filaments are extinguished. If they are kent alight it requires only a few sec-. onds, :