Protection of Radiotelegraph Receivers from Atmospheric Discharges

(Austin. Ein mit Kristallkontakt arbeitender Störungsverhinderer für den Empfang in der drahtlosen Telegraphie. Jahrb. d. drahtl. Tel. und Tel. 5, 1914, p. 451).

The work named in the title should be noted in connection with the practical use in wireless telegraphy of switching in two contact valves in order to weaken the effect of atmospheric discharges on reception. The work is also interesting in another respect, as providing material for the study of phenomena in contact detectors—phenomena that do not fit within the framework of the thermoelectric theory (see, for example, the form of the characteristic: Erskine—Murray, Handbook of Wireless Telegraphy, p. 129). Braun had already found that the resistance \(R\) of a crystal detector changes with an increase in the applied voltage. Moreover, \(R\) depends on the direction of the electromotive force. If a silicon–steel contact is taken, then at \(0.028\) volt from silicon to steel \(R_1 = 2600\ \Omega\), while for the reverse direction \(R_2 = 2400\ \Omega\); if, however, \(2.5\) volt is taken, then \(R_1 = 420\ \Omega\), and already \(R_2 = 100\ \Omega\). Austin makes use of the large change in \(R\) with increasing \(E\) in a crystal detector for protection against atmospheric discharges (Störungsverhinderer). It turns out that when such a Störungsverhinderer is inserted in a receiving radio station, the galvanometer deflections obtained are \(0.5;\ 7;\ 22;\ 240\), whereas without it they are, respectively, \(0.5;\ 22;\ 240\).

B. V. Ilyin.