A.C. Valve Response

Radio Record, Volume III, Issue 28, 24 January 1930, Page 29

A.C. Valve Response

, Noticeable T ime-Log Wit a battery-operated set, throwing the switch that turns on the current results in immediate action. If the set is tuned to a station, music, or speech issues from the loudspeaker in a fraction of a second. This is not true of modern sets operated by alternating current. There is a lapse of anywhere from ten to thirty seconds between the throwing of the switch and the. first sound from the loudspeaker. The delay is caused by the slow heating of the relatively thick cathode element in valves such as the type 227 and 224. Many attempts have been made to decrease the time lag, but an improvement in this direction is worth while only if it can be accomplished without affecting the efficiency of the valve and the length of its life. In any event, decreasing the time lag below the present figure is of relatively little importance. Most people will not object to waiting a fraction of a minute for the start of a period of musical or other entertainment to which they may listen for several hours.