THE 99 VALVE

Radio Record, Volume I, Issue 15, 28 October 1927, Page 13

THE 99 VALVE

Many of ihe best imported broadcast. receiving sects are now constructed for using 199 type valves. The 199 is a 3-volt valve and requires .06 amperes, which is Jess than one-fourth the cur-

be Waele ti li A HH HE Hit Wi) Hu rent consumption of the 5-volt type, which requires .25 amperes. it is fully as rugged in construction and‘ as well able to withstand overload as the larger valve. Its failure is usnally due to over-voltage supply, being normally operated from three dry cells in series, Their combined 4} volts should be reduced to 3 volts by a rheostat, but this is often neglected. Consequently it is subjected to 60 per cent. overload, whereas a 6-yolt yalve or a 6-volt storage battery has onlv 20 per cent. overload. A receiver using 3-yolt valves should always be equipped with a high resistance voltmeter which is in circnit at all times so as to show the voltage at which the valves are operating. The valve should never be driven above 3.2 volts when the 'B" battery is connected, If the set does not then give proper volume, either it or the valves are defective.