Use of 250 Type Valves

Radio Record, Volume III, Issue 3, 2 August 1929, Page 35

Use of 250 Type Valves

[t often seems that in their eagerness to be nmong the first to make use of a new valve, some radio engineers, enthusiasts and writers, do not give due consideration ‘to the proper use of such valves. In some instances, this has been the case with the 250type valve. This valve type was primarily prought forth to satisfy the demand for power amplifiers for use in theatres and other largepgathering places. When used in such connections, the use of an amplifier before the last stage capable of providing a voltage amplification sufficient to bring out the pest in the power stage is required. The use of a push-pull power stage using two 250-valves is not generally recommended, except for instances where extraordinarily large power output is required. Certainly such an am-~ plifier bas no place in the average home. For ordinary home use, the greatest advantage of the 250 valve lies in the fact that it will give, with lower plate voltages, an, output equivalent to that obtained with a 210-type vaive at much higher voltages. For home use, therefore, the plate voltage used should not be higher than 300 volts. —