Power Valve Distortion

Radio Record, Volume III, Issue 13, 11 October 1929, Page 10

Power Valve Distortion

ANY listeners have now installed power valves in their receivers with the idea of improving their tone quality, but through neglecting to inerease the plate voltage on the power valve in the last stage, have been disappointed with their results. It should be noted that an’extra terminal.should be included’ as by merely connecting another battery in series will result jin distortion caused by working the other valves at the wrong points of their characteristic curves. With modern improvements in receiver and valve design,’ and with the fnereased power of transmitting stations, the grid swing applied to the jast valve in any set using more than two valves, is so great that ordinary "general purpose" valves cannot deal with it adequately. and poor tonal qualities result, With sufficient anode voltage, the power valye, when proper grid bias is applied, is designed to handle a large grid swing, and when used, greatly improved reception follows. . . Usually it is best to work with as high a grid bias value as possible without weakening reception, but manufaeturers always provide working data with their valves, and this should always be followed. ,