AERIALISMS

Sun (Auckland), Volume II, Issue 563, 16 January 1929, Page 14

AERIALISMS

A small fixed condenser connected between the slider of a potentiometer and that end of it which is connected to the filament of the valve makes a very useful by-pass in H.F. circuits using potentiometer control. Accumulators should always be kept in a cool, dry place. Never hang your ’phones near an accumulator, as the gassing and fumes are capable of causing injury to the delicate windings. For very short-wave work, do not forget that a magnifying lens mounted near the dial may be a great help in calibrating and tuning. The difficulty in obtaining smooth reaction control in a short-wave set can often be overcome by means of a potentiometer the ends of which are across the filament, the slider being connected to the grid leak. One of the commonest causes of a bad humming noise is a break in the earth’s lead. Never allow acid from the accumulator to come into contact with the carpet, as the effect of the acid will be to eat away the fabric, and quickly to destroy it. Phone diaphragms should not be pulled upward against the magnetism; but, if they have to be removed, they should be slipped carefully across the supporting ring in a sideways direction, to keep them from bending. Do not forget that an earth lead which looks quite all right may be broken underground, where the effect is just the same as if the external lead were broken.