A Direct-Reading Decremeter and Wave Meter

A new type of direct-reading decremeter and wave meter is described. It is based on the Bjerknes method, but much simplifies the measurement and increases the accuracy thereof. The variable condenser of this wave meter is of a special type, the movable plates being cut to an appropriate outline. By placing a fixed capacity in parallel with this variable condenser, which fixed capacity is adjusted once for all in each instrument, a standard and predetermined calibration curve can be used with all instruments. The design and construction of the apparatus is given in detail, and a number of measurements with it are considered critically. Several methods of determining the decrement of the instrument itself are shown. The instrument can also be used as an exciting circuit of known wave length and decrement. An interesting example of heterodyne reception of sustained oscillations with this instrument is described.