Signedetched and white filled: WAVEMETER / TYPE 174-C SERIAL NO. 1232 / GENERAL RADIO CO. / CAMBRIDGE, MASS.
on face of meter: HOT WIRE / GALVANOMETER / MODEL 127 NO. 20402 / GENERAL RADIO CO. / CAMBRIDGE, MASS.
FunctionWavemeters can be used to check the wavelength of a strong signal source. It can also check the output of a transmitter for harmonics.
The output of this instrument is an electric current, which is read using a galvanometer, which is included.