Test Instrument

The Type 732-A Distortion and Noise Meter has been designed to measure the combined harmonic distortion at 400 cycles. In practice it is loosely coupled to the output stages of the transmitter, preferably to the antenna loading coil or one of its as

The Class 730-A Transmission Monitoring Assembly installed at WNAC. The operator is shown using the Type 731-A Modulation Monitor. The Type 732-A Distortion and Noise

Meter is just below

The Class 730-A Transmission Monitoring Assembly installed at WNAC. The operator is shown using the Type 731-A Modulation Monitor. The Type 732-A Distortion and Noise

Meter is just below

Panel view of the Distortion and Noise Meter. Note the open, easily-read scales. Full-scale ranges of 1%, 3%, 10%, and 30% are provided sociated circuits. The radio-frequency energy picked up from this circuit is passed to the distortion meter which reads directly in percentage the total r-m-s distortion which is present on the audio-frequency envelope of modulated carrier.*

Measurements are made with the distortion meter simply and quickly. All that is necessary is to make an adjustment to a reference level with the tone on, and then to turn one dial to read the distortion directly on a large meter. The whole operation does not take more than ten seconds, even with inexperienced personnel.

A wide range of distortion can be measured with this instrument, the maximum distortion that can be read being 30%. The sensitivity is sufficiently sensitive to permit measurements at low distortion levels. A distortion of 1% will give a full-scale deflection on one of the measuring ranges, and distortions as low as 0.2% are easily readable.

+1 0

Post a comment