213C North Atlantic Phase Angle Voltmeter

The North Atlantic 213C Series Phase Angle Voltmeters are solid-state instrument which combines the ability to measure both phase angle and magnitude of complex ac signals and vector components with respect to a reference voltage. Designed for phase sensitive operation at a pre-specified frequency withing 30 Hz to 10 kHz, it utilizes passive phase shifter circuits to assure long-term stability and high accuracy over the spectrum. Front panel controls permit instantaneous selection of voltage ranges and functions.

As a total voltmeter, the Model 213C is capable of measuring signals within a frequency range of 10 Hz to 100 kHz. The Model 213C has its frequency response limited to that if the signal isolation transformer. The signal input voltage, in the transformer mode, is limited to .75f (f=signal frequency in Hertz).

As a phase-sensitive null meter, the 2 μV nulling sensitivity of the Model 213C permits high-resolution ratio-metric measurements. This allows measurement of low-level voltages of the reference frequency in the presence of noise, hum, and other spurious signals. As a phase meter, angles are read on a parallax-free scale calibrated in 1° increments.

The Model 213C also includes a front panel switch for switching the transformer in or out of signal input circuit thereby allowing isolation of either the Reference or Signal channel.