323 – Analog AC Voltmeter – Ballantine Laboratories

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Test and Measurement

The Ballantine 323 True RMS analog ac voltmeter uses advanced true rms circuitry to achieve square law response from rugged, fast responding silicon diode detectors with no thermal lag and overload vulnerability inherent in thermocouple devices.

These true rms meters respond to the equivalent heating power of the waveform being measured, yielding accurate readings for signals from pure sine waves to complex waveshapes such as distorted sines, squarewaves, pulses, noise, switching power supplies signals, and more. Also, when used with instrument shunts, the 323 provides true rms current measurements on non-sinusoidal waveforms.

Using a Ballantine proprietary suppressed-zero logarithmic voltage scale (linear dB scale), the 323 provides constant reading accuracy from end to end, as well as increased resolution and readability.

Key Features:

  • True RMS Response, including harmonics & crest factors to 21
  • Voltage range: 300 µV to 300 V full scale, 1% basic accuracy
  • Superior input flexibility
  • Selectable floating or grounded operation
  • Frequency range: 2 Hz to 25 MHz, usable from 1 Hz to 75 MHz
  • Full field portability, AC mains powered, optional rechargeable battery
  • Fastest response without thermal lag or delicate thermocouples

Crest Factor: 10 at 0.7 Full Scale, 7 at Full Scale, increasing to 21 at 1/3 Full Scale, except as limited by maximum input of 330 V rms sinewave or ±465 V pk.

Noise < 30 µV (input terminated with 50Ω ). Noise adds to signal as the square root of the sum of the squares. Input Impedance Signal High to Low, 2 MΩ || 15 pF, ranges above 30 mV; 2 MΩ || 25 pF, ranges 1 mV to 30mV. Signal Low to Case ground, > 40 MΩ || 400 pF.

Input Terminal BNC, floating or grounded with respect to chassis. Convertible to floating or grounded 3/4-inch spaced banana jack binding posts with supplied Model 618 adapter.

Overvoltage Protection 500 V (dc + pk ac) all ranges to 1 kHz. Ranges above 30 mV, limited to 10Ranges 30 8 V-Hz. mV and below limited to 107 V-Hz.

Common Mode Rejection Ratio > 120 dB @ dc. > 80 dB at 60 Hz.

Meter Response Front panel meter time constant control provides selectable meter responses of 0.25 sec for input frequencies above 100 Hz; 0.5 sec for frequencies above 40 Hz; 5 sec for frequencies from 2 Hz to 40 Hz.

AC to DC Converter Output Positive 1 V dc at full scale, to 0.1 V at bottom scale any range. Accuracy ±1% full scale. Output available simultaneously with meter indications. Output proportional to mean square of input signal.

Reference Conditions 24° ± 2 °C, 80% RH, ac mains 117 V ±2%, mains frequency 50 to 420 Hz, warm-up 1 hr. Temperature coefficient typically 0.1% per °C from 15° to 30°C and 0.2% per °C from 0° to 10°C and 30° to 40°C.


  • 323-06, 323-20 ac mains or internal rechargeable NiCad by front panel switch, 10 W max. Battery operating time 40 hrs.
  • 323-07, 323-21, ac mains only, 10 W max.
  • ac: 103 to 132V, 206 to 264 V, 50 to 420 Hz

Size & Weight

  • H-155 mm (6.1″) x W-198 mm (7.8″)x D-259 mm (10.2″)
  • Net: 3.4 kg (7.5 lbs), with battery 4.3 kg (9.5 lbs)
SKU: 160
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