High Resistance AVO Universal Multimeter Model 1

Avo (Brand), Automatic Coil Winder and Electrical Equipment Co., Avo Ltd; London

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  • Year
  • 1948–1951 ?
  • Category
  • Service- or Lab Equipment
  • Radiomuseum.org ID
  • 363468

 Technical Specifications

  • Wave bands
  • - without
  • Power type and voltage
  • Dry Batteries / 1 x 1.5, 1 x 4.5 Volt
  • Loudspeaker
  • - - No sound reproduction output.
  • Material
  • Bakelite case
  • from Radiomuseum.org
  • Model: High Resistance AVO Universal Multimeter Model 1 - Avo Brand, Automatic Coil
  • Shape
  • Tablemodel, with any shape - general.
  • Dimensions (WHD)
  • 8.25 x 7.25 x 5.25 inch / 210 x 184 x 133 mm
  • Notes

  • High Resistance AVO Universal Multimeter: Model 1

    The High Resistance AVO universal multimeter was a pioneering instrument of its time, first introduced around 1948 and produced for only a brief period (until approximately 1951).
    Model 1 was the first Avometer to reach 20,000 ohms-per-volt sensitivity on DC voltage ranges, representing a significant advancement over earlier meters. It also provided 1,000 ohms-per-volt sensitivity on AC ranges, supporting voltage measurements from 2.5 V to 2,500 V DC and from 10 V to 2,500 V AC. The DC current range was from 50 μA to 1,000 mA, while the resistance measurement ranged from 0.1 Ω to 5 MΩ.

    Model 1 featured a 5-inch clear scale with an anti-parallax mirror, housed in a Bakelite case powered by a 4.5 V battery and a 1.5 V cell, with space for a spare battery. An optional magnetically shielded metal case was available for environments sensitive to stray magnetic fields. It featured an automatic overload cut-out and a galvanometer mode where the zero could be offset up to 30% of full scale by a simple knob.

    Notably, Model 1 lacked an AC current measurement range and did not include the "divide by 2" button found on some earlier AVOmeters, simplifying its control interface. The low ohms range was uniquely scaled left-to-right, differing from conventional meters.

    Primarily aimed at radio and early television servicing, Model 1’s higher input impedance greatly reduced loading errors in high-impedance circuits, improving measurement accuracy. Its short production run was due to rapid technological advances and set the stage for subsequent multimeter models.

  • Net weight (2.2 lb = 1 kg)
  • 6.25 lb (6 lb 4 oz) / 2.838 kg
  • Price in first year of sale
  • 19.50 GB £
  • Literature/Schematics (1)
  • -- Original prospect or advert (Electronic Engineering Sep 1950, Page 18.)
  • Author
  • Model page created by Gary Cowans. See "Data change" for further contributors.

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