Vintage AVO High Resistance Avometer Type HRM Universal Multimeter Bakelite

ITEM SPECIFICS

Brand: AVO / The Automatic Coil Winder & Electrical Equipment Co. Ltd.

Model: High Resistance Avometer (Type H.R.M.)

Serial Number: No. 242-348

Era: Mid-20th Century (c. 1940s – 1950s)

Sensitivity: 20,000 Ohms per Volt DC / 1,000 Ohms per Volt AC

Voltage Rating: High Voltage Terminals up to 2500V AC/DC

Casing Material: Heavy Molded Black Textured Bakelite

Country/Region of Manufacture: United Kingdom (London, S.W.1)

DESCRIPTION

A classic early British AVO High Resistance Avometer (Type H.R.M.), manufactured in London by The Automatic Coil Winder & Electrical Equipment Co. Ltd.

The High Resistance Model was designed specifically for sensitive radio, electronics, and telecommunications testing, offering an impressive DC sensitivity of 20,000 Ohms per Volt.

KEY FEATURES:

Molded Bakelite Housing: Heavy-duty textured black Bakelite casing with original leather carrying strap.

Dual Rotary Selectors: Independent dials for mA / \Omega and VOLTS range selection.

Twin High-Voltage Terminals: Corner post terminals rated to 2500V D.C. and 2500V A.C.

Controls: Mechanical zero adjustment lever ('Z'), push button controls (\Omega LOW / \Omega ZERO), and automatic overload cut-out reset button.

Top Battery Compartment: Clean internal battery compartment beneath the top slide cover.

Rear Specification Plate: Original instruction plate attached to the reverse with technical specifications and British patent no. 404857.

CONDITION REPORT

Cosmetics: Bakelite case is in very good condition with no cracks, chips, or major deep scratches. Switches and knobs turn cleanly.

Dial & Glass: The glass window is clear and undamaged. Dial face is clean and legible with minor age toning. The needle rests freely.

Strap & Back Plate: The original leather strap is intact but exhibits typical surface cracking, dryness, and wear from age. Rear instruction label is fully intact with mild yellowing and light edge fraying near the corner rivets.

Battery Bay: Clean battery contacts without signs of severe acid leakage or heavy corrosion.

Functional Status: Untested for operational accuracy; sold as a vintage collectible, display item, or project piece. Leads are not included.

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CONDITION: Please review all photos for full condition details prior to purchasing.

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