Avo Meter

The Avo-meter was a British brand of multi-meter, latterly owned by Meager. The most widespread of the range was the Model 8, which was produced in various versions from the 1950s until 2008, the last version being the Mark 7.

It is often called simply an AVO and derives its name from the first letter of the words amperes, volts, ohms. It was conceived by the Post Office engineer Donald Macadie in 1923

founded probably in 1923). The first AVO was put on sale in 1923, and although it was initially a DC-only instrument many of its features remained almost unaltered right through to the last Model 8.

ACWEECO later became known as AVO Limited and manufactured instruments with the AVO trademark.

The original AVO multi meter was manufactured continuously since its first appearance in 1923. The final model was made in October 2008, when its production was terminated only due to increasing problems with obtaining the spare mechanical parts. The final AVO Model 8 introduced in 1951 became an electronic device present in the market for 57 years without major modifications.

Technical features

It was by far the best instrument of its kind in the UK from 1923 to at least the 1960s. Almost uniquely for a radio repairman’s multi-meter it measures alternating current up to 10 A as well as AC and DC voltages up to at least 1000 V. The Model 8 Mk. V included additional inputs to measure up to 3000 V. As an ohmmeter it measures from 0.1 Ω up to 200 kΩ in three ranges. The instrument has an accuracy of ±1% of FSD on DC ranges and ±2% on AC ranges. Its maximum current draw of 50 μA at full-scale deflection (corresponding to 20,000 ohms per volt) is sufficient in most cases to reduce voltage measurement error due to circuit loading by the meter to an acceptable level. A pair of rotary switches are used to select the range to be measured, being arranged in such a way as to minimize the risk of damage to the instrument should the wrong range be selected. Further protection is provided by an overload cut-out and fuses. It was a superb example of British radio engineering in its heyday and was found in many R&D laboratories and virtually every radio repair workshop throughout the country. Even nowadays it can still be found in regular use.

Present times

Despite continuing demand from customers, production was stopped in 2008, reportedly due to increasing problems with suppliers of mechanical parts.The last meter to leave the factory was an Avo-meter Eight Mk 7 (Serial Number 6110-610/081208/5166) which was presented in February 2010 to the winner of a competition run by the Megger company

AVO Training Institute

In 1963 Multi-Amp and AVO created Multi-Amp Institute. In 2004 the Institute became AVO Training Institute, Inc. with the headquarters in Dallas, Texas. AVO Training Institute was established for providing training in electrical engineering, particularly regarding safety, maintenance and testing of electrical equipment, also by using instruments from competitive manufacturers.

In 1996 the Institute was certified with ISO 9001 and so far over 230,000 electrical maintenance and testing technicians and engineers from around the world have attended training courses.

The Institute has a Technical Resource Center – an online store offering books, standards, training materials, Personal Protective Equipment, and tools.  The actual training can be organised in different sites around the world, for example at the Megger facility in Paris.

The AVO Electrical Engineering Division was created in 2002 and it specialises in power system studies, specifically arc flash hazard analysis

Author :

Ayon Bit

ayonbit@yahoo.com