Final version of AVOmeter model 8 Mk7 (produced from 1951 to 2008)

Early version of the AVOmeter.

The Avometer was a British brand of multimeter, latterly owned by Megger. 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.^[1]

[edit] 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 multimeter it measures alternating current up to 10 A as well as the standard AC and DC voltages up to 1000 V; as an ohmeter 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 (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 minimise 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.

[edit] Present times

Despite continuing demand from customers, production was stopped in 2008, reportedly due to increasing problems with suppliers of mechanical parts.^[2]

[edit] See also

• Megger (current owners of the Avometer design)

[edit] References

[edit] External links

• Model 7 Avometer
• Model 8 Avometer

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