Avometer Model 10

 I have found very little information about this multimeter, it appears to have been made mainly for the export market. It incorporates two transistors which are used in the meter tripping mechanism.

Avometer Model 70 series

AVO produced the "70 series" range of analogue pocket meters with 2000 Ohms/Volt sensitivity and 3 inch scale lengths at the beginning of the 1970's. 

The following is from a 1972/3 catalogue

Avometer Model 71

No image, this model was soon superseded by the more accurate and virtually identical model 72. The 1A fuse was omitted in the Model 72. See the circuit diagram on the right (open in new window to view)

Avometer Model 72

first introduced in 1972

Avometer Model 73A

Avometer Model EM272

Click on image above to view instructions  which include the circuit diagram

Post Office Model 12D

This appears to be a variation of the model 72 shown above with the addition of a neon fuse failure indicator and omission of 1000Volt DC range

Avometer Model 12

meter multi range no15A GPO is identical

Specialised for automotive tests; no transformer; no cut-out but diode protection for movement. Supplied to British General Post Office telephones and labelled 'meter multi range no.15A G.P.O'

DC 3.6, 9, 18, 36 V - sensitivity 5 mA
DC 3.6, 36 A
AC 9, 18, 90, 360 V - sensitivity 11 mA
R 1, 10k ohm (25, 250 ohm center)

no picture

Heavy Duty AVOMETER

1948-8 Early version

Based on Model 7 type design. Early version has  screw terminals

DC 1, 5, 50, 500 V - sensitivity 1 mA
DC 50mA, 500 mA, 1A, 10 A
AC 1, 5, 50, 500 V - sensitivity ???
AC 50, 500 mA, 1, 10 A
R 500, 50k ohm (12.5, 1250 ohm center)

Heavy Duty AVOMETER (BR version)

This one made in 1985

  Resistance on bottom of scale plate; banana terminals

DC 1.5, 3, 15, 75, 150, 750 V - sensitivity 1 mA
DC 75mA, 300 mA, 1.5, 15 A
AC 3, 15, 150, 750 V - sensitivity ???
AC 1.5, 15 A
R 500, 50k ohm (12.5, 1250 ohm center)

Heavy Duty AVOMETER Mk5

DC 10, 25, 250, 1000 V - sensitivity 1 mA
DC 10, 100 mA, 1, 10 A
AC 10, 25, 250, 1000 V - sensitivity
2 mA on 25+ volts, 5 o
AC 10mA, 100 mA, 1A, 10 A
R 500, 50k ohm (12.5, 1250 ohm center)

(actual meter movement is 600 microamp FSD)

HEAVY DUTY AVOMETER Mk.V (as described in 1960 advertisement)
A multi-range A.C./D.C. electrical measuring instrument of specially robust construction designed for outdoor work and where conditions of rough usage exist. The instrument is housed in a moulded Bakelite case and the movement has been designed to withstand severe shock without damage.

It is a moving-coil meter with a knife-edge pointer and an anti-parallax mirror to facilitate accurate reading. The 3t in. scale is very open and clear. Current consumption is 1mA. at full scale deflection on D.C. volts and 2mA. on A.C. volts.

The following ranges of readings are 'available from one pair of terminals, the range selection being effected by means of' a single rotary switch: -

D.C. VOLTAGE: 1000,250,25, 10 volts.
D.C. CURRENT: 100mA, 1A, 100 mA., 10mA.
A.C. VOLTAGE. 1000,250,25, 10 volts.
A.C. CURRENT: 10A, 1A, 100mA, 10mA.
RESISTANCE: 0-500 ohms (Midscale 12.5 ohms).
0-50,000 ohms (Midscale 1,250 ohms).

Further ranges can be provided by means of extension transformers for A.C. current, shunts for D.C. current, multipliers for A.C. and D.C. voltage, and a Resistance Extension Range Unit.
Supplied complete with leads and interchangeable test prods and clips.

Size: 7.5 X 5.525 X 4 in. Weight: 5.5 lb.

AVOmeter Model 16

Models 14 15 and 20 are of similar construction varying only in the number of ranges covered (model 14 has no AC current ranges)

Electronic Avometer Type EA 113

same size and general appearance as the models 14 through 20

The Electronic AVO meter EA113 is a highly regarded and at the time innovative very sensitive and accurate analogue test instrument, incorporating solid state amplifier circuitry - which increased its sensitivity, making possible its use on high impedance circuits without affecting either the operation of the circuit or the reading of the meter.

This model ATR 1000 is also available in a Heavy Duty version Avometer 1000 HD. The British Telecom SA9083 Linesmans Test Meter is similar. The instrument illustrated here was marketed by Newey and Eyre and branded 'NEWLECAVO'
The gap in the handle is to allow the leads through as the terminals are underneath the top edge of the meter.

Ranges:
DC: 0.3 V, 3V, 10V, 30V, 100V, 300V, 1000V
AC: 10V, 30V, 100V, 300V, 1000V
DC: Current 50µA, 10mA, 100mA, 1A, 6A
AC: Current 10mA, 100mA, 1A, 6A
Resistance: 1-10k ohm, 100k-1M ohm, 1k-10M ohm

Acknowledgments

Images other than those of the meters in my possession have been gleaned, cleaned up and resized from various sites on the internet.

The basic details of many of these instruments have been compiled and provided by Andrew Usher who felt that there was a need for an AVO page similar to that for Simpson meters shown here: www.simpson260.com