General Information

Serial #

34764-A-952

Part Number

1

Total Parts

3

AKA

N/A

Patents

N/A

General Description

Metal casing/leather carrying strap/plexiglass readout window/backlite control knobs.

Dimensions

Note: These reflect the general size for storage and are not necessarily representative of the object's true dimensions.

Length

27.0 cm

Width

25.0 cm

Height

17.0 cm

Thickness

N/A

Weight

N/A

Diameter

N/A

Volume

N/A

Lexicon

Group

Communications

Category

Radio

Sub-Category

N/A

Manufacturer

AKA

Avo

Country

England

State/Province

Unknown

City

London

Context

Country

Canada

State/Province

Ontario

Period

Used 1950's to 1980's

Canada

Used in Canada

Function

Used to make a variety of electrical measurements in testing radios and other equipment.

Technical

Example of good quality British made multimeter of the period and one of the major manufacturers of this type of equipment.

Area Notes

Unknown

Details

Markings

'MODEL/ 7/ UNIVERSAL/ AVOMETER' appears on casing front. All dials labelled. 'ACCURACY B-S-1 NO. 34764-A-952 PART NO. 10945-19' printed on face. Four scales, all labelled. Panel on back of casing bears following info.: ‘UNIVERSAL AVOMETER MODEL 7 WORKING INSTRUCTIONS, IMPORTANT. GENERAL. To ensure accurate readings, use the instrument face upwards. If necessary, set the pointer to D.C. zero by means of the screw in the panel. The A.C. switch must be at its D.C. position for this operation. On A.C. ranges the pointer is automatically displaced from D.C. zero to correct for internal losses, the 1½V cell being employed for this purpose. D.C. tests can only be carried out with the D.C. switch set to the appropriate range and with the D.C. switch set to the appropriate range and with the A.C. switch at its D.C. position. The reverse procedure applies to A.C. tests. To prevent damage to the instrument, see that it is set to a suitable range before connecting to the circuit under test. When in doubt set to the highest range and work downwards, there being no necessity to disconnect the leads. Do not however, switch off by rotating the switches to blank positions. The automatic cut-out completely protects the instrument in the case of normal overload by interrupting the main circuit. If it operates DO NOT re-set with the leads connected to the supply, but ensure that the fault is cleared before continuing tests. Since mechanical shock may cause the cut-out to trip, handle the meter carefully. Do not lubricate the plunger. / The___ 2 button is for use when measuring current and voltage only, and if the meter is on a normal range, it should never be pressed when the pointer shows more than half scale deflection. The resistance of the meter is the same on the press button range as on the normal one. Press the button firmly./ KNOB "Q" MUST ALWAYS BE REPLACED IN NORMAL POSITION AFTER USE./ A copper oxide rectifier is incorporated for A.C. measurements and the instrument calibrated for sinusoidal input (form factor 1.11.). Special care should be exercised when using high voltages. If the meter is used to measure voltage calling for an external multiplier, or to measure current in such a circuit, it must be used at the earth potential end./ AMPERES [underlined]: Ten ranges D.C. and eight ranges A.C. are incorporated. These ranges may be extended by the use of external shunts (100mV) or transformers (secondary to suit a current range)./ VOLTS [underlined]: Ten ranges D.C. In addition the 2mA range can be used as one of 100mV or 50mV with the button pressed. Eight ranges A.C. suitable for out-put measurements at audio frequency. All normal ranges of D.C. and A.C. except 10V. A.C. consume 2mA at full scale deflection (500 ohms per volt) or fmA at full scale for press button ranges (1,000 ohms per volt) the current being proportionally less for smaller deflections. The 10V A.C. and 5V A.C. ranges consume 20 and 10mA respectively at full scale deflection./ OHMS [underlined]: Three self-contained ranges and two using external voltage. The press button should not be used on resistance ranges./ 10,000 and 100,000 ohms ranges [underlined]: Before commencing tests on these ranges, it is advisable to check, and if necessary, to adjust for both voltage and resistance of the 1½V cell by means of the potentiometer "P" and resistance "R": (1) Connect leads together. (2) With switch at 100,000 ohms position adjust by "P" so that the pointer indicates approximately 0 ohms. (3) Adjust by "R" when on 10,000 ohms range until pointer takes up the same position irrespective of whether the switch is on the 10,000 or 100,000 ohms range. (4) Set accurately to zero ohms by means of "P"./ MEGOHM RANGE [underlined]: Before testing on this range, it is necessary to adjust as follows: (1) Connect leads together. (2) Set switch to 1 megohm position. (3) Raise adjusting knob "Q" and rotate in a clockwise direction until the pointer indicates 0 ohms. After carrying out tests on this range, return knob "Q" to its normal position in the panel./ BATTERY REPLACEMENT [underlined]: If it is impossible to obtain zero ohms setting, the internal batteries should be replaced, a 1½V cell for the two lower ranges and two 4½V batteries for the high range./ 10 & 40 MEGOHM RANGES [underlined]: These ranges are available by using the 100 or 400V A.C. or D.C. ranges respectively in conjunction with a suitable source of voltage. It is safe and correct to use a voltage between 2/3 to 2½ times that of the range in use, adjustment for zero on the ohms scale being carried out by means of "Q" knob. After adjusting for voltage the test resistance is connected in series, its value being that shown on the ohms scale multiplied by 1,000 or 4,000 as the case may be. With these high voltages the circuit should not be handled while "live". Return "Q" knob to its normal position in panel after tests./ CAPACITY [underlined]: 50 ~ A.C. mains supply from 65 to 250V should be connected to the meter when set to its capacity range, and the "Q" knob should be operated as in the megohm range, to bring the pointer to its infinity capacity position. The unknown condenser should then be connected in series, direct indication of capacity being shown within usual commercial limits of accuracy. Frequencies other than 50 cycles may be used, but this affects the voltage necessary for adjustment. 250V A.C. must not be exceeded. Return "Q" knob to its normal position after tests./ POWER AND DECIBELS [underlined]: This range gives a maximum of 2 watts, the impedance being 5,000 ohms. The corresponding dB scale is calibrated from -15 to +16dB the reference level (O.d.B.) being 50mW. The 10V A.C. and the 100V A.C. ranges can be used as power ranges of 200mW. The impedance being 500 and 50,000 ohms respectively. The A.C. switch position marked with a spot (31.5mA) is for the extension of power and decibels up to 20 watts and +26 d.B. when used in conjunction with external load resistances (see Instructions leaflet M.21)./ POWER FACTOR AND WATTAGE [underlined]: The two sockets marked "P.F." at the top of the panel are for use with the Model & "Power Factor and Wattage Unit". See instruction booklet: THE AUTOMATIC COIL WINDER AND ELECTRICAL EQUIPMENT COMPANY LIMITED. Winder House, Douglas Street, London, S.W.I. The "AVOMETER" is patented in the principal countries throughout the world. British Patent Nos. 200977, 404015, 464867, 476683, 476738. The word "AVOMETER" is our registered Trade Mark. ‘MADE IN ENGLAND'. / ‘412-016-636' incised into upper right of panel.

Missing

none

Finish

Black crinkle/white lettering on control buttons.

Decoration

N/A