AVO Test Set Multi Range No 1

AVO Test Set Multi Range No 1 High Sensitivity (NATO part number 6625-99-105-7050) s/n 12195-8-71 with leads clips and probes working

This, an ex-Royal Air Force instrument last calibrated in 1989 and unopened since cost me £2.00. In appearance it looks very similar to the Avo Model 8 though on closer inspection we see that the scale markings ar clearer and less cluttered, the dB range has been omitted and the ranges are in multiples of 1 and 3 rather than 1 and 2.5 on the model 8. Apart from this Test Set No 1 has a steel protective casing, is fitted with an internal fuse and the internal components are potted in epoxy resin. Electrically the circuit which also has a 37.5 uA movement is almost identical to that of the model 8 (apart from the values of the resistors). I have been advised by a visitor to this page who owns both the AVO 8 and the AVO 9 that this instrument is a military version of the AVO 9 MK 2

How old is it? Most AVO meters can be dated from the last 3 or 4 digits of the serial number under the right hand end of the scale. These define the month and year of manufacture. For example No. 12195-8-71 would mean that this one was made in August 1971.

Weight Of the three Avo multimeters featured on this site this is the heaviest by far at 3795 grams.

For further information have a look at my pages on the model 8 AVO and Model 7 here and here