Yay another old relic from the past, made in UK sometime between 1956 and 1964 — AVO Model 8 MK2. AVO stands for Ammeter-Voltmeter-Ohmeter.
AC and DC ranges are controllable by individual knobs. When the knob on the left is set for AC for example, you use the right knob to control the range of AC measurement. When a knob is set upright to either the AC or DC position the meter is connected and working. If neither knobs are set to AC or DC the meter is disconnected, protecting you from damaging the meter or getting inaccurate measurements by using it on the wrong setting. Has individual knobs to zero out the meter on the resistance setting. Even has the mirrored panel on the display to limit parallax error.
This thing is accurate, and the build quality cannot be overstated. It is as big as a brick, and weights probably almost as much as one. The meter was calibrated in the laying down position and is most accurate in that arrangement. Hard to see, but the whole front panel has a o-ring to keep dust and water out.
Visit the fanboy site here and become one — http://www.richardsradios.co.uk/AVOmultimeters.html
No way I could photograph this thing and relay it in all its glory. Anyway you get the idea. It goes without saying, but “they don’t make ’em like that anymore.” Serial number 73872 handwritten in pencil in various places.
Look at the bottom board, wrapped in wire. I believe those are wire wound “precision” resistors, the precision of the resistor based on how long the length of wire is. A world-class meter, top of the line for it’s day.
AVO 8 MK2 schematic
AVO MK1 and MK2 user manual HERE