The instrument is exactly 30μA and it has the correct internal resistence. In October 1960 AVO added protection to the 30μA meter of the Mk IV and it consisted of back to back silicon diodes across the meter terminals. In addition, AVO also fitted a 8μFcapacitor across the terminals.
This instrument is NEW and already equipped with these features to increase its protection.
Beside that, AVO Mk III, Mk IV and 160 used a 10kΩ shunt resistor (making it effectively a 40μA meter). I am including a10Ω ±0.1% 25ppm/ºC resistor that can be mounted in the meter PCB (check pictures) if your original resistor is damaged.
This instrument is 122x100mm, a bit larger than the original but fits perfectly in AVO models MkIII, Mk IV and 160 (please check pictures).
I own AVO Mk III, Mk IV and 160 and all of these meters were bought with a damaged galvanometer. AVO instruments are very sought after and a
working instrument is extremely expensive. You might find one with a damaged meter or without it for a decent price.
So, this KIT includes the 30μA meter with a PCB that contains the 2 diodes, a 8.2μF Panasonic polipropilene capacitor and a 0.1% precision resistor that I can send assembled or not in the PCB.
Contact if you need help or have questions.
The price includes tracked shipping to any part of the world.