The Universal AvoMeter

AvoMeter Model 9 SX

Created: January 2009
Updated: 19th January 2014

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In early 2009, I bought an AvoMeter Model 9 SX for about £10. It needed a bit of a clean, but otherwise it works fine. The lower terminals have at some point been replaced by the newer safety types, and some of the bronze paint has come off. This didn't matter to me as I wasn't looking for a pristine example, but rather a model that wasn't too expensive and works, as I intend to make good use of it. All the AC, DC and Ohms ranges work, and the batteries that were included with it also seem to work fine.

The serial number indicates that this model would have been made in 1963. As far as I'm aware, the only difference between this Model 9 SX and the earlier Model 8s, is that it has a metal case and that some of the internal components are potted. This model is also known as Test Set Multi Range No. 1. The only other examples of Test Sets/Model 9s that I have seen have been a few photographs on the internet, and a couple in college, however, all these have been newer (late 1960s/early 1970s) and have had different scales (similar to the newer models such as MkIV). 

Switches and Cut-Out

The AvoMeter has a interesting (and useful) cutout mechanism, which will disconnect the meter from the inputs in the event of an overload. When the pointer bashes the end of the scale, it triggers the mechanism which pops out the switch on the front. You then remove the overload, and press the switch back in. Unfortunately, the cut out doesn't work on this particular meter.

I'd have to say that these old Avos have the best range switches of any multimeters. Many people debate which multimeter has the best range switches, and my vote goes to the old Avo. They are wonderfully solid and clicky :).

At the time of updating this page (2014), the AvoMeter is in pieces. I had taken it apart to clean the switches and investigate how the cut out mechanism works. I was unable to repair the cut out, but so far haven't got round to putting the meter back together. That will have to be a job for a rainy day.

Information and Photographs

Have a look at for more information on AVO Meters, and a comparison of the newer and older scales.

Below are several pictures of my AVO Meter. Click on the images to see them at their full resolution.

Photo of AvoMeter Model 9 SX

The AVO Meter on my desk. The Metal case is probably the most heavy part of this model. Some of the bronze paint from the top and the white paint from the front has come off, and the lower terminals have been replaced by the safety type which are often found on newer multimeters.

AvoMeter Instructions

The instructions on the back explain how to operate the instrument. These ones aren't in very good condition but are readable. I don't know who owned this meter previously, but it could have been a school. There's a sticker on the bottom of the meter which says it was originally with the Royal Electrical and Mechanical Engineers.

Measuring a voltage

The AvoMeter correctly measures the 5 Volt output from the fixed power supply. The inexpensive digital meter is also connected to the same power supply.

Centre of the scale

Centre of the scale

Start of the scale

Start of the scale

Cool websites I recommend you should check out:

ClassicAmiga - Your Guide to everything Amiga

Amiga Computing and Retro Gaming

Link to Dave Jones EEVBlog

Electronics Video Blog

Electronics, Solar Power and Metrology

Old-School Game Blog

Other links:

The Aussie Space Time Traveller

E-Maculation - Macintosh Emulation

EEWeb - Electrical Engineering Community