AVO Meter for Sale on eBay

The AVO Meter (also known as AVOMETER) is often for sale on eBay where you can find Model 7, Model 8, and many others in the series. It is without a doubt that this is a popular meter because it has a damped needle response, which majestically floats over the dial. Designed to military specifications, it can operate in a wide range of environments, and most important of all, it is robust and lasts.

Buying a used meter on eBay can be tricky, and there are many pitfalls. The main pitfall comes when it is for sale as "Untested" or "Spares and Repairs". Granted, that this is a very complicated electronic measuring instrument and your average seller may not understand how to operate it, however it is risky buying a meter listed as untested. There are sellers who genuinely do not know how to use it; however, unscrupulous sellers also use the same heading for selling things that are beyond repair.


Spares and Repairs

To qualify for "Spares and Repairs", the meter should be in a reasonable condition, inside and outside, and has a reasonable chance of working, or has sufficient spares inside. However, I managed to buy one meter, which was cobbled together from broken parts taken from other meters. The meter movement was broken and showing signs of repair, the voice coil burnt, in addition to a faulty rectifier, faulty switches, faulty boards, and missing parts. There were no usable spares, and it was beyond repair because everything was broken or faulty.

Battery Acid Damage

I also bought another meter, which had battery acid damage. The acid had leaked onto the printed circuit boards and consequently all the copper traces had dissolved. The acid had also eaten into the coils and the switch contacts, and therefore something like this is beyond repair and not much use for spares either.

Smashed Avometer

I also bought one meter from a total toe-rag, and when it arrived, it had only two screws, of the wrong type, securing the back cover. When I removed the back cover, I was astounded to find that all the boards were smashed as if someone had taken a hammer to them. I contacted the seller to inform him, but he said that selling it as "Spares or Repairs" covers him. Therefore, I asked him about returns, because the listing had nothing specific about returns, but again his answer was that those three words cover him for that as well!

Test it Before Selling – "The Pete Test"

AVO Test

A genuine seller can make more money if they test the meter, which would provide a small measure of confidence that it is working for the most part. Many people do not realise that this meter can measure voltage without requiring internal batteries. All you need is a pair of wires, each connected to the bottom pair of red and black captive terminals. The terminal caps unscrew to facilitate the connection of a stripped wire; therefore, you do not require the original probes either.

  1. Make sure that the overload cut-out switch is pressed in.
  2. Set the right-hand knob to DC, which is when the arrow is pointing straight up.
  3. Set the left-hand knob to 3 in the DC volts range.
  4. Connect the wires to a new "AA" size 1.5 V battery.

If the needle freely moves close to 1.5 on the scale then the meter is working for the most part. Take a photograph of the meter scale to upload in your listing. This basic test does not mean that everything is working, but it does mean that the main parts of the meter are working, and therefore gives confidence to the buyer.

Not Repairable

A meter consists of many parts, many of which are not repairable and replaceable. Here is a small list of parts that are not repairable.

  1. A dislodged meter movement
  2. Burnt meter voice coil
  3. Broken meter movement springs
  4. Burnt overload cut-out contacts
  5. Broken range selector switch
  6. Excessively smashed PCB

Repairable

Here is a list of faults that are repairable with replacement components.

  1. Broken or burnt resistors
  2. Faulty capacitors
  3. Burnt resistance coils and shunts
  4. Missing screws
  5. Broken dial glass
  6. Cracked PCB
  7. Balancing a meter movement
  8. Missing or broken captive terminals

Cost / Price

The AVO enjoyed a very large production run reaching into the millions. During the Second World War, the Armed Forces and the scientific communities placed tens of thousands of orders. After the war, it had huge sales worldwide, with well over a million units sold by 1966.

The AVO meter is valuable only because of its usefulness, and therefore a working meter is more valuable than a non-working one selling as untested. Consequently, an "Untested" meter loses value sharply. For example, a meter on its own, with worn out range markings, missing battery cover, scratches, missing captive terminals, and untested, should sell for five pounds.

However, the other extreme end of the scale is a meter in mint cosmetic condition, together with the original leather case, probe wires, and manual. The seller has bought new batteries for it and tested it showing that it is fully functioning, hence a meter such as this can sell in the order of hundreds on a good day.