The AVOmeter model 6 was a development of the original AVO multimeter which started life back in 1923. You will find more information here about these instruments and other similar models. AVO also produced a range of smaller multimeters which are described here.
model 6 s/n 6540
This model has a 3 mA movement housed in an aluminium
case. The model 6 which was first made in about 1934/5
is quite a rarity as by that time the firm was also producing the more
versatile universal AC/DC models.
As can be seen the model 6 which incorporates a divide by 2 button
looks much the same as the model2 but has terminals rather than
leads. The earlier model has a sensitivity of 6mA
The model 6 with the divide by 2 button shown here looks much the same as the previous model 2 except the horse shoe magnet is aligned at right angles to the panel.
The paint on the scale of this instrument had flaked and
curled up completely inhibiting any forward movement of the pointer, my
attempts to glue the curled pieces were singularly unsuccessful,
resulting in more damage and causing it to come away in flakes. I stuck
these back as best I could into position and scanned the result. Then
after some editing on the computer printed out a reasonable facsimile
as shown here on the right, this was glued on top of what remains of
the original scale markings.
This is how the model 6 looked like
before it was cleaned up and fitted with new terminals
Batteries A rectangular 1.5 volt cell with a brass terminal and a flying lead for the negative connection. The 1.5 volt battery can be replaced with a single cell size D to with soldered connections.
What is it worth? This one was a gift, but this model is fairly rare so a collector might expect to pay £40 or so. The model 8 being more sensitive is probably a better investment, you should be able to buy a model 8 MkII for£10- 20 which you will find equally as good as the later models.