AVO Multimeter survey

[Paul Adams]

Yes I said no more avo’s, but couldn’t resist this one, and after reorganizing the workshop I found that I had room for even more

Model ‘D’ serial 21004-745-1945.

Oh, and some before and after pictures, and of the reorganized workshop.

Paul.

[pmmunro]

Paul,

You appear to have reached your three score and ten - Avometers that is, we won't talk about years.

However, if you are looking for suggestions, perhaps you might like to consider some diversification into Electronic Avometers, the CT38 and CT471, Models 10, 14, 15, 16 and 20 - and perhaps a few more Model 12s?

Nice work on the latest 'D' - you could always consider the "other makes" type Ds just for completeness.

Thanks for the information.

PMM

[Paul Adams]

Has anyone any idea what model this avo is? There’s no instruction plate on the rear to identify it from that, but on the scale plate there is this: Type ‘V’ 10S/821. Serial: 302.V.448, I’ve not seen one of these before.

As you can see it nearly arrived in two pieces as there’s a crack on the right hand side of the meter, another mystery is that there was a spring and a small screw rattling about inside, and I have yet to find where these have come from.

Also there's no mechanical zero ohms adjust on the front of the meter, will need to take it apart to investigate further.

The cut-out is seized and also the ‘press’ button on the ‘low ohms switch’

Paul.

[Paul Adams]

More pics....

Paul.

[pmmunro]

Paul,

It's an HR Avometer from c. 1948 to 1951. You should find some discussion of the type on the forum a few months ago.

There are two basic versions with different resistance ranges and there was a Panclimatic version.

The movement is a 50 microamp block magnet type but with the Model 7 acceleration cut-out facility. This was not carried on into the Model 8, possibly because this moving coil arrangement seems to have been very delicate. Model HRs seem to suffer from o/c moving coil faults.

PMM

[Paul Adams]

It became apparent of the mystery of the mechanical zero, now I have removed the movement I can see were the spring that was rattling about inside has come from. It has a piece broken off, like the one on the left of picture 1.

The one on the left won’t fit as the inside diameter is too small on the ‘z‘ knob, it came from an 8 mk1.

Anyway I made a similar one from an old battery holder (the quick and dirty approach), and bent it to shape.

The zero works now, which is about all.

PMM, Thank You for that info, I will take a look.

Paul.

[Phil G4SPZ]

Not more Avos, Paul?! That "workshop" of yours could better be described as a "showroom"...!

I also recognised the High Resistance Avometer. The odd-looking lettering on the switch faces is the giveaway. If the movement is actually OK, you have a relatively rare item there... let us know once you've tested it fully.

Phil

[ririsko]

Hello,


I just bought a nice box with "Universal Avometer" on its front plate but I am a little bit confused about its age. It looks to be "Test Set Multirange No.1 High Sensitivity" - due to this text on the scale (and 1-3-10...3000 range), but I am unable to locate valid SER.No to know its age. There is a Part. No. 13574-80 in the right bottom corner of scale and SER. No.5967 (but these numbers are handwritten, over-stroked and replaced by numbers 5336) in the left bottom corner.

Is there any chance to help? If you need some pictures, please let me know what detail can be useful, I will upload them.

Many thanks in advance,

Richard

[pmmunro]

Richard,

Some pictures would definitely help. One of the front panel showing the general appearance and ranges, details of the scale plate, especially the lower edge at left and right, and the instruction plate on the back should do.

PMM.

[ririsko]

Thanks, PMM

I tried my best and pictures (front panel, bottom plate with instructions and detail of scale plate) are included. Sorry for poor quality, I have just mobile phone camera available now, but I think it will be readable enough - except of Serial.No. at the left, second number I mentioned (5336) is written with very thin and light grey pen and is not readable on the picture, only its shadow is there on the picture, sorry about it.

thanks again,
Richard

[Gulliver]

I have an Avometer 8 MK II S/N 92249-C-659

It looks a bit ratty with the paint coming off the scale but it works fine.

I have parts of another, S/N 57523-C-357

[jmedley]

I have two AVO 8s

9645-C-1152

10827-265

Jim

[phasedout]

Hi, yet another Avo 40, serial No 6806-1141, am i correct in assuming this was made in November 1941....regards....Alan.

[HamishBoxer]

I have an AVO 8 MK4 but there is no serial number on the dial. Or inside battery cover,any thoughts??

[pmmunro]

Richard,

The serial number change on your meter would suggest that it has been repaired by a movement exchange at some time. However the serial number does not seem to be complete as I would expect some date code in addition to the basic number.

The Dover address means that it was made after 1964, when the Dover factory opened. It was probably made before 1972 because the Model 8 Mark V was intended to replace all previous Model 8 and Model 9 instruments from then and was designed to meet a NATO specification. However it is difficult to be certain about military versions because there is no way of knowing what contracts were placed at any given time. Although a new version meeting NATO requirements became available I would not be surprised if some department or specification insisted on a previous version.

Sorry I can't date your meter more exactly; eventually, once it has all been collated, it may be possible to be more exact.


Gulliver,

Could I confirm that it is the scaleplate and not the instruction plate that is damaged? It is unusual for Model 8 scaleplates to loose paint although it is a common failing on pre-1939 Avometers in which, in most meters, the scaleplate paint was applied over the nickel plating which provided the mirror arc.

Jim,

Your model 8s will be a Mark I- 1952 - (not actually asigned a mark number by ACWEECO) and the other a Mark III, 1965. Thanks for the data.

Alan,

I think your Model 40 is one of the first to use this serial number pattern in which case it will be from 1941. A photograph would help to confirm this. The earliest Model 40 meters (from 1939/40) had serial numbers in the form 40YY-XXXXX.

Hamish,

Later Model 8 Mark IV Avometers had their serial numbers on self-adhesive labels on the left hand side of the back case in the style of the Mark V. On some meters there was a second label in the battery compartment, but I don't know if this started with the Mark IV or if it was always done.

The Mark IV case usually cracked from around the fixing screw holes and a Mark V style replacement was supplied as a spare part. These redesigned cases were black with a leather grain surface finish in contrast to the smooth shiny grey of the original Mark IV case. If your meter's case has been replaced, it is unlikely that the serial number label would or could have been transferred.

PMM

[HamishBoxer]

Very intresting Thank You,certainly the case is grey and MK4 is on the movement.

[Paul Adams]

Another one for the 'showroom' as Phil put's it; AvoMinor, S/N: U.126116-853.
Complete with original cotton covered leads and box.

Paul.

[line sync]

Hi
I,ve got an AVO 7 mk2 in good condition with its leather case and set of test leads.
The serial no is :- 5xxxx-A-855 .
I would like to get this meter up and running again but obtaining the batteries is a bit of a problem , can any one out there offer some advice please .

Thanks , Robin

[russell_w_b]

Originally Posted by line sync

'...but obtaining the batteries is a bit of a problem , can any one out there offer some advice please .'

The AVO 7 II takes a 'D'-Cell and a couple of 4.5V MN1203's, doesn't it?
http://www.amazon.co.uk/Battery-carb.../dp/B0012ZJRBU

Or just use a 9V PP3 in a bit of bubble-wrap?

[line sync]

Thankyou for your reply russel.
I,ll order 2 of those 4.5v batteries tomorrow.
I,ve never used this meter before so had no idear what the batts looks like other than the 1.5v cell was square shaped.

Robin