AVO Multimeter survey

[rob_bush]

Hi,
Another Avo to add to the survey - I have an AVO8 MK3 with the serial number 46753 - 966 hand written on the meter face.
If it is of any interest, I also have a resistance range extension unit with it, and
I could send photos of these units.

Cheers, Rob_B

[Paul Adams]

Here's a few more: 2255-IV-1169 (Model 9 mk4), mint condition still has seal in case.
22392 (Multiminor mk5).
10050874 (Heavy Duty)
68894-1267 (Model 8 mk3)

All bargains that i couldn't resist ! and what's more i now have over 20 AVO's, i think i may be addicted.

[kelvinmunson]

I have a Model 7X with the serial number on a label on the side...... very difficult to read.

Appears to read Ser No 46592 7X/6...... so no indication of when manufactured ?

Regards

Kelvin

[kelvinmunson]

I have just picked up a couple of AVOs.

Model 8 Mk IV & 9 Mk IV....... (what does this mean, are there 2 versions of this type of unit and how can they be identified ?) No serial number I can find, is it hidden somewhere ?

Model 40 ser No 7407-8-852........ guess this is an August 52 creation ?

Regards

kelvin

[kelvinmunson]

A further addition:-

Model D Ser No 21826-1045.

This has a single 1.5V battery fitted, is this correct ?

Regards

Kelvin

[derbeian]

I have a model 7 with the serial number hand printed on the scale 14263-A-350.

Regards

Ian

[pmmunro]

Rob_b,

Thanks for contributing. The resistance extension units are much less common than the meters but still turn up from time to time. Do you have a set of batteries for the high resistance range? These are rarer still and a good photograph of the batteries would be interesting.

Antony G,

Thanks for the information. Congratulations on finding a Model 9 Mark IV in such good condition. A high proportion have cracks around the screw holes in the case - easily induced if overtightened. Is the serial number on the scaleplate or on a label on the side of the case? (See comment below).

Don't worry about your collecting compulsion too much - 20 Avometers is only an obsession, you will be truly addicted once you pass the 100 mark! It all goes to show how many are still about.

Kelvin,

Looks like you too are now well on the way to addiction to the Avo collecting bug. Thanks to you and all other contributors for the incoming information.

The Model 8 Mark IV was a Thorn rationalisation of the Avometer which attempted to reduce production costs. You will find more detail earlier in this and other threads. The same rear instruction plate was used on both the Model 8 and the Model 9.

The Model 8 has the traditional 1 - 2.5 -10 scale progression and English language markings, the Model 9 was an "international" version with 1 - 3 - 10 scale progression and symbolic markings.

With typical Avo logic in designations, i.e. undiscernible to the outsider, the Model 8 Mark III was introduced in June 1964 followed by the first Model 9, the Mark II, in September 1964. (This is based on Avo Wireless World advertisements which appeared every month at this time). In 1970, both were redesigned as described above without there ever having been a Model 9 Mark III.

Later, possibly all Mark IV serial numbers were on a self-adhesive label on the side of the case, as for your Model 7X, and may have been repeated within the battery compartment.

By December 1972 all versions of the Models 8 & 9, including the military, panclimatic and screened versions had been replaced by the Model 8 Mark V which was designed and tested to a NATO specification. The Post Office testmeter 14C is also essentially am Model 8 Mark V - if anyone knows if there is any difference in specification I would be interested to have details.

Can you confirm that the intermediate character of your Model 40 is an '8' - a 'B' is probably more likely?

The Model D uses just a single 1.5 volt cell for its resistance ranges. (Battery Dry, 1 1/2 volt No. 6, 5S/2000)

The first attachment shows a replica of the original type alongside a later NATO replacement, the second attachment shows how the replica was made and what it looks like before the case is dipped in wax. (For the chronological purists, the 18th January 1945 was a Thursday, but I expect that Crompton Parkinson were working at least six days a week at the time).

PMM.

[kelvinmunson]

Originally Posted by pmmunro

The Model 8 has the traditional 1 - 2.5 -10 scale progression and English language markings, the Model 9 was an "international" version with 1 - 3 - 10 scale progression and symbolic markings.

Later, possibly all Mark IV serial numbers were on a self-adhesive label on the side of the case, as for your Model 7X, and may have been repeated within the battery compartment.

Can you confirm that the intermediate character of your Model 40 is an '8' - a 'B' is probably more likely?

The Model D uses just a single 1.5 volt cell for its resistance ranges. (Battery Dry, 1 1/2 volt No. 6, 5S/2000)

The first attachment shows a replica of the original type alongside a later NATO replacement, the second attachment shows how the replica was made and what it looks like before the case is dipped in wax. (For the chronological purists, the 18th January 1945 was a Thursday, but I expect that Crompton Parkinson were working at least six days a week at the time).

PMM.

Hi PMM,

Many thanks for the interesting information.

The Model 8/9 has the 1-3-10 scale progression and symbolic markings ; so it is a Model 9 Mk IV

Can't find a label inside of the battery compartment of the 7X, but will let you know if I spot anything.

The intermediate character in the serial number of the Model 40 is a 'B' .

The Model D has a D-cell battery with a screw in the positive terminal, very similar to the one shown in your image of the internal construction of the original battery.

best Regards

Kelvin

[Paul Adams]

Hi PMM,
Many thanks for your reply, and i can confirm that the serial number is on the scale plate.

I have included some photo's for your perusal !

Paul.

[rob_bush]

Hi PMM, Many thanks for your reply, unfortunately I don’t have any of the high voltage batteries for the resistance range extension unit, but it looks like they are still made by the American Eveready company as a type 413. they appear to be available in the UK here: http://www.smallbattery.company.org.uk/A413.jpg
there are photo's on this site and on ebay of these batteries.

Cheers, Rob.

[kelvinmunson]

Hi PMM

I now have a Pan-Climatic No 1, ser no 7048-1S-464.

It has a nice beige case, in good condition, minus the metal battery cover, and I need to check what battery it needs. There is a Type D on the RHS and a large space with a couple of (front and back) flat plates on the LHS

[pmmunro]

Kelvin,

The Test Set No.1 based on the Modeln 8 and uses the same cell and battery. For the highest resistance range this should be a 15 volt BLR121 or similar as discussed previously within the forum.

As you will see there are alternatives and some users choose to make up their own battery from a stack of coin cells.

PMM.

[Paul Adams]

Hi Everyone,
Twenty Five AVO's now, and the latest edition a AVO 8 mark 7, nice but i much prefer the old bakerlite case's not these plastic efforts.

Paul.

[Moonman]

Hi, I have two Universal AVO Minors and am trying to work their ages out. One is U.67453-644 which I guess is June 1944 and the other is U.26796-88, which I can't decipher. Any bofins know the code? Very interested, Thanks Moonman.

[Paul Adams]

Hi All,
Another Serial Number for the collection, a model 12 bought from a friend of a work colleague.
3,898-6-71. Complete with 360Amp shunt.

[redrikus]

I just bought this one on an auction site.

It replaces my original that I had used since I was 15. I loaned it to someone and they ran off with it.

I now have a Panclimatic MkII (I think). It has a bronze hammered metal case and came in a professionally made wooden case which has Admiralty user instructions printed on what looks to be a metal back plate for the meter.

These instructions detail how to use various high current shunts and a 3600 Volt adapter. Unfortunately these accessories are not with the meter.

The serial number is Model 8. No 170533-C265.

I have ordered a 15Volt battery and hope to make the Ohms x100 ragne work.

[Stockden]

and another one..

This is an ex-CAA Model 8 Mk2 (I think) though it's marked with a broad arrow and "10S/16411". The serial number is 39853-C-1055.

[mjvor130]

I have an Avominor SN 64024-541 in its original case but with no leads. It was given to me by my very good friend the late Harry Currie, Senior Lecturer, Liverpool John Moores University, who rescued it before it was scrapped.
I love the label which states "REMOVE THIS PLATE TO EXPOSE CELL" (not battery). I never see the word CELL these days unless it's referring to a US mobile 'phone.

[Darren-UK]

"Cell" in the electrical sense is most likely correct, depending on what the Avominor uses. A battery is a bank of cells, so what are nowadays termed AAA, AA, C and D are technically cells and not batteries. The PP3, PP7 and PP9 are batteries as they (usually) contain cells in series.

"Cell" in the mobile 'phone context means something totally different. None of this is relevant to this thread though, so we'll leave it at that.

[Paul Adams]

Another Model 8: Serial 20704-C-154
Bought at a Car Boot for £4.