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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders.

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Old 17th Dec 2018, 4:14 pm   #1881
avocollector
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Default Re: AVO Multimeter survey

Latest buy = Avometer Model EM 272 Black label inside says KC No 0526163 EM272.
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Old 17th Dec 2018, 7:38 pm   #1882
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That's really good News Phil,
Thanks for letting us know.
Fantastic News, as I seem to remember some concern about Paul's
well being not that long ago on the Forum.

I was going to ask if anybody had seen or heard from Paul.
I don't know him personally, only from his posts on this Forum,

He also holds the Number One Spot for the most Serial Numbers given
to this Thread. By some Margin!

I hope we will see him back here sometime soon


Ian
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Old 17th Dec 2018, 9:40 pm   #1883
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We don't have access to passwords, but I've reset Paul's and emailed him the details.
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Old 17th Dec 2018, 10:11 pm   #1884
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Bill, that’s very kind of you. However the e-mail address for Paul that is on your files had to change when his PC failed, and he can no longer access that account. However, I’ll take the liberty of sending you a PM with Paul’s current e-mail address.

Thanks again for your help.
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Old 17th Dec 2018, 10:32 pm   #1885
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Thank You Bill, and Phil.

It's been a while since I was last on, sorry to have worried everyone.

Paul.
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Old 17th Dec 2018, 10:35 pm   #1886
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Hi Paul,

Great to have you back! Thanks also to Bill for his prompt intervention.

Paul, you’ll have to remind us what you managed to do with that last job lot of Avos you bought... thirty or more, I seem to recall?

Phil
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Last edited by Phil G4SPZ; 17th Dec 2018 at 10:37 pm. Reason: Typo
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Old 17th Dec 2018, 10:39 pm   #1887
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The famous Paul!, Hello, is Aitor from Canary Islands, an Avo collector!!
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Old 17th Dec 2018, 11:34 pm   #1888
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Nice job on that Type 107 Paul, glad to hear you are well.

Dave
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Old 20th Dec 2018, 8:51 pm   #1889
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Another one, AVO 40mk2

serial number 12678 40 /74
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Old 27th Dec 2018, 1:06 am   #1890
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Another one to my collection:

AVO 8 mk5

SERIAL NUMBER 0025151 LA

On a label at right hand side and in battery compartment
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Old 28th Dec 2018, 3:01 pm   #1891
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AVO 8 first generation serial number 6955 C 852

August 1952
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Old 28th Dec 2018, 5:04 pm   #1892
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AVO 40 mk2

Serial number 14827-B-657

In a Bakelite case with a label in the left AVO LTD DOVER ENGLAND
SETIAL NUMBER 12678. 40/74

I think this case is from another avo correct?

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Old 28th Dec 2018, 10:08 pm   #1893
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Aitor,

You are right; the case is not the original for your meter. AVO opened the Dover factory in 1964 although production continued at both London and Dover for some time.

PMM.
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Old 28th Dec 2018, 10:42 pm   #1894
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Thanks.

Then the original for a 1957 avo 40 mk2 should be Bakelite or metal as AVo 40 mk1? or this one is valid without the label?

I can read in the metal plate on the back of the bakelite case "universal Avometer model 40... Avo ltd Dover".

So i think is from an AVO 40 made much later? The thing is that the plate in spite of having "Dover" has also AVO 40, and Avo 40 as far as i know finish in 1952, and the manufacturing in Dover began as you sad in 1964, so the plate should read AVo 40 mk2 or not?

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Old 31st Dec 2018, 9:16 am   #1895
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Aitor,

The Model 40 was produced well into the 1970s although I don't know when production finally stopped. Metal and phenolic (Bakelite) cases seem to have been used almost at random until the late 1960s after when most seem to have been the phenolic type.

PMM
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Old 31st Dec 2018, 2:09 pm   #1896
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We have 3 Models 40's recorded from 1978, but none after this Date.
The latest being Nov 1978.
So they were made at least up to this Date.

However, I know of at least One Model 7 from 1987, so AVO were
obviously still able to manufacture the old School Meters long after
1978.

Unfortunately, I can't say what type of Case any of them had, as this
information was never recorded in the Survey.


Ian
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Old 1st Jan 2019, 1:12 pm   #1897
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Universal Avominor Model 1A 1951-1156 (Nov 1956) New purchase.

Nothing particularly special since over 3,300 were made, but interesting in regard to the ZD03063 military provisioning number on the carcase (and ZD03062 on the leather case)
On the instruction plate there are two faint purple stamps, the commonly found circular avo stamp, and also an Air Ministry crown with '33' below it. This seems to confirm the previous owner's belief that is is ex RAF....and might even confirm that the ZD references were specific to the Air Ministry (unless you know better!)

Well cared for and unsullied/undisturbed inside, but given a tweak and a clean as errant readings started to manifest.

This is what i call a shoehorn model- the top 3 voltage ranges are mounted on a (phenolic?) backpack, 5 welwyn 1% tolerance resistors, but clearly cherry-picked as the tolerance is far better than 1%, nearer to 0.2%. Comparable in fact to the wire wound bobbins previously used. This could have been a contract requirement...?
This backpack has fly-leads which are single core, and are prone to fracture when disturbed, so i dispensed with the leads and installed multi-core PTFE leads (courtesy of Vactite in Bootle, a very old reel)

The lack of access bestowed by this backpack makes it 'false time economy' not to attend to every single gremlin that might be lurking, so the central shaft of the ohms pot. was polished and visible flakes of iron removed from the area of the magnet, and every possible dot of debris removed. Even so i had to go in a second time as an extra flake of iron only 10 thou across had moved itself into position to jam the movement, and one (of the three!) switch contacts that has to close for DC & OHMS to function needed to have it's leaf bent upwards.

I really wasn't expecting much from the Low Resistance Range, but it turns out that if all 4 wander plug terminals used for this range are clean and bright it is dead accurate at 2 ohms and 20 ohms.

Dave
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Old 1st Jan 2019, 3:20 pm   #1898
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Hello, reading the complete thread, i found that on post 1339, on page 67, the user Palmerino speaks about a tool to test the cardinal points "according the diagram of the technical manual of AVO 5"


".... I built a wooden box with a glass window to balancing test the movements, a tool to test the cardinal points of the movements according to the digram of the technical manual of Avo5...."



Does anybody have that manual or that information about that tool.

Thanks

Aitor Eneko
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Old 1st Jan 2019, 4:41 pm   #1899
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No... but i have seen pictures of a replica box used for balancing. The box allows the movement needle to sit horizontally and also vertically, free from air drafts/draughts. If it does not do this either the tail weight or side weights are incorrect.

In my experience, not many Avos made from the 1950's onwards will require rebalancing, other than Avominors which sometimes do benefit from this.

Avometers from the 1940's or earlier are often slightly out of balance, it appears different balance weight metal was used and it was not protected very well from corrosion. An Avo from the 'forties with a seriously undersize tail-weight will be unusable until it is corrected. Some of these older tail-weights can completely corrode away, especially if a wire shunt has burned out and spread oxidation and soot around inside the casing.

A very good idea of whether the balance is acceptable is gained without dismantling the meter. Set the needle to zero, then move meter with handle uppermost and tilt it to the left until the 0-0-0 line is horizontal. The needle should sit on the zero line.
Then tilt the meter so the 0-0-0 line is vertical- the needle should still sit on the zero line.

I originally got this from an article on 'Balancing D'Arsonval meter movements'

I have managed to get good results re-balancing without a glass sided box, if the room is draft free and heat rising from the hands is avoided, it can be done. If the tail weight is slightly overweight i would not try to reduce it- instead i would add a small paint counterweight further up the needle.

The tail weight is far more critical than the side weight. Some meters did not need a side weight at all.

Setting up the cardinal points across the scale is something they did at the factory, not something that would need to be re-done now.

Dave
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Old 1st Jan 2019, 5:10 pm   #1900
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Thanks for the info. I will try to find the Technical manual for the AVO 5, i am curious to see the tool to test the cardinal points.
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