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Old 22nd Feb 2017, 3:49 pm   #1401
mole42uk
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Default Re: AVO Multimeter survey

I've now a small collection of AVO EA113 multimeters:

494.1069 s/n 388
816.270 s/n 697
5.642.1175 s/n 5471

I started out wanting just one......
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Old 4th Mar 2017, 10:01 pm   #1402
Phil G4SPZ
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Default Re: AVO Multimeter survey

I have been given a nice Model 8 Mk III which, for a change, is in full working order: serial number 10827-265.
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Old 11th Mar 2017, 1:18 pm   #1403
The Philpott
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Default Re: AVO Multimeter survey

...I was given an 8/III a few months ago with s/n 12777/365, which with reference to Phil's s/n indicates an impressive production rate..

The dials are a bit sloppy but it all works. I think the key to longevity is to resist the temptation to whizz the dials round to 12 o'clock every time you put it away- i now adjust the dials before use not after. Moving parts are a killer as always!
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Old 16th Mar 2017, 1:24 pm   #1404
micheal
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Default Re: AVO Multimeter survey

Do you mean the range selector knobs?

Mike
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Old 16th Mar 2017, 6:38 pm   #1405
The Philpott
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Default Re: AVO Multimeter survey

Yep, range selectors. Usually when i take the back off one of the meters i see a small amount of grease on the rotary contacts and the cam rotors, but they inevitably do lose a bit of precision in their action with extended use. Have had one or two jam solid at a certain point, when the rotary spade clouts a certain fixed contact, instead of sliding between. Tweaking required, access permitting.
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Old 1st May 2017, 1:27 pm   #1406
Phil G4SPZ
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Default Re: AVO Multimeter survey

My first EA113 has joined the collection, and has now been repaired and is working nicely. The only serial number I can find on it is stamped into the rear case, no. 1377.
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Old 7th May 2017, 8:18 pm   #1407
Pelham 18
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Default Re: AVO Multimeter survey

Hi all,I have a few AVO's
Model 7
7740 4351
7545 22153
758 1616
37896 A1252

7mk11
58426 A855
73883 A 1157
89114 A 1061

Model8 mk11
572131 c 257
165162 c 1163

8mk111
4422 c 1064

8mk1V
unable to find number

8mk5
0527048 8V

Test set multi no1 high sensitivity
10397 1270

That is all.
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Old 20th May 2017, 12:32 pm   #1408
Superscope
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Default Re: AVO Multimeter survey

Hi to everybody in the Forum,

My humble collection of AVO Meters consists of the following:

Model 8 Mk II 48549.C.656 (Very Early MkII I think. Back Plate says Model 8 only.)
Model 8 Mk V 02154 8V/4/79 (Actually an MMR 14C front Panel ex Post Office)
Model 8 Mk VII 8060 1003 1193 (Bar Code Label, I assume this is the Serial No?)

Model 9sx 6305-15-863 (Test Set MultiRange No1 High Sensitivity)

Can anybody point me in the direction of a Service Manual for the 8 Mk VII ?
I need to sort out a sticky Meter Movement.

My favourite by far is my 9sx.
What a difference in quality between it and the Model 8 Mk V onwards!

Ian
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Old 24th May 2017, 9:44 pm   #1409
neikeel
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Default Re: AVO Multimeter survey

Hi
I wonder if this thread is still being followed?
Anyway as long time lurker I thought I ought to join.
My AVO is a Model 8 and it has serial 143233-C-762
Cheers
Neil
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Old 27th May 2017, 11:59 am   #1410
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Default Re: AVO Multimeter survey

Hello there,
If anyone is still interested.
A new AVO addict here, (actually I've been a fan of AVOs for decades)
I Recently obtained a Test Set No.1 serial number 4304-468.
I also have:
a Model 7 (Mk. I) No. 71047-A40672
a Model 8 Mk. II No. 82286-C-1158
a Model 8 Mk. III No. 17473-665

It has a blown resistor, which from perusing the forums, appears to be
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Old 6th Jun 2017, 5:48 pm   #1411
The Philpott
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Default Re: AVO Multimeter survey

Yes chaps this thread is most definitely still current! It is an ongoing thing.

I encountered an odd Admiralty meter a little while ago, and am putting brief details of it here for reference. The scale plate is '47A' type, and the identity circle on the front is also 'Model 47A'. However, above the identity circle is painted a letter 'S', which has then been been overcoated with varnish or shellac, to protect it from erasure/abrasion. The instruction plate on the rear is a standard Model 40 item, and the meter has all the internal extras associated with a Model 40.

Someone (forgotten who, but thankyou!) has provided the attached typed document which looks to me like an old Admiralty repair guide/summary dedicated to RN Avometers.. If you look at the bottom of the page marked as No.67 it transpires that some Model 40's were supplied to the admiralty as 47A lookalikes, but painted with 'S' to identify them. I may have been premature in calling these meters Model 47AS, as it seems they are just a 40 with a few cosmetic changes!

I would be interested to know how many are extant, but i don't imagine they are very rare. Mine has had a very hard life and took some bringing back. It's identification number is 17543-1144R.
Attached Files
File Type: pdf AVO47a copy.pdf (917.3 KB, 138 views)
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Old 7th Jun 2017, 4:16 pm   #1412
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Default Re: AVO Multimeter survey

Dave,

That is an very interesting article for a number of reasons. Thanks for posting it.

It has the characteristics of having been written by someone who had a good understanding of electrical instruments but no access to either ACWEECO or Admiralty technical information. They quality of writing shows a good general education, very likely someone who had been educated to at least HNC level, so probably a senior NCO or junior officer. There are a number of terms which are technically sound but different to those used by the manufacturer; for example "Overload relay" instead of "Cut-out". The writer seems concerned to pass on the information to others who needed to repair Avometers and the assumption that these would be Admiralty issue meters is implied. My understanding is that ship's personnel would have been directed to return faulty instruments to an official repair depot, but this would not have been easy for a ship's company on the other side of the world in wartime.

The article would have taken many long and patient hours of research and drawing. The drawings are to a very high standard suggesting that the author had drawing office training, also indicated by the standard of hand lettering in the titles. In fact the drawings are to a much higher standard than contemporary ACWEECO drawings. The typescript is a bit rough, possibly having been written on a well-worn typewriter and one with a ribbon which was past its best. That would probably rule out the services of an official typist, unless Admiralty standards were below normal at the time.

Note 6 is about the matter we were discussing, the supply of an 'S' variant of the 47A. The statement about these having been supplied instead of standard 47As implies that the writer knew what was being supplied to the Admiralty, more likely for a dockyard NCO or officer than someone in a ship. However someone shore based would probably have had access to official manuals. I don't know what manuals were ever available for these meters but it's highly unlikely that any Admiralty contract would not have required user and service manuals to be provided. (The 1940s Navy equivalent of the Air Ministry "APs").

It would be very interesting to know the source of this article. If the writer had produced over sixty pages to a similar standard before getting to the 47As, he (I assume it was a "he" given the culture of the times) had quite a passion for technical writing and a lot of time to devote to it. We have to wonder where, and in what circumstances it was written.

PMM
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Old 7th Jun 2017, 11:59 pm   #1413
Phil G4SPZ
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Default Re: AVO Multimeter survey

The writer's description of the acceleration trip mechanism was also worthy of praise.
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Old 8th Jun 2017, 9:09 am   #1414
noble kiwi
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Default Re: AVO Multimeter survey

Special thanks Dave,

The above posts have certainly livened up the thread and have proven exceedingly interesting. The author of the instructions shows truly admiral talent and it forms a worthwhile addition to factory information which I for one will retain on file. Particularly worthy is the layout of the circuitry.

Trevor.
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Old 8th Jun 2017, 10:47 am   #1415
jamesinnewcastl
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Default Re: AVO Multimeter survey

Quote:
Originally Posted by mole42uk View Post
I've now a small collection of AVO EA113 multimeters:

494.1069 s/n 388
816.270 s/n 697
5.642.1175 s/n 5471

I started out wanting just one......
I've got 4 now - a childhood dream realised - I also have a copy of the marketing data sheet that I read and re-read a hundred times as a boy. Centre-Zero.... mmmmmmm


James
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Old 8th Jun 2017, 6:40 pm   #1416
The Philpott
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Default Re: AVO Multimeter survey

Thanks chaps, just tracked where the pdf doc. came from, Richard A kindly supplied it when i queried this particular version of meter. He said that it dates from 1945, but i don't have any other info. at this time.

17543-1144R was the meter on which i learnt how to re-balance movements, as they were corroded away completely, leaving only a bit of white powder. There is an overheated voltage winding on the top board, which was overloaded to the point where the board itself has swelled up. (Yes, it stinks!) I do wonder if the smoke from this event precipitated inside the meter and caused the corrosion between the dissimilar metals involved.
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Old 11th Jun 2017, 3:06 pm   #1417
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Default Re: AVO Multimeter survey

http://www.rnmuseumradarandcommunica...tion%20six.pdf

This is where the piece about the model 47/40 came from, maybe there might be other interesting things to be found there?
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Old 12th Jun 2017, 1:05 pm   #1418
Boater Sam
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Default Re: AVO Multimeter survey

Another to add to the list.

Avo Model 8 Mk III # 49298.1066

Not Harold's or William's !

In goodish order but the divide by 100 Ohms range reads the same as the Ohms range and the corresponding adjuster does nothing. Any ideas?
Sam.

Last edited by Boater Sam; 12th Jun 2017 at 1:07 pm. Reason: Grocers apostrophes.
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Old 12th Jun 2017, 3:06 pm   #1419
Phil G4SPZ
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Default Re: AVO Multimeter survey

Sam, in my experience that will be caused by one of the leaf switch contacts not making properly. Behind the AC switch there are cams and contacts, once pair closes only on the ohms/100 range and puts a shunt across the movement. I think the contacts are "h" & "j" on the circuit.

I clean these contacts with a bent pipe cleaner moistened with Servisol. Check also that the mechanical actuation pins are in the correct positions.

Leaf switch contacts are responsible for a lot of faults on the Model 8.
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Last edited by Phil G4SPZ; 12th Jun 2017 at 3:08 pm. Reason: Afterthought
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Old 12th Jun 2017, 6:03 pm   #1420
Boater Sam
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Default Re: AVO Multimeter survey

Thanks Phil, looks very probable, I noticed on the circuit that there is only one pair of contacts that change from Ohms to divide by 100 Ohms, that's another job for later in the year.
Sam.
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