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Old 29th Aug 2015, 9:52 pm   #1281
Barnmead
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Default Re: AVO Multimeter survey

I have now looked at these two that I mentioned in a posting a few days ago:

model 47A ser no 8067-342 in bakelite case with model 40 panel moulding
model 40 ser no 40185-642 in aluminium case

From the serial numbers it would seem that these two were made just a few months apart and inside they appear much the same except that the model 47A has resistor wound on glass and the other has pink hi stab ones instead.

Does this mean that only 185 model 40s were made in the first 6 months of 1942?

The 47A has a bakelite casing with a model 47A instruction plate a battery box for 1.5 and two 4.5 volt batteries. the front panel has two sets of 6BA threaded holes one of which looks as if it would have suited an aluminium case. Perhaps it is a marriage as the following site indicates (if I read it correctly) that model 40s were supplied to the Admiralty but the serial number should have letter S above the number which this one does not.

Ignore the first couple of pages, there are diagrams and nice description here:

http://www.rnmuseumradarandcommunica...tion%20six.pdf
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Old 1st Sep 2015, 10:13 pm   #1282
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Default Re: AVO Multimeter survey

I picked up an Avo Minor MK1 AM the other day, dates from May 1943.
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Old 1st Sep 2015, 10:20 pm   #1283
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Default Re: AVO Multimeter survey

Richard (Barnmead) - you have a PM.
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Old 24th Sep 2015, 3:18 pm   #1284
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Default Re: AVO Multimeter survey

A colleague gave me this today. It's number is 79591-446

Fortunately there was no battery in it! Unfortunately the glass is cracked - does nayone have a spare?
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Old 1st Oct 2015, 12:22 pm   #1285
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Hi folks, I have a lovely Model 40 here which works fine as a volt meter

The serial number on the dial is a bit of a mystery though as it's 7985 with no other numbers inside the enclosure or battery compartment

Any ideas when this was built ?

I love these old threads that never die

regards

Adrian
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Old 2nd Oct 2015, 8:05 pm   #1286
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Default Re: AVO Multimeter survey

Adrian,

I can't explain the serial number which does not belong to any Model 40 series that I am aware of. It is possible that the movement is a replacement for a damaged original and the repairer has chosen not to write the instrument's serial number on the scaleplate but usually that would just mean it was left blank.

The scaleplate does not look like a 36-range Universal Avometer one either and these would have a serial number in the form MY-XXXX.

The date however is more certain. Your meter front panel is of the style used from the mid-1940s and the "wire and disc" pointer is consistent with this. Earlier Model 40 front panels had a more rounded form of the "Universal Avometer" badge. The attached picture shows this earlier styling although it is from a 1952 catalogue. (Sorry for the poor quality image - my scanner is a victim of a Windows 8 update so I have had to rely on an extract from a larger scan).

The construction of the movement changed radically, from a horse-shoe magnet to an Alnico block type, between 1947 and 1948 but if your movement is not original this is less relevant.

The service manual for the Model 40 shows two versions, both with a block magnet movement, described as Mk I and Mk II but the changes are fairly subtle and mostly internal.

The range switch rings were laminated and riveted assemblies and the cut-out contacts were in V formation in the Mark I. In the Mark II the switch rings are mouldings and the cut-out contacts are parallel. From around 1956, the terminals changed from knurled black knobs to the red and black 4mm sockets used on all later full-size Avometers.

PMM
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Old 2nd Oct 2015, 9:30 pm   #1287
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Default Re: AVO Multimeter survey

Hi PMM

Many thanks for your detailed and informative reply, I had the unit apart yesterday but didn't take any photos so I'll have to go back in to get more component details.
But as it stands if anyone asks I'll say itis a 1948 model 40

Thanks again for your time

regards

Adrian
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Old 4th Oct 2015, 4:27 am   #1288
Dan Payne
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Default Re: AVO Multimeter survey

I just picked my first one up at a swap meet this morning. Model 8, No 34733-C-555.

Cheers, Dan

Last edited by Dan Payne; 4th Oct 2015 at 4:35 am.
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Old 4th Oct 2015, 2:46 pm   #1289
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Default Re: AVO Multimeter survey

Dan,

Congratulations! One Avometer - sensible acquiaition, two Avometers - could be useful, three Avometers - where will it all end?

Your Model 8 from May 1955 is probably just about the time of the change from Mark I to Mark II, most easily distinguished from the outside by the terminals and of course any labelling. Does yours have the black knurled screw terminals or the red and black sockets?
This information would be useful in determining the exact month of the change.

PMM.
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Old 4th Oct 2015, 5:12 pm   #1290
Dan Payne
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Default Re: AVO Multimeter survey

Hi PPM,
This Model 8 does have the black, straight knurl knobs on all 4 posts. Face and case I assume to be Bakelite with steel battery lid. From all I could find it appears to be a standard model 8. This is all that could be found on the outside for identification. Needs a bit of a clean up and batteries for a start.

Cheers, Dan
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Old 4th Oct 2015, 7:25 pm   #1291
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Default Re: AVO Multimeter survey

Thanks for the information Dan. It looks like your meter is what we would now call a Model 8 Mark I, although it was simply a Model 8 at the time.

You should find information on cleaning and improving the appearance of your meter in threads on this forum.

PMM
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Old 4th Oct 2015, 8:13 pm   #1292
Dan Payne
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Default Re: AVO Multimeter survey

Thanks PMM,
Will look into the cleaning. I have the 15volt battery being looked into and working on some test leads. I would say it is in pretty good shape given the vintage but will need a bit of a tear down to free up a few sticky features and a check under the hood.
Cheers, Dan
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Old 5th Oct 2015, 10:36 am   #1293
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Default Re: AVO Multimeter survey

Quote:
Originally Posted by pmmunro View Post
Congratulations! One Avometer - sensible acquiaition, two Avometers - could be useful, three Avometers - where will it all end?
Let’s hope it doesn’t end up like this , far too many now and I have finally stopped buying them, due to lack of space.

Paul.
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Old 5th Oct 2015, 11:26 am   #1294
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Default Re: AVO Multimeter survey

Quote:
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...far too many now and I have finally stopped buying them...
You've said that several times before, Paul! Seriously though, I saw Paul's collection some time back when it was not quite as big, and it was magnificent then. It's awesome now!

I suggest we hold a National Avo Day. To celebrate, Paul could wire all his Avometers in series and demonstrating them all showing the same readings...
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Old 11th Oct 2015, 8:00 pm   #1295
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Default Re: AVO Multimeter survey

Latest meter in the Collection, Heavy Duty Avometer number 14230-562R. I assume that means it was made in May 1962. A mk5 version I think. Fully working & in great condition, sadly no leads.
I'm not sure what the R stands for if any one can let me know that would be great.
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Old 12th Oct 2015, 8:29 pm   #1296
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Pmark34,

Your HD Avometer is a Mark V made in May 1962 and it is exceptionally good condition. It is not easy to find this model with an intact Bakelite case which belies the "Heavy Duty" label. The original version really was heavy duty as it had a cast aluminium case.

I don't know the significance of the "R" suffix to the serial number. There was a railway signalling version, and in fact this model range was specifically designed for that application. However, the railway signalling version has different ranges and does not have the variable sensitivity function. The suffix could be to show that the movement has been replaced and stand for "repaired" or "rebuilt" but this is pure speculation.

PMM
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Old 12th Oct 2015, 10:22 pm   #1297
Pmark34
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Thanks for the reply, interesting thought about the R meaning repaired or rebuilt.
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Old 15th Oct 2015, 11:41 pm   #1298
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Default Re: AVO Multimeter survey

Another HD Avometer to add to the collection from a local antiques / junk shop, but this time a British Rail Siignal Eng Dept one No,2387-1178.so Nov 1978. Sadly not in as good condition as the other HD Avo,.Looks like its been droped at some time as the top of the case has cracks in it that have been glued back together,Also the handle is missing .When I bought it the glass some how was between the needle and the scale plate.Quick strip down & a bit of super glue & thats sorted.Although the meter case is in a bit of a sorry state. The leather case is in great condition & the meter seems to read ok & accurately (have only tested voltage & ohms so for)
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Old 16th Oct 2015, 1:02 pm   #1299
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Default Re: AVO Multimeter survey

Is that really a piece of Veroboard in the bottom? What would that be for?
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Old 16th Oct 2015, 5:06 pm   #1300
pmmunro
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Quote:
Originally Posted by Pmark34 View Post
Another HD Avometer to add to the collection from a local antiques / junk shop, but this time a British Rail Siignal Eng Dept one No,2387-1178.so Nov 1978. Sadly not in as good condition as the other HD Avo,.Looks like its been droped at some time as the top of the case has cracks in it that have been glued back together,Also the handle is missing .When I bought it the glass some how was between the needle and the scale plate.Quick strip down & a bit of super glue & thats sorted.Although the meter case is in a bit of a sorry state. The leather case is in great condition & the meter seems to read ok & accurately (have only tested voltage & ohms so for)
Park,

Your meter looks like it has had a, sadly typical, hard life. It's strange that someone thought it necessary to obliterate the owner's name engraving yet keep the serial number visible. This, and the perforated bottom board suggest it may be synthesised from parts from several meters. The obviously hand written serial number may be for the same reason although in older Avometers all or part of the scale writing would have been by hand.

The very nice leather case was also probably from another meter.

PMM
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