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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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13th Sep 2018, 1:23 pm | #1 |
Dekatron
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,108
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'Admiralty' Avometers marked letter 'J'
This might deepen the mystery rather than go towards explaining it, but the letter 'J' on the scale-plate also appears on this Ad.Patt. Voltmeter- moreover the hand in which it is written looks very familiar! The manufacturer's name is not given but it is feasible it is a 'special' produced by ACWEECO to order.
It certainly needs to come apart as it is over-reading, so I will be on the look-out for familiar components or assemblies. Dave |
13th Sep 2018, 1:36 pm | #2 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,554
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Re: 'Admiralty' Avometers marked letter 'J'
What is that circle that looks like it is in the glass?
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13th Sep 2018, 1:47 pm | #3 |
Dekatron
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,108
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Re: 'Admiralty' Avometers marked letter 'J'
It's a connecting wire, coiled 1.5 times for fracture resistance. (It looks like it has to tolerate movement of the zeroing screw.)
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13th Sep 2018, 1:53 pm | #4 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,554
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Re: 'Admiralty' Avometers marked letter 'J'
They have gone to quite a bit of effort to make it last.
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13th Sep 2018, 6:33 pm | #5 |
Dekatron
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,108
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Re: 'Admiralty' Avometers marked letter 'J'
There are no further clues inside, but the (non-linear) over-reading fault is most likely down to the hair springs- they are growing nasty patches of dark green crystals.
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14th Sep 2018, 6:39 am | #6 |
Octode
Join Date: Jul 2004
Location: Dundee, UK.
Posts: 1,813
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Re: 'Admiralty' Avometers marked letter 'J'
I don't know if ACWEECO made any panel meters, either for commercial or military use, during the 1930s. They did market panel instruments during the 1960s, probably once the new Dover works had reached full production and overcome the long backlog of demand for portable multimeters.
During the Second World War, a shadow factory was needed to meet demand for multimeters making it less likely that any manufacturing capacity was available for panel meters. PMM |
14th Sep 2018, 8:25 am | #7 |
Pentode
Join Date: Oct 2016
Location: Dover, Kent, UK.
Posts: 237
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Re: 'Admiralty' Avometers marked letter 'J'
Its certainly not an ACWEECO meter. As Peter suggested, ACWEECO/AVO sold panel meters in the 1950/60's, but they were standard rectangular shaped panels.
They also sold the base movement assemblies to a number of companies.....including Marconi, Hewlett Packard and Wayne Kerr. Andy G |
14th Sep 2018, 10:17 am | #8 |
Dekatron
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,108
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Re: 'Admiralty' Avometers marked letter 'J'
Thanks. Testing on a variety of reference voltages from 1.6v to 7.5v produces odd (but repeatable) results- accurate at 1.6v and 4.1v but around 20-22% high elsewhere. I think that this fits in with the dynamics of rotted springs but am not certain- do the symptoms tally in your mind/s?
Meter overall has resistance 533ohm as per the scaleplate. Dave |
14th Sep 2018, 12:37 pm | #9 |
Pentode
Join Date: Oct 2016
Location: Dover, Kent, UK.
Posts: 237
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Re: 'Admiralty' Avometers marked letter 'J'
Not sure it has any relation to your movement, but i've just found an Avo drawing for a movement assembly that states it is a Taylor 'J' type movement. This was sold as a spare asssembly, during the time Taylor were part of AVO (In Dover)
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15th Sep 2018, 2:33 pm | #10 |
Dekatron
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,108
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Re: 'Admiralty' Avometers marked letter 'J'
Interesting. 'Display only' as it stands- but not junk since the case is intact.
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