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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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25th May 2019, 3:44 pm | #1 |
Heptode
Join Date: Jul 2010
Location: Wellington, New Zealand.
Posts: 653
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Avo 8???
Bought this off the local NZ internet auction site trademe. Not seen one quite like it before as it has no divide by 2 button just a reverse MC one and a divide by 100 ohms position as well as a LR switch position (Low Resistance). On the back the instructions seem to say it's a 8 mk 3 but both the front and the meter say only 8.
Don't know how rare these models are but if anybody has any info that would be great. Some pics below. |
25th May 2019, 5:07 pm | #2 |
Dekatron
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,108
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Re: Avo 8???
Excellent! i think that is indeed a fairly early Mk.III Model 8. They were up to serial number 79,000 by year 1968 so 2,400 is an early bird. The little '8 ball' button on the front facia has been seen before, but not very often. Perhaps it is a feature that was phased out as time went on.
There will be probably be more windings inside than you would find on a later Mk III, component resistors proliferated later on in the production run. This is the swiss army knife of Avo's i suppose, but the x100 gap between the resistance ranges is a little bit of a handicap. Dave |
25th May 2019, 5:20 pm | #3 |
Dekatron
Join Date: Nov 2003
Location: Fakenham, Norfolk, UK.
Posts: 4,259
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Re: Avo 8???
Hmm... does not the back plate refer to the meter being a Model S MkIII?
https://www.vintage-radio.net/forum/...d.php?t=124814 Paul |
25th May 2019, 5:50 pm | #4 |
Octode
Join Date: Jul 2004
Location: Dundee, UK.
Posts: 1,813
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Re: Avo 8???
Based on advertising, the Model 8 Mk III was introduced in June 1964, so you're right Dave, this would be an early Mk III. Possibly the "8 Mk III" buttons were not available early on but I think you're right they fell into disuse later.
Avocollector, The Model 8 always had a REV MC (Reverse Moving Coil) push button switch. The Divide by Two facility was used on the Model 7 and Model 40 of this era and was first used in 1933 to expand the 20 ranges of the "Universal Avometer" to 34 ranges, soon afterwards becoming 36-ranges. The feature was patented (GB 423199) but the patent was successfully chalenged by Taylor Instruments. I haven't found any evidence that the feature was ever used by Taylor, not unless you count the Model 8 Mk V as a Taylor instrument since its centre pole movement was to a Taylor patent and the Mk V design was largely the responsibility of an engineer who came from Taylor when they were taken over by AVO. PMM |
25th May 2019, 7:24 pm | #5 | |
Octode
Join Date: May 2016
Location: Oxfordshire/Bucks borders, UK.
Posts: 1,604
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Re: Avo 8???
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Avometer, vintage Fluke and Marconi collector. Also interested in vintage Yaesu and KW. |
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25th May 2019, 7:50 pm | #6 |
Dekatron
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,108
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Re: Avo 8???
Paul-
Does look like an 'S' but it's likely just an '8' with a scratch across it! (Edit- Anthony beat me to it) NZ Peter- Watch that leather strap; they're (only) good for 50yrs or so.. Any held up to my ear that crackle when pinched get de-commissioned! Dave |
26th May 2019, 2:20 pm | #7 | |
Heptode
Join Date: Jul 2010
Location: Wellington, New Zealand.
Posts: 653
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Re: Avo 8???
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26th May 2019, 2:26 pm | #8 |
Heptode
Join Date: Jul 2010
Location: Wellington, New Zealand.
Posts: 653
|
Re: Avo 8???
Thanks to everybody for the information - not come across one of these models before and all the other earlier 8's I've got are marked 8 mkII or 8 mk III from memory on the front button. Must go and get them out and have a look!! Amazing the variants - before I started collecting these about 10 years ago there were just large black Avos in my mind and I never realised there were different models until I joined this forum.
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26th May 2019, 2:36 pm | #9 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,554
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Re: Avo 8???
At college we had 7s and 8s and were told all about ohms per volt.
10 meg ohm electronic volt meters were quite special at the time but we were shown one. I have ended up with two 9s in my workshop but at least they are the same ohms per volt as 8s and with only a small difference in the ranges get pretty close to an 8 on valve gear. |