4th Jun 2021, 9:31 pm | #2801 |
Dekatron
Join Date: Aug 2016
Location: Colchester, Essex, UK.
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Re: AVO Multimeter survey
Richard, when you have a delve could you advise the average resistance of the fuses? Would be useful to check it against my Model 4- i can't recall whether it was intact on purchase or i just fitted a resistor. Thanks!
Dave |
4th Jun 2021, 10:48 pm | #2802 |
Octode
Join Date: May 2017
Location: St Austell, Cornwall, UK.
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Re: AVO Multimeter survey
Hi Richard,
Probably not worth asking, but just in case, can you confirm that it has the Bakelite Control Knob covers, and when you do open it, that it has the Movement Magnet perpendicular to the Scaleplate like found in the Model 7's and 40's. Should be, as that is quite a late Model 5, but it's always worth testing the Avo theories when the option is available. Is the case original ? Not actually sure how you would tell though, I have never seen a Model 5 with a Case! How about the Leads ? Dave, All the Fuses I have measured that were in tact when I got them have all been around 4 Ohms as per the ACWEECO Schematics. I say around, because they have generally been about 4.2 or 4.3 Ohms, but then my Equipment isn't calibrated, but I think that is fairly accurate. Is it Drift, or was that how they were made? We will probably never know. On the Fuse I restored a Year or so back for a Model 5, I found 4.6 Ohms was a better match for the Meters accuracy, but then after 70 odd Years anything could have drifted some what. I think it's worth calibrating the Fuse to the Meter these Days, as it isn't like you are going to be buying new ones anytime soon. Ian |
5th Jun 2021, 10:39 am | #2803 |
Pentode
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Re: AVO Multimeter survey
Thanks for the comments and suggestions. No further ahead yet but here are two pictures
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Richard |
5th Jun 2021, 11:06 am | #2804 |
Octode
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Re: AVO Multimeter survey
That's a nice find Richard,
Looks like you have Two spare Fuses as well. What a result! Are they working Fuses ? Ian |
6th Jun 2021, 3:09 pm | #2805 |
Pentode
Join Date: Dec 2002
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Re: AVO Multimeter survey
Sadly both fuses are duff.
I have now with difficulty prised it apart and can confirm the magnet is perpendicular to the front panel. Black metal casing, Wooden battery box, serial number also scratched on back of scale plate.
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Richard |
6th Jun 2021, 3:13 pm | #2806 |
Dekatron
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Re: AVO Multimeter survey
- Note the colossal winding for the high voltage range. Found to be intact on my Mod 4, much to my surprise.
Dave |
6th Jun 2021, 3:45 pm | #2807 |
Octode
Join Date: May 2017
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Re: AVO Multimeter survey
The Model 5 is a really nice Avo Meter in my humble opinion and as
has been mentioned previously, the Low Resistance Range is quite accurate (significantly better than 5% in my experience) and useful. Richard's Meter confirms again, that the later Meters have the Perpendicular Movement Magnet, Bakelite Control Knobs, and the Battery Bay Spikes are on the backs of the P and R controls rather than having their own Mountings on the back of the Front Panel. Ian |
11th Jun 2021, 8:52 pm | #2808 |
Pentode
Join Date: Dec 2002
Location: Norfolk, UK.
Posts: 168
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Re: AVO Multimeter survey
I have read with interest the helpful thread back in December 2018 "Avo 36 range restoration" particularly about the fuses as all mine are dead and bridged with fine wire.
Answers to your questions: The leather case was is almost identical to other genuine AVO ones I have except it has green felt like lining and steel rather than brass buckles and studs for the shoulder strap. The leads were cloth covered and ended in a screwed (1BA?) piece of brass rod into which the probes or croc clips fit, Hook spades on meter ends. I have made new leads. The Z adjuster on mine is chrome plated. The case appears original and lists 36 ranges. Unlike later meters the anti-tamper screw is on the lower left hand side. I discovered an open circuit on one of the high value resistors and burnt out end turns on the R ohms adjuster, both now fixed. Fortunately with a magnifying glass I found the broken ends and after many attempts managed solder a piece of copper wire to join them up. I used an inch or so of wire from a 400 ohm resistance bobbin wrapped around one of the fuses to get about 4 ohms and found the meter was remarkably accurate, not bad for something made when I was a toddler!
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Richard |
12th Jun 2021, 2:04 pm | #2809 |
Nonode
Join Date: Mar 2008
Location: Virginia Water, Surrey, UK.
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Re: AVO Multimeter survey
Could someone please add a link to the post with the latest survey, maybe also adding it to post #1 at the top of this huge thread?
Mods? (I can't find the Survey 4th Edition) many thanks -Jeremy
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12th Jun 2021, 2:13 pm | #2810 |
Nonode
Join Date: Mar 2008
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Re: AVO Multimeter survey
Three Model 8s spotted on an Ebay advert:
(not showing on the 3rd Edition Survey) 8 Mk I s/n 4455-C-452 (Apr 1952) 8 Mk II s/n 69621-C-158 (Jan 1958) 8 Mk III s/n 102742-969 (Sep 1969) -Jeremy
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25th Jun 2021, 10:53 am | #2811 |
Octode
Join Date: May 2017
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Re: AVO Multimeter survey
I have only just noticed that the Avo Test Bridge, has not been previously
recorded in the Survey Database. Ok, it's not an "AvoMeter", but it is an Avo and it is a Meter and more importantly, it's analogue with a Moving Coil Meter so ticks all the Survey Boxes. I think it would be nice to record this Instrument going forward and I know a fair few of these still survive and several Forum Members have them. So if anybody has one, and would like to dig the Serial Numbers out, I will update the Survey accordingly. Also, if anybody knows any more information about them, that would be useful. I know a Circuit Diagram is available, and one of our Forum Members produced a nice Restoration Manual quite a while back. Ian |
25th Jun 2021, 12:35 pm | #2812 |
Pentode
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Location: Dover, Kent, UK.
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Re: AVO Multimeter survey
Ian,
My Test Bridge is serial number 53061046, which I think is October 1946 Andy |
25th Jun 2021, 1:23 pm | #2813 |
Octode
Join Date: May 2017
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Re: AVO Multimeter survey
Thanks Andy,
Well, that's two of them in the Survey now then! Is that Serial really in one continuous Number ? The Photo I posted earlier was a September 1944 model Serial Number 4030-944 Which would indicate that not a lot in the grand scheme of things were being made. 1500 in Two Years is not so many. Ian |
25th Jun 2021, 4:16 pm | #2814 |
Pentode
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Re: AVO Multimeter survey
My AVO Test Bridge serial number 4181-1144
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Regards Trevor BVWS member |
25th Jun 2021, 11:01 pm | #2815 |
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Re: AVO Multimeter survey
Mine is 2693-1243 and carries additional markings as shown.
Phil
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26th Jun 2021, 7:32 am | #2816 |
Octode
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Re: AVO Multimeter survey
Thanks to Andy, Trevor and Phil,
That's Five Test Bridge Serial Numbers in the Database in less than 24 Hours. I pulled one from the Restoration Manual itself. Great result! Based on this limited amount of Data, I would estimate that this Bridge was released probably somewhere around 1940 at the earliest. Although I have seen references stating 1939, the figures don't currently support a launch Date quite that early, but we still need more Serial Number Data to improve any conclusions we can gather. Phil Is the Overlay fitted to your Test Bridge a Homebrew item made by STC or, is it an Avo item do you think ? Obviously a similar idea to the Power factor overlay found on the Model 7 Ian |
26th Jun 2021, 10:53 am | #2817 |
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Re: AVO Multimeter survey
Hi Ian,
At a guess, it was made by STC, but equally it could have been from a batch made by Avo for STC to their specification. The front panel STC legend is very neatly engraved, or more likely moulded-in. I have a model 7 with a Marconi legend similarly engraved. Phil
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Phil Optimist [n]: One who is not in possession of the full facts |
26th Jun 2021, 8:40 pm | #2818 |
Hexode
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Location: Bristol, UK.
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Re: AVO Multimeter survey
Serial number of my bridge is 7311-648 Les.
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26th Jun 2021, 11:12 pm | #2819 |
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Re: AVO Multimeter survey
This thread has prompted me to dust off my ATB and try it out. Seems to work on all ranges, although the calibration is a bit out as would be expected.
The Restoration Manual actually quotes the year 1936 when this instrument was launched.
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Phil Optimist [n]: One who is not in possession of the full facts |
2nd Jul 2021, 7:15 am | #2820 |
Diode
Join Date: Jul 2021
Location: Perth, Western Australia, Australia.
Posts: 2
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Re: AVO Multimeter survey
My AVO is a model 8 serial number 6104-C-652. I use this when working on valve radio equipment.
Thank you Owen. VK6YBA. |