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Old 9th Apr 2014, 11:08 pm   #1141
Phil G4SPZ
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Default Re: AVO Multimeter survey

Quote:
Originally Posted by martiR2R View Post
Why do I need 3 of them!
Just three? You only "need" one Avometer, but it's nice to have a couple of spares just in case, or in my case about 25 spares. And mine's a very modest collection by some standards! Your new Model 7 acquisition dates from May 1944 and, if it's anything like my instrument of similar age, probably has a horseshoe magnet and a coiled bimetallic temperature compensator.
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Old 10th Apr 2014, 10:54 am   #1142
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Default Re: AVO Multimeter survey

Just can't resist a bargain!
It does indeed have the horseshoe magnet etc.

Thanks
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Old 10th Apr 2014, 12:32 pm   #1143
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Default Re: AVO Multimeter survey

The military are moving in now, in the shape of an Admiralty Pattern 47A, serial number 16349-944. After refurbishment, this will go into the wooden box with the multipliers and shunts to become a 48A.

I noticed with some interest that in their 1952 catalogue, Avo were marketing the 48A as the "Avo Industrial Test Set", in which the instrument itself was a Model 40. I haven't checked the ranges, but I wonder whether they had lots of war surplus stock on hand that wasn't taken up by the Admiralty?
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Old 10th Apr 2014, 3:32 pm   #1144
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Default Re: AVO Multimeter survey

Phil,

This is the advertisement for the "Industrial Test Set No. 1 an No. 2" from the Avo 1958 catalogue. The price of either set in 1963 was £41-10-0. The Model 40 and Model 7 then costs £21-0-0.

The Model 40 had an extra resistance range compared to the 47A/48A and my impression is that the Admiralty Pattern models had a marine finish with more internal parts being varnished.

It is quite likely the the "many request" of the advertisement came from ex-matelots who had used these during the War. It is even possible that they were issued to civilian contractors who were working on Admiralty contracts in HM Dockyards. Supply of multimeters would have been directed to essential users at the time and the Naval Authorities may have loaned meters to allow work to progress.

It would be interesting to know the numbers issued to Royal Navy ships given that there may have been several on bigger hulls. Although of little significance compared to the human losses, I often wonder how many Avometers are lying at the bottom of the World's oceans.

It would be interesting to see the Admiralty Specification for the 47/48/47A/48A. The 47 and 48 were based on the contemporary 36-range Universal Avometer.

It would seem likely that the Model 7 might have been used for radio/radar work on HM ships at the same time and I would very much like to know how these multimeters were applied from anyone who may have used them at the time.

I did hear about a 48A with a calibration label dating to the 1990s. If this is genuine, it would suggest that some of these were still on the Admiralty books around 50 years after manufacture.

I once made a swap with a doctor in the US for a rare Avometer. My end of the bargain was a restored Air Ministry Type 'D' which for which I made a replica box similar to a 47A. I painted the box Air Ministry dark grey and embossed an actual date of manufacture in an unobtrusive place so that it would not be mistaken for an actual artifact from the same date as the meter.
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Old 11th Apr 2014, 7:16 am   #1145
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Default Re: AVO Multimeter survey

Thank you for that information, Peter. Fascinating as always! I've seen quite a few Model 48A box sets, and the shunts and multipliers have all been pristine, showing no signs of actual use.

I find the wording of old Avo adverts delightfully colourful.
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Old 16th Apr 2014, 3:13 pm   #1146
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Default Re: AVO Multimeter survey

Recently acquired is this DC Avometer, serial: 4451.

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In rather good condition for it’s age, apart from the crazing on the scale plate.

I have another one of these, but on the to-do-list, as there are various parts missing from it.

Oh and I don’t think the front terminal posts are original, as my other one of these had a cable coming from the bottom centre of the meter, like this picture taken from a book.

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Old 17th Apr 2014, 5:53 pm   #1147
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Default Re: AVO Multimeter survey

Congratulations Paul, I saw that one and hoped it would go to someone here.

It looks to me as though it once belonged to someone with some degree of skill who made a very presentable replacement battery cover and the terminal modification. It's never safe to make categorical statements about Avometer features, but I think all the13-range DC Avometers had fixed leads.

That looks like a row of Multiminors on your shelf. Do you have a Multiminors MK II? They seem to be very rare; I managed to buy one about a year ago but it seemed to get lost in the post - great waste!

PMM
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Old 17th Apr 2014, 6:57 pm   #1148
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Default Re: AVO Multimeter survey

Yes, well spotted Paul, a very nice early instrument and no doubt quite rare.
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Old 19th Apr 2014, 5:46 pm   #1149
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Default Re: AVO Multimeter survey

Quote:
Originally Posted by Phil G4SPZ View Post
The military are moving in now
Likewise Phil, I recently acquired this 9SX in rather good condition complete with the old batteries, which surprisingly haven‘t leaked.

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Serial Number: 8660-15-765.

Quote:
Originally Posted by pmmunro View Post
That looks like a row of Multiminors on your shelf. Do you have a Multiminors MK II? They seem to be very rare; I managed to buy one about a year ago but it seemed to get lost in the post - great waste!
PMM, I don’t have one of those, as mine are all Mk4 and 5’s, only wish I did.

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Old 23rd Apr 2014, 11:11 pm   #1150
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Default Re: AVO Multimeter survey

Where is the S/N number listed on an Avo Model 8 Mk3?
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Old 24th Apr 2014, 2:32 am   #1151
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Default Re: AVO Multimeter survey

Should be on the scale, see post 1
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Old 24th Apr 2014, 12:26 pm   #1152
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Default Re: AVO Multimeter survey

bottom right hand side of the scale, you will probably need to peer down at an angle to see it, as it's slightly obscured by the case edge.
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Old 26th Apr 2014, 11:19 pm   #1153
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Default Re: AVO Multimeter survey

I have made a couple of attempts to post to the list (with as yet no joy) hopefully 3rd time lucky.

I used at work a couple of AVO's a Model 8mkIII and a model 9. I so liked them I at the time purchased one new, I have since in the last couple of years obtained 3 others.

The first (the new one) is a UNIVERAL AVOMETER MK 8 V, serial no (on label on side of meter) 03124 8V/1/76 meter itself is almost unmarked, but is out by a couple of percent on ALL ranges. I have been told this will be due to R27, the build out resistor in series with the meter itself going high.
I purchased this meter new late 1976 (price was just under $200 Australian, more than a weeks wages at the time) and has NEVER been dropped. The original 15v battery lasted to around 5 years ago, ie lasted well over 30 years.
Meter has AVO horizontal case, purchased for 5 dollars a few years ago at a electronics swapp meet.
I have NEVER been sorry I purchased this meter.

The next two were purchased at swap meets........

No model number but name,TEST SET MULTI RANGE No 1 HIGH-SENSITVITY 6625-99-105-7050, Serial no 1296.267, good cndition, few marks but white paint in lettering very faded.
This meter was used by the RAAF until recently, was labeled batterie removed.
With dark brown vertical case.

8 MKII serial no 126498-0-861, good condition, wrong battery cover, this cover is from an 8 MK III

This last one was purchased from the estate of one of the locals that has passed away.

9SX serial no 6727-IS-1262, excellent condition, almost unmarked
text above meter on narrow edge, "6625-R.A.F.-IOS-17447 AVO MULTIMETER TYPE 9SX"
On back, "TEST SET MULTI RANGE" "PAN-CLIMATIC No 1 (HIGH-SENSITVITY)"
This meter REALLY looks near new.


These last 3 checks out to be very accuarate, well within specs. On the Model 8 mk II, the needle when its moving fast gives one the impression there is a slight hesitation at around 2/3rds scale. Varing the needle slowly over this point using a variable voltage power supply gives not the slightest indication of a problem.

Lindsay
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Old 27th Apr 2014, 11:22 am   #1154
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Default Re: AVO Multimeter survey

Lindsay,

Glad you made it - welcome to the forum and the survey.

Your information is of considerable interest as it adds to our knowledge of where different models were used. The Australian services seem to have kept hold of their Avometers until very recently judging by what appears here and on eBay.

It take that you mean the thick film swamp resistor by the "build-out" term. This is a known fault. The cure is to change it, usually for a 10-turn cermet pre-set pot and to adjust this pot to give a combined resistance for the moving coil and swamp of exactly 2667 ohms. You will find this difficult to measure with an auto-ranging digital multimeter as it will pulse the circuit to find the best range and you can't measure the resistance of a moving coil while it is moving through a magnetic field.

In your case the rest of the meter should be entirely original so it should be permissible to use the 50 microamp. range to calibrate the movement. Otherwise the movement must be calibrated first and the overall resistance set correctly as the movement characteristics have to be matched to all the shunt values. You should then have a very accurate meter which measures well within specification.

If you haven't worked on a Model 8 Mark V before, you will have to remove the two plastic plugs with the "AVO" markings at the bottom of the case and the two case screws inside the battery box. The blue flexible printed wiring is very delicate and must be handled carefully to avoid cracking some of the tracks.

If you would like a copy of the Model 8 Mark V service manual, please send me a private message.

Best regards,

PMM
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Old 27th Apr 2014, 8:53 pm   #1155
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Originally Posted by threeseven View Post
bottom right hand side of the scale, you will probably need to peer down at an angle to see it, as it's slightly obscured by the case edge.
Thanks, will look again tomorrow
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Old 27th Apr 2014, 8:54 pm   #1156
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Default Re: AVO Multimeter survey

Many thanks for the reply PMM, glad my info was of use. The "swamp" resistor is the one as you say. The info about the fault came from someone who actually used to repair AVO's, he also stated it was a known fault
I do not have a digital Multimeter of any kind considering my AVO's and three APO number 3 multimeters (made by Australias old telcommunication and mail dept, the PMG) to be excellent if used with intelligence. These latter are excellent meters only 1000 ohms / volt but accurate and built like a battle ship.

Lindsay
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Old 30th Apr 2014, 9:03 am   #1157
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Default Re: AVO Multimeter survey

A new acquisition:

Model 7X: 3105-A-267

Model 7X Panclimactic. Unlike my "Test Set MultiRange #1", the metal back does not enclose a bakelite inner shell, so is a lighter instrument.
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Old 30th Apr 2014, 9:26 am   #1158
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Default Re: AVO Multimeter survey

Thanks LCTorana - it's interesting to know what's there on your side of the world.

The 'X' prefix denotes a panclimatic meter with encapsulated vulnerable components. The Model 7 acquired a Bakelite rear case during the Second World War, probably because aluminium as originally used was better for spitfires than Bakelite, although wood worked well for Mosquitoes. Later, AVO reverted to aluminium back cases for the Model 7 and Model 40.

Your Test Set Multirange No 1 is a military variant of the Model 8 or 9 SX, denoting a panclimatic meter with a magnetic screen in the form of the steel outer case. The later Model 8 Mark V has an inherently screened, centre-pole movement which needs no external screening.

My price lists and catalogues do not list a screened Model 7 but unusual Avometers do turn up and the company would make specials for organisations who were willing to pay - usually with public money, not always unwisely spent - for them.

PMM
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Old 30th Apr 2014, 2:27 pm   #1159
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That's interesting - My Model 7 from 1948 has a metal back case with a black crackle finish that is a near-match for the front panel.
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Old 12th May 2014, 11:15 am   #1160
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Default Re: AVO Multimeter survey

Another 2 have joined my collection,
8 mklll, s/no, R 877768-1001
In fabulous condition, only issue is weak damping on the movement, more than likely just the swamp resistance, should be easy enough to sort.
Very pleased as I've been looking for a mint Mklll for a few years now.

Also, an 8 MkV :O S/no 0023500KA

Again in mint, fully working condition with case, all probes, leads, clips, warranty book and user manual. The only issue is very minor, the rubber dust boot around the cutout button is decomposing. Hope I can find a replacement.
I'd previously decided to avoid the later plastic Avo 8's with all their potential issues but then I realised my collection should have representation from that era. So the V, being the best of them is it.
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