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Old 2nd Aug 2013, 11:00 pm   #1061
pmmunro
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Default Re: AVO Multimeter survey

Paul,

Thanks for that information. The big resistor mounted diagonally between the boards is a further variant which I haven't seen before.

PMM
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Old 14th Aug 2013, 11:03 am   #1062
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Hi I have just noticed this forum and I use an Avo meter that I picked up in from a dealer of used equipment about 23 years ago.

It is in good working order and is the only multimeter I use.

I picked this model as my father has one from his days working at ATV and I used to use it when a child, and I like the style and robustness of the model.

It is an ex MOD one in a good condition green leather case which has an unused carrying handle rolled up inside. The meter is in excellent condition with only some minor wear and damage to the painted case from normal use. The battery terminals are not corroded and it has a fuse and spare inside. When I bought it there was a large pile of these in the shop, 50+, and I picked the one with the combination of best case and condition available, as all were the same price, £18 from memory.



I have replaced the 15v battery in the past, but currently I do not have one fitted as seldom need that range and they are expensive, but works fine on the 1.5v battery resistance ranges.

I am not sure what exact model number it is, Has a label from 29Comd Wksp REME with a test date of Aug 89. There is a hand written serial number on the dial 162 1266, does this mean it was Dec 1966?

This is a huge thread and I don't have time to trawl though but would be interested to know what year it dates from.

Any idea where I can get a good red lead? mine is perished, black is OK? Will modern 4mm leads fit into the terminal holes?

Further info on y meter, it has the instruction plate on the back, but no model number anywhere I can see.
the case has 162-12-66 written on in black marker, and stamped on the top the mod arrow and 6625-99-105-7049, but strangely inside the same case 6625-99-105-7056.

IIt clearly has had the leads swapped at some stage with contemporary units as the black lead finishes with 7051, and the red with 7062. Case is marked Test set multirange No. 1

The AC scale has a blank indicator between the 300v and the 1000 & 3000V position
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Old 15th Aug 2013, 8:14 pm   #1063
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Default Re: AVO Multimeter survey

Ken,

Could you provide photographs of the front panel, instruction plate and the scale plate please?

This will help in answering your questions on your meter's type and age.

The terminals do accept a standard 4mm plug and any suitable leads will serve for your instrument. Officially, the leads should have a resistance of 0.02 ohms per pair but in practice any suitably robust and insulated leads will be fine. Genuine AVO leads are frequently offered on eBay but sell for high prices, up to £30 per pair. The later Avo leads were plastic insulated but for some reason NATO specification leads seem mostly to have been rubber insulated, and perishible, much later.

PMM
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Old 17th Aug 2013, 12:35 pm   #1064
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Default Re: AVO Multimeter survey

Pictures as requested
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Old 17th Aug 2013, 12:36 pm   #1065
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And a few more of interest
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Old 18th Aug 2013, 9:32 am   #1066
Ian G Bennett
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Default Re: AVO Multimeter survey

More AVO info for Sticky.
AVO model 40 MK 2 Serial number 91995 40/1/76
in brown tan leather case
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Old 18th Aug 2013, 5:43 pm   #1067
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Default Re: AVO Multimeter survey

Ken,

The Model designation of your Avometer is as given on the scale plate - "Test Set No.1 High Sensitivity".

Essentially it is a military version of the Panclimatic Model 8 Mark III with a modified, and simplified, scale plate and set of ranges, similar to the Model 9 in their 1 - 3 - 10 sequence. The thermistor on the back of the movement is consistent with this and so a date of 1966 would be correct.

Some people would claim, with some considerable justification, that this model is the best Avometer ever made.

PMM.
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Old 18th Aug 2013, 11:42 pm   #1068
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Default Re: AVO Multimeter survey

Thanks, must have been lucky when I spotted it then.

I only use it for routine house and garage repairs, but is satisfyingly chunky and robust feeling to use.

Does the handwritten serial number suggest the scale has been replaced?

I did note when I opened it for the first time to take the photo that there must have been a seal screw under the calibration label which has been broken out of the case and slightly damaged the casing inside to open the unit before without damaging the label.
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Old 19th Aug 2013, 12:34 pm   #1069
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Ian,

It is possible that the movement of your meter has been replaced at some time but more likely that the serial number is original and was hand written during intial manufacture.

It was only around the time your meter was made that AVO began to use scaleplates selected from a range of 10 or 12 linearity characteristics (scale shapes). There may be a number at the bottom centre of your meter's scaleplate showing which one of the range has been selected.

Prior to that, the radial scale lines were hand ruled during calibration onto a scaleplate with pre-printed arc and numbering. Even earlier, the figures were also hand written.

This gives considerably better accuracy than simply pre-printing scaleplates but means that simply exchanging scaleplates from one movement to another will compromise the accuracy.

PMM.
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Old 19th Aug 2013, 6:17 pm   #1070
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Default Re: AVO Multimeter survey

Mine's an AVO 9 Mk IV 43385 94/5/71.

I bought this direct from AVO on 24 August 1971 (invoice no 041739) for £34.80 plus 45p carriage.

The 'Ever-ready Leather Case' was an additional £6.30. Sadly this bio-degraded a couple of years back. I got a replacement case via e-Bay (Test Set Multirange No. 1, NATO stock number 6625-99-105-7049). Seems to be leatherette-covered cardboard, rather than leather. Cost me almsot as much as the meter did in 1971.

The meter has seen very little use but recently started reading 20% low on all ranges. See my other post on this forum!!
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Old 19th Aug 2013, 11:47 pm   #1071
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Quote:
Originally Posted by percivjr View Post
Mine's an AVO 9 Mk IV 43385 94/5/71.

I bought this direct from AVO on 24 August 1971 (invoice no 041739) for £34.80 plus 45p carriage.

The 'Ever-ready Leather Case' was an additional £6.30. Sadly this bio-degraded a couple of years back. I got a replacement case via e-Bay (Test Set Multirange No. 1, NATO stock number 6625-99-105-7049). Seems to be leatherette-covered cardboard, rather than leather. Cost me almsot as much as the meter did in 1971.

The meter has seen very little use but recently started reading 20% low on all ranges. See my other post on this forum!!
Thats a coincidence. Just 7 differrent from the number on my case. I bet it was in the same mod surplus lot that I picked my meter from in about 1990 in a surplus equipment store in leeds.
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Old 20th Aug 2013, 10:10 am   #1072
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Quote:
Originally Posted by ken3966 View Post
I bet it was in the same mod surplus lot that I picked my meter from in about 1990 in a surplus equipment store in leeds.
No! I bought mine directly from AVO in 1971.
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Old 20th Aug 2013, 7:56 pm   #1073
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Quote:
Originally Posted by percivjr View Post
Quote:
Originally Posted by ken3966 View Post
I bet it was in the same mod surplus lot that I picked my meter from in about 1990 in a surplus equipment store in leeds.
No! I bought mine directly from AVO in 1971.
I meant the mod id number on the case which you bought. When I looked through the batch some meters were broken so presumably salvageable items like the case were seperated and sold on.
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Old 20th Aug 2013, 8:35 pm   #1074
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Quote:
Originally Posted by ken3966 View Post
I meant the mod id number on the case
Sorry, I misunderstood.

But no, the case was 'BNIB' as they say. In a plastic bag, in a slightly musty smelling cardboard box. Probably released from NATO's multimeter case mountain somewhere.

I just Googled my NATO number and found a couple of interesting (well maybe not that interesting) links including this: http://www.nsn-now.com/Indexing/View...=6625991057049

Perhaps there is scope for a separate "Avo case survey" thread here!!
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Old 21st Aug 2013, 8:06 am   #1075
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Strange as within this thread my mod case number was also on someone else's case with a different meter inside, as I already had mine when he posted about his
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Old 21st Aug 2013, 5:34 pm   #1076
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One last post before I get banned for taking this thread off-topic.

I've just worked out that the number on the outside of the case lid (6625-99-105-7049) is the stock number for the meter.

The number on the inside of the case lid (mine is 6625-99-638-5520) is the stock number for the case.

Note that these are stock numbers, not serial numbers. Search here:

http://www.iso-group.com/nsn-search/...O-Part-Number/
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Old 22nd Aug 2013, 12:01 am   #1077
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Default Re: AVO Multimeter survey

Two more baby Avometers - they breed, you know - have arrived at the Avo orphanage and will receive the required amount of TLC in due course.

DC Avominor S/N 40955-16 needing some attention
DC Avominor S/N 89534-647 in perfect working order (that's a first...)

The first meter is the early pattern with the small resistance 'zero' knob and the 6-120-300 volt ranges. Would the serial number suggest January 1936?

The second meter is an interesting one, in the later style with the 6-60-300 volt ranges with the scaleplate professionally marked "Property of M.I.M.C.Co.Ltd". It came in a small leather case bearing the same legend, neatly housing the meter plus a set of test leads. This appears to have been made by Avo specifically for Marconi International Marine Communications, yet by 1947 this model of instrument would have been rather outdated.
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Old 26th Aug 2013, 10:51 am   #1078
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I've spotted an elderly AVO for sale, s/n 74879-A-258 and in addition to the usual voltage, current, and ohms ranges, it has scales for mW, W, µF & db. (See attached photos).

I take it that the date of manufacture is February 1958, but this appears to be a rather special model and possibly one of a limited number.

Asking price is equivalent to about 30 UK Pounds.

Can anybody identify the user or function this meter may have been built for?

Cheers

Billy
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Old 26th Aug 2013, 11:36 am   #1079
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Billy,

While all Avometers are special to us, some are more so than others due to their design or rarity.

The one you have seen is in fact a standard Model 7 Mark II from February 1958 as you rightly interpret from the serial number.

The mW, W dB and microfarad scales are all standard facilities which the Model 7 always had from its introduction in 1936. The first three of these are intended to measure the audio output of radio receivers and the microfarad scale uses an internal capacitor and an external alternating voltage supply to measure capacitance.

The model was gradually developed through the years and was in production until the early 1980s. The version here has a block magnet movement which replaced the original horseshoe magnet type around 1948, and the later design of terminals. When first introduced in 1936, the Model 7 had a considerably higher sensitivity than previous Avometers due to its 1mA fsd movement. This gives the Model 7 a sensitivity of 500 ohms per volt normally and 1000 ohms per volt with the "divide by two" button pressed.

The intended application of the Model 7 was radio work but the coming of television and radar made a higher sensitivity of 20,000 ohms per volt, as in the Model 8 (May 1951), desireable.

The Model 7 came to be regarded as a multimeter for general electrical work but continued in production with the simpler Model 40 throughout its production life.

Avometers regularly sell on Ebay in the UK and for £30 you would expect a very good example of a Model 7. If your luck's good, you can buy one for less than the cost of postage from the seller.

For more information on the attributes of the Model 7, see the user manual. You should find this on-line, or send me a private message with an email address if you want.

PMM
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Old 26th Aug 2013, 1:44 pm   #1080
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Billy,

As Peter suggests, £30 is a relatively high price for what is a fairly common instrument in unknown condition. I have struggled to sell fully restored and calibrated examples here in the UK for £25! However its relative rarity in your part of the world may well affect the asking price. In good working order, these meters are a delight to use and a Model 7 is virtually the only test equipment you need for servicing vintage valve radios.

Before parting with any money I would be tempted to ask to give it a thorough inspection and a few tests. Look closely inside the battery compartment for evidence of corrosion, which can be quite destructive if the old discharged batteries have been left inside for many years. Check that the pointer can be zeroed accurately and that the movement is free to travel over its full scale. Take a PP3 9-volt battery with you plus a couple of test leads, and try to measure the AC mains voltage to check the AC side of things.

Phil
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