UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Test Gear and Workshop Equipment

Notices

Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders.

Reply
 
Thread Tools
Old 8th Jul 2007, 5:24 pm   #201
G Barham
Banned
 
Join Date: Mar 2005
Posts: 46
Default Re: AVO Multimeter survey

Hi,

I've just acquired a VERY old avometer...It's a full size unit ...no model or mark numbers, 20 ranges and a very odd 1.5V battery in the back (no room for any other battery) which has the positive terminal with a round nut and the negative comes out of the battery as a piece of wire. Serial number is 125-4628.

I believe it's from the 1930's

Regards

Tony.
G Barham is offline   Reply With Quote
Old 8th Jul 2007, 8:17 pm   #202
Dave Moll
Dekatron
 
Dave Moll's Avatar
 
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 5,396
Default Re: AVO Multimeter survey

The description of your battery sounds rather like this one.
__________________
Mending is better than Ending (cf Brave New World by Aldous Huxley)
Dave Moll is offline   Reply With Quote
Old 9th Jul 2007, 10:47 am   #203
SPCh
Rest in Peace
 
SPCh's Avatar
 
Join Date: Nov 2004
Location: Antwerp, Belgium
Posts: 345
Default Re: AVO Multimeter survey

Congratulations, Tony; and thanks

Your 20 Range AVO (a Model 3, but never called that by AVO) is the first one submitted via this survey. Yours dates from December 1935.

Being the early days of copper-oxide rectifiers, the AC scale could not be made linear, so there are two calibrated scales (both 0 - 120) - one for AC and one for DC.

Predating the overload cut-out, it has a fuse, but beware, it has a resistance (4 ohm) which is essential to the calibration.
SPCh is offline   Reply With Quote
Old 9th Jul 2007, 8:09 pm   #204
G Barham
Banned
 
Join Date: Mar 2005
Posts: 46
Default Re: AVO Multimeter survey

Well Thanks for letting me know ....I've just checked the thing out on a battery and (at least) on DC it's woking fine !

I have no use for it, I paid a 5.00 for it at a boot sale and considering it's age it's in excellent condition...the battey compartment looks almost pristine and it's made of wood !!!!! I think I bought it just to stop it being knocked about by the Philistines.

I also bought some sort of resistance expansion unit which fits the 2 teminals on the meter and presumably with the help of some higher voltage batteries allows the meter to read a higher range of resistance ... Possibly this unit is not as old as the AVO because it's says it's for a model 8.

I personally like the model 2 & 4 but I do have quite a few Model 8 MK6 and even a model 8 panclimatic thing in a metal case.

I must be going soft in my old age..... I should stick to Flukes....


Regards

Tony.
G Barham is offline   Reply With Quote
Old 10th Jul 2007, 10:19 am   #205
G Barham
Banned
 
Join Date: Mar 2005
Posts: 46
Default Re: AVO Multimeter survey

Hi

I've just looked an another oldish meter I have ...from all the useful info on this site it appears it's a NATO test set..marked Test Set No. 1 High Sensitivity 6625-99-105-7050 with a metal outer case and earthing screw.

Ser. no 13574-80.

One odd thing..the case appears to be dark brown Bakelite rather than black ...perhaps a trick of the light.

Regards

Tony.
G Barham is offline   Reply With Quote
Old 11th Jul 2007, 6:40 pm   #206
SPCh
Rest in Peace
 
SPCh's Avatar
 
Join Date: Nov 2004
Location: Antwerp, Belgium
Posts: 345
Default Re: AVO Multimeter survey

Tony,

The number you quote for your TS-1 is not, in fact, the serial number, but the Part Number of the scale-plate (instead of hand-calibrating the scale for every individual instrument, they matched the nearest "standard" scale-shape to the measured values).

The serial number will be hand-written low down in the left-hand corner of the scale-plate; it's probably in a fetching shade of indigo by now. If you could report it on the "Survey" thread I'd be grateful.
SPCh is offline   Reply With Quote
Old 12th Jul 2007, 9:50 am   #207
G Barham
Banned
 
Join Date: Mar 2005
Posts: 46
Default Re: AVO Multimeter survey

OK...it seems I gave the wrong number for my Test set No. 1 High sensitivity with dark brown plastic case and metal surround with earthingnut/bolt and very heavy including black Military carry case.

It should have been ACW/R572 Ser. No. 3909.

......all these numbers make my brain hurt !

Regards

Tony.
G Barham is offline   Reply With Quote
Old 21st Jul 2007, 12:24 am   #208
adeftereos
Triode
 
adeftereos's Avatar
 
Join Date: Jan 2005
Location: London, UK.
Posts: 32
Default Re: AVO Multimeter survey

Hi,

I've just picked up a Model 8 MKII. The serial number is 96327-C-959. It needs a good clean but otherwise appears to be intact.

Cheers

Angelos
adeftereos is offline   Reply With Quote
Old 22nd Jul 2007, 12:04 pm   #209
wave solder
Hexode
 
wave solder's Avatar
 
Join Date: Feb 2007
Location: Chesterfield, Derbyshire, UK.
Posts: 342
Default Re: AVO Multimeter survey

I have just acquired another meter. it is a "meter multirange No. 15 G.P.O. Avometer model 12 SN 1348-765.

I also have here a meter movement made by AVO It is in its own case with a window behind the scale a bit like the meter out of a CT160 valve tester.

On the scale is printed part No. 12031-1.E.T.1 There is also a serial No 5233-U-1152.
The 6 scales printed on the scale plate are:-

0-100,000 Ohms, 0-100 A&V, .0001-.5 uF, 0-1,000 Megohms, .05-5 W, -10-+10 db.
Does anyone have an Idea what this orphaned meter was removed from ?
wave solder is offline   Reply With Quote
Old 22nd Jul 2007, 12:45 pm   #210
pmmunro
Octode
 
Join Date: Jul 2004
Location: Dundee, UK.
Posts: 1,427
Default Re: AVO Multimeter survey

Wavesolder,

From the ranges and the resemblance to the movement from a Valve Characteristic Meter, it is likely that your movement comes from an Avo "Electronic Testmeter". There were several models from the late 1940s into the 1960s.

They appear irregularly on ebay.

PMM.
pmmunro is offline   Reply With Quote
Old 22nd Jul 2007, 3:52 pm   #211
jay_oldstuff
Octode
 
jay_oldstuff's Avatar
 
Join Date: Jan 2005
Location: Hyde, Greater Manchester, UK.
Posts: 1,074
Default Re: AVO Multimeter survey

Ok just back from sambrook and ive bought my first proper avo so ill share the details with you,
its a model 7X universal avometer serial no 943-1523 and its a panclimatic model, i baught it for 25 fully serviced by a retired avo man complete with manual carry strap batteries and new test leads,not used it in anger yet but just the feel of it oozes quality, personnely i think i got a bargain
only thing i would like to know is an approximate date of manufacture, can anyone help?

Jay
__________________
The light at the end of the tunnel is probably the headlight of an oncoming train
jay_oldstuff is offline   Reply With Quote
Old 22nd Jul 2007, 6:59 pm   #212
SPCh
Rest in Peace
 
SPCh's Avatar
 
Join Date: Nov 2004
Location: Antwerp, Belgium
Posts: 345
Default Re: AVO Multimeter survey

It's difficult to say EXACTLY, because I've not come across enough early panclimatic Model 7s to have established a pattern, but my educated guess would be that it OUGHT to have been made around the time the Allies were invading mainland Italy.

Nobody can now give you the day or what the weather was like (there WAS a time this MIGHT have been traceable) but if it conforms to the normal patterns (this was a transition time for serial number formats) it would have been calibrated some time in September 1943.

I'll PM you for for more details, and we'll see if we can resolve it more certainly.

It's the "oozing quality" which holds the afficionados in thrall.
SPCh is offline   Reply With Quote
Old 22nd Jul 2007, 8:43 pm   #213
SPCh
Rest in Peace
 
SPCh's Avatar
 
Join Date: Nov 2004
Location: Antwerp, Belgium
Posts: 345
Default Re: AVO Multimeter survey

I couldn't PM you - you don't seem to exist ! Try sending me one so that I can reply.
SPCh is offline   Reply With Quote
Old 22nd Jul 2007, 8:44 pm   #214
pmmunro
Octode
 
Join Date: Jul 2004
Location: Dundee, UK.
Posts: 1,427
Default Re: AVO Multimeter survey

There may be something of a mystery here, depending on how useful the information which I have on panclimatic versions of Avometers is.

I have no record of any reference to panclimatic meters until after the Second World War but would welcome any verifiable information concerning exactly when they were introduced.

As SPCH states, the serial numbers of Model 7s were in a state of transition around 1943 and I would agree that the serial number of the movement would place it in this period.

The doubts arise because, when you say that it has been reconditioned by an "Avo" man, do you mean that this is someone who worked for Avo - which was ACWEECO , in 1943 - only the meters were "AVO" at that time - someone who worked for one of the service agents, or someone who has independent experience of repairs?

It could be that your repair man is primarily concerned in getting meters working to his satisfaction and is less concerned with historic accuracy. Who can say that there is anything wrong with this approach? It could mean however that the movement, which carries the serial number, is from a different period to the rest of the meter.

The date of the movement should be relatively easily established. If it is from 1943, it will have a horseshoe magnet. If it has a magnet in the form of unpainted blocks (alnico) it is from the late 1947 to c. 1956 period. Red wrinkle paint on the magnet blocks puts it after 1956. Finally, the last of the Model 7s again had unpainted magnet blocks but these are smaller than the earliest block types and the anti-parallax mirror will be held in place by masking tape rather than held in an aluminium carrier.

If you are interested in dating your meter, internal and external photographs would help a great deal.

PMM.
pmmunro is offline   Reply With Quote
Old 23rd Jul 2007, 6:15 pm   #215
jay_oldstuff
Octode
 
jay_oldstuff's Avatar
 
Join Date: Jan 2005
Location: Hyde, Greater Manchester, UK.
Posts: 1,074
Default Re: AVO Multimeter survey

wow ok some interest in this wonderful instrument
i.ve had a little time to play today and see just how accurate it is, i hucked it upto my verible bench supply and bench dvm 10v shoeing on the bench supply scale 10v showing on the dvm and 10v showing on the avo, also tried it with a couple of resistors a 1K 1% tolerance one showed on the scale at 1000 ohms

i have included some pics which may answer some questions, if you would like any more please ask

as to the date i was expecting someone being able to tell me what decade it was made in not the year and the month, absolutely fantastic.

Jay
Attached Thumbnails
Click image for larger version

Name:	avo-1.jpg
Views:	284
Size:	174.8 KB
ID:	11070   Click image for larger version

Name:	avo-2.jpg
Views:	233
Size:	163.1 KB
ID:	11071   Click image for larger version

Name:	avo-3.jpg
Views:	231
Size:	181.8 KB
ID:	11072   Click image for larger version

Name:	avo-4.jpg
Views:	222
Size:	144.1 KB
ID:	11073   Click image for larger version

Name:	avo-5.jpg
Views:	240
Size:	170.6 KB
ID:	11074  

__________________
The light at the end of the tunnel is probably the headlight of an oncoming train
jay_oldstuff is offline   Reply With Quote
Old 23rd Jul 2007, 8:00 pm   #216
SPCh
Rest in Peace
 
SPCh's Avatar
 
Join Date: Nov 2004
Location: Antwerp, Belgium
Posts: 345
Default Re: AVO Multimeter survey

Okay; we're making progress.

The number you quoted (engraved above the kidney-window) is NOT the serial number, but some sort of owner's stock number, probably military.

The serial number is the one given at the bottom right hand corner of the scale-plate. It seems (from the picture) to be a digit missing, but would date the movement (at least, and probably the instrument too) from somewhere between March 1955 and January 1956.

The general appearance - specifically the red and black screw-socket terminals, and (if that were not enough !) the small print on the decal - make it definitely a Model 7 Mark II, and since these were being cranked out at between 1000 and 1500 units per month around that era, a likely date (from the serial number and truncated date code) would be July 1955 (the implication being that the date code on the scale-plate is missing a terminal "5").

((This is one reason why the Survey is wothwhile: it can "locate" the doubtfuls to within quite a narrow date band.))

As to it being a panclimatic, as you claimed, I wouldn't bank on it. The colour rendering on the picture suggests black-black rather than brown-black, and if it WERE a panclimatic the serial number wouldn't agree with the date code.

Don't fret about it. Even with the prospect of global warming, UK won't need "panclimatic" for a long, long time. Be happy; you've got yourself a nice bit of kit: well-designed, well-built, originally hand-calibrated, and with a good pedigree.

Don't be tempted to "calibrate" it against a DVM; if you can get it checked against a recognised Secondary Standard it will be worth the outlay. Otherwise, just put your faith in it, and GO.

(Next time I'm in your part of the country (I get there from time-to-time, and never travel with out my calibration kit) we can make a date and I'll do the "full Monty" on it for you in exchange for a G&T).

Thanks for the "treasure-hunt" - some of us actually find this sort of exercise fulfilling !
SPCh is offline   Reply With Quote
Old 23rd Jul 2007, 9:07 pm   #217
Brian R Pateman
Nonode
 
Brian R Pateman's Avatar
 
Join Date: Jun 2005
Location: Western Lake District, Cumbria (CA20) - UK
Posts: 2,136
Default Re: AVO Multimeter survey

Quote:
Originally Posted by SPCh View Post
Don't be tempted to "calibrate" it against a DVM; if you can get it checked against a recognised Secondary Standard it will be worth the outlay. Otherwise, just put your faith in it, and GO.

I'd agree with the sentiment expressed by SPCh.

It's a very useable instrument and if you can get it to Cumbria I would be happy to calibrate it for you once I get the workshop up and running again (about the end of August / mid September I think when the builders have finished).

Use it anyway, it will probably be as accurate as you need it to be!

Regards,
__________________
Brian
Brian R Pateman is offline   Reply With Quote
Old 23rd Jul 2007, 10:33 pm   #218
pmmunro
Octode
 
Join Date: Jul 2004
Location: Dundee, UK.
Posts: 1,427
Default Re: AVO Multimeter survey

Jay,

The pictures are a great help. From the front panel appearance I would conclude that the front panel and fittings are definitely from mid 1950s onwards. The mouldings are crisp with much sharper edges than seen on meters before this time.

I read the model "button" above the "Universal Avometer" badge as "7X" which would indicate a panclimatic instrument. If that is the case, the Bakelite front panel moulding should be a dark brown rather than the characteristic black of ordinary Avometers. It is difficult to judge the front panel colour against the red background, but the rear case definitely looks chocolate brown in your photograph.

It is unlikely that a repairer would have rebuilt a standard Model 7 on a panclimatic front panel, but by no means impossible. It just takes the best part of a day's work and possibly some remedial fault finding once it is apparently done. This means that there is a high probability that the components subject to panclimatic treatment are correct and even more likely if the instruction plate and rear case are for the panclimatic version.

The serial number on the scale plate is NOT consistent with the normal sequence and I would suggest that it is not a factory serial number but rather one written on by a repairer. This would be supported by the lack of uniformity in the lettering. The factory serial numbers were hand written but generally very evenly. The other anachronism about the movement is the faded red lettering on the power arc of the scale plate. This was in use in the late 1940s but definitely not in the era from which the front panel comes.

One feature which would date the movement without opening the meter could be the pointer. In the 1940s, the pointers were a thin wire with a small disc to attract the attention of the user. From around 1950 onwards, the pointers were the knife edge type formed from a flattened aluminium tube.

One concern I would have is about scale linearity. It is possible that the repairer has been tempted to transfer just the scale plate from one movement to another. Sometimes this is valid but until the mid 1960s, around the time of Avo's move from London to Dover, the radial lines on each scale plate were hand ruled using a dividing scale which used cardinal scale points, calibrated against a standard, as their reference from which to interpolate the scale lines. On these scale plates there are centre punch marks visible above the top scale arc at the cardinal points. From the mid 1960s, a range of pre-printed scale plates - 12 for the Model 8 -, each having a different linearity "law" was available. The movement was checked against a standard and the closest scale plate type which maintained the required degree of accuracy selected. These scale plates have a single or two-figure digit on the scale plate at the bottom centre.

As others have said you seem to have a very useable instrument, even if the components are not all from the same period. Remember however that a Model 7 is basically a 500 ohms per volt instrument (2mA for full scale deflection), 1000 ohms per volt with the "divide by two button" pressed. There will therefore be an appreciable loading effect on many circuits.

PMM.
pmmunro is offline   Reply With Quote
Old 23rd Jul 2007, 10:56 pm   #219
SPCh
Rest in Peace
 
SPCh's Avatar
 
Join Date: Nov 2004
Location: Antwerp, Belgium
Posts: 345
Default Re: AVO Multimeter survey

From the latest contribution, I'm not sure whether PMMunro is agreeing or disagreeing with me. Either way, I suggest you take HIS word for it.

If ever you're in Dundee, let him open it up and sniff inside.
That will be the ultimate test: he'll give you the year, month, and the weather, (and probably the name of the girl who sealed it !)

We both agree, however, use, trust and enjoy the privilege.
SPCh is offline   Reply With Quote
Old 24th Jul 2007, 8:35 pm   #220
russell_w_b
Dekatron
 
russell_w_b's Avatar
 
Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
Posts: 3,510
Default Re: AVO Multimeter survey

Hello!

I'm new on here, but I thought I'd add my twopenn'orth anyway...

I have an ex-NATO 'Test-Set Multirange No:1', effectively an 'AVO 8 Mk 5' with Her Maj's Government arrow on it, and the inscription: 'AVOMETER' above 6625-99-650-2823 which I take to be the NATO stock number. Beneath that is says: 'For Transit Set To 'Off' and 'DC' ' with helpful white markers. It bears the date (I think it will be the date) 9/85.

It's a fine instrument (I have a receipt for it...), although I prefer the construction of the AVO 8 Mk III and its ilk. I was told that the AVO 8 MkIII will measure AC up to about 70 KHz but the newer instrument (like mine) is restricted because of the effect of the flexi-connectors within. Is this true? What frequency will my AVO 8 MkV be good to?

I take on board all comments that abound regarding use and the simplicity, reliability and compactness of modern DMMs, which are fine for absolute measurements (and resistance) but you can't beat an 'AVO' for observing rate-of-change. I have come across circuits that specify a 20kOhm/Volt meter for correct loading when measuring, and care has to be exercised with a DMM as they are sensitive enough to read near-full V if one casually happens to have a probe in the hand, with the other hand to deck.
__________________
Regds,

Russell W. B.
G4YLI.
russell_w_b is offline   Reply With Quote
Reply

Thread Tools



All times are GMT. The time now is 9:28 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Copyright ©2002 - 2021, Paul Stenning.