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 12th Dec 2018, 12:35 pm   #1861
Superscope
Octode
 
Join Date: May 2017
Location: St Austell, Cornwall, UK.
Posts: 1,018
Default Re: AVO Multimeter survey

Jeremy,
Thanks for the Serial Numbers.
Duly added to the List.

Dave,
With reference to your Model 4, I pulled this reply over from the 36 Restoration Thread
as I thought it more appropriate here.
Thanks to PMM if he reads this, as his Model 4 Serial was invaluable.
We only had Two Model 4's on the List, and one of them was yours Dave without a Date.
We now have Three and Two with Dates.

We have to be careful with such a small Data Sample, but I estimate around 31 Model 4's
were being produced per Month on average between Late 1934 and early 1935 based on the Two Dates we now have.

That would put the Date of your Model 4 Mid February -to- Mid March 1934.
Boils down to whether PMM's Meter was early or Late January.

As I think I mentioned before, the Model 4 seems to be the rarest AVO out there.
We have double that amount of Original Models 1's in the Survey.

Seems the Dates only started on the Model 3's.


Ian
Superscope is offline   Reply With Quote
Old 12th Dec 2018, 2:47 pm   #1862
Guest
Guest
 
Posts: n/a
Default Re: AVO Multimeter survey

Thanks for the information. Very interesting.

Avo 1 is very rare to see, also Avo 2,3, 4.

Here in the Canary Islands, i remember to see in the house of my friend Angel (who passed away in 1999 with 70) a couple of very old AVos, and many laboratory and field equipment from the 1920´s due to he worked in the Spanish telephone company for 45 years. Also a very big valve collection (thousands). It is a pity i did not collect that serial numbers and photos at the moment.
  Reply With Quote
Old 12th Dec 2018, 10:04 pm   #1863
pmmunro
Octode
 
Join Date: Jul 2004
Location: Dundee, UK.
Posts: 1,797
Default Re: AVO Multimeter survey

The survey should eventually give an indication of which Avometers are rarest but some of the candidates are:

"The Avometer" (Model 1, 7 ranges) the original and the subject of the first patent for a multimeter. Production was probably on a very limited basis as the concept became established. Production was from August 1923 to October 1927, when production of the 13 range DC Avometer began at Rochester Row, London.

34-range Universal Avometer (Model 4) - in production for only a few months between December 1933 and June 1934 - replaced by the 36-range Universal Avometer.

22-range DC Avometer (Model 6) - overshadowed by the Universal Avometers, and possibly did not sell in large numbers. Advertised during 1936 and mentioned almost as a footnote in other advertisements up to 1939 when production seemed to stop. Extremely rare.

Model 7 prior to 1939. This instrument was introduced in August 1936 but survivors from before 1939 seem to be extremely rare.

Air Ministry Type D, 10A/10610 (Not the later 10S/10610). An Air Ministry meter based on the 36-Range Universal meter. Protection by fuse, not an automatic cut-out.

High Resistance minor. The first 20,000 ohm per volt meter made by ACWEECO. Unusual but not impossible to find.

There are also variants of the later mainstream Avometers, HR, Model 7 and Model 8 which are rare, including some military versions, home and export, and the Braille meters.

Some of the early Heavy Duty Avometers are not common such as the metal cased Great Western Railway original with the die-cast aluminium front panel. (Actually delivered to the Western Region of BR in 1948). This was a truly heavy duty instrument unlike the later versions which for some reason had very vulnerable phenolic resin cases.

There was, at least in prototype form a Heavy Duty Mark VI meter but, while I believe one was reported here, it may not have gone into full-scale production.

An export drive in the late 1960s resulted in the design of the Models 14, 15, 16 and 20 and the EA113. Some were possibly never offered in the UK and only the EA113 was sold domestically in significant quantities. It is difficult to say if these are rare, but the Model 15 & 15 do not appear to be at all common. From the same era, the Model 10 may never have been readily available on the home market. Its case was similar in design to the DA116/7 but in a rarer unattractive shade of nicotine stain beige.

Other Avo units which may not even have gone into production due to the onset of the Second World War were a low resistance "Ductor" type of milliohm meter and a high resistance meter. The AVO Oscillator of 1935 is not at all common and although a Capacitance meter was advertised in 1936 I do not recall any reports of survivors.

This is probably not an exhaustive list but perhaps others would like to contribute their thoughts and experience.

PMM
pmmunro is offline   Reply With Quote
Old 12th Dec 2018, 10:55 pm   #1864
The Philpott
Dekatron
 
The Philpott's Avatar
 
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,081
Default Re: AVO Multimeter survey

At more or less the same time as the High Resistance DC 'minor was released there was the Low Resistance Ohmmeter based on the same (reinforced/stepped side) casing as the HR. I know of two in existence, one of which is in poor condition from impact damage and corrosion. Instrument No.370 made in Apr 1941 and No.375 in May 1941. Both restored as far as possible.

The movement of the LRO appears to be of a unique current rating, and as with all meters based on this casing the glass is perilously thin, meaning it is not a pocket meter in the truest sense.

Dave
The Philpott is offline   Reply With Quote
Old 14th Dec 2018, 1:30 am   #1865
Refugee
Dekatron
 
Refugee's Avatar
 
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,549
Default Re: AVO Multimeter survey

Here is a photo of the nato number for the carry case on my Multiminor shown in post#1776.
Attached Thumbnails
Click image for larger version

Name:	IMG_0241.jpg
Views:	81
Size:	102.4 KB
ID:	174553  
Refugee is online now   Reply With Quote
Old 14th Dec 2018, 1:12 pm   #1866
Guest
Guest
 
Posts: n/a
Default Re: AVO Multimeter survey

My Avo 8 mk3 serial number 11860-365

Case in very bad condition

The 15 volts battery is a Spanish cegasa, a battery for cameras, that cost 100 pesetas in the past, more or less half pound, 0,60 euros very expensive in the past.
Attached Thumbnails
Click image for larger version

Name:	F59F8046-6DDF-4DA2-8E4F-AF133D6C3514.jpg
Views:	87
Size:	65.8 KB
ID:	174571   Click image for larger version

Name:	3C2A7B65-0E61-497D-8A36-A49260461654.jpg
Views:	95
Size:	50.7 KB
ID:	174572   Click image for larger version

Name:	DAA2E552-205D-475F-8388-39157D084947.jpg
Views:	84
Size:	90.5 KB
ID:	174573   Click image for larger version

Name:	24A782B0-BA1B-4889-AE24-12B2BE76DE84.jpg
Views:	96
Size:	53.2 KB
ID:	174574   Click image for larger version

Name:	A7A72147-A47A-4F84-BEDF-29C8145D0AEB.jpg
Views:	84
Size:	38.2 KB
ID:	174575  

  Reply With Quote
Old 14th Dec 2018, 1:13 pm   #1867
Guest
Guest
 
Posts: n/a
Default Re: AVO Multimeter survey

The battery
Attached Thumbnails
Click image for larger version

Name:	68D0497B-7048-452A-9E33-69AC276AE65E.jpg
Views:	83
Size:	20.4 KB
ID:	174576   Click image for larger version

Name:	B107E5D1-40F4-4DA0-9917-E63958637CE7.jpg
Views:	83
Size:	39.3 KB
ID:	174577  
  Reply With Quote
Old 14th Dec 2018, 4:55 pm   #1868
Superscope
Octode
 
Join Date: May 2017
Location: St Austell, Cornwall, UK.
Posts: 1,018
Default Re: AVO Multimeter survey

Ah! Refugee,
Your Multiminor with the Blood Red Tinting Trick!

Didn't realize that was a Military variant until your Case Photo.
I can see the NSN now on the very top of the Meter Scaleplate, but can't read it.

Can you tell me what the NSN is for the actual Multiminor ?

I was only correlating the NSN's for the Model's 7,8 & 9's but it would be wrong not to include other AVO's as & when they become available.

Forum,
I should clarify my earlier comment that the Model 4 is the Rarest AVO.

That only refers to full sized AVO Models, and only applies to the base Model, not any of their Variants and those which are logged on our Database.

Unfortunately, it shows my bias towards the Full Size Meters, but I am seeking help on a cure for this.

A couple of Heavy Duty and AVO Minors have crept into the House recently to Help me.

Ian
Superscope is offline   Reply With Quote
Old 14th Dec 2018, 5:30 pm   #1869
Guest
Guest
 
Posts: n/a
Default Re: AVO Multimeter survey

I noticed that my Avo 8mk3 from 1966 is different inside than this Avo mk3 from 1965

Does anybody studied the differences during the production of the same model? The variations I mean
  Reply With Quote
Old 14th Dec 2018, 5:31 pm   #1870
Refugee
Dekatron
 
Refugee's Avatar
 
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,549
Default Re: AVO Multimeter survey

There is another nato number inside the case.
6625-99-538-8065
Then there is the important number on the scale plate.
Attached Thumbnails
Click image for larger version

Name:	IMG_0247.jpg
Views:	71
Size:	50.1 KB
ID:	174600  
Refugee is online now   Reply With Quote
Old 14th Dec 2018, 6:51 pm   #1871
pmmunro
Octode
 
Join Date: Jul 2004
Location: Dundee, UK.
Posts: 1,797
Default Re: AVO Multimeter survey

I bought a small quantity of each type of terminal cap from Megger in Dover just after Model 8 production ended but only have a few left which I expect to need for my own restorations. The part numbers are 3816-502 (Black) and 3816-503 (Red). The price had increased considerably from the previous batch which was listed at £0.17 each or I would have bought more.

It might be worth contacting Megger to see if there are any left or if further stocks were ordered but I think the policy was not to replenish and parts which were sold out.

This is perhaps a part which could be reproduced by 3D printing, possibly on a commercial scale and supply them in a similar way to the electrolytic capacitors available throught the BVWS. It might even be worth commissioning an injection moulding die as the part is so small and one mould would cover both colours. I would willingly contribute a couple of new samples to use as patterns and I could produce a CAD drawing.

I would expect that quite a few forum and BVWS members would be interested at a price around 50 pence each.

PMM
pmmunro is offline   Reply With Quote
Old 14th Dec 2018, 7:25 pm   #1872
Phil G4SPZ
Dekatron
 
Phil G4SPZ's Avatar
 
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,735
Default Re: AVO Multimeter survey

Quote:
Originally Posted by Aitor Eneko View Post
I noticed that my Avo 8mk3 from 1966 is different inside than this Avo mk3 from 1965

Does anybody studied the differences during the production of the same model? The variations I mean
This is one of the most frustrating yet compelling facets of Avometer collecting. Many of us start with a single Avo, then realise that there are several Models, and decide to try collecting one of each. Soon it dawns on the collector that each Model comes in several Mark numbers, and the potential size of the collection expands yet again. Then there are the halfway-house types, like the Model 7 Mk IIs with the black Bakelite terminal knobs of the Mk I. Eventually, like Aitor, you discover that there are innumerable variations, inside and outside, even within the same Model and Mark number.

Personally, I’ve concluded that every individual Avometer is unique, almost a prototype, and attempting to collect ‘one of each’ is doomed to failure. But by that time, of course, it’s too late and your house is full of Avometers...
__________________
Phil

Optimist [n]: One who is not in possession of the full facts
Phil G4SPZ is offline   Reply With Quote
Old 14th Dec 2018, 11:29 pm   #1873
The Philpott
Dekatron
 
The Philpott's Avatar
 
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,081
Default Re: AVO Multimeter survey

The difference i did notice between Avo 8/III meters from 1965-1966 is several wound shunts in the earlier unit were component resistors in the later one. My 1965 meter also has a scale-plate with thinner type (but the same font). IIRC,The later Mk III (eg 1968) has smaller Morganite pots. for trimming resistance ranges. The board on which they sit suits either type.

A recent limited supply of second-hand terminal caps dried up very recently, and towards this point the price unfortunately doubled. They were not cheap. The originals are prone to split (especially the red ones) and both colours can also slip on the splines (once this has happened it keeps happening) or come adrift and jam inside the leads. 3D printing could hold the answer if the correct material and tolerances are done-perhaps by trial and error. The originals, i find, are less prone to split if warmed up before fitting. Megger don't list them any more but it could indeed be worth a query.

There are certainly a lot of older (fuse equipped) meters with the special fuse blown and bypassed. My type E meters suddenly became accurate on K=2 when i found an original fuse and replicated the value.

I used a Model D on the car today but did make a slight correction for temperature.

Dave
The Philpott is offline   Reply With Quote
Old 14th Dec 2018, 11:50 pm   #1874
Guest
Guest
 
Posts: n/a
Default Re: AVO Multimeter survey

I will be interested in the 3D CAPS.

Perhaps we can begin this project.
  Reply With Quote
Old 16th Dec 2018, 10:28 am   #1875
The Philpott
Dekatron
 
The Philpott's Avatar
 
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,081
Default Re: AVO Multimeter survey

Rarity:

A rival for the rarest (and most obscure) full-size avometer is the Type 107 (OY test-meter) a military contract.

It's fundamentally based on a fairly early Model 8 but has early terminals at the top (possibly not connected..?) and newer red/black main terminals at the bottom. The ranges are unique (as is the 0-50 range on the scaleplate) and there are lots of unused blank positions on the rotary switches. Peculiar metal mountings are on the side of the case, we did wonder if it was part of a gimbal facility. If you study images of this meter it gives the impression that it has been photo-shopped to make almost every aspect of it unusual!

As far as I know 2 are in captivity, one of which underwent a very clever and painstaking repair to a seriously damaged facia. Very little has come to light about this meter, in the back of my mind (and in the absence of anything more conclusive) I thought it might have been a cold war contract and carried on Nimrods, Shackletons, etc.

Dave
The Philpott is offline   Reply With Quote
Old 16th Dec 2018, 10:14 pm   #1876
pmmunro
Octode
 
Join Date: Jul 2004
Location: Dundee, UK.
Posts: 1,797
Default Re: AVO Multimeter survey

One of the captives.

The top two terminal positions are fitted with blanking caps which appear to be fixed Mk I style terminals.

There is no instruction plate on the back supporting the hypothesis that the side fixings were intended to hold the meter down in some way.

Any information about the intended use would be most welcome. I tried contacting "Vulcan to the Sky" but got no reply.

PMM
Attached Thumbnails
Click image for larger version

Name:	Front Panel_r.jpg
Views:	102
Size:	70.1 KB
ID:	174738   Click image for larger version

Name:	Side_r.jpg
Views:	79
Size:	36.3 KB
ID:	174739  
pmmunro is offline   Reply With Quote
Old 16th Dec 2018, 11:35 pm   #1877
Superscope
Octode
 
Join Date: May 2017
Location: St Austell, Cornwall, UK.
Posts: 1,018
Default Re: AVO Multimeter survey

I have to concede, that this AVO Type 107 might well qualify for the Rarest Full Size Avo Meter.

I didn't know about this Meter before, because as yet, I don't think any Serial Numbers have ever been logged for either of them.

Unless we could get Serial Numbers on the Two in Captivity (Assuming they have any!), it's
difficult to fit them in the Survey!
Although their importance means they should go in somewhere.

Might just have to log them with out Serials, something I haven't done with other Models.
Does anybody know anything about their Dates?

Ian
Superscope is offline   Reply With Quote
Old 17th Dec 2018, 12:46 am   #1878
pmmunro
Octode
 
Join Date: Jul 2004
Location: Dundee, UK.
Posts: 1,797
Default Re: AVO Multimeter survey

Sorry, I should have included the serial number; OY-659-122. This is in accordance with this model being known by the "OY" designation. I would suggest that this number sets the date at June 1959 which is cnsistent with the characteristics of the instrument construction.

PMM

Last edited by pmmunro; 17th Dec 2018 at 12:48 am. Reason: Addition of date comment
pmmunro is offline   Reply With Quote
Old 17th Dec 2018, 2:05 pm   #1879
The Philpott
Dekatron
 
The Philpott's Avatar
 
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,081
Default Re: AVO Multimeter survey

Paul Adams restored the other Type No.107, major plastic surgery detailed in his thread of 26th July 2014. I cannot read the serial number though. As Peter has said the REV MC facility is rotary, marked NOR. and REV., and similar to the K rotary switch on a Model D.

The resistance ranges are separated by 'decade' rather than 'century', again this is at odds with a Model 8, but gives good accuracy over a more limited range. (Like a Model 7 or 40.)

The whole thing is so specifically designed that a rather narrow field of use must have been required..probably at altitude. Optimised for reading rather low DC currents, and no AC current facility-transformer deleted.

Dave
The Philpott is offline   Reply With Quote
Old 17th Dec 2018, 3:37 pm   #1880
Phil G4SPZ
Dekatron
 
Phil G4SPZ's Avatar
 
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,735
Default Re: AVO Multimeter survey

Dave, your mentioning Paul Adams’s Model 107 prompted me to give him a ring, as I hadn’t heard from him or seen him for ages, and as he wasn’t in good health I feared the worst. I’m pleased to say that he’s still with us! He suffered a major computer virus and lost his Forum password. I’ll see what can be done to get him back on.

He still has his massive collection of Avometers.
__________________
Phil

Optimist [n]: One who is not in possession of the full facts
Phil G4SPZ is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 9:06 pm.


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 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.