AVO Multimeter survey

[stickfly]

Good evening everyone.
Another AVO acquired : 2260
This is written by hand on the scale, bottom left, but no date number.
The back says Test Set No1 Multirange (High Sensitivity)
There are several stickers on it which suggest a date of November 1972.
The last calibration sticker says it was last calibrated December 1997.
There is also a label on top, by what looks like some sort of terminal that says 254 / FEM. (?)
I loaded some batteries and the resistance ranges are working, then checked the batteries which read ok. I've not tried AC volts.
I'll have a closer look this weekend but it's looking fairly good at the moment.
Regards ..... Gary

[pmmunro]

A manufacturing date of 1972 would be correct. The Test Set No. 1 is basically a NATO Specification Model 9SX (Screened and Panclimatic). The brownish tinge to the colour of the front panel indicates that the moulding material is fungus resistant.

All prior commercial and military versions of the Models 8 & 9 were replaced by the Model 8 Mark V by 1973. For the Model 8 Mark V, neither screening nor panclimatic treatment were required to meet the specification.

PMM

[Superscope]

It's unusual not to have a Date Code on these, but it does happen.

It may possibly have had a New Movement at some point.
Serial Numbers or bits of, are often neglected on New Movements.

I looked up the serial No, and it points to 1967, probably around Aug/Sep.
A new Serial Number Range started in 1966, hence your relatively low
number.
This of course assumes, the Serial No is correct and no numbers are
actually missing. If the number was (1)2260, it would be late 1971.

Nothing is guaranteed though, in the Avo World.


Ian

[The Philpott]

Interesting stuff you've got there Gary, it does get addictive and acquiring becomes collecting- just don't consider seeking an example of every variation of every model of meter they ever made, as this way madness lies- you'll never do it!

The ones I use most are Model 8/III, Model D and Type E (Avominor) Test meter. The last two originate from Air Ministry contracts and are very every bit as useful to have around as a Model 8. The Model 40/47A/48A series are a bit of a white elephant (in my opinion) as the choice of ranges isn't particularly helpful.

If you've acquired a meter in a wooden box, leave it open for a bit in case there's residual moisture. The leather handles tend to attract mould if left in still/damp air.

Dave

[Ex Greeny]

One more for the Avometer Survey. I have a Model 8 Mark3. Serial no: 19189. 665, with red and black screw and plug in terminals. Complete with brown leather case.
Alan.

[stickfly]

Many thanks for the extra information everyone.
Dave, I know I'll probably upset some purists here regarding the wooden boxes but : Although there are people who think that old things should be left to look old & decrepit, I wanted the box to last a few years longer. The wood was very dry and had some splits starting to appear so I cleaned the box with very fine wire wool and then gave it a few coats of linseed oil to impregnate the wood with a little moisture. (Seems to work for the wife, although she doesn't use linseed oil )
I also bought some leather straps online and made new leather handles for the AVO's & boxes. The original ones had some nasty cracks which felt like they could snap at any time, in fact one box already had a handle that had broken one end. I have kept the originals in the boxes.
I also found some crumbling spacers that seemed to be made of some sort of thick felt in the boxes, presumably to stop the AVO knocking around too much. I replaced them with some modern sticky back felt sheets cut to fit the bottom & sides so that the AVO fits snugly.
Regards ..... Gary

[stickfly]

I bought an AVO 8 some weeks ago but when I received it I noticed the serial number was on a sticker. Except, the sticker doesn't look the same as in the auction photo's, so I looked at the seller's past sales and could see the same AVO pictures for a previous AVO sale. I then looked at what he had for sale now and, lo and behold, he has another AVO for sale with the same photo's.
Would the serial number be anywhere inside the AVO ?
Photo 1 shows the AVO advertised
Photo 2 shows the AVO I received
Photo 3 shows the sticker on the advertised AVO
Photo 4 shows the sticker on the received AVO
There's nothing to say which number 8 it is but the scale & whole meter looks very clean.
Regards ..... Gary

[The Philpott]

Not sure where the s/number is on those versions Gary.

I agree about the leather handles, i have cut new ones for any that have started to lose integrity; they can certainly harden up badly where they meet the metal rivets.

I have a Model 47A wooden box very similar to yours, the only weakness i have found with these is the screws holding the hinges can loosen or shear off with age (brass, of course.)
I gave one particular box internal retaining straps to stop the lid opening more than about 110 degrees to avoid stressing the hinges. My Admiralty 48A box and it's meter had a strong smell of 'ship'- seemingly a blend of fuel oil and heavy duty grease. Sadly dispersed now, the genie has escaped.

Dave

[pmmunro]

Originally Posted by stickfly

Many thanks for the extra information everyone.
Dave, I know I'll probably upset some purists here regarding the wooden boxes but :

I wouldn't worry too much Gary.

One of the main reasons I have for colllecting Avometers (and I have a few) is to trace their detailed history and for this reason I would take a curator's approach, but not to the extent of leaving any which could reasonably be restored to working condition, unrepaired - using original materials.

Professional museum staff seem to place more emphasis on leaving artifacts "as found" but that may detract from the available information as much as preserve it. I suspect that some of the incentive for "purity" may be that many museums have neither the knowledge nor the ability to carry out a valid restoration. There is a large centre lathe in the Royal Scottish Museum which is missing part of its saddle and has no toolpost. Without these, you need to know that something is missing to understand the exhibit. It needs an intelligent approach and, as in engineering, there is no single correct answer.

Have a look at http://sparkmuseum.com and go to page "Restoration of the Marconi Multiple Tuner" and see what you think. Is the before or after condition more informative about the equipment? I find the telegraph instrument restoration work of Fons Vanden Berghen very attractive and would think it does much to attract interest, but he's destroyed no end of "patina"!

You could also argue that your meter is not a museum piece. It is still a working instrument which should be repectfully maintained - and used!

I once made an Admiralty style wooden box, pianted RAF grey, for a ex-Air Ministry Type 'D' Avometer for someone else. I made it look as near to what such a thing might have been had the Air Ministry specified it but discreetly marked it as a "reproduction" so that here was no ambiguity about is "provenence".

PMM

[stickfly]

Originally Posted by The Philpott

Not sure where the s/number is on those versions Gary.

I gave one particular box internal retaining straps to stop the lid opening more than about 110 degrees to avoid stressing the hinges. My Admiralty 48A box and it's meter had a strong smell of 'ship'- seemingly a blend of fuel oil and heavy duty grease. Sadly dispersed now, the genie has escaped.

Dave

Dave, I like the idea of the retaining straps. The stress on the hinges had occurred to me and I thought that I must do something about it when I get around to it.
Regarding the ships smell : I remember the smell of diesel fumes mixed with cigarette smoke which was at it's worse on the diesel submarines, this mixture forms a unique smell that I only got close to smelling outside of the Navy in one place : A bus station garage where buses were idling while the mechanics were smoking.
Regards ..... Gary.

[Sinewave]

Originally Posted by The Philpott

Interesting stuff you've got there Gary, it does get addictive and acquiring becomes collecting- just don't consider seeking an example of every variation of every model of meter they ever made, as this way madness lies- you'll never do it!

Dave

That’s how I went mad, I think I’ve got most if not all variants of the model 8 across the seven marks, such as the regular ones, post office, BT, NATO etc…..plus other variants of some of the other models, I think I’ve got around 240 Avometers because of this utter mad addiction.

[Sinewave]

Originally Posted by stickfly

I bought an AVO 8 some weeks ago but when I received it I noticed the serial number was on a sticker. Except, the sticker doesn't look the same as in the auction photo's, so I looked at the seller's past sales and could see the same AVO pictures for a previous AVO sale. I then looked at what he had for sale now and, lo and behold, he has another AVO for sale with the same photo's.
Would the serial number be anywhere inside the AVO ?
Photo 1 shows the AVO advertised
Photo 2 shows the AVO I received
Photo 3 shows the sticker on the advertised AVO
Photo 4 shows the sticker on the received AVO
There's nothing to say which number 8 it is but the scale & whole meter looks very clean.
Regards ..... Gary

That’s standard on the Model 8 from the mark 5 onwards, serial on a sticker as shown. The other place you may find a serial is also inside the battery compartment.

[Phil G4SPZ]

A new acquisition, donated by a kind friend. Avo Model 9 Mk II, serial number 2776.366. The instruction plate says “AVO Ltd., Dover, England” and “A member of the Thorn group”.

The cut-out won’t latch, but it will make a nice meter once restored. My first Model 9, in fact.

[The Philpott]

Phil, with that meter you gain a 10mA AC range- testable with a resistor and a neon!
One of mine wouldn't work on that range until i'd fettled one of the leaf switches.

Dave

[Phil G4SPZ]

Interesting, thanks Dave. Beneath all the grime - the previous owner was a vintage car enthusiast - there lurked a very good meter! I managed to reset the cut-out, so now the meter is working and accurate on DC voltage, current and all ohms ranges, AC ranges yet to be tried. No corrosion in the battery box and even a BLR121 in there to be re-stuffed. Two prods, two croc clips plus a decent case which has cleaned up well, so I am very pleased!

[stickfly]

OK everyone,
I know I'm going to look very silly now but is there an actual list of all AVO's listed in the survey, with Model & Serial Numbers etc.
Regards ..... Gary

[stickfly]

Good evening.
I received another AVO today, a Model 7 that I bought as a donor unit.
Serial number : 42573-A-553
It has had the mod for the PP3 battery done, with a large D3 1.5v battery soldered to a pair of wires attached to the terminals.
I was prepared to use this unit as spares, especially the countersunk screws around the sides that secure the box to the mech'. Unfortunately, all of these screws have been replaced with Philips head M3 screws that have been just force screwed into place.
It seems to be in working condition but the resistance ranges are a little strange ... when turning the R knob to zero the range, the needle will fly from side to side. The tiniest movement of the knob can make the needle move fully to the RH end of the scale or move to the LH end.
The glass is good, though, and I could use that for another meter that has a broken glass.
Absolutely ridiculous, I know. I only bought this unit for parts for other units but I'm stuck with my mind saying " You can fix this " especially as I can't use the screws from it.
******.
Regards ..... Gary

[stickfly]

Sinewave,
Thanks for that but there's nothing in the battery compartment.
The AVO looks shiny & new but has nothing to identify it.
Much lighter than the earlier AVO's though & works well.
Regards ..... Gary

[pmmunro]

Gary,

The screws which you need for your Avometer case are 6 BA and should be non-magnetic. The originals were nickel plated brass with slotted domed countersunk heads, except for the more deeply recessed on on the lower right-hand side. This was an ordinary countersunk screw and would have been covered by a wax sealing plug with an inspector's stamp.

The main reason for using non-magnetic screws was probably to avoid their being picked up by the movement's magnet. It's unlikely that these screws, had they been steel, would have had any significant effect on the readings.

It seems you may have a faulty wire-wound 'R' Pot, possibly just a moving contact which is not in continuous contact with the wire wound track. (It's an open pot. assembled on the front panel). This may be easily put right but will involve unsoldering the connecting wires to the movement and taking the movement off the front panel. There are some very important points to know about how to do this and the procedure has been been described many times in a number of threads on this forum.

PMM

[Phil G4SPZ]

Originally Posted by stickfly

I only bought this unit for parts for other units but I'm stuck with my mind saying "You can fix this”…

Been there, done that. You have my sympathy. I’ve lost count of the number of radios, clocks and Avometers I’ve bought as ‘donors’ and ended up restoring, sometimes years later