AVO Multimeter survey

[Sinewave]

Originally Posted by 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

The sticker on the side identifies it, that's the serial and date code.

[Phil G4SPZ]

Originally Posted by Phil G4SPZ

…even a BLR121 in there to be re-stuffed…

Ten alkaliine button cells type AG10, GP189, SR54 or LR1130 are a perfect fit at a cost of just £1, inside a length of heatshrink sleeving - just the original battery’s end caps and no spacers are required. The meter now works perfectly on all resistance ranges.

Incidentally, I find on virtually all Avo 8/9 models that the /100 ohms range only zeroes properly after scrupulous cleaning of the battery and the meter’s terminals, together with all connecting parts of the main terminals, test leads and prods. In this case, judicious use of a small rotary wire brush was necessary on the battery terminals. The fuse can also be a source of unwanted resistance.

[stickfly]

Received another today.

A Model 7 : 35471 - A - 752

Came in a wooden box with 2 sets of original leads + Multiplier + Shunt.
Couldn't test it as the batteries had swollen up so much I couldn't remove them, I had to remove the battery box first. I couldn't believe how tight the case was, it took an age of careful prising before it would open. Looks like there's a resistor or 2 in the green sleeving. (To replace a bobbin ?)
My next job is to fit holders for an AA battery + PP3 battery and see if anything works.
Regards ..... Gary

(Actually, it won't work with just the batteries sorted as the cut out button won't stay in position, it's permanently popped out.)

[Phil G4SPZ]

Cut-outs are relatively logical and usually easy to sort out - aim for cleanliness plus freedom of movement, but no lubricants. Don’t do what I once did though, drop the hairspring on a dusty workshop floor took me an hour to find it!

[stickfly]

Originally Posted by Phil G4SPZ

Cut-outs are relatively logical and usually easy to sort out - aim for cleanliness plus freedom of movement, but no lubricants. Don’t do what I once did though, drop the hairspring on a dusty workshop floor took me an hour to find it!

Phil, if I could gather up all of the time that I've spent looking for items that I dropped and add it onto my life, I'd have an extra 15 years to go
Regards ..... Gary

[stickfly]

Update Phil,
Just decided to press the cut out button in & out to check how free it is and it has now reset.
So I decided to use a 9v PP3 to see if the DC Volts works : It does but the pointer sticks at 8.2v every time.
Still, it's progress I suppose.
I'll leave it alone until the weekend when I fit the battery mod's.
Regards ..... Gary

[Phil G4SPZ]

It sounds like debris caught in the moving coil’s air gap. Again, a straightforward but delicate job for which the movement will have to be removed.

[stickfly]

Thanks again Phil.
I've got 5 days off work from Friday and my wife will be at work, so plenty of time to have a good look.
Regards ..... Gary

[Sinewave]

Gary, since you've caught Avodiction, there's a model 5 on ebay which you should add to your Avotorium. I have about 5 of them already, so this one's yours

[Superscope]

If the Model 5 mentioned is the one in the group of Three Avometers for
sale, then be aware that it has the wrong Terminals on it, so they have
been changed at sometime.




Ian

[Sinewave]

It's still a Model 5 though, not a reason to not get it.

[Phil G4SPZ]

One reason not to get it is the scaleplate, which will be quite a task to restore.

I am very fond of my own 36-range Model 5, partly because of its very useful 1,000 ohms range which can be read with ease down to 0.1 ohm.

Ian is right about the terminals, which should look like the attached.

Phil

[Sinewave]

Again, I don't think that's a reason not to get it. If its for collecting purposes, it's fine as it is. Ok, it may not be ideal if you want to use it, but the older meters like this I collect and don't use. I did notice the terminals, which look like what are on the HR models, so perhaps it's an indication that it has been used and may well be in good working order other than the scale plate?

I do use some Avometers, but usually much later ones such as the 8 mark 5.

[Superscope]

Originally Posted by Sinewave

It's still a Model 5 though, not a reason to not get it.

Indeed,
My point was only to highlight that fact that the Meter has an incorrect replacement part.

It's important this information is highlighted, so that it doesn't become accepted incorrectly
as being original going forward.
Most collectors I would assume would want their collections to be historically accurate if possible.

Model 5's are not particularly rare, so you don't have to wait to long for one to pop up.
Plenty of very good ones out there, even with good Scaleplates.

Those HR Terminals (actually used on a lot of other Avo equipment) are seen quite
often on repaired Vintage Avo's. The original Terminals had much thinner threads (4BA I think),
than the later ones (2BA) so breakage was probably common.



Ian

[Station X]

One post moved to a new thread here:-

https://www.vintage-radio.net/forum/...d.php?t=198271

[Phil G4SPZ]

Quick question: are any of the Avo enthusiasts, collectors, restorers and other contributors to this long-established thread planning to visit the Retro Tech show on 21st May? It struck me that it would be nice to put a few faces to the names!

[Sinewave]

Originally Posted by Phil G4SPZ

Quick question: are any of the Avo enthusiasts, collectors, restorers and other contributors to this long-established thread planning to visit the Retro Tech show on 21st May? It struck me that it would be nice to put a few faces to the names!

Possibly. I think we did meet there one year? Years ago this was.

I might do it for a day out, although I really shouldn't be buying anymore equipment. Baby number three arrived three weeks ago, so it's difficult committing to anything that far ahead!

[Phil G4SPZ]

Babies… congratulations. I know the problem, but in my case with grandchildren!

Nearer the time, perhaps we can agree a meeting time and place.

[stickfly]

Evening everyone,
Another to add to the list.
Model : Admiralty 48A, Serial number : 12352-943
In box with 2x Shunts + Multiplier + Transformer and leads.
As ex RN I couldn't resist when it was offered to me
Haven't tested the unit yet.
Regards ..... Gary

[The Philpott]

All those bits look to belong together Gary, note the wingnuts on the AC current transformers are rough finished without nickel plating (so they're austerity spec, appropriate to 1943.)

The hand painting on the scale plate was done by the same employee as the Model 47A(S) that i brought in from the shed yesterday- i recognise the handwriting!

The Admiralty meters seem to have had an easier life than the Air Ministry meters, so it's likely to be viable. You might find one or of the high voltage shunts to be open circuit if they're wire-wound rather than component based.

(Heavy, aren't they? You probably have 8kg of test equipment there.)

Dave