AVO Multimeter survey

[Sinewave]

A quick look by eye shows this Precision Avo to be working very accurately testing it with a Time Electronics calibrator.

It's a lovely instrument, never thought I'd own one due to how rare they are.

[Phil G4SPZ]

The All-Wave Oscillator is missing its two cylindrical ‘dummy aerials’, normally stored in the two holes in the front panel. We have one of these oscillators at the Museum, with dummy aerials kindly donated by a Forum member.

[Sinewave]

I found it inside the oscillator after hearing a rattling. It's also missing two valves. What I'll do is make another thread soon and show you the inside and you can tell me what else is missing as I've never seen inside one of these before.

[pmmunro]

Another early Avometer for the survey: 13-range (DC) Avometer, Serial No. 4151, (Douglas Street production) has just sold at auction for £102.

I would estimate its date of manufacture to be around 1932/3. It is in very good cosmetic condition and appears to have the original, fixed, test leads.

From the price it would seem that at least two people were very keen to have it.

PMM.

[Sinewave]

There are some very serious collectors about prepared to pay top price for these early Avos now.

I bought one of these some time ago for £20. Sadly, lost in the post.

[AndyGilham]

Originally Posted by pmmunro

Another early Avometer for the survey: 13-range (DC) Avometer, Serial No. 4151, (Douglas Street production) has just sold at auction for £102.

I would estimate its date of manufacture to be around 1932/3. It is in very good cosmetic condition and appears to have the original, fixed, test leads.

From the price it would seem that at least two people were very keen to have it.

PMM.

That was me..... I bid £100 could not go any higher..... so I sadly missed out!?
Does look in great condition.... I hope another forum member got it!

Andy

[The Philpott]

The 13-range you mention was in timewarp condition, remarkable. I didn't even consider bidding for it as DC only examples don't interest me as much as they do some people- so it will give someone else far more pleasure than it would me.

Dave

I did not buy it!
It is a very good example of Avo model 2, and i do not have one in my collection, but as i paid too much for my Avo model 4 i did not want to repeat my fault seeing it was going to be sold for a big amount.

Congratulations to the winner; hope to see it here soon!

[Barnmead]

Sinewave's acquisition led me to unearth my precision avometer and to look on web for serial numbers of others.
mine 441-567 (6625-99-104-5783)
others
247-466
272-566
589-967
709-670 (this is a Mk2 version)

[The Philpott]

I will email you shortly with some images of the peculiar Model 40(S) i am working on Richard.

Dave

[Electronpusher0]

I have Model 40 to report in. Purchased at my local car boot for a fiver, pretty good nick, battery cover and the black probe present, no corrosion in the battery compartment.
Serial 5826-B-951

Its odd because it definitely says model 40 on the front and on the dial (no Mk2) and yet it has the two PF sockets at the top which would indicate a Mk2.

Peter

[The Philpott]

PF sockets offered as an option on late Model 40 MkI, i believe.

Dave

You are right, i have an Avo 40, with PF and the interior is the same of a 40 mk2, there is a thread about it.

[Granitehill]

Another for the survey :

EA113 , serial 6523-1177.

I got it in faulty condition from the usual auction site. The fault turned out to be one smoked resistor in a (fortunately) easily accessed place. It's a lovely thing, and didn't cost silly money (it was very grubby when I got it, but it cleaned up nicely).

Used almost daily.

[sparkymike]

I have just got hold of a Universal Avometer, model 48A in wooden box, complete with two shunts, multiplier and transformer in dusty/grubby condition,
but so far with the exception of the battery terminal that will have to be cleaned all seems to be good. There is a serial number on the dial plate that reads 1o656-143-R the is another plate on the lid of the box that give a different number. (possibly the meter has been replaced with another?)
I will post some photos after tea given time.
How is the battery connected in this model. ? A flying lead to the brass corner post and battery wedged up to the sprung brass fork ?
One of the wire wound pots is free but the other two seem to be seized.
Will investigate further. I would like to re-varnish the outside of the box. Can you still buy the old style brown varnish. I believe there should be some felt in the lid to protect the meter is that correct?
Mike.

[The Philpott]

I think there should be felt in the lid (there should certainly have been some around the sides of the base)

The original cell type had a screw terminal which engaged with the sprung fork, the other terminal was a wire en-bloc with the cell, which joined to the brass post at the corner of the battery compartment. This cell is obsolete so you are stuck with modifying the meter for a C or D cell (easily done)- but you might want to investigate the siezed pots before bothering! The meter might have been somewhere wet for a while causing the bakelite to swell. Completely siezed pots are uncommon - it may have had a hard life.

Dave

[Superscope]

Hi Mike,

I am assuming the Second Digit on the Serial Number is a 0 not an o ?

A Picture paints a Thousand Words.

The correct Battery for the 48A would have been a Rectangular/Square shape
approximately 30 x 30 x 80mm Equivalent to an Ever Ready R1662.

Although, being a Military Meter, the Batteries would have been
Military Branded items.
Somewhere on the Forum, there are Photo's of the original style Battery.

In the meantime, I have added some photos of the commercial Ever Ready Equivalent.

The Same Battery was used in the 36 Range Meters.

As Dave mentioned, the Battery is held onto the Positive Battery Terminal Fork by a Brass Nut.



As regards the Felt, yes there would have been Four small Squares of Felt, one on each side of the Meter compartment.
Two Pieces covering the Wooden Standouts along the sides and Two smaller pieces Top and Bottom.
It is likely you can still see where they were once Glued down.

There would also have been Two pieces on the Stands offs in the Lid to protect the meter,
and a Strip along the bottom to stop the Transformer and Multiplier rattling around.

Ian

[sparkymike]

Yes, typo on the serial number. 0 and not o.
Now checked the meter on AC volts and surprise, its ok !! It was probably in a damp garage for a while and the case had more than a matchbox full of what looked like insect eggs plus two grubs. I found two woodworm holes in the case, but no more so need to find the Rentokill tin and give it a good squirt. Both wooden case hinges were seized, but after a lot of heat and WD 40, they are fine. A small repair was needed on the Bakelite case for the transformer and that was not easy as both large wingnuts were solid and they need to come off to remove the case. Will the aid of a heat gun directed on wingnut but away from transformer case, I eventually removed them and case now repaired. There is a piece of Paxolin bridging the glass tube on the middle coil in the multiplier and that was bent and ready to drop off so new one will be made with the correct thread. (6BA probably).
Mike.

[The Philpott]

The one time i broke open a piece of wood and saw furniture beetle grubs, they were pale pink in colour. I use chemicals if i want to kill them, but the new way some people use is to bag up the offending article in plastic and put it in the freezer at minus 18 for a week or two.

'Solid Wingnuts, Batman!', as the boy wonder might have said.. It almost sounds like it has been living on the coast for a while, exactly the sort of thing that would be snapped up by stupids and upcycled- which makes it satisfying it's being restored.

Dave

[sparkymike]

Perhaps I am stupid for restoring it !! Ha!
A few repairs to do to the case, but all minor, like a crack or split here and there. I use Titebond, the USA wood glue available easily over here. It blends nicely with the wood and does not leave a white line like PVA glues. I also have here the old pearl glue that you warm up in a pot and is the stuff that most old furniture was assembled with and that is a reversible fix as you can warm it up to release joints.
Getting back to main topic, I should post pictures shortly.
Mike.