AVO Multimeter survey

[The Philpott]

..No problemo, my memory does this Peter, but usually regarding what i had for dinner an hour ago- then a minute later the fog clears!

The functionality to weight ratio of the Avo HR is quite poor- no AC current ranges and DC current only up to 1 amp. The terminals are rather spindly as well, prone to getting bent when extended. After some tweaking I actually got mine within specs as described on the rear of the meter.

Dave

[AndyGilham]

Picked up a 1983 Avometer Model BM10. Quite a bit different from the original Model 10, becoming a BM10 when The company became Megger.

[micheal]

The AVO model 10 is a multi meter.
The AVO/MEGGER BM10 is a insulation tester.

Mike

[AndyGilham]

You think I should know that..... good point! ����

[pmmunro]

The casing style was the same for several instruments including the DA116 & DA117, with different colours of plastic used for the mouldings. The Model 10 looks at first glance to have been used in heavily nicotine poluted atmosphere, even when new.

If anyone wants a scan of the Model 10 user manual, please let me know.

I don't know if the Model 10 was an export-only model but it doesn't seem to have been widely advertised in the UK.

PMM

[AndyGilham]

Peter,
I do have a couple of Model 10 in the collection.....But you don't see many! I also have a couple of user manuals in different formats.
It's a nice little instrument.

Andy

[Superscope]

I found the elusive Long Reach Probe recently, which fitted in the
Battery Cover recess found on most of the early Model 7, 40 and 8's.
I thought it might be of interest to some, since these seem to be very Rare.

I assume these must have been produced in their Tens of Thousands over the years,
but very few seem to have survived.
Not sure if these were optional extras or included with the Test Lead Set if it had the necessary Battery Cover.

Having only seen the occasional Photo, I didn't know much about this Probe and was
surprised to find that the Probe is actually Rubber Covered and not solid Bakelite as I thought.
It is basically an early version of the later Conical Test Lead Probe.
I actually prefer the design of this early Probe to the later ones.


Ian

[Phil G4SPZ]

Thanks Ian. Now you've posted that picture, I vaguely recognise it and I reckon I have the remnants of one, or something very like it, in my junk box. I'll look it out.

[Superscope]

Hi Phil,

These Probes seem to be a surprisingly Rare AVO items.
They must have been made in their Thousands, but it's Rare to see them.

Surprisingly, the one I picked up is in pretty good shape. Not perfect, but the
Rubber is in very good shape.
I think the Rubber piece mid Shaft is either cut down or not original though.
I would expect this piece to be longer to match the shape of the Battery Cover recess.




Ian

[Phil G4SPZ]

Here’s mine. Like your example, it’s in black - surely they must have been made in red too? Perhaps not. Anyway, mine doesn’t have a rubber sleeve over the centre of the prod. You’re quite right, though, such a sleeve would have been a slightly larger diameter to fit in the recess. Here’s a thought... perhaps the sleeve was originally available in red, to be slipped on as an indicator whilst being used as the +ve probe? Or rather, to be pulled off if the long reach probe was being used as the negative.

Apart from a small portion of the insulation about 5mm long that has broken away near the tip, my example is in very good condition, the rubber is still flexible and shows no signs of cracking or perishing.

So, there are at least two of these things in existence! Unless, of course, you know different...

Does anyone have any old Avo catalogues or adverts showing this probe?

Phil

[Aitor Eneko]

https://www.vintage-radio.net/forum/...d.php?t=151966

[Phil G4SPZ]

The probes on the right of the picture in Aitor’s thread appear identical to the ones owned by Ian and myself, and they fit perfectly into the moulded shape within the battery cover. Hard to imagine they’re not Avo products.

[Superscope]

Thanks for the Link Aitor,

I knew you brought the subject up of this Probe before, but I was looking for
it in the wrong place.
Didn't realize it was on it's own unique thread.

Having re-studied the Photo of the Probes you posted, I would agree with Phil.
It makes no sense that the Two Probes on the Right are not the correct ones.
I re-posted your Photo here for reference.

I noticed that they are very slightly different, probably due to being different ages and Batches.

Interestingly for me, the one Second from Right has the exact same Rubber Sleeve that
mine has.
I had assumed mine had been cut down or replaced, but maybe this is not the case.
I would assume though, that at some point, probably very early on, this sleeve would have been longer to match the Battery Cover.
Maybe it was to tight a fit so was made shorter to accommodate that.

The Large Probe on the Left for sure, is a much later design, and whereas it might fit the
Battery Cover, it's shape would be very inconvenient to carry in the Lid.


Any more Photos anyone?


Ian

[Superscope]

AVO Advertisement from 1955 attached,
seemingly showing this Long Reach Probe!

Also showing what seems to be a short Sleeve after all.

Ian

[Phil G4SPZ]

That’s definitely the same probe, well spotted Ian! The picture in the advert suggests that every Avo 8 came with a long reach probe as well as a pair of leads, two ‘normal’ prods and two croc clips. If that’s the case, and given that the battery cover contained a purpose-made receptacle to hold said long reach probe, how come so few of these probes seem to have survived?

A lot of Avo 8s came with the plain flat metal battery cover. Perhaps the long prod, probe-holding battery covers etc were optional extras at additional cost.

[Aitor Eneko]

Originally Posted by Superscope

......Any more Photos anyone?


Ian

That is all i have in my computer..

[The Philpott]

A further quirk related to battery compartment covers is this- there is a variation in the distance between the fixing screws. Not much, but just enough to ensure that i was unable to swap these over: An Aluminium one from a 48A and a Bakelite one from a 47A(S).

The threaded section that the fixing screws go into can also vary depending on whether the meter was intended to wear a metal or bakelite battery cover...(not to mention the large difference between the thickness of the aluminium/bakelite meter case..)

i don't have any early probes. Could there have been an arrangement where the factory subsequently considered early probes to be unsatisfactory/unsafe and issued a gratuity of some sort for those returned to them...? Or perhaps they simply were prone to seize up and got binned wholesale.

Dave

[Phil G4SPZ]

I must admit I’ve never really liked the (later) spring-loaded latching probes. Apart from the probe tip, which tends to slip off the contact being probed - not good in the confined environment around a B7G or B9A valve base - the sliding contact within the probe can go intermittently high resistance. I had to scrap one once that refused to respond to cleaning. I haven’t actually used one of the older black long-reach probes in anger, but I daresay they may suffer from the same problems.

[Accumulator]

I'm new on here and this is my first post so forgive if I screw it up! I'd like to add a few numbers to the AVO survey as follows:

Minor; 69724-1042
7; 71142-8749
7; 7887-A-1248
7; 7841-5566
7 MK2; 83959-a-360
8/9 MK4; 3817 370
8 MK5; 2241-0397
8 MK5; 03562 V/4/77
8 MK5; DC No. 037959 on label on the side with number 8 below it.

They are not all in working order and I can't remember where I gathered them over lots of years.
I may have one or two more.Time to have a sort out I think.

[The Philpott]

Further to the quest for unusual probes, i can't remember which meter these arrived with, but it would have been a Universal Avominor of some sort.

I believe that they are the original ones (although the wander plugs fitted are clearly not original, being simple side entry jobs where the wire can be held by simply tightening up the knurled part.)

The red probe has had new silicon sleeving fitted, but whoever did this was unable to shift the last piece of woven insulation and left it in place. The probes are quite nice and sharp, and a coppery colour rather than brassy.

The threaded brass section is hollow to allow the wire and the probe to be soldered in.

The rubber insulated wire is rather rigid, not too many conductors- although very old i think it has been salvaged from elsewhere- it feels like household wiring.

Dave