AVO Multimeter survey

[The Philpott]

I think that the good condition of the early meters contributed to the price, but i can't deny that is a lot of money (coincidentally similar to the final bid on a Model 1 that changed hands recently)

Dave

[Sinewave]

Good grief! That's record price for those. Plus about £123 fees on top, making it £623 for 8 x Avos.

[pthomas]

It has been ages since I restored an Avometer. However, I couldn’t resist this Avometer 9 that was going cheap with nobody else interested. It was another for parts or non-working example so I thought that I would add it to my collection. Serial number 18320-569. It needed work mainly because the ohms ranges were out, and it was almost impossible to zero using the small potentiometers even with decent batteries. Everything else was very accurate. It turns out that one of the blue resistors on the shunt (number R18 measures) 211 ohm but should have been 450 ohms. It has had some distortion on the outside so might have either degraded or been overloaded. Also, R21 needed a small correction. It was not obvious without thinking it through that shunt values would affect the ohms ranges. Anyway, it works fine now and is astonishingly accurate. I noticed on the back it refers to a metal oxide rectifier but mine looks as though it has silicon types. AC is flat to about 30Khz which is incredible. A few pics to show the work plus my recent Avometer HD 5892-1069 which is also a very nice instrument and works flawlessly.

[Barnmead]

I was sorry to see them go and really surprised (and pleased) at the hammer price.The iconic design and their ubiquity has made them so collectable. I feel it is sad that there seemed to be much less interest in the many other instruments I have collected and been given over the years.

[The Philpott]

Post 3043- Model 9/II

Pthomas, those resistors are high quality so it probably had been overloaded at some point to generate such a drift, i reckon. The rectifier will have been replaced at some point, it would have started life with a copper oxide one with the general appearance of one of Barnes Wallis' bouncing bombs.

There's a graph (in the Model 8/III manual) which details AC frequency response on two selected ACV ranges, and it shows that this generation of meters are outstanding in this respect, even by more recent standards.

Your meter may soon be getting to the age where the leather strap starts to react with it's holding rivets, and hardens up. Keep an eye on this!! Once the nickel plating has worn through the brass and the leather affect each other in a negative way.

Dave

[noble kiwi]

It has been sometime since I have checked in here, however I have just acquired a Universal AvoMinor and feel duty bound to record its credentials, i.e. No.2140-35. It came with its original small, tatty but worthwhile, book of songs and probes and I would guess is of 1935 vintage or earlier. Advice would be appreciated.

It is OK accept for an open 500 volt multiplier and lack of wiper pressure in respect of the ohms adjuster. I consider that the former is best left as, is rather than add something non standard, but would like to fixe the latter problem if possible.

The mechanical set up presents real problems and I can not see how, even if fully stripped down, removal of the wiper assembly is provided for. I have given thought to "wiping" the contact blade, as one would treat a 3,000 type relay contact, but the lack of room appears to rule this out. Any ideas would be very much appreciated. Trevor.

[The Philpott]

Trevor, that would be March 1935, meter number 2140.
If you were to tack a component resistor across the o/c bobbin to restore function it's something that could easily be reversed to maintain originality..just a thought.

I know that i have removed the ohms wiper on one of these meters, i just need to open mine up to reboot my memory as to how it was done.

Dave

[The Philpott]

If you are completely sure it's lack of wiper pressure (and not dulling of the contact between the battery contact blade and brass shaft) then....

If the movement has all it's connexions removed (and also 1 or 2 obstructing wires removed) then i THINK that lifting out the movement also lifts out the crescent shaped pot winding. This then gives you freedom to bend the wiper towards you....with no need to de-solder it from the shaft.

You also have access to check the (1mm thick!) glass is secure, and clean all the dust out. Just make sure the Z screw is engaged with the stirrup when replacing the movement, otherwise the zero can't be adjusted.

I've peered inside and i believe this is possible...Discuss!

Dave

[The Philpott]

Thinking about it, the battery box and/or it's connections might have to be removed also, but this shouldn't be a major problem.

[Superscope]

Well, it didn't take long for an Avo meter from the Richard Allan Collection
to turn up on ebay, together with an opportunistic price hike!

Less than a Week.




Ian

[The Philpott]

I'm sure the mods will have a peek at it, if he or she is a forum member it would seem to be outside the rules (let alone the spirit of the rules!)
One hopes it's not a forum member, obviously..

Dave

[Pamphonica]

Bought in a public auction, it’s the buyers right to sell as they see fit.
Although we here might disapprove.

[Superscope]

Indeed,

The Items were Won outside of this Forum and are being Sold outside of this Forum.

I did see a comment from somebody on this Forum who was at the auction,
can't remember who, but they mentioned the same Buyer seemed to be buying up a large number of items.
I assume it was a Telephone Bidder.

I think I have probably identified that Buyer! but I don't know if they are
a Forum Member.

But for sure, a lot of Richards Radio's and Avometers are now on Ebay as we speak.
Twenty items at least that I have identified after a quick look.

I can't comment on the Radio's, as that's out of my area of expertise, but
the Avometers I would say, were not bought particularly cheaply and are now
advertised at an unrealistic price.
I expect them to be re-listed many times at reduced prices going forward.

It's a shame though, that they didn't go to collectors, and were snapped up for
commercial gain.

Fun for me though, as I can put my Analytical Hat on.


Ian

[radio69]

Yes, I came across a few of them. I reckon at least half of RR's test equipment must now be listed by one particular seller. The BIN prices are all absolutely eye-watering.

This has become a familiar pattern in recent years; items at unrealistic prices just sitting there for years and years with no interest.

[Sinewave]

Originally Posted by The Philpott

I'm sure the mods will have a peek at it, if he or she is a forum member it would seem to be outside the rules (let alone the spirit of the rules!)
One hopes it's not a forum member, obviously..

Dave

Only if purchased via here, which it wasn't, from my understanding.

[Pamphonica]

Lets get back on topic...

A visit to Audiojumble today netted some new Avometers:

1. Model 2 (presumably a 2A as it has smooth front) s/n 5923 . VG condition, reading 12% low.
2. DC Avominor Type HR s/n HR123-88. o/c movement.
3. Avo Low Resistance Ohmmeter s/n L.R. 252-440 (never seen one of these before!)
4. Avo Minor s/n 28511-240

I think this one is already logged:
Avometer High Resistance (Model 2) 2811-B-1050 (quite a late one)

All these are logged on the Google Form as well.
(see post 1533: https://www.vintage-radio.net/forum/...postcount=1533 for links to see the Google database outputs to date)

all best
Jeremy

[Phil G4SPZ]

Jeremy, any chance of a pic or two of the Low Resistance Avometer, please? I’ve not seen one before. Does “low resistance” refer to its sensitivity or its ohms ranges? I’m guessing the latter…

[Pamphonica]

There are details on Richard’s Radios.
http://www.richardsradios.co.uk/avominordata.html

[Phil G4SPZ]

Thanks, Jeremy, very interesting.

I have a Megger ohmmeter with ranges of 0-3 ohms and 0-30 ohms. It is a larger, heavier and far more expensive instrument, and I wonder if Avo brought out their LR ohmmeter in direct competition? Not many could have been sold, judging from its rarity.

Well done on acquiring it!

[The Philpott]

Post 3056-

Well done Jeremy, I have collated the serial numbers of the LR Ohmmeter and the Avominor Type HR in my little 'bible' as they fascinate me. We are now aware of three of the former and ten of the latter! Quite early on in a Wireless World ad they were both listed but had CANCELLED printed across them. The serial numbers however went up to (at the very least) LRO 375 units and HR 566 units.

I have persuaded my LRO to function and it's quite accurate. It seems that the movement has an FSD current that is unique to this model, but if my musings are correct a movement from an HR could have it's sensitivity reduced as a replacement (a last resort as they are both rare anyway..) The impressive thing about an HR is that such a small meter has sensitivity of 20kohms per volt.....allied with Siemens resistors which may have become in short supply at that time.

Jeremy has the earliest examples of these two miniatures known to me at this point- April 1940 and Aug 1938.

As regards the Avo model 2 that is 12% low, this figure could represent a slight tangle in one of the hairsprings, ie two parts of the spring have become overlapped.

Dave