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Old 8th May 2020, 10:59 pm   #2521
Phil G4SPZ
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Default Re: AVO Multimeter survey

I’d love to own a VC1 Dave, but one has never cropped up inside any Avo I’ve acquired! I have always wondered how they work, though. There is no input switching, so I assume the inverter imposes a continual drain on the D cell. Presumably this is miniscule until a resistance measurement is actually being made. Does the VC1 come with instructions or any information about how the life of the D cell is affected?
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Old 9th May 2020, 7:44 am   #2522
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Default Re: AVO Multimeter survey

I've not measured the Current Draw myself, but there is a nice Write
up of the VC1 on the Richards Radios Website.

http://www.richardsradios.co.uk/vc1.html


I did search for a VC1 Schematic and other Documentation in the past,
but Documentation for it seems rarer than the VC1 itself!



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Old 9th May 2020, 9:20 am   #2523
Phil G4SPZ
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Default Re: AVO Multimeter survey

Thank you for that link, Ian, very interesting and everything I ever wanted to know about the VC1! A quick calculation shows that the VC1 will drain the D-cell within about 5 years at worst. Hardly a problem, but if you have one of these permanently in circuit inside an Avo in your collection, it is worth putting a note in your calendar to check it every now and again.
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Old 11th May 2020, 6:57 pm   #2524
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Default Re: AVO Multimeter survey

There was a post about the VC1 some time back from Dekatron

https://www.vintage-radio.net/forum/...d.php?t=158281

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Old 17th May 2020, 10:14 pm   #2525
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Default Re: AVO Multimeter survey

Hi Dave,
nearly a month after your encouragement to improve the readability of the dials on my old Avo 7 I have made some progress! I first had a quick test with Tippex Rapid that I happened to have at home, having seen it mentioned on an earlier thread - disaster I'm afraid.

Ordered a £1.38 engraver's wax pencil as Plan B and had a session with it on the DC switch tonight, which I'm really chuffed with. Thanks for your helpful advice and encouragement, it is a pleasure to use now that I can easily see what range is set. I'm wondering whether to cover the top surface of the switches when completed to preserve the effect, but don't anticipate too much switch fiddling as it's dedicated to ammeter duties with my lamp-limiter.

Cheers
Chris
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Old 18th May 2020, 12:41 am   #2526
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Default Re: AVO Multimeter survey

A mixture of Tippex and spirit based varnish.
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Old 18th May 2020, 11:18 am   #2527
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Default Re: AVO Multimeter survey

Yep, looks like you got the mixture just right there! Nice, especially around the screw - and none actually in the slot, well done.

Cheers
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Old 19th May 2020, 11:55 am   #2528
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Default Re: AVO Multimeter survey

On the subject of 15v Batteries, talked about earlier.

I had a look on the usual Auction Site last night and
was surprised to see a proliferation of 15v Batteries
at much more reasonable prices than they used to be.

Ones that jumped out, are this interesting one which
can be refilled (allegedly, but I've not tried one as £14.95 is a bit steep for something I can do myself).

https://www.ebay.co.uk/itm/AVO-8-MET...IAAOSw5pRcPKV2

Incidently, if you plan to refill with those AG10 Watch Batteries, you would
be better buying them from a Jewellers rather than the Pound Shop.
They sell/use proper Batteries, not the cheap Tat found in Poundland!

This one:

https://www.ebay.co.uk/itm/2x-10F20-....c100009.m1982

Although, I think they mean compatable with the B121 not the B154 which is
the smaller round 15v Battery.
I'm tempted to get a couple of these for testing.

There are plenty of others for under £5, which I don't think is an unreasonable
price if they last a Year or Two.



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Old 19th May 2020, 1:25 pm   #2529
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Default Re: AVO Multimeter survey

Yesterday on eBay, a couple of fuse for model 4/5 with box was sold at 16 pounds I think.

I have never seen them new in box before. If somebody from
here bought them, perhaps can tell us the exact resistance value.
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Old 19th May 2020, 4:33 pm   #2530
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Default Re: AVO Multimeter survey

Hi Aitor,

They were posted a couple of weeks ago for £34 + postage.

There were no takers.

Difficult to value, but they are very unique.
Like you, I have never seen anything like it before, so it just goes to show,
anything could be out there waiting to be discovered.

Then they disappeared, allegedly because they were lost or broken.

Then they re-appeared last week for £14.99 with one very definitely broken.

Seller claims they got dropped, but with all honesty, I doubt the Fuse
would break like that if you threw it at a brick Wall.

I think he probably tried to open one with pliers and got caught out.
The Bakelite Tube I think was sometimes glued down from new.
I know I would be very tempted to look inside a new unmolested Fuse.

or maybe he dropped it, and then stood on it by accident.
Either way, it's a bit of a shame.

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Old 19th May 2020, 4:59 pm   #2531
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Default Re: AVO Multimeter survey

Someone got them for £16, maybe someone from here? We'll find out in due course perhaps.
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Old 19th May 2020, 6:29 pm   #2532
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Default Re: AVO Multimeter survey

..I did ask for a resistance measurement across the fuses but for whatever reason it didn't happen.
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Old 19th May 2020, 7:01 pm   #2533
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Default Re: AVO Multimeter survey

As far as I know, the Resistance of the Avo Fuses is 4 Ohms.
That's what I've always been lead to believe.

Although, when I restored my Model 5 a while back, 4.8 Ohms was a
better match for the meter.

I can't say for sure, but when I was researching these Fuses, I
came to the conclusion, that this Value probably wasn't chosen specifically
by AWEECO, but was simply the result of the way the Fuse was made and it's design Capacity.

I do have an older Meter with what appears to be an unmolested Fuse, so if I get time, I will try to get an actual measurement.


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Old 19th May 2020, 7:53 pm   #2534
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Thanks
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Old 19th May 2020, 9:51 pm   #2535
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Default Re: AVO Multimeter survey

My Model 4 had a blown fuse which i re-stuffed at 4 ohms. (4.7 ohm and 27 ohm 1/4 watt resistors in parallel.) It does not now act as a fuse- but does allow the meter to work.

I was tempted by the listing for NOS fuses but in reality my meter is so tatty that they would be better going to someone with one in good condition.

I do have a couple of the black tubes that go over this general type of fuse (from a Type E)- but had no difficulty removing them- they just pulled off. The reason i ended up removing them was i couldn't fit resistors inside them..

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Old 20th May 2020, 10:02 am   #2536
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Default Re: AVO Multimeter survey

Ok, I dug the Fuse out this Morning from an early 30's Meter.

The Tube is fixed on, it might pull off, but I don't want to chance it.
The hole in the Tube is sealed with Black Wax.

I have no idea if this was normal from New, or it indicates that it
might have been repaired in the past.

It measures 4.12 Ohms according to my Fluke 287 which although
not Calibrated, is of reasonable quality and I think can be trusted to
be fairly accurate.

So, no real surprises there.



I can repair old Fuses, provided all the original Parts are still present.
That is, the Two small Screws, the Metal End Point and an undamaged
Bakelite Substrate.

I can't Guarantee the mA Rating but it would be in the order of 120mA.
I can normally get the Ohms to within +/- 0.2 Ohm subject to my Fluke.



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Old 4th Jun 2020, 7:05 am   #2537
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Default Re: AVO Multimeter survey

Good morning forum member, i hope everyone is keeping safe.

I have just taken delivery of an Avometer Model 16 that purchased from Canada for a reasonable £20. Which is great when i see a Model 15 just sold on Ebay for £107.
The serial number of this instrument is 6951.V.569 (May 1969)

Andy
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Old 4th Jun 2020, 4:43 pm   #2538
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Default Re: AVO Multimeter survey

Quote:
Originally Posted by AndyGilham View Post
Good morning forum member, i hope everyone is keeping safe.

I have just taken delivery of an Avometer Model 16 that purchased from Canada for a reasonable £20. Which is great when i see a Model 15 just sold on Ebay for £107.
The serial number of this instrument is 6951.V.569 (May 1969)

Andy
Yes, my eyes watered at that final price!
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Old 4th Jun 2020, 4:55 pm   #2539
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Default Re: AVO Multimeter survey

I picked this up in March. It's in a bit of a state, someone's got at it in the past, so I think it'll just be a display item.

No. 074-1063.
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Old 5th Jun 2020, 11:08 pm   #2540
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Default Re: AVO Multimeter survey

I'm not sure if this is the right place for this, but I have an early digital AVO multimeter, it comprises of a digital system mainframe type D.S.109 with a multimeter module type M.M.110.
There is an advert in the May 1969 wireless world here (page 3/A1); https://worldradiohistory.com/UK/Wir...ld-1969-05.pdf


It was completely dead when it arrived earlier this year, but re-soldering some bad joints on the +/-12V supply PCB has got it going again in manual mode, it still needs more work to get the internal trigger working (the PCB on the right is not missing, just forgot to put it back when I took the picture), the internal Muirhead reference cell is knackered too.

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David

Last edited by factory; 5th Jun 2020 at 11:27 pm.
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