UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Test Gear and Workshop Equipment

Notices

Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders.

Reply
 
Thread Tools
Old 2nd May 2020, 9:44 pm   #2501
Superscope
Octode
 
Join Date: May 2017
Location: St Austell, Cornwall, UK.
Posts: 1,018
Default Re: AVO Multimeter survey

Hi Aitor,

The Horse Shoe Magnet Movement was in production until at least 1947.

This co-incides with the Serial Number Format change, hence an attempt to see if
these changes happened together at the same time.

If they did, the Model 7 Serial Number Format will be a very useful indicator of the
Movement Type. (At least as to it being a Horse Shoe type or not).


Ian
Superscope is offline   Reply With Quote
Old 2nd May 2020, 11:12 pm   #2502
Phil G4SPZ
Dekatron
 
Phil G4SPZ's Avatar
 
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,756
Default Re: AVO Multimeter survey

Hello Ian,

I have two Model 7 Mk II instruments with the older black domed terminals. They’re probably my favourite 7s, although both currently need attention. They both have black crackle-finish alloy cases and PF sockets.

The serial numbers are 53379-A-155 and 62451-A-256 and I’m pretty sure they are already in the ‘database’. Thanks for your continuing efforts!
__________________
Phil

Optimist [n]: One who is not in possession of the full facts
Phil G4SPZ is offline   Reply With Quote
Old 3rd May 2020, 10:46 am   #2503
Superscope
Octode
 
Join Date: May 2017
Location: St Austell, Cornwall, UK.
Posts: 1,018
Default Re: AVO Multimeter survey

Hi Phil,

Thanks for the update.

Yes, the Model 7 is wonderful Instrument, very underestimated and over looked.
I have found the build quality to be of an exceptional standard.
Still useful for many tasks, and many still 100% within Spec after 60+ Years.

Although I understand very early ones were a bit ropey, and I have found very late ones (1970's) to be less substantially built!



Ian
Superscope is offline   Reply With Quote
Old 3rd May 2020, 7:18 pm   #2504
AndyGilham
Pentode
 
Join Date: Oct 2016
Location: Dover, Kent, UK.
Posts: 237
Default Re: AVO Multimeter survey

What we really need is somewhere we can all upload images of the meters we own, external and internal, a library of visual information.
I don't think this forum is suitable, as its for discussion rather than a gallery.

However, if everyone is interested, I can look into a site that does this and we can set some rules and started uploading image data

Any opinions?

Andy
AndyGilham is offline   Reply With Quote
Old 3rd May 2020, 8:28 pm   #2505
Superscope
Octode
 
Join Date: May 2017
Location: St Austell, Cornwall, UK.
Posts: 1,018
Default Re: AVO Multimeter survey

Hi Andy,

For the purposes of a Visual Gallery of AvoMeters, that Site already exists, it's the
Richards Radios Web Site.

A very well written and informative Website.



Ian
Superscope is offline   Reply With Quote
Old 3rd May 2020, 11:13 pm   #2506
AndyGilham
Pentode
 
Join Date: Oct 2016
Location: Dover, Kent, UK.
Posts: 237
Default Re: AVO Multimeter survey

Ian,
I know Richards website very well and it’s fantastic, we can never replace that great site. , i’ve Visited his house and seen his collection first hand.... awesome!

But that not what I meant.... I am talking about each of us uploading of our own meters. We can then see all the little variations we talk about. Imagine a model 7 folder with 50+ sub folders and each folder under a serial number and containing photo of the instrument and it’s internals.

I already take stacks of folders for each of mine and keep them separate so I have quick visual reference of the instruments and their internals.

Andy
AndyGilham is offline   Reply With Quote
Old 4th May 2020, 12:02 am   #2507
Phil G4SPZ
Dekatron
 
Phil G4SPZ's Avatar
 
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,756
Default Re: AVO Multimeter survey

Quote:
Originally Posted by AndyGilham View Post

I already take stacks of folders for each of mine and keep them separate so I have quick visual reference of the instruments and their internals.
Sadly, I'm not so well organised! I think the task of opening up and photographing even my small collection would remain in the 'round tuit' pile for ever...
__________________
Phil

Optimist [n]: One who is not in possession of the full facts
Phil G4SPZ is offline   Reply With Quote
Old 4th May 2020, 11:22 am   #2508
Sinewave
Octode
 
Sinewave's Avatar
 
Join Date: May 2016
Location: Oxfordshire/Bucks borders, UK.
Posts: 1,604
Default Re: AVO Multimeter survey

I did start some time ago trying to photograph everything I have. I need to finish it and do something with it, though I won't go to the extent of opening meters. I need to complete an audit of my collection also.
__________________
Avometer, vintage Fluke and Marconi collector. Also interested in vintage Yaesu and KW.
Sinewave is offline   Reply With Quote
Old 6th May 2020, 5:52 pm   #2509
Barnmead
Pentode
 
Barnmead's Avatar
 
Join Date: Dec 2002
Location: Norfolk, UK.
Posts: 168
Default Re: AVO Multimeter survey

Andy made an interesting comment in post 2492. In my collection of full sized avometers there are 3 which have additional scale markings which indicate that they may be different from some of their siblings.
My markings:
VT Ltd on HRM 1226-150
G&H on model 8 45836-C-456
GH on model7 6412-A-748
Perhaps others might like to look closely at the lower right hand side of the scale plate as there may be others. Perhaps these meters were specially made for particular clients. Or is it just that the scale plates or the movements were outsourced.
__________________
Richard

Last edited by Barnmead; 6th May 2020 at 5:53 pm. Reason: spelling!
Barnmead is offline   Reply With Quote
Old 6th May 2020, 10:31 pm   #2510
The Philpott
Dekatron
 
The Philpott's Avatar
 
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,148
Default Re: AVO Multimeter survey

Post No.2512
-Have noticed G&H on a couple of Avominor scaleplates. Assumed this was outsourcing as it is not in quite a well hidden location.

'The following is hazardous and should not be attempted due to risk of fire and/or explosion:'

Managed to re-stuff a BLR121 battery this evening, courtesy of a small 'sparkling thunder' bottle rocket made by Bright Star Fireworks.
I picked up an expended rocket and noticed the plastic thinwall tube was very close in size and flexibility to the tube i needed. Procured a fresh rocket and emptied it, then washed out the tube as the powder can be quite corrosive. The plastic was cut down to 30mm, which slid quite well into the BLR121 clamshell.
I had a pack of (five) CR1025 lithium cells and a spring of a suitable length and strength. The positive terminal of the end cell sat against the spring, and the neg. against the stainless end terminal of the battery, as per the original arrangement. It's vital to retain the stainless end pieces if a re-stuff is attempted. (One is wider and is designed for the pos. end)

The screamer rocket in question is 15" in length including the stick. It came in an assortment a few years ago.

The pd off-load is 16.4v with these new cells, which is well within the adjustment pot. range- and it probably uses a fresh section of the high resistance adjustment pot. so may result in cleaner operation.

The most critical part i have found is finding a nice shiny spring of a suitable rating. The battery clamshell has been taped up but the spring i used is not quite strong enough to try and force it apart.

Dave
Attached Thumbnails
Click image for larger version

Name:	DSC01685.jpg
Views:	97
Size:	51.8 KB
ID:	205132   Click image for larger version

Name:	DSC01687.jpg
Views:	87
Size:	52.5 KB
ID:	205133  
The Philpott is offline   Reply With Quote
Old 7th May 2020, 2:45 pm   #2511
The Philpott
Dekatron
 
The Philpott's Avatar
 
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,148
Default Re: AVO Multimeter survey

Para 1 should read 'in quite a well hidden location'
Dave
The Philpott is offline   Reply With Quote
Old 8th May 2020, 1:06 pm   #2512
Superscope
Octode
 
Join Date: May 2017
Location: St Austell, Cornwall, UK.
Posts: 1,018
Default Re: AVO Multimeter survey

Dave,

What is the diameter of those CR1025's ?

I've restuffed with x10 Alkaline 1.5v Watch Battery's up till now.
(Ok, I know their Cells, but nobody calls them Watch Cells!

But it's a lot to pack in and the Life expectancy of those cheap "Pound Shop"
ones leaves a lot to be desired.

Lithium I think will be much longer Life.
Do Lithium Cells exhibit the same type of Corrosion when they run flat like those Watch Battery's (Cells) do?


Ian
Superscope is offline   Reply With Quote
Old 8th May 2020, 2:18 pm   #2513
Phil G4SPZ
Dekatron
 
Phil G4SPZ's Avatar
 
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,756
Default Re: AVO Multimeter survey

I think the code is CR1032 = 10mm diameter, 3.2mm thick. The common CR2025 is 20mm diameter, 2.5mm thick.

Pound shop cells tend to leak whilst still in the packaging! Whilst many of them are OK, they don’t have the shelf life that lithium cells do.
__________________
Phil

Optimist [n]: One who is not in possession of the full facts
Phil G4SPZ is offline   Reply With Quote
Old 8th May 2020, 8:11 pm   #2514
The Philpott
Dekatron
 
The Philpott's Avatar
 
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,148
Default Re: AVO Multimeter survey

The CR1025 Lithiums i bought are 10mm diam, 2.5mm thick. The gap remaining to be filled (as there are only five cells) is around 17.5mm (so a 20mm spring was ok, diameter around 8mm which i got away with.)

I don't think i have encountered an oozing lithium button cell yet, but believe them to be less corrosive than alkalines. When they do vent they have a very distinctive sweet smell.
These ones had an expiry date Dec 2023.

Both of the BLR121's i had previously restuffed with alkaline AG10's had just started to weep (expiry date Dec 2018 as i recall) but pd was still up at 15.2v. You just can't trust 'em....but the quick clean up job was really my fault for leaving them 1.5 years overdue.

Fortunately I found enough springs and rockets to re-pack all 3 of my batteries, and they're all making good contact..for once!

Dave
The Philpott is offline   Reply With Quote
Old 8th May 2020, 9:29 pm   #2515
The Philpott
Dekatron
 
The Philpott's Avatar
 
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,148
Default Re: AVO Multimeter survey

I believe the capacity in mAh of the CR1025's is a little lower than the alkalines. I will update in future if they cause any trouble. They were cheap- too cheap really, at £2.50 for ten. But we'll see.

Dave
The Philpott is offline   Reply With Quote
Old 8th May 2020, 9:46 pm   #2516
Phil G4SPZ
Dekatron
 
Phil G4SPZ's Avatar
 
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,756
Default Re: AVO Multimeter survey

Capacity is less of an issue than leakage-free long life! I doubt whether even one-hundredth of the mAh capacity is ever used up in taking actual resistance readings.
__________________
Phil

Optimist [n]: One who is not in possession of the full facts
Phil G4SPZ is offline   Reply With Quote
Old 8th May 2020, 10:36 pm   #2517
The Philpott
Dekatron
 
The Philpott's Avatar
 
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,148
Default Re: AVO Multimeter survey

Agreed Phil- i think the VC1 voltage converter unit is only rated for 80 or 90uA output, for most tests i imagine the demand is a fraction of this.
Dave
The Philpott is offline   Reply With Quote
Old 8th May 2020, 10:59 pm   #2518
Phil G4SPZ
Dekatron
 
Phil G4SPZ's Avatar
 
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,756
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?
__________________
Phil

Optimist [n]: One who is not in possession of the full facts
Phil G4SPZ is offline   Reply With Quote
Old 9th May 2020, 7:44 am   #2519
Superscope
Octode
 
Join Date: May 2017
Location: St Austell, Cornwall, UK.
Posts: 1,018
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!



Ian
Superscope is offline   Reply With Quote
Old 9th May 2020, 9:20 am   #2520
Phil G4SPZ
Dekatron
 
Phil G4SPZ's Avatar
 
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,756
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.
__________________
Phil

Optimist [n]: One who is not in possession of the full facts
Phil G4SPZ is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 10:10 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.