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Old 9th Nov 2017, 1:06 am   #1
Techman
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Default Nashton universal DC meter

Made by Nash & Thompson Ltd. Chessington, Surrey.

I picked this up at the recent surplus and junk auction. I'm not too sure why I bought it but someone had to I suppose. I thought it would probably be useful for parts, particularly the valves, and as it turns out it has a couple of nice, clean Mullard ECC83 valves inside.

I'm not familiar with this particular meter and it seems that there is something that's supposed to go in the empty tube which can be accessed externally from the round hole in the bottom of the case. As far as I know, this particular meter hasn't been covered on this forum or anywhere else, so before I do anything with it I thought it would be a good idea to cover it here and see what's known about the instrument (if anything) - pictures below:-
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Old 9th Nov 2017, 5:53 am   #2
TonyDuell
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Default Re: Nashton universal DC meter

My first thought about that tube/hole is that it's for a battery for the Ohms ranges. Does any common cell fit?
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Old 9th Nov 2017, 8:55 am   #3
Ted Kendall
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Default Re: Nashton universal DC meter

I agree. I have a VVM in the same series.
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Old 9th Nov 2017, 2:48 pm   #4
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Default Re: Nashton universal DC meter

I think you're absolutely right folks. I was thinking that these old valve voltmeters took all their supplies from the mains power supply. I've just opened up an old Heathkit one that I've had for many years and found a festering 'C' cell still lurking inside! I must have known about these batteries and just forgotten over the years - haven't seriously used one since the early 70s. I remember having one of those great big wooden case model 26 things made by Electronic Instruments Ltd. and I'm sure it didn't have any internal batteries. Unfortunately I can't check as regrettably it 'disappeared' during the last house move.

The 'tube' in the Nashton looks a little long for just one cell, but that could be just an illusion. It looks about the right diameter for a 'C' cell, so I'll have to try one (or two) and see. I suppose I ought to remove that cell from the Heathkit now I've found it, as I happened to find a festering grid bias type battery in its multimeter brother a couple of months ago that had November 1970 penned on it and it had made a bit of a mess of the surrounding metalwork. The 'C' cell shown below in the Heathkit is likely to date from around the same time and would probably be the last time they were properly being used.
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Old 10th Nov 2017, 2:02 pm   #5
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Default Re: Nashton universal DC meter

Well it's not 'C' cell size. It would seem to take a cell or battery of around three quarters of an inch in diameter by about two and three quarter inches in length. I seem to remember a now obsolete battery of around this size when I was a youngster that fitted various toy boats and torches etc. I wonder if this meter is older than I thought, perhaps early 60s or even late 50s? I had initially thought it was probably early 70s, but as can be seen in a picture below, its sockets take the older imperial wander plug size.

The control knob on the top right of the front panel with +&- under it is actually a six position switch but with nothing to indicate any of the positions - crazy? The last two positions clockwise do actually change the polarity of the voltage reading input but what about the other four positions? It's not accurate in reading and there's around 0.01 volt on the voltage terminals, so obviously some leaky capacitor and calibration problems, which are to be expected on the unit of this age.

It seems to be quite rare as there's nothing to be found on the net about this instrument. It'll probably join the other similar items in the collection for the time being.
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Old 10th Nov 2017, 6:31 pm   #6
Herald1360
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Default Re: Nashton universal DC meter

Number 8?


Two cells in a card tube so 3V.


https://www.radiomuseum.org/r/ever_d...tery_no_8.html

Or maybe half a No.8. Had a Russian multimeter (still have actually) that used half a No.8 to power either its cutout circuit or the ohms range. Can't remember which.....
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Old 15th Nov 2017, 6:40 pm   #7
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Default Re: Nashton universal DC meter

Thanks Chris, that's the one I was thinking of. I remember cutting one or two of these in half when I was a kid and finding the individual cells. Then finding that one per battery had died before the other, so putting the best cells together to make another battery - that lasted for a little while longer, but not very long.

Does anyone have a rough date for this meter?
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Old 18th Nov 2017, 11:06 am   #8
Ted Kendall
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Default Re: Nashton universal DC meter

Late 50s/early 60s I'd say, judging by the general look of mine.
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Old 2nd Dec 2017, 7:38 pm   #9
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Default Re: Nashton universal DC meter

Thanks for that, Ted.

Of course what I didn't think of was that as the two valves are likely to be original fitments, there will be a date and factory code etched onto the glass.

Although I've had a bit of a look at various code lists, I'm no expert on this and I was expecting a slightly longer code rather than the three digit code that's on each valve. I have to say that it's not something I've ever particularly looked into with valves before, but the code seems to be 'B8E' on both valves - the pictures below don't show the codes very well, but I'm sure there will be some valve code experts that will be able to give me chapter and verse on the valves and their codes, thus dating both them and the meter.

Many thanks in advance for any information.
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Old 2nd Dec 2017, 10:57 pm   #10
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Default Re: Nashton universal DC meter

Quote:
Originally Posted by Techman View Post
I picked this up at the recent surplus and junk auction. I'm not too sure why I bought it but someone had to I suppose. I thought it would probably be useful for parts, particularly the valves, and as it turns out it has a couple of nice, clean Mullard ECC83 valves inside.
Well done on buying and preserving this meter. Whatever you do, please don't strip it for parts! It seems quite a rare beast.

I have three Heathkit VTVMs which use an internal C cell for the ohms ranges. As has been said, yours probably took a No 8 battery. I don't think there are any modern equivalents for the zinc-carbon primary cells used in the No 8, but the "sub-C" rechargeable type might fit. Otherwise, you could try two AAA cells in a suitable tube with spacers.

If you're feeling flush, the Small Battery Company* market a replica No 8 or 2R10 at a rather expensive price.

* No connection with this supplier other than as a satisfied customer.
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Old 3rd Dec 2017, 8:18 pm   #11
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Default Re: Nashton universal DC meter

Thanks for that, Phil. When I'm at one of these sales and am tempted to buy something that I don't really need and that may have no real use, the excuse that I make to myself is that at least it will be useful for spare parts. The reality is that the item often doesn't get used for parts and becomes part of the collection. It certainly seems to be very rare as I could find nothing about it when I did a google search, other than a mention of a similar type of Nashton unit, not a VVM, offered with other items in the for sale section on here several years ago - I think Ed Dinning claimed it. The funny thing was that this type of item usually sells for a quid, but I was surprised to see someone else stick their hand up for a quid, so I had someone bidding against me and ended up paying 4 for it! It was, however, announced and correctly described as a valve voltmeter and perhaps the other bidder had ideas that it might have some useful valves inside. Anyway, it's unlikely that it will be broken for parts, especially as you've asked me not to

I don't need any ECC83 valves for anything at the moment as I've already got plenty and I'm rather more of a valve hoarder than a valve seller. Actually, I don't think I've ever sold a valve, other than in the course of a chargeable repair. That valve coding seems very random to me. It looks like the code on these particular valves indicate the Blackburn factory and possibly made in May 58, 68 or 78? I'll have to start checking all the other Mullard ECC83 etc. valves that I have and see if I can make anything of this coding system.
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