Metrawatt Metravo 3 questions - UK Vintage Radio Repair and Restoration Discussion Forum

jobsworth · 16th Sep 2012, 11:48 pm

Dear Forum Members

I came across a rather neglected but interesting multimeter at a car boot sale and bought it for a quid. On closer inspection it looked as if it had been kept in damp conditions. It didn't work and part of the front fascia was missing, the part that provided information about the five terminal sockets that take a standard 4mm banana type plug. I was able to coax it into life through the use of some switch cleaner and a gentle bit of reaming to the 5 terminal sockets on the top of the front fascia. Everthing is working relatively fine now, the X1 ohm scale is way off so I will investigate further at some stage.

I do have some questions though. I have not been able to locate a manual for this device, it is Austrian and probably unusual in the UK. Firstly there are a series of illustrations on the rear panel that show different connections for the various measurements that can be done. I understand most of them but one has me perplexed and I wonder if anyone is able to shed light on it. The diagram that is bottom left shows the meter connected to something with a symbol that has a G in a circle with an AC symbol beneath and also connected in a different set of sockets on the meter but these have what appears to be some sort of component. Does anyone have a clue as to what that is all about?, is G a galvanometer? or does it stand for Gerate? and what is the other thing that is connected, is it a resistor? a capacitor?

Secondly inside the meter there is a copper or brass "thing" that is over some coils. The things is made from thin sheet brass or copper and reminds me of a bimetal strip for some reason. The sheet is slightly convex in profile. Is it a screen to reduce "hum" in the coils? will it move if it heats up and make contact with the coils?

I have included some photos of the various bits I have spoken about but also some of the innards. (provided I can get them attached!!!)

Thanks in advance

Regards

Chris F

glowinganode · 17th Sep 2012, 9:25 am

Hi Chris.
The brass strip will be the current shunt for the 3A current range, the other coils will be the shunts for the lower current ranges. The 12A range shunt is on the reverse side and is visible in picture 3, bootom left.
The G symbol does suggest a (voltage) generator, the component I take to be a resistor.
I think what it is suggesting, if you connect the supply and load as illustrated, you can measure the voltage or current without having to move any leads and without interrupting the supply to the load. Useful for instance if you were monitoring a motor on load.
Cheers, Rob.

Herald1360 · 17th Sep 2012, 12:17 pm

The whole style of this meter reminds me somehow of the Russian unit that I bought about 40 years ago. Certainly the diagrams on the back and the general typefaces used. I wonder if it's a badge engineered job of some sort?

glowinganode · 17th Sep 2012, 12:34 pm

Yes, it reminds me of the Bloc imports you could buy down Tottenham Court Road in the 70's.

Andrewausfa · 17th Sep 2012, 12:59 pm

I spotted one their 'Metrahit' meters recently at what seemed a reasonable price and, as you do, did a bit of background research to see if they were a reputable firm which it seems they are. German firm based in Nuremburg, still extant and have been making test gear for many years

Andrew

jobsworth · 17th Sep 2012, 1:52 pm

Thank you so much for your responses, that has cleared things up for me and now it all makes sense (especially now I have read up about current shunts and how they can be used in measurements).

Regards

Chris F

stuarth · 18th Sep 2012, 11:26 am

I have a modern German made "Metramax" digital meter which is marked with no less than 3 brand names, "Gossen", "Metrawatt", and "Camille Bauer", so these companies were merged at one time at least. I also have an analogue meter visually very similar to the one shown (but with completely different ranges) which is branded "Iskra", and was made in Yugoslavia.

The styling of the meter shown is strikingly similar to the Austrian Unigor range which are branded "Goerz electro", or "BBC Goerz", and are also sold under the "Venture" and "Kelvin/Kelvo" brands for Smiths Industries. I believe the Unigor 6e was also available branded as a Simpson 2795. The Unigor meters all feature a very effective cut-out.

The Metrawatt and Unigor ranges have very similar styling, but I haven't found a direct connection between the companies.

Several Russian made multimeters have a passing resemblance to the Metrawatt/Unigor meters, including the taut-band movements, but I expect that these a cheap copies of the German/Austrian brands.

S

pmmunro · 18th Sep 2012, 4:51 pm

The three companies, Gossen, Metrawatt and Camille Bauer have been amalgamated for some time and trade in many countries as "GMC". The constituent companies have a long history of high quality instrument making in Germany.The ABB (Asea Brown Boveri) group became a major shareholder in Metrawatt in 1968 which I believe they still hold. There's an extensive history here, although it loses something in translation! http://www.myphotoweb.com/Gossen/info/history.htm.

The company's own website is worth looking at, especially the link to a somewhat "hyper" Australian reviewing a top-of-range electrical power meter. If you need it, you'll pay more for the input protection circuitry than some cheap multimeters.

http://www.gossenmetrawatt.com/

Mertawatt multimeters have appeared with ABB and AVO labels, in fact at one time all digital Avometers were relabelled Metrawatts.

PMM

16th Sep 2012, 11:48 pm	#1
jobsworth Tetrode Join Date: Apr 2010 Location: Croydon, London, UK. Posts: 69	Metrawatt Metravo 3 questions Dear Forum Members I came across a rather neglected but interesting multimeter at a car boot sale and bought it for a quid. On closer inspection it looked as if it had been kept in damp conditions. It didn't work and part of the front fascia was missing, the part that provided information about the five terminal sockets that take a standard 4mm banana type plug. I was able to coax it into life through the use of some switch cleaner and a gentle bit of reaming to the 5 terminal sockets on the top of the front fascia. Everthing is working relatively fine now, the X1 ohm scale is way off so I will investigate further at some stage. I do have some questions though. I have not been able to locate a manual for this device, it is Austrian and probably unusual in the UK. Firstly there are a series of illustrations on the rear panel that show different connections for the various measurements that can be done. I understand most of them but one has me perplexed and I wonder if anyone is able to shed light on it. The diagram that is bottom left shows the meter connected to something with a symbol that has a G in a circle with an AC symbol beneath and also connected in a different set of sockets on the meter but these have what appears to be some sort of component. Does anyone have a clue as to what that is all about?, is G a galvanometer? or does it stand for Gerate? and what is the other thing that is connected, is it a resistor? a capacitor? Secondly inside the meter there is a copper or brass "thing" that is over some coils. The things is made from thin sheet brass or copper and reminds me of a bimetal strip for some reason. The sheet is slightly convex in profile. Is it a screen to reduce "hum" in the coils? will it move if it heats up and make contact with the coils? I have included some photos of the various bits I have spoken about but also some of the innards. (provided I can get them attached!!!) Thanks in advance Regards Chris F Attached Thumbnails

17th Sep 2012, 9:25 am	#2
glowinganode Octode Join Date: Apr 2009 Location: Aylesbury, Buckinghamshire, UK. Posts: 1,522	Re: Metrawatt Metravo 3 questions Hi Chris. The brass strip will be the current shunt for the 3A current range, the other coils will be the shunts for the lower current ranges. The 12A range shunt is on the reverse side and is visible in picture 3, bootom left. The G symbol does suggest a (voltage) generator, the component I take to be a resistor. I think what it is suggesting, if you connect the supply and load as illustrated, you can measure the voltage or current without having to move any leads and without interrupting the supply to the load. Useful for instance if you were monitoring a motor on load. Cheers, Rob. __________________ We have done so much, for so long, with so little, we are now qualified to do anything with nothing. Last edited by glowinganode; 17th Sep 2012 at 9:35 am.

17th Sep 2012, 12:17 pm	#3
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Metrawatt Metravo 3 questions The whole style of this meter reminds me somehow of the Russian unit that I bought about 40 years ago. Certainly the diagrams on the back and the general typefaces used. I wonder if it's a badge engineered job of some sort? __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

17th Sep 2012, 12:34 pm	#4
glowinganode Octode Join Date: Apr 2009 Location: Aylesbury, Buckinghamshire, UK. Posts: 1,522	Re: Metrawatt Metravo 3 questions Yes, it reminds me of the Bloc imports you could buy down Tottenham Court Road in the 70's. __________________ We have done so much, for so long, with so little, we are now qualified to do anything with nothing.

17th Sep 2012, 12:59 pm	#5
Andrewausfa Octode Join Date: Dec 2010 Location: St Ives, Cambridgeshire, UK. Posts: 1,180	Re: Metrawatt Metravo 3 questions I spotted one their 'Metrahit' meters recently at what seemed a reasonable price and, as you do, did a bit of background research to see if they were a reputable firm which it seems they are. German firm based in Nuremburg, still extant and have been making test gear for many years Andrew __________________ Invisible airwaves crackle with life. Or they should do. BVWS Member

17th Sep 2012, 1:52 pm	#6
jobsworth Tetrode Join Date: Apr 2010 Location: Croydon, London, UK. Posts: 69	Re: Metrawatt Metravo 3 questions Thank you so much for your responses, that has cleared things up for me and now it all makes sense (especially now I have read up about current shunts and how they can be used in measurements). Regards Chris F

18th Sep 2012, 11:26 am	#7
stuarth Heptode Join Date: Feb 2010 Location: Heysham, Lancashire, UK. Posts: 669	Re: Metrawatt Metravo 3 questions I have a modern German made "Metramax" digital meter which is marked with no less than 3 brand names, "Gossen", "Metrawatt", and "Camille Bauer", so these companies were merged at one time at least. I also have an analogue meter visually very similar to the one shown (but with completely different ranges) which is branded "Iskra", and was made in Yugoslavia. The styling of the meter shown is strikingly similar to the Austrian Unigor range which are branded "Goerz electro", or "BBC Goerz", and are also sold under the "Venture" and "Kelvin/Kelvo" brands for Smiths Industries. I believe the Unigor 6e was also available branded as a Simpson 2795. The Unigor meters all feature a very effective cut-out. The Metrawatt and Unigor ranges have very similar styling, but I haven't found a direct connection between the companies. Several Russian made multimeters have a passing resemblance to the Metrawatt/Unigor meters, including the taut-band movements, but I expect that these a cheap copies of the German/Austrian brands. S

18th Sep 2012, 4:51 pm	#8
pmmunro Octode Join Date: Jul 2004 Location: Dundee, UK. Posts: 1,813	Re: Metrawatt Metravo 3 questions The three companies, Gossen, Metrawatt and Camille Bauer have been amalgamated for some time and trade in many countries as "GMC". The constituent companies have a long history of high quality instrument making in Germany.The ABB (Asea Brown Boveri) group became a major shareholder in Metrawatt in 1968 which I believe they still hold. There's an extensive history here, although it loses something in translation! http://www.myphotoweb.com/Gossen/info/history.htm. The company's own website is worth looking at, especially the link to a somewhat "hyper" Australian reviewing a top-of-range electrical power meter. If you need it, you'll pay more for the input protection circuitry than some cheap multimeters. http://www.gossenmetrawatt.com/ Mertawatt multimeters have appeared with ABB and AVO labels, in fact at one time all digital Avometers were relabelled Metrawatts. PMM