Show your Multimeter!

[pelule]

The AC signal heats up a resistor for a certain tim. Then a DC voltage is connected instead to the same resistor, which creates the same amount of heat. The DC voltage is displayed as RMS value.
Basic physics. The riesistor sensor component is the critical element for the potential error.
Same method is used in the HP3400A.
Advantage: able to measure AC signal with high frequency and high crest factor.
Disadvantage: expensive and slow.
For a detailed description google for the Fluke 8506A manual. There is a detailed description of the operation.
Also here in eevblog there find a some thread for this method.
/pelule

[VK5RC]

Sounds the same principle as "thermistor' type RF power meters e.g. HP 432 and 8478. From an RF viewpoint allows nice/easy calibration at DC.
Rob

[AF6LJ]

Has anyone ever seen this one?




These units were quite popular back in the USSR. This one is still within specs.

P.S. I have access to many of different vintage soviet devices. And I can take a few photos of them if someone wants.

That is very cool; we don't get to see much Russian test gear here in the west.

[Martin.M]

Sue, the most russian test gear we see here is ready to fight 

[Andrey_irk]

OK. Since we have a scope on this topic already, I'll show you something more interesting.
This scope I use at home. It's called C1-117. I saved it from a total destruction, because it has a lot of gold and other precious metals inside, so people just destroy them to take it especially if it doesn't work.
Although, the bandwidth is not very high (15MHz) notice the vertical scale of 0.1mV/div! Also it has cursors, which is uncommon among soviet scopes.
And it is quite compact in comparison with other analog scopes.

[Andrey_irk]

Sue, the most russian test gear we see here is ready to fight 

Is it the heritage of Soviet Army? Where did you get it?

[Harb]

The AC signal heats up a resistor for a certain tim. Then a DC voltage is connected instead to the same resistor, which creates the same amount of heat. The DC voltage is displayed as RMS value.
Basic physics. The riesistor sensor component is the critical element for the potential error.
Same method is used in the HP3400A.
Advantage: able to measure AC signal with high frequency and high crest factor.
Disadvantage: expensive and slow.
For a detailed description google for the Fluke 8506A manual. There is a detailed description of the operation.
Also here in eevblog there find a some thread for this method.
/pelule

They are pretty simple in their operation....

To much voltage in and they catch fire (AKA Thermal), hence Rooted Meters Suck

[JustSquareEnough]

Here is my collection of multimeters,

Nice! do you have a reference to the case's you are using for test lead storage?

[Iwanushka]

Sue, the most russian test gear we see here is ready to fight 

Is it the heritage of Soviet Army? Where did you get it?

By the markings looks like it was used either in factories that made military stuff or it was used by military itself.

Edit: I've seen some of these in factory that made night vision gear, but factory was looted in a few minutes after it closed ;(

[Martin.M]

maybe you can help me to repair this little scope,
I think there is one of the early smd IC defekt, and I don`t know where I can get them.
They do simply functions, relatives of TTL, or a 5 transistor array. When switching ON it make one way from left to right, then stop.
seems to be the trigger or like that.

greetings
Martin

[Iwanushka]

maybe you can help me to repair this little scope,
I think there is one of the early smd IC defekt, and I don`t know where I can get them.
They do simply functions, relatives of TTL, or a 5 transistor array. When switching ON it make one way from left to right, then stop.
seems to be the trigger or like that.

greetings
Martin

Hey Martin,

Sorry for the delay, could you send me a photo of the IC and part number, I will ask around @ local forums and guys who repair CCCP scopes, but if this scope is full of gold it might be hard to get it, most of scopes that had nothing but gold inside were ripped apart by gold diggers, also I will try to find the datasheet, then maybe you can make something up from current parts.

[Neomys Sapiens]

No, I'm not going to pile 'em up for a photo shoot.
Rather, I will feature some of them over the next weeks, which have some very interesting features..

But first, the (incomplete) list

Prema 6001
Schlumberger: 7151, 7045
Tektronix: DM501A, DM502, DMM150
Fluke: 8060, 87, 12, 79-III, 27/FM
Siemens: Multizet A1000, Multizet A1001, B1010, Multizet T, VMG1
Metrawatt/GMC: Unigor 6e, Unigor A43, Unigor A41, Metramax12, Metravo 4E/4H/4S/4D, Metravo Elektronik, Unigor3p, Metravo3, Metratest3
Hartmann&Braun Elavi15N, Elavi5, Elavi5N, Multavi6
Simpson 467(PSM45), Beckmann DM25xL, ICE Microtest80, Soar3100, AN-USM213, AN-PSM6, HP E2377A
Neuberger PKD4 (2x)
ITT Metrix MX1200S (Clamp Multimeter)
Amprobe 37xR-A-D

Patients and those waiting to be given away are excluded

First one was a far-eastern analogue similar to the Ultron UM-204, but branded differently, if I recall it right.  Then a Metravo 2H. Then things escalated quickly.
What can I say? they tend to accumulate, and yet, many of them have quite unique features.

Missing ones: there is a extremely rare Siemens, which looks like the A1000, but is a real A/D multimeter.
Also, I'm willing to try a 867 and I will probably replace the 87 by a 289. Keithley 2001 might be next benchtop dmm. Maybe a Siemens B1023, a Metravo 2035, the RMS version of the MetraMax12 (14), ...
Of course, the bigger Prema DMMs (5017/8017) are something that one should not chase away if it started to follow me around aaand I worked with the Analogic DP-100 a.k.a. UDL-45 and I liked it!
So, way to go.

By the way, does anyone have definitive information about the first REAL multimeter (doing U, R, and I; and at least AC/DC for voltage)? Here in Europe, the Gossen Mavometer is often quoted, but it needed attachments for every single range. The H&B Multavi HO and the Mueller&Weigert 'Metravo' (yes, it wasn't always/only used by Metrawatt; or, there is a murky connection between those two).

[Neomys Sapiens]

So, for starters, if you were to be flown to Mars (or whereever if it makes the decision irrevocable), and you could take only ONE analogue multimeter with you, which one should one choose? The UNIGOR 6e (or 6eP) of course! Combining the advantage of an analogue meter movement with the high input impedance provided by a FET chopper amplifier and sporting the widest choice of measurement ranges known to me in a multimeter, this instrument was the undisputed high-end product of Metrawatt as long as it was built. In a Bürklin catalogue from 1988 it is still listed with a price around 1300DM. 
Its measurement capabilities include capacitance, at a time when only very few DMM did this. It is made with superb workmanship and built using discrete components only. Especially formidable are the Voltage and current ranges extending down to 1mV and 1µA FSD respectively! All U, I and R ranges are class 1 (excluding frequency error at AC). Protection features are comprehensive including an automatic cutout.

[Neomys Sapiens]

Then there is the MetraMax12, a Metrawatt (now GMC) DMM with interesting features. It allows to reduce the input impedance deliberately to 400kOhm/V, avoiding thereby a lot of false readings. Its design history dates back to the Metravo2D, which was the first of Metrawatt's 'pocketbook-sized' DMMs. But since then, autoranging, Frequency, capacitance, Min/Max and a bargraph were added over time. There is a RMS version, which is the MetraMax14. Here shown with some original accessories (the large shroud behind the 4mm connector locks onto the disk-shaped protector on the probes). Nice to have, and I take it along often (at least until I get my hands on the 14). Here it is:

[Neomys Sapiens]

And at the other end of the scale from the Unigor6e (as far as analogue multimeters are concerned), there is the ICE Microtest80. Made in Italy by ICE, whose 680E and 680R are bigger versions built to the same principle (range selection by jacks). It is about 100x90x30mm in its box and uses a single LR9 cell. And yet: AC, DC Voltage, Current and Resistance, so it is a complete multimeter! Jacks are slightly bigger than 2mm, but the 2mm plugs with spring work. And it is a convenient solution for carrying a second meter even in the compact toolkit. Voila:

[Vtile]

So, for starters, if you were to be flown to Mars (or whereever if it makes the decision irrevocable), and you could take only ONE analogue multimeter with you, which one should one choose? The UNIGOR 6e (or 6eP) of course! Combining the advantage of an analogue meter movement with the high input impedance provided by a FET chopper amplifier and sporting the widest choice of measurement ranges known to me in a multimeter, this instrument was the undisputed high-end product of Metrawatt as long as it was built. In a Bürklin catalogue from 1988 it is still listed with a price around 1300DM. 
Its measurement capabilities include capacitance, at a time when only very few DMM did this. It is made with superb workmanship and built using discrete components only. Especially formidable are the Voltage and current ranges extending down to 1mV and 1µA FSD respectively! All U, I and R ranges are class 1 (excluding frequency error at AC). Protection features are comprehensive including an automatic cutout.

I like your taste of FET-analogs. Do you have any of the accessories? Mine (Goerz Unigor6e) do have had some form of damage in the past in the needle as the red coating have partly flaked out, but still it seems to be spot on what I have been able to verify the readings with my limited equipment. Do not start to collect these high (10M+) impedance analogs.   

[Martin.M]

H+B    it have VFD tubes (Tung Sol)

[Neomys Sapiens]

Err...too late! And why shouldn't I collect them? It's not that they distract me unduly from the other ones. As for performance monitoring, I had the 6e recently calibrated without problems (company paid for it).
In between, I have a little DC calibrator and I do spot checks against the big digitals.
As for accessories, only the test leads and a pair of grey Hirschmann leads with fixed probes (they resembled the original ones by the grey wire). I have multiple Metrawatt current clamps and shunts, which could be counted as such. What I would cherish most, is the original RF probe, but I am still searching for it.
But as you liked my taste in Hi-Z analogue meters watch for the next post - it is a real jewel!

[AF6LJ]

H+B    it have VFD tubes (Tung Sol)

I love VFDs...

[Neomys Sapiens]

Now to switch to the renowned company of SIEMENS, which once had a own line of multimeters and which also underheld various alliances with products appearing under dual brands (ITT Mueller&Weigert, Norma, Gossen..)
But here they are:
Even if I praised the Unigor 6e beyond comparison, here is MY favorite analogue active (amplifier) multimeter: The Multizet A1000!
It is a semi-autoranging instrument, which uses the 0...3 and 0...10 ranges (or equivalent, scaled up or down) on the scale for optimal reading and precision. The actually selected sub-range is indicated on the small LCD, as well as DC polarity (auto!) and battery and fuse status.It was built in two versions, and the one shown here is the extremely rare second one: when you want to stay in the currently selected sub-range, you advance the side mounted power switch to the third position and the range is fixed! This feature was missing in the first version. Interestingly, it uses Fe/Cu-Ni elements for temperature (type J), not the typ K as most multimeters. But I use it more often with the original Siemens active temperature probe, which was offered as accessory. Power is by 6AA cells, and that is where the problem is: on this series of multimeters, you should really really heed the usual advice about removing the batteries when not in use! If you don't, they will corrode to the point of taking the batteries with them. That was what killed my first one (version 1). It has a sibling for DC-only measurement with zero at midscale, the Multizet A1001 (I have and use it too). And there was a real analogue/digital multimeter in the same form factor, of which I do not even know the designation and which I am searching for.

And here is a Siemens DMM, which is also quite rare and special - the B-1010
It is only missing one thing (RMS), but even without it it's a good choice for power-related work.
It has an integrated phase-sequence tester, which is connected by a triple-lead assembly fitting into the leftmost jack. Interestingly, it works quite well in 400Hz systems. Also, a 30A AC range comes handy.
It has the same form factor as the A1000 and can do temperature using type K! Does one understand this model policy? Also powered  by 6AA cells. Here with original case and probes in pristine condition:

[Neomys Sapiens]

Now, having poured myself an IPA and assured that I don't miss anything elsewhere, I'm going to show you an even rarer beast, which I doubt that many of them survive and maybe none at all outside of western Germany: The Neuberger PKD4 analogue modular multimeter kit!
The company Josef Neuberger was situated in Munich and did build multimeters and other electrical test gear since the 1930s. It is best known for its tube testers and the Unavo/Telavo multimeter series.
The PKD4 Set was probably originally conceived as a training device and later adapted for professional technical use. It was made in the 70s of the last century.
It consists of a analogue, moving-coil instrument with the usual 10/30 + Ohms scaling which has a sensitivity of 60mV/50µA. It is connected by two 4mm jacks at the right side, into which the 4mm plugs of the associated range and function boxes fit. Measurement connections are to the front side and use 4mm jacks/plugs too. And there was a lot of those boxes:
Besides basic shunt and divider boxes as well as combined I/U boxes there are those with rectification for AC and resistance boxes (containing the battery too) in various range combinations. But that is not all - there was a DC chopper amplifier based voltmeter/microamperemeter with 2MOhm/V (PA6) and an amplifier AC voltmeter covering frequencies well beyond 100kHz with 1MOhm input (PA7) as well as a static (PA8) and a dynamic (PA10) transistor tester!  It came with an optional carrying case (shown below), which could accomodate 2 basic indicators and up to 8 range/function boxes. The accompanying brochure lists not only the characteristics and usage of the modules, but gives the complete circuit diagram for each one!

The makeup of it lends itself extremely well to self-build extensions and as I have lots of ideas I will have some compatible boxes made. I am not willing to sacrifice any of mine, even the redundant ones but I also want them to look exactly the same as the original ones. I plan to make a digital base instrument too, maybe with some memory functions or even a data interface.
One little setback occurs when trying to aquire the batteries needed to operate all modules: the IEC15F20 22.5V block battery needed by the PA7 and PA8 might be well made of Unobtainium! The PA5 and PA11 resistance modules use the 10F15 15V cell, which is only marginally easier to get. The PA10 uses two half-AA (not AAA) cells. I have resorted to fit 2mm jacks in the top side to connect an external supply when possible. Maybe I could build a nice, electrically stable linear power unit for all the options in the same size as the base instrument. Presently I have 2 base instruments with 11 modules and 1 case.

Here the base instrument with one module, second picture shows them partially connected:

[Cubdriver]

Now, having poured myself an IPA and assured that I don't miss anything elsewhere, I'm going to show you an even rarer beast, which I doubt that many of them survive and maybe none at all outside of western Germany: The Neuberger PKD4 analogue modular multimeter kit!
The company Josef Neuberger was situated in Munich and did build multimeters and other electrical test gear since the 1930s. It is best known for its tube testers and the Unavo/Telavo multimeter series.
The PKD4 Set was probably originally conceived as a training device and later adapted for professional technical use. It was made in the 70s of the last century.
It consists of a analogue, moving-coil instrument with the usual 10/30 + Ohms scaling which has a sensitivity of 60mV/50µA. It is connected by two 4mm jacks at the right side, into which the 4mm plugs of the associated range and function boxes fit. Measurement connections are to the front side and use 4mm jacks/plugs too. And there was a lot of those boxes:
Besides basic shunt and divider boxes as well as combined I/U boxes there are those with rectification for AC and resistance boxes (containing the battery too) in various range combinations. But that is not all - there was a DC chopper amplifier based voltmeter/microamperemeter with 2MOhm/V (PA6) and an amplifier AC voltmeter covering frequencies well beyond 100kHz with 1MOhm input (PA7) as well as a static (PA8) and a dynamic (PA10) transistor tester!  It came with an optional carrying case (shown below), which could accomodate 2 basic indicators and up to 8 range/function boxes. The accompanying brochure lists not only the characteristics and usage of the modules, but gives the complete circuit diagram for each one!

The makeup of it lends itself extremely well to self-build extensions and as I have lots of ideas I will have some compatible boxes made. I am not willing to sacrifice any of mine, even the redundant ones but I also want them to look exactly the same as the original ones. I plan to make a digital base instrument too, maybe with some memory functions or even a data interface.
One little setback occurs when trying to aquire the batteries needed to operate all modules: the IEC15F20 22.5V block battery needed by the PA7 and PA8 might be well made of Unobtainium! The PA5 and PA11 resistance modules use the 10F15 15V cell, which is only marginally easier to get. The PA10 uses two half-AA (not AAA) cells. I have resorted to fit 2mm jacks in the top side to connect an external supply when possible. Maybe I could build a nice, electrically stable linear power unit for all the options in the same size as the base instrument. Presently I have 2 base instruments with 11 modules and 1 case.

Here the base instrument with one module, second picture shows them partially connected:

That's a very cool old piece of gear!  Interesting concept.

Very nice!

-Pat

[anachrocomputer]

My latest multimeter acquisition, a Fluke 37. I got this one really because of its industrial design -- the storage compartment, the carrying handle, the clip-on stand and so on. I think that electrically, it's a Fluke 27. Just in a different (much bigger) case. I haven't started to restore it yet, but will clean it and probably also clean the zebra strips in the LCD.

[mmagin]

It's fascinating that FET VOMs seem to have had a much bigger run in Germany and continental Europe in general than in the US.  It seems like here they just existed in a short decade between VTVMs and 3.5 digit DMMs.

I have recently obtained a Micronta (Radio Shack) 22-220A which seems to need repair.  I'm hoping that if it's the matched JFET pair that's damaged I won't have too hard of a time replacing it.  It's an µPA68H according to the schematic I found elsewhere on the web (reposted here because it was too much effort to find).

It's particularly amusing that they borrowed the industrial design of the Simpson multimeters, albeit cheaply.  It's made in China (no mention of Taiwan, so I assume mainland China, so probably late 1970s or later?)

[Neomys Sapiens]

It's fascinating that FET VOMs seem to have had a much bigger run in Germany and continental Europe in general than in the US.  It seems like here they just existed in a short decade between VTVMs and 3.5 digit DMMs.

I think there are various aspects to it. At least here in Germany, you have a higher level of technical training especially at the craftsman/technician level. I mean, an engineering degree is (and was 50yrs ago) closer together on both sides of the atlantic ocean than the idea of what makes an 'electrician'. So, the problem of difficult to read analogue meters was less important, as the potential users were assumed to be properly trained for it.
Then, there might have also existed a deeper 'technical conservatism' both on the side of the instrument makers and users.
Also, US instrumentation companies such as HP, Tek, Keithley etc. were far more present in european markets than the other way round. So their DMMs were available and actively marketed. My first DMM was a Fluke 8060A and it was among the first batch sold over here. I remember selecting it over the Beckman 3030RMS, and there was no RMS handheld DMM from german manufacturers at that time (about 1983).
My boss at the engineering office, where I worked while still in school, who was certainly up to date, as we were doing quite advanced automation stuff, was not convinced - he advised me to go for one of the big Unigors, as he distrusted sampling and numeric displays not to show him really what happens.
So companies over here might have cultivated the analogue niche market for longer.
My first electronic analogue MM was a Philips PM2505, which came after the Fluke, when my older Metravo2H (passive) did not survive a unexpected contact with a 750VDC streetcar supply line in a traffic control installation.
GMC still sells an active analogue multimeter in the guise of the METRAport3A (practically the same than a Metravo 3E). Of course, both in this one and in the Siemens A1000 which I presented ICs have taken the place of the simple FET pair.
But the phenomenon is not limited to the active (FET/amplifier) variety. For example, the multimeter pool at Rockwell-Colling Germany contains lots of the old black Siemens Multizets with their class1 spec. They are calibrated regularely and treated well and I see no reason not to use them in complex lab work, where you really measure one or two signals but have ko keep an eye on some others.