These Fluke differential voltmeters were used as "secondary" standards. The dial settings at null, were used to calibrate other instruments. I have three models of these differential meters mostly for sentimental reasons yet they still compare to my modern equipment, that is, within a few millivolts. I do let them warm-up for about an hour before actually using them. (K1NVY)
Boy, did this video bring back some memories! I remember using this instrument at my first duty station after graduating from the Navy Electronics Technician School in 1970!
Very nice to find a working unit. My first exposure to Fluke was the AC/DC Differential Voltmeter 803D. It was the predecessor to this meter. Back then it was the state of the art and I was very impressed. The feature you mention of infinite input impedance was crucial to what I was doing in those days, measuring outputs of 2000 MΩ voltage dividers. It is still difficult to find a comparable device. Standard DVMs today offer a 10 MΩ input impedance and you can find 1,000 MΩ or 10,000 MΩ. Still no match for infinite. It should be noted that the infinite impedance is not achieved unless the two voltage sources are finally equivalent and current flow between them drops to zero. ~doug
Very cool. Love old tech that still compares favorably to modern stuff, especially when it uses what we'd now consider to be crude methods for getting there.
Thanks for all the great instructional videos you have produced. I know I have learned some things from you and really appreciate you sharing your knowledge! I absolutely love all the "vintage" test equipment I have.It was built to last, as I have a lot of old HP,Tektronix,Fluke, Lamda gear that still works as good as when it was produced. I see you have quite a few pieces of vintage gear that you use daily. The test equipment made today is throw away, what a shame. But I'll keep on using my antique gear, and repairing it when necessary.
Great info! It also can be used to determine the stability of a voltage source. To see this, measure an alkaline battery voltage and it is "noisy" on the most sensitive range, the null meter needle swings around. Then measure a NiCad battery and it is much more stable (have not tried lithium). Translate that to any "precision" voltage source and it is easy to see if it is faulty or not.
Very cool. I keep being surprised about the clever solutions and technologies they used back in the day to reach precisions and develop features which by todays standard are still very good. Shame you didn't show the insides, would've loved to see those rotary switches filled with resistors!
+tHaH4x0r - Ya, I am a little disappointed that Alan didn't take the cover off too. Even for just a quick look. Perhaps he can do a follow up video where he takes a look inside and tries to do the calibration. Can't be that hard to calibrate can it?
That was staggering for a few reasons... Fluke (Or John Fluke) were going for years more than I realised.. Even way back they were producing instruments that far exceeded the then standard in my opinion of the Avo 8 multimeter. Nice video Alan, I know I said in the past I wasn't fond of old instrument (save for a few examples) but this is awesome..... thanks for that.. (Well in spec too......)
Neat stuff! That precision, that mechanical-electronic integration! Was wondering if you could put some of the old manuals, datasheets, app. notes, handbooks online (without violating any law). Sadly, our generation has not seen too many equipment with an "Operating Principle" section in the manual.
This is similar to my AN/USN-381 differential voltmeter in it's layout and controls. The AN/USN-381 is a DC only instrument with a specified accuracy of 0.005% in a ruggedized case and a 15kV input range.
I'm pretty sure I remember Dave Jones talking about those dividers too; 'course at my age CRS disease takes an ugly toll. Hopefully we'll get a peek inside to see the what must be nice mechanical linkages sometime in the future. 73 - Dino KL0S
+Dino Papas Several other have commented that he did talk about Kelvin Varley in video #210 - I'll have to go back to see if that is the one that I recall...
Thank you for video, informative and interesting as usual. Minor correction: error was 0.012%, not 0.0012% as you said. So an insignificantly out of spec it is.
Your memory isn't failing you. Dave *did* touch on the subject of Kelvin-Varley dividers, but not in its own video. You can find the segment at about the 26 minute mark in this video about a DC voltage standard. And he also spent a couple of minutes before that explaining why a regular Kelvin divider is problematic. Dave, the master waffler!ruclips.net/video/onqsjDJq4I0/видео.html
Great bit of test gear you got there, never seen those before, to be honest i didn't even understand how it operated after you explained it but after i saw it in operation i noticed that it's pretty much a comparator with a variable reference. Also do you have any ideas for the upcoming video? If not may i suggest rf output stages, antenna impedance or what makes for an efficient transmiter ? Take care.
A voltage divider is to be built to give 5v out put from 12v in put figure .the maximum load power is 5v design a divider to provide output range 5.25-4.75v for load rang 3w -5w what is the no lad voltage out the put ?what is the efficiency for two cases of load? can u sir answer it fast please
W2aew, how is a differental voltmeter different compared to using a new modern 4 wire kelvin meter? I'm confused about this Kelvin Varley Divider and 0-11vdc reference because a new modern 4 wire kelvin meter uses current source instead of a Kelve Varley Divider and 0-11vdc reference.
Why do you advance the digit wheels slowly, one step at a time? Doesn't the pointer always give you the next digit of the voltage so you can just dial it right in? Or would it wear out the mechanism to advance the wheels too fast?
The pointer does tell you where to set the wheel. However, since this instrument is ~50 years old, I didn't want to put any undo stress on the old plastic.
Great instrument! I could have sworn that Dave had a video on Kelvin Varley dividers. Maybe it's hidden inside one of his videos about the Krohn Hite voltage standard?
Nice and very interesting but you didn't let us see the coolest part - the innards ;) The mechanics of those dials would be very interesting to see. The ingenuity of dials and switches of old instruments can be amazing.
very pretty instrument and a very clever way to do the messurement. Did the zero bolt can't improve the accuracy?? or did you had already cheked about it ???
Ohh ok ... by the way I want to congratulate you, all of your videos are very accurate and very didactic, in many times better than the manufacturer do on their on products.
4½ digit DMM's are neither especially uncommon nor expensive. They couldn't match or exceed the accuracy of this wonderful old boat ⚓???🤨🤔 I have 2 such meters that I use daily: A 1985ish Brunelle (a rebranded "GW" "Goodwill" job; one of which packed it in after just 2-3yrs. use🤷) & an early-mid 70's (!!!) Fluke 8060. Both meters have held their accuracy superbly over the years, unlike my 3 HP Bench DMM's (a 4½ digit 3465A, which just crapped out on me earlier this week, & my two 5½ digit 34750A's which REALLY don't hold their calibration very well or long at all 🧐). Google was happy to suggest this video for me, & an excellent little tutorial about vintage Differential Voltmeters ("DVM"s?🤔🤣) it is, thank you. I looked this up because someone offered me a 1968 Lambda LS-513 for $30 "as is" (don't worry. I think $5 is a generous offer too. $10 if it actually works!). So it seems the famous power supply people made some other good stuff as well! And then after watching this... something in the back of my mind just popped out to remind me...I DO have a working but hurting (severe noise) Fluke "DVM" myself!🤔💡 An 873AB "portable" that could run both on 120VAC as well as on its internal & long-since puked & irreplaceable NiCd battery pack. Looks pretty much like the 887 featured here; I wonder if it's much older given the lower model # assigned to it?🤔 Or maybe it was just a lower performance model?😏 I'm putting together a "retro" Audio test-bench setup where the idea is to have nothing newer than 40yrs old on it, preferably 60+! I want the huge, heavy, & hot vacuum tube stuff with the noisy fans in 'em to keep them "cool" (🤣🤣🤣). Stuff in metal cases. Built to last, & built to be easily serviced & calibrated. I'll tolerate some transistors, I'm addicted to DMM resolution & accuracy; even if you can't make rhyme or reason out of noisy readings on them, & they have crappy frequency response too. Unlike say, my HP 400DR VTVM & trusty Simpson 260...😎
Thank you for this great content. That's serious performance with regard to the manufacturing date. Also precision stability over time to me it looks awesome. Is it fair to say that this unit can be used as a null detector down to 1uV on the 1V range ?
+Ovidiu M The dials go down to 10uV on the 1V scale, so you could likely interpolate a bit beyond this, but then you're really pushing well against the accuracy limits.
+w2aew If only you had access to the resources of a well known test and measurement division of a multinational conglomerate that begins with a D... :)
Great demonstration. A wonderful example of engineering and craftsmanship. I'm sure the insides are just as cool.
These Fluke differential voltmeters were used as "secondary" standards. The dial settings at null, were used to calibrate other instruments. I have three models of these differential meters mostly for sentimental reasons yet they still compare to my modern equipment, that is, within a few millivolts. I do let them warm-up for about an hour before actually using them. (K1NVY)
Man this is one of the coolest things I've ever seen. We have one of these at work just sitting around. I was wondering about it and found your video.
Boy, did this video bring back some memories! I remember using this instrument at my first duty station after graduating from the Navy Electronics Technician School in 1970!
Alan,
I have a 887A model.
I recall this type of meter from when my Dad had his electronics business when I was a teenager.
Very nice to find a working unit. My first exposure to Fluke was the AC/DC Differential Voltmeter 803D. It was the predecessor to this meter. Back then it was the state of the art and I was very impressed. The feature you mention of infinite input impedance was crucial to what I was doing in those days, measuring outputs of 2000 MΩ voltage dividers. It is still difficult to find a comparable device. Standard DVMs today offer a 10 MΩ input impedance and you can find 1,000 MΩ or 10,000 MΩ. Still no match for infinite. It should be noted that the infinite impedance is not achieved unless the two voltage sources are finally equivalent and current flow between them drops to zero. ~doug
Amazing how that all these years later, there is still no good modern substitute for certain applications.
Very cool. Love old tech that still compares favorably to modern stuff, especially when it uses what we'd now consider to be crude methods for getting there.
Thanks for all the great instructional videos you have produced.
I know I have learned some things from you and really appreciate you sharing your knowledge!
I absolutely love all the "vintage" test equipment I have.It was built to last,
as I have a lot of old HP,Tektronix,Fluke, Lamda gear that still works as good as when it was produced.
I see you have quite a few pieces of vintage gear that you use daily.
The test equipment made today is throw away, what a shame.
But I'll keep on using my antique gear, and repairing it when necessary.
so cool to get an accuracy beyond .01% for something that old! Thx for sharing!
Very informative video Alan. Impressive piece of vintage gear. Big thumbs up.
Great info! It also can be used to determine the stability of a voltage source. To see this, measure an alkaline battery voltage and it is "noisy" on the most sensitive range, the null meter needle swings around. Then measure a NiCad battery and it is much more stable (have not tried lithium). Translate that to any "precision" voltage source and it is easy to see if it is faulty or not.
Very cool. I keep being surprised about the clever solutions and technologies they used back in the day to reach precisions and develop features which by todays standard are still very good. Shame you didn't show the insides, would've loved to see those rotary switches filled with resistors!
+tHaH4x0r - Ya, I am a little disappointed that Alan didn't take the cover off too. Even for just a quick look. Perhaps he can do a follow up video where he takes a look inside and tries to do the calibration. Can't be that hard to calibrate can it?
Well, I guess you can say "Respect" for Flukes design.
That was staggering for a few reasons... Fluke (Or John Fluke) were going for years more than I realised.. Even way back they were producing instruments that far exceeded the then standard in my opinion of the Avo 8 multimeter. Nice video Alan, I know I said in the past I wasn't fond of old instrument (save for a few examples) but this is awesome..... thanks for that.. (Well in spec too......)
Awesome meter, thanks for sharing it with us!
Great Video! I love this type of vintage equipment :)
I am impressed
Condition seems amazing for 50 years old.
Nice vid. A teardown sure would be interesting. Thanks for all your great videos.
Neat stuff! That precision, that mechanical-electronic integration! Was wondering if you could put some of the old manuals, datasheets, app. notes, handbooks online (without violating any law). Sadly, our generation has not seen too many equipment with an "Operating Principle" section in the manual.
This is similar to my AN/USN-381 differential voltmeter in it's layout and controls. The AN/USN-381 is a DC only instrument with a specified accuracy of 0.005% in a ruggedized case and a 15kV input range.
I'm pretty sure I remember Dave Jones talking about those dividers too; 'course at my age CRS disease takes an ugly toll. Hopefully we'll get a peek inside to see the what must be nice mechanical linkages sometime in the future. 73 - Dino KL0S
+Dino Papas Several other have commented that he did talk about Kelvin Varley in video #210 - I'll have to go back to see if that is the one that I recall...
thanks for sharing. that is an awesome piece of equipment.
Thanks, Alan. I love that old stuff, but my back doesn't.
Thank you for video, informative and interesting as usual. Minor correction: error was 0.012%, not 0.0012% as you said. So an insignificantly out of spec it is.
+SLEAGD Yeah, I mis-spoke - thanks for catching that!
Your memory isn't failing you. Dave *did* touch on the subject of Kelvin-Varley dividers, but not in its own video. You can find the segment at about the 26 minute mark in this video about a DC voltage standard. And he also spent a couple of minutes before that explaining why a regular Kelvin divider is problematic. Dave, the master waffler!ruclips.net/video/onqsjDJq4I0/видео.html
+Gameboygenius Thanks - I made the appropriate changes in the video notes and annotation.
Great bit of test gear you got there, never seen those before, to be honest i didn't even understand how it operated after you explained it but after i saw it in operation i noticed that it's pretty much a comparator with a variable reference.
Also do you have any ideas for the upcoming video? If not may i suggest rf output stages, antenna impedance or what makes for an efficient transmiter ?
Take care.
A voltage divider is to be built to give 5v out put from 12v in put figure .the maximum load power is 5v design a divider to provide output range 5.25-4.75v for load rang 3w -5w what is the no lad voltage out the put ?what is the efficiency for two cases of load?
can u sir answer it fast please
W2aew, how is a differental voltmeter different compared to using a new modern 4 wire kelvin meter? I'm confused about this Kelvin Varley Divider and 0-11vdc reference because a new modern 4 wire kelvin meter uses current source instead of a Kelve Varley Divider and 0-11vdc reference.
nice equipment
Why do you advance the digit wheels slowly, one step at a time? Doesn't the pointer always give you the next digit of the voltage so you can just dial it right in? Or would it wear out the mechanism to advance the wheels too fast?
The pointer does tell you where to set the wheel. However, since this instrument is ~50 years old, I didn't want to put any undo stress on the old plastic.
Beautiful. Now to take it apart?
WOW. That is beautiful ❤❤❤
Great instrument! I could have sworn that Dave had a video on Kelvin Varley dividers. Maybe it's hidden inside one of his videos about the Krohn Hite voltage standard?
+Pn Junction It was, link now appears in the video notes.
Nice and very interesting but you didn't let us see the coolest part - the innards ;) The mechanics of those dials would be very interesting to see. The ingenuity of dials and switches of old instruments can be amazing.
very pretty instrument and a very clever way to do the messurement.
Did the zero bolt can't improve the accuracy?? or did you had already cheked about it ???
+Fauser Neves The "zero" adjustment is a trimmer to adjust the meter to 0 when the inputs are shorted. This adjustment is only needed periodically.
Ohh ok ... by the way I want to congratulate you, all of your videos are very accurate and very didactic, in many times better than the manufacturer do on their on products.
Another great video, thanks !
73 N8AUM
Another nice vid Alan. Thanks.
Demo it as a megohmmeter please?
These days would it make sense to use one of these if you have a modern handheld multimeter? Or can modern handhelds do the job reasonably well?
Handhelds do not have the resolution to do the same job. Modern benchtop DMMs would work well.
4½ digit DMM's are neither especially uncommon nor expensive. They couldn't match or exceed the accuracy of this wonderful old boat ⚓???🤨🤔
I have 2 such meters that I use daily: A 1985ish Brunelle (a rebranded "GW" "Goodwill" job; one of which packed it in after just 2-3yrs. use🤷) & an early-mid 70's (!!!) Fluke 8060. Both meters have held their accuracy superbly over the years, unlike my 3 HP Bench DMM's (a 4½ digit 3465A, which just crapped out on me earlier this week, & my two 5½ digit 34750A's which REALLY don't hold their calibration very well or long at all 🧐).
Google was happy to suggest this video for me, & an excellent little tutorial about vintage Differential Voltmeters ("DVM"s?🤔🤣) it is, thank you. I looked this up because someone offered me a 1968 Lambda LS-513 for $30 "as is" (don't worry. I think $5 is a generous offer too. $10 if it actually works!). So it seems the famous power supply people made some other good stuff as well! And then after watching this... something in the back of my mind just popped out to remind me...I DO have a working but hurting (severe noise) Fluke "DVM" myself!🤔💡
An 873AB "portable" that could run both on 120VAC as well as on its internal & long-since puked & irreplaceable NiCd battery pack. Looks pretty much like the 887 featured here; I wonder if it's much older given the lower model # assigned to it?🤔 Or maybe it was just a lower performance model?😏
I'm putting together a "retro" Audio test-bench setup where the idea is to have nothing newer than 40yrs old on it, preferably 60+! I want the huge, heavy, & hot vacuum tube stuff with the noisy fans in 'em to keep them "cool" (🤣🤣🤣).
Stuff in metal cases. Built to last, & built to be easily serviced & calibrated. I'll tolerate some transistors, I'm addicted to DMM resolution & accuracy; even if you can't make rhyme or reason out of noisy readings on them, & they have crappy frequency response too. Unlike say, my HP 400DR VTVM & trusty Simpson 260...😎
>
Thanks - now I just need to find someone that might be interested in this box of gold...
Thank you for this great content. That's serious performance with regard to the manufacturing date. Also precision stability over time to me it looks awesome. Is it fair to say that this unit can be used as a null detector down to 1uV on the 1V range ?
+Ovidiu M The dials go down to 10uV on the 1V scale, so you could likely interpolate a bit beyond this, but then you're really pushing well against the accuracy limits.
Fix it and adjust it, would be interesting....
+Burkhardj I can certainly re-cap the unit, but I don't have the voltage standards necessary to properly calibrate it.
+w2aew If only you had access to the resources of a well known test and measurement division of a multinational conglomerate that begins with a D... :)
I just don't have access to those resources locally. I work in the field...
You are not totally wrong, Dave talked about theKelvin-Varlay in EEVBlog #210 ruclips.net/video/onqsjDJq4I0/видео.htmlm28s
73 DC5AJ
+Alexander Jessautzki Thanks, I made the adjustments in my notes and video annotation.
John D
Wwwaaaaaa:))) You just shoot My review about this dif meter now :) I want to do also in tomorrow. Shit :))) You are faster :)))
Ok I will do a tear down and cleaning :)
+BMR Studio Oops, sorry about that. You can certainly do a review because mine was just a quick overview. Definitely would like to see the tear down!
+w2aew Its ok, I just joking :) I will do a tear down today , then I mention - attach Your original video.