Re: [volt-nuts] Need Fluke 332B PCB contacts
Hi Chris, I haven't found a stocking source for the contacts. Elco/AVX requires an order of at leasst 5000 units before they will tool up for a run. I looked extensively for some of these contacts at our local hamfest a few weeks ago, but came up empty. One of the forum members (from Australia) saw my post and sent me a salvaged contact strip having about 20 of the contacts. The strip was in good condition, none of the contacts were damaged, and fits nicely on the new PCB. Don't know if he has any more of the contact strips. I haven't finished building the new chopper amp board yet (lack of time), but I think it will work out well when I get it installed and calibrated. Cheers, Dave M Chris Farley via volt-nuts wrote: Hi Dave, Did you ever find contacts to build your board? I've uncovered some documentation and deciphered the part number structure, and have put in for multiple p/n quotes at a surplus/parts hunter company I've dealt with in the past. IF some of these contacts are located and available, the minimum order amount is typically around $100... So depending on unit price, this may or may not be a cost effective venture... Would like to hear your thoughts on this. Regards, Chris kc9ieq From: Dave M To: FEBO Volt-Nuts ; Yahoo Fluke_DMM Sent: Saturday, July 29, 2017 3:18 PM Subject: [volt-nuts] Need Fluke 332B PCB contacts Does anyone have any surplus (or for sale) of the bifurcated contacts used on the PCB assemblies in a Fluke 332B DC Voltage Standard? They're identified as ELCO/AVX Varicon Series 5208 contacts, p/n 02-016-013-5-200. Need at least 16 of them for an upgraded chopper amp replacement board, needed to get my 332B back in operation. Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Need Fluke 332B PCB contacts
Yes, that's the mod that I'm looking to do. I got a PCB from Andreas Bergmann (he's on this list frequently) for postage from Germany. Good quality board. All of the parts used on the board are readily available, except for a set of the Elco contacts. I sent an email to AVX a couple days ago, but after more reading on the EEVBLOG thread, I don't hold much hope that those contacts will still be available. Possibly a surplus store or hamfest will be the only possible remaining source. Might be possible to salvage the contacts from the old chopper board, which is pretty much useless as it is, because the chopper is totally dead (got good drive, but totally dead). Not all of the contact positions are actually used, so there's a bit of a fudge factor there. I think that 5 of the positions are not used by the circuit.. The board from Andreas is a 2-sided board with plated-through holes, so that will offer some mechanical strength for the contacts. Cheers, Dave M roman wrote: Dave, Re your chopper board upgrade - are you looking at the design from friedrich-messtechnik.de? I have been thinking about the chopper as part of my ongoing project to "improve" my 332B. I have some questions about the chopper - is this a good place, or is it better to start a thread on eevblog (or somewhere else)? Roman -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Dave M Sent: Sunday, 30 July 2017 5:45 AM To: FEBO Volt-Nuts; Yahoo Fluke_DMM Subject: [volt-nuts] Need Fluke 332B PCB contacts Does anyone have any surplus (or for sale) of the bifurcated contacts used on the PCB assemblies in a Fluke 332B DC Voltage Standard? They're identified as ELCO/AVX Varicon Series 5208 contacts, p/n 02-016-013-5-200. Need at least 16 of them for an upgraded chopper amp replacement board, needed to get my 332B back in operation. Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Need Fluke 332B PCB contacts
Does anyone have any surplus (or for sale) of the bifurcated contacts used on the PCB assemblies in a Fluke 332B DC Voltage Standard? They're identified as ELCO/AVX Varicon Series 5208 contacts, p/n 02-016-013-5-200. Need at least 16 of them for an upgraded chopper amp replacement board, needed to get my 332B back in operation. Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Fluke 332B
David, I have a 332B as well, although it's been loaned out for the past couple of years to a friend. I have the US Army manual PDF also, and have found it to be pretty complete, at least complete enough to get us through a couple of repairs. What is missing from the manual? The second page in the PDF has a statement that says: "This manual is an authentication of the manufacturer’s commercial literature which, through usage, has been found to cover the data required to operate and maintain this equipment. Since the manual was not prepared in accordance with military specifications, the format has not been structured to consider level of maintenance, nor to include a formal section on depot overhaul standards. This manual contains copyrighted information that is printed with permission of John Fluke Manufacturing Company, Seattle, Washington." From that statement, I expect that the Army manual is just a reproduction of the commercial Fluke manual for the 332B. Cheers, Dave M David C. Partridge wrote: Amongst the stuff I recently acquired is a Fluke 332B (sn 4151). I found the manual for the 332D on the Fluke website, but can't find one specifically for the 332B apart from an incomplete US Army version. I have some questions: 1) Does anyone know where I can find the matching manual 2) If not, how useful is the 332D manual? 3) It was last calibrated in 2010, and appears to be consistently low in output (about 5mV at 100V, 25mV at 500V, 50mV at 1000V) after being on for an hour. Is that the sort of error I should expect after that period? 4) I'm leery of the chopper amp, did anyone (Dr. Frank?) do a retrofit using a modern chopper op-amp or similar? Thanks Dave ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Prologix USB-GPIB Controller
Jerry, Sorry, but need a USB interface. Dave M jerry wrote: I have a NI-GPIB card. I can't remember the interface it needs, might be ISA, can't remember but not all computers have more than one ISA slot. $50 including US flat rate shipping is the best I can do. Original message From: Russ Ramirez Date: 10/7/2016 12:35 (GMT-08:00) To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] Prologix USB-GPIB Controller I do, what is he willing to spend on one roughly? The unit is one year old and is working - I believe I have the box, disk, and pamphlet. Russ On Fri, Oct 7, 2016 at 2:15 PM, Dave M wrote: Does anyone happen to have a Prologix USB-GPIB Controller available for sale? One of my friends needs one for his bench. He is retired and on a limited budget, and would like to find one cheaper than MSRP from Prologix. Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Prologix USB-GPIB Controller
Does anyone happen to have a Prologix USB-GPIB Controller available for sale? One of my friends needs one for his bench. He is retired and on a limited budget, and would like to find one cheaper than MSRP from Prologix. Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP 3458A
The Component Level Information Packet. (CLIP) for the 3458A can be downloaded from : http://exodus.poly.edu/~kurt/manuals/manuals/HP%20Agilent/HP%203458A%20Component-Level%20Information%20Packet.pdf or https://xdevs.com/doc/HP_Agilent_Keysight/3458A/doc/3458A%20CLIP.pdf The Assembly Level Rerpair Manual can be downloaded from https://www.keysight.com/main/gated.jspx?lb=1&gatedId=102018:epsg:man&cc=US&lc=eng&parentContId=101297:epsg:pro&parentContType=pt&fileType=VIEWABLE Cheers, Dave M Tom Knox wrote: Hi Hicham; The real experts are at Keysight. I do work with these a bit, but am not familiar with this error and would be very interested in what the problem turns out to be. If you do not already have one I recommend purchasing the Component Level Service Manual from Keysight. Sorry I could not be of more help. Best Wishes; Thomas Knox Sr Test and Measurement Engineer Ascent Concepts and Technology Boulder Colorado 80305 1-303-554-0307 act...@hotmail.com From: volt-nuts on behalf of Hicham Chamsi Sent: Thursday, September 15, 2016 11:15 AM To: volt-nuts@febo.com Subject: [volt-nuts] HP 3458A HP 3458A DMM ISSUE H Hier moi HI to all volt-nuts I receive an email from volts nut, so i learn from this email that you are expert, please i need a help on error 205 out of range 95. i follow the instruction of Illya but no result HP 3458A ISSUE Hello to all I receive an email from volts nut, so i learn from this email that you are expert and you can help me, please i need a help on error 205 out of range 95. i follow the instruction of Illya but no result, i hope you could help me. also i want the equivalent of Jfet transistor N channel 1855-0743, i look too long for this i don't get any characteristique in order to substitute it. Best Regards Hicham Répondre Transférer Facture Iam juin Juliet Réception H Hier *moi* ___ ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP3450A Reference Peltier Chambers
Yes, I'm aware of the problems with AC drive to a Peltier. However, the 3450A drives the chamber to 43 degC with DC, so that isn't a problem. In fact, it's a pretty simple drive circuit, runing stable state at 1.5 - 2 volts. My interest is in how best to fix the components to the Peltier. Seeing a picture of the innards of the 3450A chamber would help. I have a few 12V Peltier junctions of various powers ratings, and have no other thoughts as to what to use them for. Making a small chamber to ascertain the zero tempco point of my reference zeners seems to be an easy project. This isn't for a constantly-on instrument; it's for short-term data gathering. Thanks, Dave M Poul-Henning Kamp wrote: > ---- > In message , "Dave M" > writes: > >> I was intrigued by the use of a Peltier chamber to control >> the temperature [...] > > It's a very obvious idea, but it runs into one of the widely unknown > footnotes about peltiers: Don't feed them AC. > > The thermal/mechanical stress when you change direction of the > current significantly shortens their life. > > I should add that I have not found any studies which say to what > degree this depends on the magnitude of the current, so an oven > balancing around a couple of mA may not be a problem, but switching > polarity on several amps will be. > > One complication is the difference in directional efficiency: The > warm side receives about 4 times as much energy as is removed from > the cold side. > > Unless you electrically compensate for this, your PID will be > *really* confused. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] HP3450A Reference Peltier Chambers
I've been looking at the various voltage reference schemes used in HP's 345x line of DMMs. I was intrigued by the use of a Peltier chamber to control the temperature of the reference element in the HP 3450A DMM. I looked in the service manual for that unit, but I couldn't find a good picture of the reference assembly. Would anyone having a 3450A be adventurous enough to pull it apart enough to take a few good pictures of the innards? I found a Sales Amplifier paper from HP that roughly describes the reference assembly, but no good pictures. I'm wondering if the diode under test and a thermistor should be mounted directly to the surface of the Peltier device or to a copper or aluminum interface between the Peltier and the thermistor & diode. Any thoughts? How did HP do it in the 3450A chamber? I have a number of 1N825 and 1N827 diodes that I'd like to toy with. In particular, I'd like to build such a Peltier controlled chamber to ease the task of finding the zero tempco spot on the zeners. Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Fluke 720a self calibration repair
Rob Thanks for the offer. I received an offer of a (nearly) complete unit from another list member. If that turns out well, I should have all the spares that I'll ever need. If it doesn't work out, I'll surely be back in touch with you. Dave M Rob Klein wrote: Dave, How many of those pots do you need? I've had the innards of an 88(something) lying around for ages and your welcome to a few, if you're willing to pay shipping from the Netherlands. With only the trimmers in a small box, that should not break the bank. Met vriendelijke groet, Rob Klein. Verstuurd vanaf mijn tablet Dave M schreef: I tried to find this style trimmer pot with a wirewound resistance element, but found that all I could find was the Cermet type. It appears that wirewound pots have all been replaced by Cermet. the wirewound pots had a 1W power rating, whereas the Cermet pots arte only rated at 3/4W. In the 720A, the reduced power rating won't be an issue, but in some vintage equipment, it might be. I've also tried, to no avail, to find a source for the metal-cased wirewound trimmer pots used on the K-V divider in some older Fluke differential voltmeters, such as the models 883A, 885A and 887A. Does anyone know of a source for replacements for those pots? I have an 887A on the shelf that I'd like to get back to original condition if I could find a couple of that style trimmer pot. They're only 2 ohms, making the search even more difficult. At this point, my only recourse is to find a defunct donor unit at reasonable cost, and salvage the parts. Does anyone have a hangar queen that I could get for shipping charges? I'd be really happy to get mine back on the road to health. Cheers, Dave M Tony wrote: Apologies - my mistake - I wasn't paying sufficient attention when Google decided that this was a perfect match when searching for 300SP-1-502: http://uk.farnell.com/webapp/wcs/stores/servlet/Search?st=3400s&catalogId=15001&categoryId=70005471&langId=44&storeId=10151 But £180.27 each whereas Newark, the US arm of Farnell only want $120 or approx £80 for the same part! Are there really that many Brits who put up with being ripped-off to these levels? Tony H On 26/09/2015 01:27, Charles Steinmetz wrote: Charles wrote: I had to look it up. The company was Arrow (800 833 3557). The pots were manufactured by Bournes with a manufacturer part number of 300SP-1-502. Unit cost $7.73 in 2011. I bought 26 so my cost was about $200. I wanted a "Manufactured in America" part but can't remember if that was too pricey or not. Tony wrote: They are now $92.55 from Arrow now and Farnell want over $200 each if you buy 25 or more There don't seem to be any obvious cheap alternatives for 10 turn 20ppm/C 5W pots. The original pots were Bunker Ramo-Eltra (later, Bunker Ramo-Amphenol) P/N 3800P-502. These were 20-turn, 5k, 10%, 1W, +/-50 ppm/C wirewound parts in the 34b rectangular package. The Bourns 3005P-1-502 matches these specifications (I suspect "300SP" in Charles's message was a typo). I do not know if the pin layout is the same as the 3800P-502. Verical has the lowest price on the 3005P-1-502 that I could find in a quick search, $7.68 each. Others charge from $9 to $14. Tony -- what part number were you quoting specs and prices for? I found nothing searching for "300SP-1-502." Best regards, Charles ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Fluke 720a self calibration repair
Yes, I see. Please excuse my stupidity. Dave M Charles Steinmetz wrote: Dave wrote: It appears that wirewound pots have all been replaced by Cermet. Horse puckey. See the current Bourns 3005 datasheet (below). As I posted previously, it is WW. Charles ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Fluke 720a self calibration repair
I tried to find this style trimmer pot with a wirewound resistance element, but found that all I could find was the Cermet type. It appears that wirewound pots have all been replaced by Cermet. the wirewound pots had a 1W power rating, whereas the Cermet pots arte only rated at 3/4W. In the 720A, the reduced power rating won't be an issue, but in some vintage equipment, it might be. I've also tried, to no avail, to find a source for the metal-cased wirewound trimmer pots used on the K-V divider in some older Fluke differential voltmeters, such as the models 883A, 885A and 887A. Does anyone know of a source for replacements for those pots? I have an 887A on the shelf that I'd like to get back to original condition if I could find a couple of that style trimmer pot. They're only 2 ohms, making the search even more difficult. At this point, my only recourse is to find a defunct donor unit at reasonable cost, and salvage the parts. Does anyone have a hangar queen that I could get for shipping charges? I'd be really happy to get mine back on the road to health. Cheers, Dave M Tony wrote: Apologies - my mistake - I wasn't paying sufficient attention when Google decided that this was a perfect match when searching for 300SP-1-502: http://uk.farnell.com/webapp/wcs/stores/servlet/Search?st=3400s&catalogId=15001&categoryId=70005471&langId=44&storeId=10151 But £180.27 each whereas Newark, the US arm of Farnell only want $120 or approx £80 for the same part! Are there really that many Brits who put up with being ripped-off to these levels? Tony H On 26/09/2015 01:27, Charles Steinmetz wrote: Charles wrote: I had to look it up. The company was Arrow (800 833 3557). The pots were manufactured by Bournes with a manufacturer part number of 300SP-1-502. Unit cost $7.73 in 2011. I bought 26 so my cost was about $200. I wanted a "Manufactured in America" part but can't remember if that was too pricey or not. Tony wrote: They are now $92.55 from Arrow now and Farnell want over $200 each if you buy 25 or more There don't seem to be any obvious cheap alternatives for 10 turn 20ppm/C 5W pots. The original pots were Bunker Ramo-Eltra (later, Bunker Ramo-Amphenol) P/N 3800P-502. These were 20-turn, 5k, 10%, 1W, +/-50 ppm/C wirewound parts in the 34b rectangular package. The Bourns 3005P-1-502 matches these specifications (I suspect "300SP" in Charles's message was a typo). I do not know if the pin layout is the same as the 3800P-502. Verical has the lowest price on the 3005P-1-502 that I could find in a quick search, $7.68 each. Others charge from $9 to $14. Tony -- what part number were you quoting specs and prices for? I found nothing searching for "300SP-1-502." Best regards, Charles ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Fluke 750a batteries.............
I use https://www.mail-archive.com/volt-nuts@febo.com/ to search the archives. That ulility seems to return more relevant results than Google, although I use Google too, sometimes have to use both to get what I'm after. Cheers, Dave M David Garrido wrote: WOW Thank you for that. I must not know the best way to search the archives. I only know to go to google and type in my search and add volt-nuts febo.com <http://febo.com/> Is there a better way to search the archives that I am not aware of? Cheers, David ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Fluke 750a batteries.............
David, I have a (recently purchased) 750A as well, but haven't used it yet. I have the same problem with the batteries. I found this post in the archives from 2012: On 11/22/2012 7:49 AM, Steve Smith wrote: > Regarding the 750A batteries: I replaced mine with four ER14250/LS14250 1/2AA 3.6V 1200mAh lithium cells. Remove the original mercury battery holder and replace it with a dual AA cell holder. Use the kind that has the batteries side-by-side because you need to connect to the center tap between the cells. Wiring is pretty much identical to the way the mercury battery holder was wired. Install the lithium cells in a series string and you have +/-7.2V which is a bit higher than the +/- 6.75V of the mercury batteries but still works. The lithium cells have slightly more mAh capacity than the mercury cells and a much longer shelf life which works well for the 750A as the protection circuit draws very little current. Don't disable this protection circuit, it's too easy to fry the divider string if you're not paying attention. Thanks - Steve My guess is that the trip voltage will be changed a little bit, but not enough to allow damage in case of overload. Sounds like a reasonable solution Cheers, Dave M David Garrido wrote: Hello All, I posted this over at the HP yahoo group as well, so pardon the redundancy if you belong to both or more. My new to me Fluke 750a reference divider arrived last evening and I have been having one heck of a time finding info on replacement battery options others have used on their 750a's. Fluke spec'd (2) 6.7v mercury cell batteries for the overload protection circuit and these are clearly no longer available. What is everyone using for power? I am hoping to not use a separate DC supply for this app. The only manual I can find is here: http://bama.edebris.com/manuals/fluke/750a/ <http://bama.edebris.com/manuals/fluke/750a/> I have been able to find Wein batteries that are 1.35v zinc/air and I could stack and shrink wrap 5 of those in series to arrive at 6.75 very stable volts, but they are a minimum of $4.50 each cell. I was hoping to find a more affordable / elegant solution. Will the circuit handle (2) 3.6v Li-Ion in series instead? Any thoughts? Cheers, David ___ ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Making a Reference IC
The original reference has a shorted Zener. I verified that with a curve tracer (that was a couple years ago, but I remember it well. I saw the post from Hank, and have emailed him about the 732A stuff that he has. I think my easiest and least expensive approach to getting this instrument back on the bench is to build a circuit with an LM399A and fix it onto the 731B reference board. Cheers, Dave M Todd Micallef wrote: Dave, What is the problem with the original reference? I have not heard of too many failing. There was also a reply from Hank on another message. Perhaps he can provide the needed parts from a 732A? Todd On Mon, Sep 14, 2015 at 6:45 PM, Dave M wrote: After making a mess in my garage while searching for it, it turns out that that my Fluke is a 731B. It appears to use the same Voltage Reference IC as the 731A, so no big deal there. I found a previous discussion about the 731/732 reference ICs. Seems that the ICs are either from Motorola (MCA1914/MCA1924/MCA1934) or GE (RA3). Doubtful that GE continued production of that IC very long, so my guess is that these are Motorola parts. It's all moot, since none of the parts are still in production. I'm afraid to contact Fluke for a quote on the IC/Resistor set. Don't think my heart could stand the shock. I'd really like to get this unit back in operation, but I don't want to break my bank account to do it. I have a few LM399s on the shelf, so I guess that will be my best approach to a repair. Thanks for the discussion, Dave M M K wrote: On 12/09/2015 23:12, Dave M wrote: I realize that better references are available. I was thinking of resurrecting a long-defunct Fluke 731 that I have in the garage. The reference IC is bad in it, and (1) I don't want to throw it away without a meager attempt at repair, and (2) I don't want to spend a lot of money on it because it's in pretty bad physical condition. I was hoping that someone could lend a touch of advice on those old references. I have a few 1N827A reference zeners, and a washtubful of transistors. Maybe something could be cobbled together that would get the 731 back in operation. Maybe not to original specs, but close, which is better than nothing. Thanks for your reply, Dave M Jack Mcmullen via volt-nuts wrote: Just thinking why would you reinvent a transistor/zener reference when the industry's voltage reference chips are in the $2.00 or less single quanities with performance far exceeding anything previously available in discrete components?? -Original Message- From: Dave M <dgmin...@mediacombb.net> To: FEBO Volt-Nuts <volt-nuts@febo.com> Sent: Sat, Sep 12, 2015 1:58 pm Subject: [volt-nuts] Making a Reference IC I was looking at the schematics for the Fluke 731 and 732 voltage references. these, and several other brands and models of voltage references, use the same or similar reference ICs as their basis. The reference ICs are a Zener/NPN transistor pair on a single substrate. Please view in a fixed-width font such as Courier. | | C | | | | | | B /| / | E | | +--- | /--/ / -- | | Just thinking... would it be possible to make a reference with similar characteristics with discrete components (a low tempco Zener and a transistor)? They would likely have to be closely coupled thermally and maintained at a constant temperature within an oven or by a peltier device. What criteria would apply to the selection of the parts? Dave M There has been some of those references available second hand from ebay, mostly pulled, but some may be counterfeit, so look for sellers with pictures showing it as old. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. When the people fear the government, there is tyranny. When the government fears the people, there is liberty -- Thomas Jefferson Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Making a Reference IC
After making a mess in my garage while searching for it, it turns out that that my Fluke is a 731B. It appears to use the same Voltage Reference IC as the 731A, so no big deal there. I found a previous discussion about the 731/732 reference ICs. Seems that the ICs are either from Motorola (MCA1914/MCA1924/MCA1934) or GE (RA3). Doubtful that GE continued production of that IC very long, so my guess is that these are Motorola parts. It's all moot, since none of the parts are still in production. I'm afraid to contact Fluke for a quote on the IC/Resistor set. Don't think my heart could stand the shock. I'd really like to get this unit back in operation, but I don't want to break my bank account to do it. I have a few LM399s on the shelf, so I guess that will be my best approach to a repair. Thanks for the discussion, Dave M M K wrote: On 12/09/2015 23:12, Dave M wrote: I realize that better references are available. I was thinking of resurrecting a long-defunct Fluke 731 that I have in the garage. The reference IC is bad in it, and (1) I don't want to throw it away without a meager attempt at repair, and (2) I don't want to spend a lot of money on it because it's in pretty bad physical condition. I was hoping that someone could lend a touch of advice on those old references. I have a few 1N827A reference zeners, and a washtubful of transistors. Maybe something could be cobbled together that would get the 731 back in operation. Maybe not to original specs, but close, which is better than nothing. Thanks for your reply, Dave M Jack Mcmullen via volt-nuts wrote: Just thinking why would you reinvent a transistor/zener reference when the industry's voltage reference chips are in the $2.00 or less single quanities with performance far exceeding anything previously available in discrete components?? -Original Message- From: Dave M <dgmin...@mediacombb.net> To: FEBO Volt-Nuts <volt-nuts@febo.com> Sent: Sat, Sep 12, 2015 1:58 pm Subject: [volt-nuts] Making a Reference IC I was looking at the schematics for the Fluke 731 and 732 voltage references. these, and several other brands and models of voltage references, use the same or similar reference ICs as their basis. The reference ICs are a Zener/NPN transistor pair on a single substrate. Please view in a fixed-width font such as Courier. | | C | | | | | | B /| / | E | | +--- | /--/ / -- | | Just thinking... would it be possible to make a reference with similar characteristics with discrete components (a low tempco Zener and a transistor)? They would likely have to be closely coupled thermally and maintained at a constant temperature within an oven or by a peltier device. What criteria would apply to the selection of the parts? Dave M There has been some of those references available second hand from ebay, mostly pulled, but some may be counterfeit, so look for sellers with pictures showing it as old. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Making a Reference IC
I realize that better references are available. I was thinking of resurrecting a long-defunct Fluke 731 that I have in the garage. The reference IC is bad in it, and (1) I don't want to throw it away without a meager attempt at repair, and (2) I don't want to spend a lot of money on it because it's in pretty bad physical condition. I was hoping that someone could lend a touch of advice on those old references. I have a few 1N827A reference zeners, and a washtubful of transistors. Maybe something could be cobbled together that would get the 731 back in operation. Maybe not to original specs, but close, which is better than nothing. Thanks for your reply, Dave M Jack Mcmullen via volt-nuts wrote: Just thinking why would you reinvent a transistor/zener reference when the industry's voltage reference chips are in the $2.00 or less single quanities with performance far exceeding anything previously available in discrete components?? -Original Message- From: Dave M <dgmin...@mediacombb.net> To: FEBO Volt-Nuts <volt-nuts@febo.com> Sent: Sat, Sep 12, 2015 1:58 pm Subject: [volt-nuts] Making a Reference IC I was looking at the schematics for the Fluke 731 and 732 voltage references. these, and several other brands and models of voltage references, use the same or similar reference ICs as their basis. The reference ICs are a Zener/NPN transistor pair on a single substrate. Please view in a fixed-width font such as Courier. | | C | | | | | | B /| / | E | | +--- | /--/ / -- | | Just thinking... would it be possible to make a reference with similar characteristics with discrete components (a low tempco Zener and a transistor)? They would likely have to be closely coupled thermally and maintained at a constant temperature within an oven or by a peltier device. What criteria would apply to the selection of the parts? Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Making a Reference IC
I was looking at the schematics for the Fluke 731 and 732 voltage references. these, and several other brands and models of voltage references, use the same or similar reference ICs as their basis. The reference ICs are a Zener/NPN transistor pair on a single substrate. Please view in a fixed-width font such as Courier. | | C | | \ | \| | | B /| / | E | | +--- | /--/ / \ -- | | Just thinking... would it be possible to make a reference with similar characteristics with discrete components (a low tempco Zener and a transistor)? They would likely have to be closely coupled thermally and maintained at a constant temperature within an oven or by a peltier device. What criteria would apply to the selection of the parts? Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Anyone know how to make stable inductors?
Here's a paragraph from IETLab's web site on how their inductance standards are made: "Each standard inductor is a uniformly wound toroid on a ceramic core. It has a negligible external magnetic field and hence essentially no pickup from external fields. The inductor is resiliently supported in a mixture of ground cork and silica gel, after which the whole assembly is cast with a poƫting compound into a cubical aluminum case." Sounds like their objective is to isolate the winding from as many external influences as possible. Of course, the same couild be said of any physical or electrical standard. Cheers, Dave M Dr. David Kirkby (Kirkby Microwave Ltd) wrote: I was looking to make some inductors that I can use as a sanity check for my HP 4284A LCR meter. I don't too much care what their values are, but I want them to be stable with time. Any suggestions about the best way to make or buy them? I'd like values in the range of 1 nH to 100 mH. The LCR meter has 4 terminal Kelvin connections, with 4 x BNC sockets on a 22 mm pitch. The meter is at Keysight at the moment being calibrated, along with a free software upgrade they are kindly providing. So I'd like to measure some inductors when it comes back, and track their values over time, to see if the meter is drifting. The meter covers 20 Hz to 1 MHz, and has a basic uncertainty of 0.05%, so ideally I'd like to keep inductor changes to less than 0.005% over a year, so the inductor is an order of magnitude better than the meter. Maybe that is not practical. As I say, the absolute value is not important, since I only want a comparison. The calibration costs on this meter are not too bad (£207 GBP), but the calibration interval is 6 months, which is a bit annoying. I'd rather not be sending it off every 6 months if I can satisfy to myself it has not drifted too much. Luckily I don't need to satisfy anyone else. Dr. David Kirkby Ph.D CEng MIET Kirkby Microwave Ltd Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT, UK. Registered in England and Wales, company number 08914892. http://www.kirkbymicrowave.co.uk/ Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please) ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Oven thermal insulation
I bought a couple of the sample sheets of Spaceloft Areogel (Ebay # 171328843398) a couple monthas ago. Cheap enough at $7.99 for a 10x14 piece with free shipping. It's 5mm thick, and easily cut with scissors. The datasheet that was supplied with the samples say that its max temperature is 200°C, so will surely work in a 45°C oven. R-Value is advertised to be 10.3 per inch. I bought it in anticipation of building an oven for a voltage reference, as you are. I'm still considering the size & shape of the box for the oven. Other irons in the fire presently, so not on my front burner. It certainly is a better insulator than fiberglass or Great Stuff foam. I find it rather suspicious that the R-value of Great Stuff doesn't appear in any of the ads, brochures or data sheets. I think its value is more in favor of its use as a sealant trather than as insulation. Cheers, Dave M Randy Evans wrote: Frank, I don't plan on operating at 80C. I just want an insulation that can withstand up to 80C so i have a safety margin. 45C is probably too low for my environment but 50C might be doable. Thanks, Randy On Tue, Jul 7, 2015 at 12:29 AM, Frank Stellmach wrote: Hi Randy, 80°C and 'highest stability' is simply a contradiction in itself. Therefore, if you really go for highest stability, please run your voltage reference at < 60°C only, best would be 45°C! In this case, ordinary styrofoam is suitable, higher temperatures require poly sulfone, like used on the HP3458A reference board, or the VALOX(TM) plastic which is used for the LM399. Frank ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP-419A Fluke 845A Mods - HP-419A HQ schematics on my shared link
The .PDN image files can be opened on Win XP, Win7 & Win8 with Irfanview if you download and install the plugin package from the Irfanview web site. I use XP 32-bit, and the files opened just fine for me. Cheers, Dave M ludger.len...@gmx.de wrote: For all, working on a modification of the HP-419A: I have uploaded to my HP-419A share point some high quality schematics, I have created for the modification process. Link: https://www.dropbox.com/sh/czd2uc3t0uvgggz/AAC--ykVziW9rSJkdg2J_-wZa?dl=0 Important note: I created them using PaintNET on 64-bit Win7. It may impossible to open them with the 32-bit Win7 version because of the memory restrictions. I uploaded following files: HP419A optimized original schematic complete (with doc).PDN (the original amplifier schematic with some additional notes) HP419A optimized original schematic complete.PDN (the original amplifier schematic) HP419A optimized original schematic (3µV mode).PDN (amplifier schematic in the 3µV mode) Enjoy and feel free to comment. BR PeLuLe Gesendet: Donnerstag, 25. Juni 2015 um 18:55 Uhr Von: "Dave M" An: "Discussion of precise voltage measurement" Betreff: Re: [volt-nuts] HP-419A Fluke 845A Mods - shared link Randy, False alarm. When I downloaded the PDF again, it came through fine. The file that I downloaded originally was only about 75K, not the 500K file that I got the second time. Sorry for the alarm. Thanks again for sharing your work. Dave M Randy Evans wrote: Dave, I checked the HP-419A marked up schematic and I find it very clear and readable. Does anyone else have problem reading the pdf file? Thanks, Randy Evans On Wed, Jun 24, 2015 at 6:38 PM, Randy Evans wrote: Dave, I should have checked it. I will generate a higher resolution version tomorrow. Randy On Wed, Jun 24, 2015 at 10:49 AM, Dave M wrote: Rady, Many thanks for the uploads. One issue... the marked-up PDF of the HP 419A schematic is virtually unreadable. Could you post a higher resolution image of the markup details? Don't really need the full schematic, just the areas where the connections to the new circuit are made. Thanks again, Dave M Randy Evans wrote: I have created a shared link to my working folder with the details of the HP-419A and Fluke 845A modifications. It is an in-process design so I suspect there may be many questions. Just send your questions and I will try to answer them. In the meantime, I will try to find time to clean up the design a bit. Hopefully I created the link correctly. Let me know if you have any issues with the link. https://www.dropbox.com/sh/7b3hsy0j0wq35hw/AABkmVptTwVu2EJFRqtSdAjya?dl=0 Randy Evans AE6YG ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP-419A Fluke 845A Mods - shared link
Randy, False alarm. When I downloaded the PDF again, it came through fine. The file that I downloaded originally was only about 75K, not the 500K file that I got the second time. Sorry for the alarm. Thanks again for sharing your work. Dave M Randy Evans wrote: Dave, I checked the HP-419A marked up schematic and I find it very clear and readable. Does anyone else have problem reading the pdf file? Thanks, Randy Evans On Wed, Jun 24, 2015 at 6:38 PM, Randy Evans wrote: Dave, I should have checked it. I will generate a higher resolution version tomorrow. Randy On Wed, Jun 24, 2015 at 10:49 AM, Dave M wrote: Rady, Many thanks for the uploads. One issue... the marked-up PDF of the HP 419A schematic is virtually unreadable. Could you post a higher resolution image of the markup details? Don't really need the full schematic, just the areas where the connections to the new circuit are made. Thanks again, Dave M Randy Evans wrote: I have created a shared link to my working folder with the details of the HP-419A and Fluke 845A modifications. It is an in-process design so I suspect there may be many questions. Just send your questions and I will try to answer them. In the meantime, I will try to find time to clean up the design a bit. Hopefully I created the link correctly. Let me know if you have any issues with the link. https://www.dropbox.com/sh/7b3hsy0j0wq35hw/AABkmVptTwVu2EJFRqtSdAjya?dl=0 Randy Evans AE6YG ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP-419A Fluke 845A Mods - shared link
Rady, Many thanks for the uploads. One issue... the marked-up PDF of the HP 419A schematic is virtually unreadable. Could you post a higher resolution image of the markup details? Don't really need the full schematic, just the areas where the connections to the new circuit are made. Thanks again, Dave M Randy Evans wrote: I have created a shared link to my working folder with the details of the HP-419A and Fluke 845A modifications. It is an in-process design so I suspect there may be many questions. Just send your questions and I will try to answer them. In the meantime, I will try to find time to clean up the design a bit. Hopefully I created the link correctly. Let me know if you have any issues with the link. https://www.dropbox.com/sh/7b3hsy0j0wq35hw/AABkmVptTwVu2EJFRqtSdAjya?dl=0 Randy Evans AE6YG ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 3458A reference boards on ebay
I'd go for a deal like that as well. I have a small number of LM399s that I'd like to put to use, as well as a couple LTZ1000A references. A project using either type of reference would be very exciting for me. I have a few old Fluke differential meters that have lots of nice low tempco, high quality resistors that might finally find a useful project such as this. Count me in, Dave M. Dr. David Kirkby (Kirkby Microwave Ltd) wrote: On 30 January 2015 at 12:25, Will wrote: The boards are factory rejects. I doubt all boards on eBay are in this category. Some are probably quite genuine, some may be rejects, and it would never surprise me if some are counterfeit. The problem is, I have no idea what ones are what. I don't know what the problems sourcing the parts for making a reference would be, but if a number of people wanted to make one from parts, perhaps someone could produce a PCB and people contribute towards the cost of it. Maybe leave people to get their own reference chip, as there are different grades of that. But things like the precision resistors may be easier to buy in a quantity of 10 rather than 1. I would certainly not mind buying one if a PCB was available. Even if it works out costing a bit more than a 3458A reference from eBay, I'd feel a bit happier. Dave ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP-419 and Fluke 845 Modifications
I'll second that motion, Pete. Although I don't have a 419A anymore, the mod should be a welcome feature. Although the 419A has a recorder output, it isn't isolated, nor is the instrument guarded. At least, this mod will isolate the recorder output circuit, which will be an improvement. Dave M Pete Lancashire wrote: I have used 845As and other instruments recorder output voltage to digitize what I'm measuring. I'm surprised the 419A doesn't. I just never looked before. So not like HP, I'm glad your considering adding one. On Mon, Dec 1, 2014 at 11:40 AM, Randy Evans wrote: Dave, The HP-419A is driving the need for an isolated recording output (it doesn't have one in the basic unit) and I wanted to provide one. The circuit is being designed to work with either the HP-419A or the Fluke 845A. The isolation circuit does not have to be used if not wanted since it is a completely separate circuit and not needed for the meter to work. I still need to work on the final HP-845A modifications and i will look at your suggestions. Randy On Sun, Nov 30, 2014 at 6:37 PM, Dave M wrote: Randy, Thanks for continuing with this modification. Speaking of the Fluke 845A; At first glance, you could probably leave the existing power supply inverter circuit intact, as well as the isolation transformer for the recorder output, with the recorder output transformer being driven (at the center tap) by the output of the last DC amp stage of the null amp circuit. That would maintain the isolation of the meter and recorder output, and eliminate the need for an extra amp for them. It would also maintain the guard integrity, keeping the instrument's operational characteristics as close to original as possible. By leaving the existing inverter circuit in place, you can easily derive any voltages (+ and -) that your mod needs from it, without the need for additional isolated power supplies Dave M Randy Evans wrote: I finished the H-419A/Fluke 845A design modifications but I am still trying to decide on the preferred power supply design. The basic meter circuit uses the LTC2054 and LTC6255 with two CR123 Li-Ion 3 V batteries. The basic meter circuit draws less than 0.2 mA and with 1500 mAH CR123A batteries should be able to go several thousand hours on a set of batteries. For the meter circuit, it is always battery powered and doesn't have to be plugged into the mains. I also added a TI AMC1100 isolation amplifier for recording output but it needs a 3.3 VDC isolated supply and a 5VDC output supply. The current design uses separate isolation power supplies using LT8300 ICs that work off the mains transformer so there would be no worry about failing batteries. Therefore, to use the recorder, the unit would have to be plugged in. I am trying to decide if it would be simpler to use batteries for the isolation circuit as well. If I use batteries, do I use rechargeables or non-rechargeable batteries such as the CR123s? The circuit would need one set for the input isolated circuit side and another set for the recorder output side and the batteries would not last as long as the meter circuit since the isolation circuits draw about 12 milliamps. They would still work about one hundred hours most likely and would not draw any current unless the isolation circuit is turned on (with a separate toggle switch). My preference is to stay with the LT8300 power supplies but I thought I would query the group. Any thoughts on what would be your preferences? Thanks, Randy Evans On Mon, Aug 4, 2014 at 8:33 AM, Randy Evans wrote: I am looking at modifying my (defective) HP419A and Fluke 845A Null meters using the LTC2054 zero drift op amp. I am planning on using a single 4.2 V Lithium Ion battery to power them (no AC input required and may not include, TBD). The LTC2054 has a very low bias current of typically 1pA at room temp and the bias plots vs. temp show no appreciable increase until about 50C. Conceptually, it looks pretty straight forward and, based on my Fluke 887A modifications, likely will be very stable. Since this is a very astute group, does anyone have any comments on the feasibility of this modification before I get too involved? Regards, Randy Evans ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP-419 and Fluke 845 Modifications
Randy, Thanks for continuing with this modification. Speaking of the Fluke 845A; At first glance, you could probably leave the existing power supply inverter circuit intact, as well as the isolation transformer for the recorder output, with the recorder output transformer being driven (at the center tap) by the output of the last DC amp stage of the null amp circuit. That would maintain the isolation of the meter and recorder output, and eliminate the need for an extra amp for them. It would also maintain the guard integrity, keeping the instrument's operational characteristics as close to original as possible. By leaving the existing inverter circuit in place, you can easily derive any voltages (+ and -) that your mod needs from it, without the need for additional isolated power supplies Dave M Randy Evans wrote: I finished the H-419A/Fluke 845A design modifications but I am still trying to decide on the preferred power supply design. The basic meter circuit uses the LTC2054 and LTC6255 with two CR123 Li-Ion 3 V batteries. The basic meter circuit draws less than 0.2 mA and with 1500 mAH CR123A batteries should be able to go several thousand hours on a set of batteries. For the meter circuit, it is always battery powered and doesn't have to be plugged into the mains. I also added a TI AMC1100 isolation amplifier for recording output but it needs a 3.3 VDC isolated supply and a 5VDC output supply. The current design uses separate isolation power supplies using LT8300 ICs that work off the mains transformer so there would be no worry about failing batteries. Therefore, to use the recorder, the unit would have to be plugged in. I am trying to decide if it would be simpler to use batteries for the isolation circuit as well. If I use batteries, do I use rechargeables or non-rechargeable batteries such as the CR123s? The circuit would need one set for the input isolated circuit side and another set for the recorder output side and the batteries would not last as long as the meter circuit since the isolation circuits draw about 12 milliamps. They would still work about one hundred hours most likely and would not draw any current unless the isolation circuit is turned on (with a separate toggle switch). My preference is to stay with the LT8300 power supplies but I thought I would query the group. Any thoughts on what would be your preferences? Thanks, Randy Evans On Mon, Aug 4, 2014 at 8:33 AM, Randy Evans wrote: I am looking at modifying my (defective) HP419A and Fluke 845A Null meters using the LTC2054 zero drift op amp. I am planning on using a single 4.2 V Lithium Ion battery to power them (no AC input required and may not include, TBD). The LTC2054 has a very low bias current of typically 1pA at room temp and the bias plots vs. temp show no appreciable increase until about 50C. Conceptually, it looks pretty straight forward and, based on my Fluke 887A modifications, likely will be very stable. Since this is a very astute group, does anyone have any comments on the feasibility of this modification before I get too involved? Regards, Randy Evans ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] AC calibration
Great!!@! Many Thanks!! Dave M acb...@gmx.de wrote: Dave, the title is: Thermal Voltage Converters and Comparator for Very Accurate AC Voltage Measurements by E.S.Williams. Adrian Gesendet: Montag, 25. August 2014 um 19:32 Uhr Von: "Dave M" An: "Discussion of precise voltage measurement" Betreff: Re: [volt-nuts] AC calibration Adrian, Do you have a link or title for the NIST paper that you mentioned? ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Fluke 732A battery module (and possible circuitreplacement)
Todd Micallef wrote: Mark, If you need any scans or measurements, let me know. I have one that will be disassembled for the next 24hrs. I can get this for you tomorrow evening before I replace the batteries. Todd Sent from my iPad On Aug 25, 2014, at 21:10, Mark Sims wrote: I have a 732A that is missing its battery module. Does anybody have or know of a source for a replacement? Also, would there be any interest in a replacement circuit assembly for the battery module? It would probably consist of a small board that plugs into the 2x6 pin edge connector and another small board with the ballast lamp/diode/resistor/thermistors and connections for the battery/switch/external power jack. The two boards would be connected by a short ribbon cable and would allow one to add batteries to a 732A that is missing the battery module. It would not be a complete battery module with the metal frame and backplate... ___ I'd like to have one, maybe two. I have a couple of 732A units in the shop. Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] AC calibration
Adrian, Do you have a link or title for the NIST paper that you mentioned? Dave M acb...@gmx.de wrote: fred, generally you raise a good point, I had the same issue of calibrating an ac voltage to a high level of accuracy. you need this e.g. to validate the self.cal of a 3458a or other precison stuff like the 8506a0. what i would recommend to do if you want to keep costs down is: in a nutshell, get a thermal converter in the lowest range you need and a second one on range above. build a set of resistor range extenders (rf type with appropriate connectors and housings) to expand the range to where you need to be max. get one of the thermal converter calibrated (the higher one usually, and you need to havr good cal lab, should be <10ppm accuracy) and use it to calibrate the rest. generally, up to 20khz, the accuracy is some 20 ppm anyway for thermal converters! at higher frequencies, due to reflections and stray capacitance/inductance influences, the accuracy decreases. the resistor range extenders though, if build up correctly, only have a few ppm impact (there is a paper from nist on that, but this is only typical). you can calibrate all converters to the one you got externally calibrated. do some research in the web, when you do the calibration, you need to determine the so-called constant N. then do an ac, dc+, ac, dc-, ac measurement between the the two and establish the deviation, also establish the error propagation. the end result will be a set of highly precise (low inaccuracies9 thermal converters good enough to calibrate a 3458a an better devices. if you want to spend the money, you could also buy a set of converters/range resistors (with/without a 540), that typically is a few k altogether, while a single device sometimes is available for below 100 bucks. you need to have a stable 7.5 digit nanovoltmeter though for the measurements of the tvcs (34420a or 2182 typically ) and precision (stable) dc and ac sources. but in the end, all you need is a single calibrated thermal converter. adrian Gesendet: Montag, 25. August 2014 um 18:38 Uhr Von: "Dave M" An: "Discussion of precise voltage measurement" Betreff: Re: [volt-nuts] AC calibration Well, you sort of answered your own question. The equipment is called a Thermal Transfer Standard, but instead of thermistors, it uses a thermocouple. Look at the manual for the Fluke 540B (http://bama.edebris.com/manuals/fluke/540b/) and you'll see how it's done. Basically, the AC source is input into the transfer standard, and the standard's internal reference voltage is adjusted for a null on the galvanometer. Leaving the reference voltage setting alone, a DC voltage is input into the unit, and the DC source is adjusted for a null on the galvanometer. At that point, the AC voltage source is equal to that of the DC voltage source. Ther are thermocouple-type thermal converters used for RF voltage measurements with the transfer standard. They aren't cheap, and you have to have a converter for each range of voltages that you need to measure. The thermal converters used with this type of transfer standard isn't great (50 MHz or so typical), but their accuracy far surpasses that of the thermistor type sensors. There are other brands and models of thermal transfer standards, but I have a Fluke model 540 and a few thermal converters. That's why I referred you to the manual for it. Cheers, Dave M pa4...@gmail.com wrote: Is there a way to link an AC voltage to a DC source for compare. I can check my calibrators (like a Fluke 332, 760 , 731 and a Philips) against standardcells. But for AC I can not do that. I have two AC+DC TRMS 7,5 digit meters but the last calibration was 2 years ago. My idea is in theory simple. It is based on the thermal converters used in RF powermeters. Two resistors, two high resolution temperature meters. AC on the first en DC on the second. If both are the same temperature the AC voltage is the same as the DC voltage. But I'm sure some people here have done this in the past. I would like to use it for 50 to 100 kHz (or less) and something like for 1V, 10V and 100V (and use several resistors/heaters.) Or mabey there is an other way to convert AC (for RF it can be done with lightbubs but I never tryed that) I do not mind if it is slow etc, I like this sort of experiments. You can learn a lot from it. Fred, pa4tim ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. When the people fear the government, there is tyranny. When the government fears
Re: [volt-nuts] AC calibration
Well, you sort of answered your own question. The equipment is called a Thermal Transfer Standard, but instead of thermistors, it uses a thermocouple. Look at the manual for the Fluke 540B (http://bama.edebris.com/manuals/fluke/540b/) and you'll see how it's done. Basically, the AC source is input into the transfer standard, and the standard's internal reference voltage is adjusted for a null on the galvanometer. Leaving the reference voltage setting alone, a DC voltage is input into the unit, and the DC source is adjusted for a null on the galvanometer. At that point, the AC voltage source is equal to that of the DC voltage source. Ther are thermocouple-type thermal converters used for RF voltage measurements with the transfer standard. They aren't cheap, and you have to have a converter for each range of voltages that you need to measure. The thermal converters used with this type of transfer standard isn't great (50 MHz or so typical), but their accuracy far surpasses that of the thermistor type sensors. There are other brands and models of thermal transfer standards, but I have a Fluke model 540 and a few thermal converters. That's why I referred you to the manual for it. Cheers, Dave M pa4...@gmail.com wrote: Is there a way to link an AC voltage to a DC source for compare. I can check my calibrators (like a Fluke 332, 760 , 731 and a Philips) against standardcells. But for AC I can not do that. I have two AC+DC TRMS 7,5 digit meters but the last calibration was 2 years ago. My idea is in theory simple. It is based on the thermal converters used in RF powermeters. Two resistors, two high resolution temperature meters. AC on the first en DC on the second. If both are the same temperature the AC voltage is the same as the DC voltage. But I'm sure some people here have done this in the past. I would like to use it for 50 to 100 kHz (or less) and something like for 1V, 10V and 100V (and use several resistors/heaters.) Or mabey there is an other way to convert AC (for RF it can be done with lightbubs but I never tryed that) I do not mind if it is slow etc, I like this sort of experiments. You can learn a lot from it. Fred, pa4tim ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Voltage standard spotted for sale, 4410
2014-08-12 1:25 UTC+03.00, Tom Knox : I am not sure the use of LM329's was a cost saving measure or compromise, actually the 4410 uses a different approch, it's basicly is a big oven. Guildline has been a Metrology leader for decades and has been a leader including temp measurements and oil baths so I for one would be interested in how well their approach to a voltage standard performs. The 4410 was not designed or manufactured by Guildline. Just like many of the products sold under their brand name. At the time of design the LTZ1000 was not yet available and the Fluke ref amp was obviously property of Fluke only. The only same level technology available to all manufactueres was the 1N829 zener which if carefully selected and matched can be as good as LTZ1000. Datron calibrators with multiple selected, aged and matched 1N829 zeners are a good example of that. The original 100 page (Statronics) documentation seems to be a masters thesis rather than a product manual and has a detailed description of the design process. The text mentions that the 1N829 temperature compensated zeners were discarded because of the poor availability in Australia where the unit was developed. The LM399/LM329 series was selected because it was the "best available". Band-gap type references were also evaluated but found unsatisfactory at the early stage. Will, Is that (Statronics) documentation available anywhere on the net for download? I'd be interested in reading about the technology behind the design, since I have built my own shop standard using four LM399 heated zeners. Thanks for the info, Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP-419 and Fluke 845 Modifications
From: Randy Evans I am looking at modifying my (defective) HP419A and Fluke 845A Null meters using the LTC2054 zero drift op amp. I am planning on using a single 4.2 V Lithium Ion battery to power them (no AC input required and may not include, TBD). The LTC2054 has a very low bias current of typically 1pA at room temp and the bias plots vs. temp show no appreciable increase until about 50C. Conceptually, it looks pretty straight forward and, based on my Fluke 887A modifications, likely will be very stable. Since this is a very astute group, does anyone have any comments on the feasibility of this modification before I get too involved? Regards, Randy Evans Hi Randy. Good to hear from you again. I have modified two 883A models and one 887A model DMMs using your details, with great results. I have a model 845A null meter that is working fine right now, but who knows how long that will last. I would surely welcome some research on modifying it with a zero-drift opamp. One concern that I would have with that mod would be that some mechanism would need to be added to retain the isolation of the recorder output and guard integrity that's afforded by the photo-modulator/demodulator circuit. Perhaps some kind of optically-isolated interface might be in order Some Spice runs on the original circuit would be interesting to see. Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Matched resistors
Do you have easy, low cost access to an old Fluke 801 or 803 differential voltmeter? These meters have a Kelvin-Varley divider inside that is composed of strings of resistors that are highly matched in value and tempco. If I remember correctly, the highest decade is filled with a string of 40K resistors, each succeeding smaller decade value is 1/5 of the next higher decade, but all very well matched. They should all be very well aged by now too. (Just like wine... they get better with age). Perhaps you could mix & match values to come up with suitable resistors for your project. If your project is a one-off deal, then perhaps that approach could prove viable. Cheers, Dave M From: Tony Randy, Have you considered using multiple identical resistors to reduce the variance? Depending on who you believe, you can reduce the variance of the overall resistance by SQRT(N) where N is the number of resistors in series/parallel. Its not that easy to create a good search query for this but here is one such explanation: http://paulorenato.com/joomla/index.php?option=com_content&view=article&id=109:combining-resistors-to-improve-tolerance&catid=4:projects&Itemid=4 Ideally they should all come from the same batch - ie. manufactured by the same machine from the same batch of materials. Obviously there's no way to guarantee that without close liaison with the manufacturer (you did want 10 million parts at $.10 each didn't you!) but hopefully a set of resistors which come off the same reel would come close. The absolute value isn't important however, but 'statistical gain' will also apply to the TCR and stability of the overall divider. The following assumes that both factors are similarly improved by SQRT(N), but in fact they may be rather better than that. That80? or $108 for one sealed Vishay foil divider will buy a lot of lower spec parts: ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Dekavider DV411 repair and question
To everybode who answered: Thanks, so it was not only me not finding the leftovers of delimiters. Still curious why they made it that way. No reason to replace! Dave: I am aware of the resistor wire alloys like Konstantan, Manganin, Isabellin, Evanohm and their variants. What I didnt understand yet is the wiring between the resistors and the decades and so on - its just not simple silver-coated or tinned cooper wire, it more looks like a resistive wire - big and massive, bad to solder. Bill: Do I understand right, they use the inter-resistor wiring to for compensation ? (Your mail worked fine) Sounds like a "bigger but reproducable resistance than wildly drifting cooper wire" scheme to me. I try to figure out. The repair itself worked out very nice, the workplace 34401A in dcv:dcv ratio mode was happy with the results. BR Hendrik Hendrik, I didn't catch that you were asking about the interconnecting wiring. That is likely to be the same material as used to make the resistors (Manganin). That would maintain the low tempco of the total unit, and avoid the comparatively large resistance drifts of copper wire. Manganin is hard to solder without a flux that can remove the surface oxide that forms on manganin wire. Flux used for soldering stainless steel might be a good one to try. Just be sure to clean the joints very well after using it. The old ESI standards are very nice instruments to have. I have an old ESI decade capacitance box built like the Dekavider and Dekapot units. It's quite accurate; good enough to allow me to evaluate RCL-type multimeters. Cheers, Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Dekavider DV411 repair and question
From: Hendrik Dietrich Subject: [volt-nuts] Dekavider DV411 repair and question Hi List, I partially fixed a "lowly" DV411 Dekavider from the "Electro-Measurements" epoque and wanted to report what worked out and what still is and have a general question about such devices. The part in question (just look what the cheapest one on ebay was, one made a power supply out of it) had a working first and second decade, but the can with the 3rd switch and last decade potentiometer required some work. The switch freewheeled, it didn't lock onto the right on-digit position. That was due to the slotted wheel slipping on the drive shaft out of position so it was no longer pressed against the spring-loaded ball. I was surprised that this wheel was just soldered to the drive shaft, so it was enough to push it back into the right position and solder it down with some very agressive flux (Soldeen-1). http://dg3hda.primeintrag.org/lib/exe/fetch.php?media=locking_cogwheel.jpg The 4th(5th) decade potentiometer seems to be electrically okay, but it turns 360? instead of 270?, I consider that it had some delimiters but these are scraped off. However, careful operation will be possible or replacement by a potentiometer and a adapter between the thin driveshaft of the switch to the axle of a new potentiometer. (Hoped to keep it original.) http://dg3hda.primeintrag.org/lib/exe/fetch.php?media=potentiometer.jpg For Pronographic reasons, a overview is available too. http://dg3hda.primeintrag.org/lib/exe/fetch.php?media=overview.jpg Besides hints for further repair, does someone know which alloy is used for wiring by ESI? Seems a bit hard for plain cooper. Best regards, Hendrik Hendrik, It's been more than a few years since I had my hands on one of these boxes, but I aeem to remember that the vernier potentiometers in these instruments are designed to rotate a full 360 deg. I don't know why; seems illogical, but that's the way they are. If the original pot works, I wouldn't bother changing it. It will be extremely hard to find a replacement pot with the low tempco that the original pot has. The wire used to make the resistors in these units is probably Manganin, an extremely low tempco compound. Manganin wire has been used by instrument manufacturers for many years for temperature stable resistors. I think that most lab standard resistors are made with Manganin wire, and thermally insulated from the outside world to maintain their accuracy. Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Resistors for LTZ1000A circuit
I've described the theoretical background and measurements on my LTZ1000 references (2 on my own, one identical of another volt-nut) parts #1 -#6, starting here: http://www.eevblog.com/forum/projects/ultra-precision-reference-ltz1000/165/ Those 0.1% wirewound resistors, are available from stock, they are called "econistors", 8G16, cost around 8$/? each and are distributed via a british company http://www.rhopointcomponents.com/components/resistors/precision-through-hole.html regards Frank Frank, Is there a drawing or scan for the PCB for this circuit? Are the boards or completed assemblies available for purchase? The links to the taobao.com site in the blog are obviously dead; they lead to a department store type retail site. Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Sn10Pb90
Am 13.08.2013 21:38, schrieb Rob Klein: Op 13-8-2013 20:16, Joseph Gray schreef: I came across a couple of old Fluke differential voltmeters that need some work. I thought it would be best to use low thermal EMF solder on these. I think it would be best *not* to. As far as I know, Fluke never used any low thermal EMF solder on any of its equipment, even the very top-of-the-range stuff. I certainly never seen it mentioned in any service manual for e.g. the 720, 845, 750, 752. Rob. I have encountered only one model of equipment that needed low thermal EMF solder; a Holt model 323 AC Voltage standard. The special Cd/Pb solder was needed for the low level circuitry around the thermocouples. I discovered this in my first encounter with these units. I used regular 63/37 solder for a repair and found wild excursions (tens of millivolts) in the output. A bit of reading in the manual disclosed the necessity of the special solder in the unit. Luckily, there was a small hank of the Cd/Pb solder inside the unit, which fixed the problem. As for HP and Fluke equipment, I have never heard of the need for special solder, even in the most tightly specified standards. I don't know if there would be any adverse effects if the low thermal EMF solder were to be used in those instruments, but unless it's specifically documented to be necessary, I would be reluctant to use it, especially since it's so unobtanium. Cheers, Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] ESI 2400 manual with schematics?
volt-nuts-requ...@febo.com wrote:> ESI 2400 manual with schematics? Message-ID: <4c835c4b-cadd-4d2f-95f3-00c58d7fd...@gmail.com> Content-Type: text/plain; charset=us-ascii Just picked up an ESI 2400 LCR bridge that's working flawlessly, but the manual that came with it does not have schematics or calibration info. Anybody know of a source? I've tried all the usual suspects online. TIA Dick Moore Dick, ManualsPlus lists an Op/Svc manual for the ESI 2400 on their web catalog page at http://www.manualsplus.com/catalog/product_info.php?sku=53547. Be sure to contact them before ordering to confirm that schematics are included. Cheers, Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] Low EMF solder
Please excuse me for asking this... I'm sure it's been covered before, but without an easy way to search the archives, here goes. I'm repairing a couple of old Holt 323A Audio Voltage Standards, trying to make one good one out of two. These instruments used to have small hanks of special low EMF solder to use on sensitive areas, but they have long since vanished from these units. I've tried using Sn-Pb solders, but the units go into a tizzy when I use it. Does anyone know of a source where I could buy a few ounces of the solder? I think it's a Tin-Cadmium formula, but I guess that because of the Cadmium content, it's pretty much unobtanium now. I'm sure that another formula must exist that is currently being manufactured, but they want to sell a bunch, not just a few ounces. Suggestions? Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 732 and 752 recently on ebay
And, incidentally, of the two 752's on the 'bay at the moment, the cheapest is $ 850, the other $ 1200. Op 3-11-2012 13:32, m k schreef: Did anyone see the 732a and 752a pair that recently went for 1088 sterling (~1745 dollars us)!! MK I picked up a very nice Fluke 731B at the annual hamfest here in Alabama last year for a measley $25 USD. It's only problem was a missing turns counting dial for the Delta E pot. A new dial from Mouser and it now works perfectly and proudly occupies a place of honor on top shelf above my bench. The democracy will cease to exist when you take away from those who are willing to work and give to those who would not. -- Thomas Jefferson Dave M ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Solartron 7061 Service Manual - Does anyone haveone?
From: "David C. Partridge" Subject: Re: [volt-nuts] Solartron 7061 Service Manual - Does anyone haveone? I fear he doesn't have the Maintenance (Service) Manual :( Dave -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of Dave M Sent: 24 June 2012 14:08 To: volt-nuts@febo.com Subject: Re: [volt-nuts] Solartron 7061 Service Manual - Does anyone haveone? Joe, Didier has PDF copies of the User manual, Service manual and ROM images on his manual web site at http://www.ko4bb.com/manuals/index.php. Just search for 7061. * Well, I'll be hornswaggled!! Joe, the service manual was there on his site just moments before I sent my reply to the list. It was in addition to the Operating manual and the ROM images, somewhere around 75-80 Mb in size. Perhaps it was inadvertently deleted by Didier?? You might send him an email and ask if he still has the file somewhere and put it back on the site. Dave M A woman has the last word in any argument. Anything a man says after that is the beginning of a new argument. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Solartron 7061 Service Manual - Does anyone have one?
Date: Sat, 23 Jun 2012 11:12:59 -0500 From: "J. L. Trantham" I am looking for a service manual for the Solartron 7061, paper or .PDF. Does anyone know where I might find one? Thanks in advance. Joe * Joe, Didier has PDF copies of the User manual, Service manual and ROM images on his manual web site at http://www.ko4bb.com/manuals/index.php. Just search for 7061. Dave M A woman has the last word in any argument. Anything a man says after that is the beginning of a new argument. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Fluke 731A Manual
volt-nuts-requ...@febo.com wrote: Jean-Louis, Thanks for the link. I had not found that site before. It has some interesting manuals and outstanding scans. However, I did not see the 731A listed. I found the 731B, the 732A and the 732B. The 731A is a 'Transfer Standard', older than the 731B and completely different inside. I just got one that I would like to 'restore'. I have it up and working, close to the stated voltages, but I need to get more info before I go digging into it. I just saw a 731A manual appear on theBay and we'll see if I can get it. Thanks for the help. Joe Hi J.L. From: "J. L. Trantham" Does anyone have a Fluke 731A manual available? PDF or print? http://www.on4jln.be/infos/manuals.shtml Bye, Jean-Louis => If you can't get the manual that you saw on Ebay, you can buy an original at https://www.ridgeequipment.com/store/manuals/detail.php?id=12771 Cheers, Dave M A woman has the last word in any argument. Anything a man says after that is the beginning of a new argument. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
