Re: [volt-nuts] Precision resistors
Hi Tony Absolute Calibration in the UK charged 144UKP+VAT to measure a SR104. This included pickup and dropoff using their own vehicle! Their stated capability is to +/- 0.24ppm Very happy with them so far, they can also do zener measurements, e.g 10V to within 0.23ppm, for similar price. John Tony Holt vn...@toneh.demon.co.uk writes: [...] Does anyone know how much it would cost to get a 10k resistor measured to 2ppm in the UK by a calibration company? Does anyone know how much it would cost to buy a 1% Vishay VH102Z/VHP101 or similar with a 2ppm measurement? Edwin Pettis quoted me $7.28 for one 10k resistor ($5.46 for 11 to 24) so they could be a viable way of getting accurately (approx 1ppm) measured resistors. The higher TCR, 3ppm/C would increase the uncertainties though as it would require them to be used within 1C or so of that when measured by Mr Pettis, but he can select for 1ppm TCR or less for an extra $2 which would easily be justified for this purpose. Obviously the uncertainties due to transport shocks/vibration (although Mr Pettis claims they are very rugged) and drift related to the time in transport would need to be considered. On Aug 11, 2015, at 9:00 AM, volt-nuts-requ...@febo.com wrote: Edwin Pettis states his resistors drift is typically better than 2ppm in the first year, so pretty good but you'd still need to have them measured every few years. If you have to get them professionally calibrated it may be cheaper to buy the Vishay parts. Edwin could provide the measured values as could Vishay if you bought directly from them. ___ -- John Devereux ___ 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] Precision resistors
On 11/08/2015 17:53, Richard Moore wrote: True of any resistor that you want to trust to better than 10ppm, including the Vishays. Of course, but Dr Frank's experience with the oil filled Vishay foils has been good - from another eevblog post: 'Only the hermetically sealed, oil filled types (e.g. VHP202Z) give a big advantage. Their rate is typically 2ppm/6yrs., and therefore will add about 0.02ppm/yr only. In picture 1 you’ll find long-term stability monitoring of 3 EA of my 5 VHP202Z. After 2 years, they really remain within 0.5ppm of their initial value, so that is obviously no fake advertisement. (Remark: The measurement stability was improved also during that time.)' That's pretty close to the SR104's typical drift of .2ppm/year, .5ppm max (1ppm first 2 years), but the TCR of his parts were much worse than the SR104's .1ppm typical ranging from .3ppm to 1ppm. He might well have got lucky but I read on a Chinese volt-nut type blog that Vishay originally specified 2ppm/10 years but reduced it to 6 years - presumably due to complaints/experience. Personally I would be happy to trust that they would remain within 10ppm for many years but you would have to get them measured periodically to know for certain. Depending on how cheaply you could buy one, it might be cheaper to buy new ones for 2 or 3 years rather than getting one calibrated and using them to determine the drift of the earlier parts. And you would have a collection of resistors to improve confidence in the secondary standard. Does anyone know how much it would cost to get a 10k resistor measured to 2ppm in the UK by a calibration company? Does anyone know how much it would cost to buy a 1% Vishay VH102Z/VHP101 or similar with a 2ppm measurement? Edwin Pettis quoted me $7.28 for one 10k resistor ($5.46 for 11 to 24) so they could be a viable way of getting accurately (approx 1ppm) measured resistors. The higher TCR, 3ppm/C would increase the uncertainties though as it would require them to be used within 1C or so of that when measured by Mr Pettis, but he can select for 1ppm TCR or less for an extra $2 which would easily be justified for this purpose. Obviously the uncertainties due to transport shocks/vibration (although Mr Pettis claims they are very rugged) and drift related to the time in transport would need to be considered. On Aug 11, 2015, at 9:00 AM, volt-nuts-requ...@febo.com wrote: Edwin Pettis states his resistors drift is typically better than 2ppm in the first year, so pretty good but you'd still need to have them measured every few years. If you have to get them professionally calibrated it may be cheaper to buy the Vishay parts. Edwin could provide the measured values as could Vishay if you bought directly from them. ___ 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.
[volt-nuts] Precision resistors - Fluke 5450A
One thing to watch out for on the 5450A is burned out segments in the 14-segment LED displays. The display chip they used is rather weird (each 14 segment digit is actually two 7-segment displays mixed together) and VERY unobtainium. Mine has a missing segment on one of the digits and I have not found any replacements in 5+ years) The display is not critical to operation and my missing segment does not cause any digit ambiguities. ___ 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] Precision Resistors
Sounds like a plan :) Regards, David Partridge -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Four Designs Company Sent: 06 August 2015 18:36 To: volt-nuts@febo.com Subject: Re: [volt-nuts] Precision Resistors You could acquire a Fluke 5450A ... ___ 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] Precision resistors - Fluke 5450A
Seems like a work for a small cpld... Em 07/08/2015 03:53, Mark Sims hol...@hotmail.com escreveu: One thing to watch out for on the 5450A is burned out segments in the 14-segment LED displays. The display chip they used is rather weird (each 14 segment digit is actually two 7-segment displays mixed together) and VERY unobtainium. Mine has a missing segment on one of the digits and I have not found any replacements in 5+ years) The display is not critical to operation and my missing segment does not cause any digit ambiguities. ___ 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.
Re: [volt-nuts] Precision resistors
David, Depending on the time frame needed for these resistors you can order many (but not all) of the parts from Farnell. I believe the Rhopoint resistors are the recommended brand. The high value resistors could be Caddock USF series. Another alternative would be to contact Edwin Pettis. He manufacturers custom resistors and does ship internationally. He is working on a 'project' for me that requires a replacement precision resistor. I am not sure if he can make the highest values. Your other alternative would be to order a couple of these http://www.precisionresistor.com/Digital-Multimeter-Calibrator/ They have made me some custom sets, so I know it can be done. The 10M resistor prices are extremely high and the turn around for the custom sets can be long. They do not make 20M WW resistors last time I checked. You will probably still need to buy separate resistors from Caddock. I am guessing the Fluke 5450A is difficult to get or is too expensive where you live. Todd On Thu, Aug 6, 2015 at 11:25 AM, David C. Partridge david.partri...@perdrix.co.uk wrote: Looking for a set of precision resistors for calibration purposes. I need the following values to calibrate the ohms ranges on my meters: 100 1k 2k 10k 20k 100k 200k 1M 2M 10M 20M The crucial factor isn't that they be *exactly* the values above, so I don't necessarily need 0.001% parts. Low TCR is important, and I will need to know that actual values to 10ppm or better. I'm looking for suggestions on the best choice of parts and pricing? I believe the Vishay HZ series may fit the bill for the lower values but they may be rather expensive. Regards, David Partridge ___ 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.
Re: [volt-nuts] Precision resistors
Since R is quite tied to E, i found this paper to be quite interesting ... Pettis was also the resistor expert who worked with Bob Pease in his last project trying to push the state of the art at the time for special resistors needed on the project. The invention of Evanohm http://www.edn.com/design/analog/4427151/The-last-half-century--Wirewound-resistors-Part-one http://www.edn.com/design/analog/4427940/1/The-last-half-century--Wirewound-resistors-Part-two On Thu, Aug 6, 2015 at 1:44 PM, Richard Moore richiem5...@gmail.com wrote: Check with Edwin Pettis at Ultrohm in Grand Junction, Co. H ewinds superb ww resistors using Evanohm wire with tempcos under 3ppm/degC, with 0.01% tolerance for around $14 each. I’ve bought some and have been extremely pleased. Don’t know the largest he can make or at what price… pettis...@q.com Dick Moore Message: 1 Date: Thu, 6 Aug 2015 16:25:54 +0100 From: David C. Partridge david.partri...@perdrix.co.uk To: 'Discussion of precise voltage measurement' volt-nuts@febo.com Subject: [volt-nuts] Precision resistors Message-ID: 5D9EFA13BAB94DCA901607C1EDEA4911@APOLLO Content-Type: text/plain; charset=UTF-8 Looking for a set of precision resistors for calibration purposes. I need the following values to calibrate the ohms ranges on my meters: 100 1k 2k 10k 20k 100k 200k 1M 2M 10M 20M The crucial factor isn't that they be *exactly* the values above, so I don't necessarily need 0.001% parts. Low TCR is important, and I will need to know that actual values to 10ppm or better. I'm looking for suggestions on the best choice of parts and pricing? I believe the Vishay HZ series may fit the bill for the lower values but they may be rather expensive. Regards, David Partridge ___ 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.
Re: [volt-nuts] Precision resistors
Check with Edwin Pettis at Ultrohm in Grand Junction, Co. H ewinds superb ww resistors using Evanohm wire with tempcos under 3ppm/degC, with 0.01% tolerance for around $14 each. I’ve bought some and have been extremely pleased. Don’t know the largest he can make or at what price… pettis...@q.com Dick Moore Message: 1 Date: Thu, 6 Aug 2015 16:25:54 +0100 From: David C. Partridge david.partri...@perdrix.co.uk To: 'Discussion of precise voltage measurement' volt-nuts@febo.com Subject: [volt-nuts] Precision resistors Message-ID: 5D9EFA13BAB94DCA901607C1EDEA4911@APOLLO Content-Type: text/plain; charset=UTF-8 Looking for a set of precision resistors for calibration purposes. I need the following values to calibrate the ohms ranges on my meters: 100 1k 2k 10k 20k 100k 200k 1M 2M 10M 20M The crucial factor isn't that they be *exactly* the values above, so I don't necessarily need 0.001% parts. Low TCR is important, and I will need to know that actual values to 10ppm or better. I'm looking for suggestions on the best choice of parts and pricing? I believe the Vishay HZ series may fit the bill for the lower values but they may be rather expensive. Regards, David Partridge ___ 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] Precision resistors
Wattage and precision resistors could make for a very long thread. For best stability, you do not want to heat up the resistor very much. A power rating would normally be related to a permitted temperature rise, but you might not want your resistor to rise to that temperature. This way leads to several interrelated compromises. Laurence Motteram From: volt-nuts-boun...@febo.com [volt-nuts-boun...@febo.com] on behalf of Joseph Gray [jg...@zianet.com] Sent: Sunday, 18 August 2013 2:47 PM To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] Precision resistors Raj and John, Thanks for the advice. I'll go with some mild dish detergent and water. The black, rectangular resistors are definitely marked Daven, just like all the others. The bobbins are marked .02%, 1/2 W. The black rectangles are .1% (no wattage) and the micas are simply marked 85, which I assume is the resistance. Any idea what the wattage of the black ones are? Also, what percentage and wattage would the micas be? The micas are thumb-sized squares (just so I don't confuse the metric or imperial users :-) ). Joe Gray W5JG On Sat, Aug 17, 2013 at 7:18 AM, J. Forster j...@quikus.com wrote: The red 'sealant' is Glyptal laquer. Probably safe to water wash. I would not use any solvent on the bobbins. The black encapsulates are likely Vishay, if they look like CK-05/6 ceramic caps. Alcohol should be safe for a quick rinse. -John = Nothing abrasive should be used. Soap and water and old toothbrush is what I would try. Very high values avoid water! I use a cheap ultrasonic clear for some things in the shack! Raj VU2ZAP (former resistor manufacturer) At 17-08-2013, you wrote: What is the recommended method for cleaning dirt, oil, etc from precision resistors? I'm talking about a combination of wirewound on plastic bobbins, wirewound on mica (and sealed with something) and an unknown type that is encapsulated in black plastic rectangles. These are all 1950-1960 vintage and are marked Daven. Joe Gray W5JG ___ 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. ___ 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. -- Message protected by MailGuard: e-mail anti-virus, anti-spam and content filtering. http://www.mailguard.com.au ___ 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] Precision resistors
Yes, I realize that I don't want to heat the resistors. I was asking if anyone knew the ratings for these resistors, as they are incompletely marked. I'm not looking to start a long discussion. Joe Gray W5JG On Sun, Aug 18, 2013 at 12:57 AM, Laurence Motteram lmotte...@scientific-devices.com.au wrote: Wattage and precision resistors could make for a very long thread. For best stability, you do not want to heat up the resistor very much. A power rating would normally be related to a permitted temperature rise, but you might not want your resistor to rise to that temperature. This way leads to several interrelated compromises. Laurence Motteram From: volt-nuts-boun...@febo.com [volt-nuts-boun...@febo.com] on behalf of Joseph Gray [jg...@zianet.com] Sent: Sunday, 18 August 2013 2:47 PM To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] Precision resistors Raj and John, Thanks for the advice. I'll go with some mild dish detergent and water. The black, rectangular resistors are definitely marked Daven, just like all the others. The bobbins are marked .02%, 1/2 W. The black rectangles are .1% (no wattage) and the micas are simply marked 85, which I assume is the resistance. Any idea what the wattage of the black ones are? Also, what percentage and wattage would the micas be? The micas are thumb-sized squares (just so I don't confuse the metric or imperial users :-) ). Joe Gray W5JG On Sat, Aug 17, 2013 at 7:18 AM, J. Forster j...@quikus.com wrote: The red 'sealant' is Glyptal laquer. Probably safe to water wash. I would not use any solvent on the bobbins. The black encapsulates are likely Vishay, if they look like CK-05/6 ceramic caps. Alcohol should be safe for a quick rinse. -John = Nothing abrasive should be used. Soap and water and old toothbrush is what I would try. Very high values avoid water! I use a cheap ultrasonic clear for some things in the shack! Raj VU2ZAP (former resistor manufacturer) At 17-08-2013, you wrote: What is the recommended method for cleaning dirt, oil, etc from precision resistors? I'm talking about a combination of wirewound on plastic bobbins, wirewound on mica (and sealed with something) and an unknown type that is encapsulated in black plastic rectangles. These are all 1950-1960 vintage and are marked Daven. Joe Gray W5JG ___ 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. ___ 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. -- Message protected by MailGuard: e-mail anti-virus, anti-spam and content filtering. http://www.mailguard.com.au ___ 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.
Re: [volt-nuts] Precision resistors
The red 'sealant' is Glyptal laquer. Probably safe to water wash. I would not use any solvent on the bobbins. The black encapsulates are likely Vishay, if they look like CK-05/6 ceramic caps. Alcohol should be safe for a quick rinse. -John = Nothing abrasive should be used. Soap and water and old toothbrush is what I would try. Very high values avoid water! I use a cheap ultrasonic clear for some things in the shack! Raj VU2ZAP (former resistor manufacturer) At 17-08-2013, you wrote: What is the recommended method for cleaning dirt, oil, etc from precision resistors? I'm talking about a combination of wirewound on plastic bobbins, wirewound on mica (and sealed with something) and an unknown type that is encapsulated in black plastic rectangles. These are all 1950-1960 vintage and are marked Daven. Joe Gray W5JG ___ 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. ___ 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] Precision resistors
What is the recommended method for cleaning dirt, oil, etc from precision resistors? I'm talking about a combination of wirewound on plastic bobbins, wirewound on mica (and sealed with something) and an unknown type that is encapsulated in black plastic rectangles. These are all 1950-1960 vintage and are marked Daven. Joe Gray W5JG ___ 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.
