In message <1538.12.6.201.199.1260981396.squirrel@popaccts.quik.com>, "J. Forst er" writes: >I think it could be hard to get a strain free mount arrangement that way. There are plenty of "remains plastic" heat transfer materials available, basically short-chain silicone compunds, so I don't see why that would be the case. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.

> When finished, I intend to have it calibrated at > regular intervals and use it as my house standard. What does the calibration of a standard resistor typically involve? Is it just a measurement at specific environmental conditions or is it typically done over a range of temperatures to obtain temperature coefficients? How much would one expect to pay to have a standard resistor calibrated? Randy.

Hi Rob, How is the standard going? I've had renewed interest as I just "found" a pair of 200 ohm VHA516-6 Vishay Z foils in a scrap biotech unit that came in an auction lot. Reviewing the thread I revisited the Fluke 742A comparison. While the VHAs are not as "accurate" as the 742A (50ppm for the 200R) They are MUCH more stable at the 720A power levels, 2 ppm for 6 years compared to 6ppm at 1 year for the Fluke.  So they should make a grat transfer standard. Robert G8RPI. --- On Mon, 14/12/09, Rob Klein <rob.klein@smalldesign.nl> wrote: From: Rob Klein <rob.klein@smalldesign.nl> Subject: [volt-nuts] Resistance standard To: volt-nuts@febo.com Date: Monday, 14 December, 2009, 22:01    My first post to the group, and it's Ohm-nut, rather than Volt-nut, but    I hope you'll forgive me for that :-).    The nutty idea is this: To build a Volt-nuts grade resistance standard.    Or, actually, two, perhaps three.    The first one is quite simple, but rather pricey: I have ordered four    Vishay VHP202Z's, at $ 96 each (ouch!). Expected to be delivered late    february/early march. They will be placed in a series/parallel    configuration to deliver a 10kOhm resistor that should easily rival a    Fluke 742A,    probably be even better. When finished, I intend to have it calibrated    at regular intervals and use it as my house standard.    The other two are a bit more involved, but it will be interesting to    see the results.    For these two, I will use 9 each Z201's from Vishay. These use the same    chip as the VHP202, but are molded, rather than hermetically sealed.    Also, I will use 0.01% types, rather than the 0.001% VHP's. These are    much cheaper (the 18 I need to make two standards cost less than the    four VHP's!), but also less stable over time.    To overcome the stability problem, I am looking at two ways to *make*    them hermetically sealed. The first is to house the 9 (three in series,    three    sets in parallel) in an RF shielding can, fill this up with oil and    solder it shut.    The can I have in mind is a PCB mounted type, for which I shall have to    design a board. The PCB area inside the can will be solid copper,    extending    some way beyond the outside, so I can make a proper seal. Connections    to the outside world will be through glass-sealed, solder mounted    feedthrough capacitors of low capacitance. After mounting the resistors    and a thorough cleaning, the whole thing will be baked at ~85°C    overnight    to get rid of any moisture, then filled with oil and soldered shut.    This assembly will be placed inside a sturdy metal box (Hammond model    [1]1457K1201), which will hold four low EMF binding posts (Pomona    3770).    For the second solution, I want to use much the same method, but rather    than filling the can with oil, I want to fill it with epoxy or maybe    polyurethane resin.    This is a much simpler solution, because there will be no need for the    feedthrough caps and no need to solder the can shut.    However, of course, I am aware that neither of these resins will    provide an actual hermetic seal, since they *will* absorb some    moisture. I am curious    though, as to how much of a positive effect can be gained from this    method, as the shear volume of the resin, as compared to the quantity    use to mold the    actual resistors, should at least greatly diminish any effects of    moisture.    So, if you're still with me after this, I would very much like the    knowledgeables of this group to comment on these ideas. Are they    feasible? What potential    pitfalls might I have overlooked? What oil to use (as an avid cook, I    know my olive- from my sesame oil, but I haven't a clue what type of    mineral oil to    look for :-( ).    Thanks,    Rob Klein. References    1. http://www.hammondmfg.com/pdf/1457K1201.pdf _______________________________________________ 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.

My first post to the group, and it's Ohm-nut, rather than Volt-nut, but
I hope you'll forgive me for that :-).
The nutty idea is this: To build a Volt-nuts grade resistance standard.
Or, actually, two, perhaps three.
The first one is quite simple, but rather pricey: I have ordered four
Vishay VHP202Z's, at $ 96 each (ouch!). Expected to be delivered late
february/early march. They will be placed in a series/parallel
configuration to deliver a 10kOhm resistor that should easily rival a
Fluke 742A,
probably be even better. When finished, I intend to have it calibrated
at regular intervals and use it as my house standard.
The other two are a bit more involved, but it will be interesting to
see the results.
For these two, I will use 9 each Z201's from Vishay. These use the same
chip as the VHP202, but are molded, rather than hermetically sealed.
Also, I will use 0.01% types, rather than the 0.001% VHP's. These are
much cheaper (the 18 I need to make two standards cost less than the
four VHP's!), but also less stable over time.
To overcome the stability problem, I am looking at two ways to *make*
them hermetically sealed. The first is to house the 9 (three in series,
three
sets in parallel) in an RF shielding can, fill this up with oil and
solder it shut.
The can I have in mind is a PCB mounted type, for which I shall have to
design a board. The PCB area inside the can will be solid copper,
extending
some way beyond the outside, so I can make a proper seal. Connections
to the outside world will be through glass-sealed, solder mounted
feedthrough capacitors of low capacitance. After mounting the resistors
and a thorough cleaning, the whole thing will be baked at ~85°C
overnight
to get rid of any moisture, then filled with oil and soldered shut.
This assembly will be placed inside a sturdy metal box (Hammond model
[1]1457K1201), which will hold four low EMF binding posts (Pomona
3770).
For the second solution, I want to use much the same method, but rather
than filling the can with oil, I want to fill it with epoxy or maybe
polyurethane resin.
This is a much simpler solution, because there will be no need for the
feedthrough caps and no need to solder the can shut.
However, of course, I am aware that neither of these resins will
provide an actual hermetic seal, since they *will* absorb some
moisture. I am curious
though, as to how much of a positive effect can be gained from this
method, as the shear volume of the resin, as compared to the quantity
use to mold the
actual resistors, should at least greatly diminish any effects of
moisture.
So, if you're still with me after this, I would very much like the
knowledgeables of this group to comment on these ideas. Are they
feasible? What potential
pitfalls might I have overlooked? What oil to use (as an avid cook, I
know my olive- from my sesame oil, but I haven't a clue what type of
mineral oil to
look for :-( ).
Thanks,
Rob Klein.

1. http://www.hammondmfg.com/pdf/1457K1201.pdf

Hi, I only recently joined this group, but in answer to rob, the best oil would be a long chain parrafin, can be purchased for vacuum pumps, also a solid encapsulation will shift as it ages, and that would put strain on the resistors, so they would need an initial wrap in a silicone perhaps? definately a very compliant cover of some sort to isolate the strain. Mike PS I am shortly going to set up some LTZ's for a small family of references to age and compare. Doing the sums a difference measure between each one and graphed will tell me which ones are the most stable, then after a year or so splash out and get one calibrated against a known source. > Date: Fri, 22 Jul 2011 21:24:07 +0100 > From: robert8rpi@yahoo.co.uk > To: volt-nuts@febo.com > Subject: Re: [volt-nuts] Resistance standard > > Hi Rob, > How is the standard going? > I've had renewed interest as I just "found" a pair of 200 ohm VHA516-6 Vishay Z foils in a scrap biotech unit that came in an auction lot. Reviewing the thread I revisited the Fluke 742A comparison. While the VHAs are not as "accurate" as the 742A (50ppm for the 200R) They are MUCH more stable at the 720A power levels, 2 ppm for 6 years compared to 6ppm at 1 year for the Fluke. So they should make a grat transfer standard. > > Robert G8RPI. > > --- On Mon, 14/12/09, Rob Klein <rob.klein@smalldesign.nl> wrote: > > From: Rob Klein <rob.klein@smalldesign.nl> > Subject: [volt-nuts] Resistance standard > To: volt-nuts@febo.com > Date: Monday, 14 December, 2009, 22:01 > > My first post to the group, and it's Ohm-nut, rather than Volt-nut, but > I hope you'll forgive me for that :-). > The nutty idea is this: To build a Volt-nuts grade resistance standard. > Or, actually, two, perhaps three. > The first one is quite simple, but rather pricey: I have ordered four > Vishay VHP202Z's, at $ 96 each (ouch!). Expected to be delivered late > february/early march. They will be placed in a series/parallel > configuration to deliver a 10kOhm resistor that should easily rival a > Fluke 742A, > probably be even better. When finished, I intend to have it calibrated > at regular intervals and use it as my house standard. > The other two are a bit more involved, but it will be interesting to > see the results. > For these two, I will use 9 each Z201's from Vishay. These use the same > chip as the VHP202, but are molded, rather than hermetically sealed. > Also, I will use 0.01% types, rather than the 0.001% VHP's. These are > much cheaper (the 18 I need to make two standards cost less than the > four VHP's!), but also less stable over time. > To overcome the stability problem, I am looking at two ways to *make* > them hermetically sealed. The first is to house the 9 (three in series, > three > sets in parallel) in an RF shielding can, fill this up with oil and > solder it shut. > The can I have in mind is a PCB mounted type, for which I shall have to > design a board. The PCB area inside the can will be solid copper, > extending > some way beyond the outside, so I can make a proper seal. Connections > to the outside world will be through glass-sealed, solder mounted > feedthrough capacitors of low capacitance. After mounting the resistors > and a thorough cleaning, the whole thing will be baked at ~85°C > overnight > to get rid of any moisture, then filled with oil and soldered shut. > This assembly will be placed inside a sturdy metal box (Hammond model > [1]1457K1201), which will hold four low EMF binding posts (Pomona > 3770). > For the second solution, I want to use much the same method, but rather > than filling the can with oil, I want to fill it with epoxy or maybe > polyurethane resin. > This is a much simpler solution, because there will be no need for the > feedthrough caps and no need to solder the can shut. > However, of course, I am aware that neither of these resins will > provide an actual hermetic seal, since they *will* absorb some > moisture. I am curious > though, as to how much of a positive effect can be gained from this > method, as the shear volume of the resin, as compared to the quantity > use to mold the > actual resistors, should at least greatly diminish any effects of > moisture. > So, if you're still with me after this, I would very much like the > knowledgeables of this group to comment on these ideas. Are they > feasible? What potential > pitfalls might I have overlooked? What oil to use (as an avid cook, I > know my olive- from my sesame oil, but I haven't a clue what type of > mineral oil to > look for :-( ). > Thanks, > Rob Klein. > > References > > 1. http://www.hammondmfg.com/pdf/1457K1201.pdf > _______________________________________________ > 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.

 My first post to the group, and it's Ohm-nut, rather than Volt-nut, but
 I hope you'll forgive me for that :-).
 The nutty idea is this: To build a Volt-nuts grade resistance standard.
 Or, actually, two, perhaps three.
 The first one is quite simple, but rather pricey: I have ordered four
 Vishay VHP202Z's, at $ 96 each (ouch!). Expected to be delivered late
 february/early march. They will be placed in a series/parallel
 configuration to deliver a 10kOhm resistor that should easily rival a
 Fluke 742A,
 probably be even better. When finished, I intend to have it calibrated
 at regular intervals and use it as my house standard.
 The other two are a bit more involved, but it will be interesting to
 see the results.
 For these two, I will use 9 each Z201's from Vishay. These use the same
 chip as the VHP202, but are molded, rather than hermetically sealed.
 Also, I will use 0.01% types, rather than the 0.001% VHP's. These are
 much cheaper (the 18 I need to make two standards cost less than the
 four VHP's!), but also less stable over time.
 To overcome the stability problem, I am looking at two ways to *make*
 them hermetically sealed. The first is to house the 9 (three in series,
 three
 sets in parallel) in an RF shielding can, fill this up with oil and
 solder it shut.
 The can I have in mind is a PCB mounted type, for which I shall have to
 design a board. The PCB area inside the can will be solid copper,
 extending
 some way beyond the outside, so I can make a proper seal. Connections
 to the outside world will be through glass-sealed, solder mounted
 feedthrough capacitors of low capacitance. After mounting the resistors
 and a thorough cleaning, the whole thing will be baked at ~85°C
 overnight
 to get rid of any moisture, then filled with oil and soldered shut.
 This assembly will be placed inside a sturdy metal box (Hammond model
 [1]1457K1201), which will hold four low EMF binding posts (Pomona
 3770).
 For the second solution, I want to use much the same method, but rather
 than filling the can with oil, I want to fill it with epoxy or maybe
 polyurethane resin.
 This is a much simpler solution, because there will be no need for the
 feedthrough caps and no need to solder the can shut.
 However, of course, I am aware that neither of these resins will
 provide an actual hermetic seal, since they *will* absorb some
 moisture. I am curious
 though, as to how much of a positive effect can be gained from this
 method, as the shear volume of the resin, as compared to the quantity
 use to mold the
 actual resistors, should at least greatly diminish any effects of
 moisture.
 So, if you're still with me after this, I would very much like the
 knowledgeables of this group to comment on these ideas. Are they
 feasible? What potential
 pitfalls might I have overlooked? What oil to use (as an avid cook, I
 know my olive- from my sesame oil, but I haven't a clue what type of
 mineral oil to
 look for :-( ).
 Thanks,
 Rob Klein.

 1. http://www.hammondmfg.com/pdf/1457K1201.pdf

Hi, The traditional oil for standard resistors and oil baths is Mineral Oil. The cheapest source of Mineral Oil USP for small quantities is out local grocery store at about $5.50 per pint. It is a highly purified paraffin oil. If you need a large quantity then check out Exxon Marcol 72 which is available for about $12 per liter from Measurements International. I am trying to find a much better price since I could potentially use 157 liters if I am able to get a used bath that I know of. Charlie On 7/23/2011 3:03 AM, m k wrote: > Hi, > > I only recently joined this group, but in answer to rob, the best oil would be a long chain parrafin, can be purchased for vacuum pumps, also a solid encapsulation will shift as it ages, and that would put strain on the resistors, so they would need an initial wrap in a silicone perhaps? definately a very compliant cover of some sort to isolate the strain. > > Mike > > PS I am shortly going to set up some LTZ's for a small family of references to age and compare. Doing the sums a difference measure between each one and graphed will tell me which ones are the most stable, then after a year or so splash out and get one calibrated against a known source. > >> Date: Fri, 22 Jul 2011 21:24:07 +0100 >> From: robert8rpi@yahoo.co.uk >> To: volt-nuts@febo.com >> Subject: Re: [volt-nuts] Resistance standard >> >> Hi Rob, >> How is the standard going? >> I've had renewed interest as I just "found" a pair of 200 ohm VHA516-6 Vishay Z foils in a scrap biotech unit that came in an auction lot. Reviewing the thread I revisited the Fluke 742A comparison. While the VHAs are not as "accurate" as the 742A (50ppm for the 200R) They are MUCH more stable at the 720A power levels, 2 ppm for 6 years compared to 6ppm at 1 year for the Fluke. So they should make a grat transfer standard. >> >> Robert G8RPI. >> >> --- On Mon, 14/12/09, Rob Klein<rob.klein@smalldesign.nl> wrote: >> >> From: Rob Klein<rob.klein@smalldesign.nl> >> Subject: [volt-nuts] Resistance standard >> To: volt-nuts@febo.com >> Date: Monday, 14 December, 2009, 22:01 >> >> My first post to the group, and it's Ohm-nut, rather than Volt-nut, but >> I hope you'll forgive me for that :-). >> The nutty idea is this: To build a Volt-nuts grade resistance standard. >> Or, actually, two, perhaps three. >> The first one is quite simple, but rather pricey: I have ordered four >> Vishay VHP202Z's, at $ 96 each (ouch!). Expected to be delivered late >> february/early march. They will be placed in a series/parallel >> configuration to deliver a 10kOhm resistor that should easily rival a >> Fluke 742A, >> probably be even better. When finished, I intend to have it calibrated >> at regular intervals and use it as my house standard. >> The other two are a bit more involved, but it will be interesting to >> see the results. >> For these two, I will use 9 each Z201's from Vishay. These use the same >> chip as the VHP202, but are molded, rather than hermetically sealed. >> Also, I will use 0.01% types, rather than the 0.001% VHP's. These are >> much cheaper (the 18 I need to make two standards cost less than the >> four VHP's!), but also less stable over time. >> To overcome the stability problem, I am looking at two ways to *make* >> them hermetically sealed. The first is to house the 9 (three in series, >> three >> sets in parallel) in an RF shielding can, fill this up with oil and >> solder it shut. >> The can I have in mind is a PCB mounted type, for which I shall have to >> design a board. The PCB area inside the can will be solid copper, >> extending >> some way beyond the outside, so I can make a proper seal. Connections >> to the outside world will be through glass-sealed, solder mounted >> feedthrough capacitors of low capacitance. After mounting the resistors >> and a thorough cleaning, the whole thing will be baked at ~85°C >> overnight >> to get rid of any moisture, then filled with oil and soldered shut. >> This assembly will be placed inside a sturdy metal box (Hammond model >> [1]1457K1201), which will hold four low EMF binding posts (Pomona >> 3770). >> For the second solution, I want to use much the same method, but rather >> than filling the can with oil, I want to fill it with epoxy or maybe >> polyurethane resin. >> This is a much simpler solution, because there will be no need for the >> feedthrough caps and no need to solder the can shut. >> However, of course, I am aware that neither of these resins will >> provide an actual hermetic seal, since they *will* absorb some >> moisture. I am curious >> though, as to how much of a positive effect can be gained from this >> method, as the shear volume of the resin, as compared to the quantity >> use to mold the >> actual resistors, should at least greatly diminish any effects of >> moisture. >> So, if you're still with me after this, I would very much like the >> knowledgeables of this group to comment on these ideas. Are they >> feasible? What potential >> pitfalls might I have overlooked? What oil to use (as an avid cook, I >> know my olive- from my sesame oil, but I haven't a clue what type of >> mineral oil to >> look for :-( ). >> Thanks, >> Rob Klein. >> >> References >> >> 1. http://www.hammondmfg.com/pdf/1457K1201.pdf >> _______________________________________________ >> 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. > >

On 07/23/2011 01:14 PM, Charles Black wrote: > Hi, > > The traditional oil for standard resistors and oil baths is Mineral Oil. > The cheapest source of Mineral Oil USP for small quantities is out > local grocery store at about $5.50 per pint. It is a highly purified > paraffin oil. If you need a large quantity then check out Exxon Marcol > 72 which is available for about $12 per liter from Measurements > International. I am trying to find a much better price since I could > potentially use 157 liters if I am able to get a used bath that I know of. Assuming from your address that you're in the US, check out Tractor Supply. They have USP mineral oil for about $12 a gallon. Sold as a livestock laxative. I use a lot of it in my high voltage endeavors. John -- John DeArmond Tellico Plains, Occupied TN http://www.neon-john.com <-- email from here http://www.johndearmond.com <-- Best damned Blog on the net PGP key: wwwkeys.pgp.net: BCB68D77

Hi John, Thanks for your great suggestion! We don't have Tractor Supply in Washington but I called our local farm supply (Cenex) and they have it for $17.99 per gallon. That's getting reasonable and I may find a lower price yet. Thanks again Charlie On 7/23/2011 10:30 AM, NeonJohn wrote: > > On 07/23/2011 01:14 PM, Charles Black wrote: >> Hi, >> >> The traditional oil for standard resistors and oil baths is Mineral Oil. >> The cheapest source of Mineral Oil USP for small quantities is out >> local grocery store at about $5.50 per pint. It is a highly purified >> paraffin oil. If you need a large quantity then check out Exxon Marcol >> 72 which is available for about $12 per liter from Measurements >> International. I am trying to find a much better price since I could >> potentially use 157 liters if I am able to get a used bath that I know of. > Assuming from your address that you're in the US, check out Tractor > Supply. They have USP mineral oil for about $12 a gallon. Sold as a > livestock laxative. I use a lot of it in my high voltage endeavors. > > John >

Hi Robert, Now why do I never make such a 'find'? ;-) You are right that the Z-foils are (supposedly) much more stable than the 742A, which is exactly what started me on my quest. I did receive those VHP202Z's in late March last year and did some very brief testing on them. However, what with getting married, becoming father to a son and having major work done on the house and incidentally having to run my business as well, I'm afraid I've had to curb my nuttery since then. Also, the arrival of two Fluke 5440B's in need of some TLC has taken up quite a bit of time. So, overall, not much progress on the standard front. Until, that is, I happened upon an ESI SR104, last week! That, in itself is of course all the standard I would ever require and so there is no real need to roll my own any more. Still, I wouldn't be much of a nut if I'd let that stop me. Now, at least, I have the penultimate standard to compare my home-brew against. Best regards, Rob. Op 22-7-2011 22:24, Robert Atkinson schreef: > Hi Rob, > How is the standard going? > I've had renewed interest as I just "found" a pair of 200 ohm VHA516-6 Vishay Z foils in a scrap biotech unit that came in an auction lot. Reviewing the thread I revisited the Fluke 742A comparison. While the VHAs are not as "accurate" as the 742A (50ppm for the 200R) They are MUCH more stable at the 720A power levels, 2 ppm for 6 years compared to 6ppm at 1 year for the Fluke. So they should make a grat transfer standard. > > Robert G8RPI. >

Hi Mike and Charlie, For the oil, I have decided on the stuff that is sold locally as "sewing machine oil". This is a highly refined light mineral oil, guaranteed to be acid free. As explained in my previous message, things haven't been progressing over the last 18 months, but I'm going to pick it up again soon, so stay tuned. Best regards, Rob. Op 23-7-2011 19:14, Charles Black schreef: > Hi, > > The traditional oil for standard resistors and oil baths is Mineral > Oil. The cheapest source of Mineral Oil USP for small quantities is > out local grocery store at about $5.50 per pint. It is a highly > purified paraffin oil. If you need a large quantity then check out > Exxon Marcol 72 which is available for about $12 per liter from > Measurements International. I am trying to find a much better price > since I could potentially use 157 liters if I am able to get a used > bath that I know of. > > Charlie > > On 7/23/2011 3:03 AM, m k wrote: >> Hi, >> >> I only recently joined this group, but in answer to rob, the best oil >> would be a long chain parrafin, can be purchased for vacuum pumps, >> also a solid encapsulation will shift as it ages, and that would put >> strain on the resistors, so they would need an initial wrap in a >> silicone perhaps? definately a very compliant cover of some sort to >> isolate the strain. >> >> Mike >> >> PS I am shortly going to set up some LTZ's for a small family of >> references to age and compare. Doing the sums a difference measure >> between each one and graphed will tell me which ones are the most >> stable, then after a year or so splash out and get one calibrated >> against a known source.

Hi Rob, ESI recommended "Drakeol 9 LT mineral oil" in their literature which I couldn't find in small quantities. I investigated a synthetic oil replacement called SpectraSyn PAO and Exxon offered to send a sample. After checking with a chemist at work I decided not to. He said over many years of immersion the "long chain parrafin" as Mike mentioned would be the best, and less likely to deteriorate the insulation than the synthetic replacement. I have attached a chart he sent me for the group's observation. Mitch ----- Original Message ----- From: "Rob Klein" <rob.klein@smalldesign.nl> To: "Discussion of precise voltage measurement" <volt-nuts@febo.com> Sent: Monday, August 22, 2011 8:10 AM Subject: Re: [volt-nuts] Resistance standard > Hi Mike and Charlie, > > For the oil, I have decided on the stuff that is sold locally as "sewing > machine oil". This is a highly refined light mineral oil, guaranteed to be > acid free. > > As explained in my previous message, things haven't been progressing over > the last 18 months, but I'm going to pick it up again soon, so stay tuned. > > > Best regards, > Rob. > > Op 23-7-2011 19:14, Charles Black schreef: >> Hi, >> >> The traditional oil for standard resistors and oil baths is Mineral Oil. >> The cheapest source of Mineral Oil USP for small quantities is out local >> grocery store at about $5.50 per pint. It is a highly purified paraffin >> oil. If you need a large quantity then check out Exxon Marcol 72 which is >> available for about $12 per liter from Measurements International. I am >> trying to find a much better price since I could potentially use 157 >> liters if I am able to get a used bath that I know of. >> >> Charlie >> >> On 7/23/2011 3:03 AM, m k wrote: >>> Hi, >>> >>> I only recently joined this group, but in answer to rob, the best oil >>> would be a long chain parrafin, can be purchased for vacuum pumps, also >>> a solid encapsulation will shift as it ages, and that would put strain >>> on the resistors, so they would need an initial wrap in a silicone >>> perhaps? definately a very compliant cover of some sort to isolate the >>> strain. >>> >>> Mike >>> >>> PS I am shortly going to set up some LTZ's for a small family of >>> references to age and compare. Doing the sums a difference measure >>> between each one and graphed will tell me which ones are the most >>> stable, then after a year or so splash out and get one calibrated >>> against a known source. > > > _______________________________________________ > 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.