Re: [volt-nuts] 732A and Prologix received
Bill, I have convinced myself that the problem I an seeing is due to thermals. If I move the cables (with gold-plated banana plugs) using a small towel rather than letting my hand touch the plugs, it is much more stable. If I then hold the banana plug with my hand after the reading has stabilized, the reading drifts rapidly upward. I am trying to check the stability of the reading but I haven't figured out the MATH function yet. I assume this is a programmed function using GPIB only? The stability I am seeing by manually recording readings (using NLPC of 100 and 1000) is much greater than what you are measuring on your system. Not sure how to ascertain if it's the 3458A or the 732. The value of the readings are very different between the two - the 3458 reads about 50 uV high on the 10 V output and about 12 uV low on the 1V output. Rather large differences (this is after an ACAL). I need to find some better cables to make sure the errors are not due to thermals again. Randy On Sat, Aug 23, 2014 at 10:21 AM, Bill Gold wpgold3...@att.net wrote: Randy: I get 6 volt 4 amp/hr (or 4.5 amp/hr) batteries and they will fit perfect. Power Sonic PS-640, Genesis NP4-6, Panasonic LC-R064R5C and others that are in this size and package. Order from one of the usual electronics distributors like Allied, Mouser, Digikey. This is a very common battery as it is used in a lot of EXIT signs so they are lighted when the power goes out. I don't see how the 12V 7AH will fit as they are too large. I guess you could use a 12V 5AH (PS1250) as it is the same size as 2 x 6 volt 4 AH but the terminals are in the wrong place so you will have to nibble out the aluminum plate that holds them in the 732A battery pack. You have to be careful if you use the 12v 5AH as you will have 4 extra battery connection leads to deal with and connect correctly. I would stick with the 6V 4AH. New batteries will last around 12 to 14 hours before the CAL light goes out when AC power is not applied. So shipping to Cal Lab can be a problem if it is a distance away, or you have to use a shipper like UPS or FEDEX and you ship the night before and then use their Morning delivery and the Cal Lab is expecting your 732A. Same on the way back to you. Of course you could always strap another battery on the 732A and hook it up to the ext power plug to last longer. I have seen it done. The issue is to get the Cal Lab to charge the extra battery before they ship the 732A back to you. When you remove and work on the battery pack always have the AC power plugged in. The CAL led will stay on because the 18.6 v regulated supply is working. The CAL light is to indicate that power has not been lost to the Reference Amp or other associated circuits. When the raw supply (battery) voltage drops below about 21 volts the CAL light will go out. Below that voltage the heater circuits will not work correctly and the 18.6 volt regulated supply will not regulate. The requirement is that the Reference Amp be kept alive at all times to maintain the output voltage that was measured at the time of the most recent Calibration or Certification. When the semiconductor junctions are unbiased and cool off when power is lost, and then power is restored the result will be a different 10 volts than before the power failure. My experience is that after all of the years that these units have been powered up, this won't happen and when power is lost and then restored, even months later, the 732A will come back to almost exactly the same 10 volts as when they lost power, usually with in 0.2 PPM after 24 hours of warm up. What type of hookup leads are you using when measuring the 1 volt output? What is the PLC set to? I always use 100 PLC to measure this. If you don't have low thermal connection leads you can experience uV changes for a minute or more after plugging in the leads due to the thermals generated because of the difference in temperature between the banana jacks on the 732A and the banana plugs of the leads. I have found that even just plugging in the lead will generate a thermal difference because of difference of temps and some heating due to the physical act of just inserting the plug because of friction between the jack and plug (my theory at any rate). You have to allow at least a minute or more before being able to make a measurement after plugging in the leads. I just measured the variation of the 1 volt output of my 732A and using my 3458A and I got a total difference of 0.159 uV over 40 measurements using 100 PLC on the 1 volt range of the 3458A. Using the MATH function and all of the data you can collect. That was after waiting for several minutes after plugging in the leads. I hope all of this helps. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent:
Re: [volt-nuts] 732A and Prologix received
Bill, I use a lot of the 12v 7ah batteries for my UPS backups and 732B. But yes, I was mistaken. The 12V 5ah batteries are the ones that I am using in one of my 732A. There is more play inside the tray with the 12v batteries by several mm as compared to the 6v which only has a 2-3mm. The 12v conversion is not difficult, but it is easier if the battery tray has already been machined for the 12v batteries. The battery tabs don't line up well with the existing holes and need to be widened. Two additional holes must also be added. Sourcing the batteries locally is more of a convenience than waiting for the delivery. The el-cheapo 6v batteries are a waste of money and I have 8 batteries so far to prove it. They died the first time I had a 6hr outage and would not hold a charge after that. Todd On Sat, Aug 23, 2014 at 1:21 PM, Bill Gold wpgold3...@att.net wrote: Randy: I get 6 volt 4 amp/hr (or 4.5 amp/hr) batteries and they will fit perfect. Power Sonic PS-640, Genesis NP4-6, Panasonic LC-R064R5C and others that are in this size and package. Order from one of the usual electronics distributors like Allied, Mouser, Digikey. This is a very common battery as it is used in a lot of EXIT signs so they are lighted when the power goes out. I don't see how the 12V 7AH will fit as they are too large. I guess you could use a 12V 5AH (PS1250) as it is the same size as 2 x 6 volt 4 AH but the terminals are in the wrong place so you will have to nibble out the aluminum plate that holds them in the 732A battery pack. You have to be careful if you use the 12v 5AH as you will have 4 extra battery connection leads to deal with and connect correctly. I would stick with the 6V 4AH. New batteries will last around 12 to 14 hours before the CAL light goes out when AC power is not applied. So shipping to Cal Lab can be a problem if it is a distance away, or you have to use a shipper like UPS or FEDEX and you ship the night before and then use their Morning delivery and the Cal Lab is expecting your 732A. Same on the way back to you. Of course you could always strap another battery on the 732A and hook it up to the ext power plug to last longer. I have seen it done. The issue is to get the Cal Lab to charge the extra battery before they ship the 732A back to you. When you remove and work on the battery pack always have the AC power plugged in. The CAL led will stay on because the 18.6 v regulated supply is working. The CAL light is to indicate that power has not been lost to the Reference Amp or other associated circuits. When the raw supply (battery) voltage drops below about 21 volts the CAL light will go out. Below that voltage the heater circuits will not work correctly and the 18.6 volt regulated supply will not regulate. The requirement is that the Reference Amp be kept alive at all times to maintain the output voltage that was measured at the time of the most recent Calibration or Certification. When the semiconductor junctions are unbiased and cool off when power is lost, and then power is restored the result will be a different 10 volts than before the power failure. My experience is that after all of the years that these units have been powered up, this won't happen and when power is lost and then restored, even months later, the 732A will come back to almost exactly the same 10 volts as when they lost power, usually with in 0.2 PPM after 24 hours of warm up. What type of hookup leads are you using when measuring the 1 volt output? What is the PLC set to? I always use 100 PLC to measure this. If you don't have low thermal connection leads you can experience uV changes for a minute or more after plugging in the leads due to the thermals generated because of the difference in temperature between the banana jacks on the 732A and the banana plugs of the leads. I have found that even just plugging in the lead will generate a thermal difference because of difference of temps and some heating due to the physical act of just inserting the plug because of friction between the jack and plug (my theory at any rate). You have to allow at least a minute or more before being able to make a measurement after plugging in the leads. I just measured the variation of the 1 volt output of my 732A and using my 3458A and I got a total difference of 0.159 uV over 40 measurements using 100 PLC on the 1 volt range of the 3458A. Using the MATH function and all of the data you can collect. That was after waiting for several minutes after plugging in the leads. I hope all of this helps. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Friday, August 22, 2014 9:03 PM Subject: Re: [volt-nuts] 732A and Prologix received Todd, Thanks for the info. I have several Panasonic 12V 7 AH batteries that I keep topped off and
[volt-nuts] Looking for Datron 4000 series calibration key!
Would anyone have a spare key I could purchase? I understand that you can simple bypass the key with a shorting switch, but I am trying to keep my setup looking as authentic as possible. Thanks! ___ 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] Looking for Datron 4000 series calibration key!
Chris, Where do you live? I just had some keys made last week for my Datron units. The first set fit my 4000A and 1071, but they did not fit my 4700. The 4000A key looked more like the pictures online, but the 4700 was completely different. Someone may have rekeyed or damaged the lock on the 4700. I ended up putting the 1071 tumbler in my 4700. The original one will eventually end up in the 1071. Removing the 4000 switch should not be too bad. On my 4700, I have four philips screws in the back corners. I also have three that go across the top. One of them is behind the filter cover. I pulled the back cover away from the frame enough to get to the switch. The switch is held to the back cover by its outer collar. It threads on the lock and can be loosened with some soft jaw pliers. If you can get it out, any good locksmith can make you a set in a day. Todd On Sun, Aug 24, 2014 at 11:39 AM, Chris caal...@gmail.com wrote: Would anyone have a spare key I could purchase? I understand that you can simple bypass the key with a shorting switch, but I am trying to keep my setup looking as authentic as possible. Thanks! ___ 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] 732A and Prologix received
Bill, I have never been able to use banana plugs of any kind, with my 3458A, due to their excessive thermal mass. I use 24 gauge wires to make a twisted pair by hand with no connectors for precision voltage work. As brought out in an earlier post by acbern, it doesn't matter about plating or solder at least as long as your twisted pairs are made from the same wire so the thermocouples balance out. I am a big fan of M27500 shielded twisted pair wire for everyday use. It is durable, heat resistant and capable of very low voltage use. The insulator is Tefzel and the plating used to be silver but may be something else now. It take a few minutes work for proper termination but it can be done for free. I tend to use a lot of the 24 gauge M27500 STP wire since it is fast to come to temperature, flexible and durable enough to last quite awhile. eBay always has quite a few small lengths available and Sierra Nevada Products has a bunch of it. Sierra Nevada Products says that it is Teflon but I think it may be Tefzel. I can help with termination instructions if wanted. Charlie On 8/24/2014 7:22 AM, Randy Evans wrote: Bill, I have convinced myself that the problem I an seeing is due to thermals. If I move the cables (with gold-plated banana plugs) using a small towel rather than letting my hand touch the plugs, it is much more stable. If I then hold the banana plug with my hand after the reading has stabilized, the reading drifts rapidly upward. I am trying to check the stability of the reading but I haven't figured out the MATH function yet. I assume this is a programmed function using GPIB only? The stability I am seeing by manually recording readings (using NLPC of 100 and 1000) is much greater than what you are measuring on your system. Not sure how to ascertain if it's the 3458A or the 732. The value of the readings are very different between the two - the 3458 reads about 50 uV high on the 10 V output and about 12 uV low on the 1V output. Rather large differences (this is after an ACAL). I need to find some better cables to make sure the errors are not due to thermals again. Randy On Sat, Aug 23, 2014 at 10:21 AM, Bill Gold wpgold3...@att.net wrote: Randy: I get 6 volt 4 amp/hr (or 4.5 amp/hr) batteries and they will fit perfect. Power Sonic PS-640, Genesis NP4-6, Panasonic LC-R064R5C and others that are in this size and package. Order from one of the usual electronics distributors like Allied, Mouser, Digikey. This is a very common battery as it is used in a lot of EXIT signs so they are lighted when the power goes out. I don't see how the 12V 7AH will fit as they are too large. I guess you could use a 12V 5AH (PS1250) as it is the same size as 2 x 6 volt 4 AH but the terminals are in the wrong place so you will have to nibble out the aluminum plate that holds them in the 732A battery pack. You have to be careful if you use the 12v 5AH as you will have 4 extra battery connection leads to deal with and connect correctly. I would stick with the 6V 4AH. New batteries will last around 12 to 14 hours before the CAL light goes out when AC power is not applied. So shipping to Cal Lab can be a problem if it is a distance away, or you have to use a shipper like UPS or FEDEX and you ship the night before and then use their Morning delivery and the Cal Lab is expecting your 732A. Same on the way back to you. Of course you could always strap another battery on the 732A and hook it up to the ext power plug to last longer. I have seen it done. The issue is to get the Cal Lab to charge the extra battery before they ship the 732A back to you. When you remove and work on the battery pack always have the AC power plugged in. The CAL led will stay on because the 18.6 v regulated supply is working. The CAL light is to indicate that power has not been lost to the Reference Amp or other associated circuits. When the raw supply (battery) voltage drops below about 21 volts the CAL light will go out. Below that voltage the heater circuits will not work correctly and the 18.6 volt regulated supply will not regulate. The requirement is that the Reference Amp be kept alive at all times to maintain the output voltage that was measured at the time of the most recent Calibration or Certification. When the semiconductor junctions are unbiased and cool off when power is lost, and then power is restored the result will be a different 10 volts than before the power failure. My experience is that after all of the years that these units have been powered up, this won't happen and when power is lost and then restored, even months later, the 732A will come back to almost exactly the same 10 volts as when they lost power, usually with in 0.2 PPM after 24 hours of warm up. What type of hookup leads are you using when measuring the 1 volt output? What is the PLC set to? I always use 100 PLC to measure this. If you don't have low thermal connection leads you can
Re: [volt-nuts] Looking for Datron 4000 series calibration key!
In message CALwLtXwi-mABsNta=rohet9d6b4nyn9vft6bbwzy20vdqsq...@mail.gmail.com , Todd Micallef writes: Please notice that when you read the HP3458A over GPIB you get a slightly higher precision due to more decimals being presented, than you do on the display. If you are measuring down near the noise-limit, this matters. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@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. ___ 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] 732A and Prologix received
Randy all, You have correctly concluded that some (maybe not all) of your measurement problem is thermal EMF being added or subtracted in series within your measurement interconnect. This thermal EMF is generated at the junction of dissimilar metals when accompanied with thermal gradients between the test lead and device terminals. You have to eliminate both the dissimilarity of the metal junctions as well as minimize the thermal differences. The terminals of the 3458A as well as the 732A are Beryllium Copper so you want to use the same test lead terminals. Forget the typical Tin plated lugs or even Gold plated as both are not Beryllium Copper and constitute dissimilar metals. The best solution (as usually the most expensive) is to use a set of Fluke 5440A-7005 (48) cables. I also have just as good results using the much more flexible Pomona 11174A (lugs end always stay connected to the 732A) or 11058A with more convenient shielded banana plugs. The Fluke cable has the added Guard built in but be sure to also use a Guard lead with the Pomona cabled. The Guard lead does not need to be low thermal EMF. DIY cables is usually not a good idea because the lead wire to terminal also constitutes just as critical of junction. The above cables use Tellurium Copper wire which is usually hard to find and hard to crimp properly and NEVER solder. As you observed, merely the friction of plugging in the spring banana plug and heat transfer from your fingers will require ~3-5 minutes to stabilize. Low mass terminals help with the time to initially stabilize but is not best if dealing with local air current drafts that upset the instantaneous thermal gradients between the higher mass device terminal and the lower mass lead terminal. This issue is a trade-off and is specifically considered in the Fluke cables but being careful with localized drafts around the terminals during critical measurements can virtually eliminate this error source. I have attached an ~30-hour measurement run that I consistently do that should give you some idea of expected measurement drift over time. Virtually all of the measurement drift is due to the 3458A internal temperature differences around the 7V reference caused by ambient temperature change. The drift associated with the 732A is probably about 2-magnitudes less at this ambient temp drift. In my situation, the inferred ambient temperature is cycling with the home air-conditioning. Note the initial calibration temperatures as well as the ACal temperatures and where the 3458A is measuring exactly 10V. My primary 732A has been powered without loss for 4 years and 5 years before that. The 3458A is Agilent (Loveland) Cal'ed yearly and is powered 24-7-365 except for the occasional mains power loss. The graphical measurements is using a homegrown Agilent VEE program. Don Johnson -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of Randy Evans Sent: Sunday, August 24, 2014 9:22 AM To: Discussion of precise voltage measurement Subject: Re: [volt-nuts] 732A and Prologix received Bill, I have convinced myself that the problem I an seeing is due to thermals. If I move the cables (with gold-plated banana plugs) using a small towel rather than letting my hand touch the plugs, it is much more stable. If I then hold the banana plug with my hand after the reading has stabilized, the reading drifts rapidly upward. I am trying to check the stability of the reading but I haven't figured out the MATH function yet. I assume this is a programmed function using GPIB only? The stability I am seeing by manually recording readings (using NLPC of 100 and 1000) is much greater than what you are measuring on your system. Not sure how to ascertain if it's the 3458A or the 732. The value of the readings are very different between the two - the 3458 reads about 50 uV high on the 10 V output and about 12 uV low on the 1V output. Rather large differences (this is after an ACAL). I need to find some better cables to make sure the errors are not due to thermals again. Randy On Sat, Aug 23, 2014 at 10:21 AM, Bill Gold wpgold3...@att.net wrote: Randy: I get 6 volt 4 amp/hr (or 4.5 amp/hr) batteries and they will fit perfect. Power Sonic PS-640, Genesis NP4-6, Panasonic LC-R064R5C and others that are in this size and package. Order from one of the usual electronics distributors like Allied, Mouser, Digikey. This is a very common battery as it is used in a lot of EXIT signs so they are lighted when the power goes out. I don't see how the 12V 7AH will fit as they are too large. I guess you could use a 12V 5AH (PS1250) as it is the same size as 2 x 6 volt 4 AH but the terminals are in the wrong place so you will have to nibble out the aluminum plate that holds them in the 732A battery pack. You have to be careful if you use the 12v 5AH as you will have 4 extra battery connection leads to deal with and connect correctly.
Re: [volt-nuts] 732A and Prologix received
Todd: I check the batteries every month per the 732A manual. Usually I keep a few used cells from previous packs around that seem to be ok after checking them for capacity just like checking the battery pack. I can usually spot cells going bad with that method. If I don't have a spare set then I just substitute a used cell until I receive a new set. I agree with you that the cheap ones are crap. I have used Power Sonic a lot with some a few EaglePicher and one set of Enersys. The EaglePicher are crap so I will never use them. EaglePicher have had a couple out of 8 that have failed very early. I have never tried Panasonic. So I stick with the Power Sonic's. I am not sure why the 12 volt ones would be better than the 6 volts because 12 volt is just 6 lead acid cells while the 6volt are 3 lead acid cells. If one of the 6 cells in the 12 volt battery go bad then the whole battery has to be changed. So you better buy good quality 12 volt batteries. I just can't seem to source batteries locally easily at a reasonable price. So I order them from Allied usually. Bill - Original Message - From: Todd Micallef tmical...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Sunday, August 24, 2014 8:13 AM Subject: Re: [volt-nuts] 732A and Prologix received Bill, I use a lot of the 12v 7ah batteries for my UPS backups and 732B. But yes, I was mistaken. The 12V 5ah batteries are the ones that I am using in one of my 732A. There is more play inside the tray with the 12v batteries by several mm as compared to the 6v which only has a 2-3mm. The 12v conversion is not difficult, but it is easier if the battery tray has already been machined for the 12v batteries. The battery tabs don't line up well with the existing holes and need to be widened. Two additional holes must also be added. Sourcing the batteries locally is more of a convenience than waiting for the delivery. The el-cheapo 6v batteries are a waste of money and I have 8 batteries so far to prove it. They died the first time I had a 6hr outage and would not hold a charge after that. Todd On Sat, Aug 23, 2014 at 1:21 PM, Bill Gold wpgold3...@att.net wrote: Randy: I get 6 volt 4 amp/hr (or 4.5 amp/hr) batteries and they will fit perfect. Power Sonic PS-640, Genesis NP4-6, Panasonic LC-R064R5C and others that are in this size and package. Order from one of the usual electronics distributors like Allied, Mouser, Digikey. This is a very common battery as it is used in a lot of EXIT signs so they are lighted when the power goes out. I don't see how the 12V 7AH will fit as they are too large. I guess you could use a 12V 5AH (PS1250) as it is the same size as 2 x 6 volt 4 AH but the terminals are in the wrong place so you will have to nibble out the aluminum plate that holds them in the 732A battery pack. You have to be careful if you use the 12v 5AH as you will have 4 extra battery connection leads to deal with and connect correctly. I would stick with the 6V 4AH. New batteries will last around 12 to 14 hours before the CAL light goes out when AC power is not applied. So shipping to Cal Lab can be a problem if it is a distance away, or you have to use a shipper like UPS or FEDEX and you ship the night before and then use their Morning delivery and the Cal Lab is expecting your 732A. Same on the way back to you. Of course you could always strap another battery on the 732A and hook it up to the ext power plug to last longer. I have seen it done. The issue is to get the Cal Lab to charge the extra battery before they ship the 732A back to you. When you remove and work on the battery pack always have the AC power plugged in. The CAL led will stay on because the 18.6 v regulated supply is working. The CAL light is to indicate that power has not been lost to the Reference Amp or other associated circuits. When the raw supply (battery) voltage drops below about 21 volts the CAL light will go out. Below that voltage the heater circuits will not work correctly and the 18.6 volt regulated supply will not regulate. The requirement is that the Reference Amp be kept alive at all times to maintain the output voltage that was measured at the time of the most recent Calibration or Certification. When the semiconductor junctions are unbiased and cool off when power is lost, and then power is restored the result will be a different 10 volts than before the power failure. My experience is that after all of the years that these units have been powered up, this won't happen and when power is lost and then restored, even months later, the 732A will come back to almost exactly the same 10 volts as when they lost power, usually with in 0.2 PPM after 24 hours of warm up. What type of hookup leads are you using when measuring the 1 volt output? What is the PLC set to? I always
Re: [volt-nuts] 732A and Prologix received
Randy: The MATH function is accessible from the keypad. I don't have an IEEE interface right now that works. You can also program the numeric keypad keys to have preprogrammed functions. DEFKEY I have made my own low thermal measurement leads from Pomona #4892 banana plugs and Belden #9272 wire. Why 9272, because it was handy at the time. It is tin plated copper, shielded twisted pair 20 ga. I have plans to do custom cables with 16 ga. bare copper wire that I will twist and then put a braided shield over it. I simply cannot find what I want so I will build my own cable. I have done something like this before and it worked fine. When I get a round toit. I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I have used in the past to verify my homemade low thermal leads as described above. Frankly I cannot see any difference between using the 1756 cables and my homemade cables once I give them a few minutes for the thermals to go away. As far as I can tell and measure the differences, if any, are below 0.1 ppm at 10 volts. Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A are all adjustable you may be seeing a misadjusted 1 volt from the 732A. As far as the instability of the readings it is hard to determine which is causing the problem. I have programed (DEFKEY) a numeric keypad key #1 with the following code. MATH 14;NRDGS 40;TRIG 4;TRIG ; So what this does is set the MATH to Statistics (store high reading/low reading/ and mean of the readings) in the registers, the number of readings to 40, the trigger to hold (which keeps the meter from triggering until I press ENTER and then trigger the sequence of 40 readings when I push the ENTER button. You can do all of this manually from the keypads but since I use this sequence a lot I have preprogrammed it. This is after I set digits to 8 and PLC to 100. Once those 40 readings are finished then you can access the various MATH statistic registers, using the menu, by entering MATH and then a 2 for low, a 4 for mean, and 13 for high. Of course you could do all of this through the IEEE also. The 3458A has a very rich set of measurement commands. I am still learning all of them. It depends upon what I am trying to accomplish. Since the 1.018 and 1.0 volt outputs are passive and derived from resistive dividers from the 10 volt, I don't see how they could contribute to the varying readings you are measuring. I think I would put a short on the input of the 3458A and manually set the range to 1 volt and then observe the variations that way without the 732A involved. When I do this I see a variation from low reading to high reading of 0.125 uVolts and then another 40 I get 0.155 uVolts. This is without the GUARD connected to the low side of the measurment terminals, GUARD connected doesn't seem to affect the readings. So that is the base noise of the 3458A without the 732A, somewhere below .2uVolts. When hooked up to the 732A 1.0 volt output I got a variation of 0.159 uVolts using the same 40 reading method above. I would use this to determine where your problem might exist. Just having the meter input shorted will point you in the right direction. Meter, cables or 732A. Sorry for the long dissertation. Friends get mad at me for being so detailed sometimes. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Sunday, August 24, 2014 7:22 AM Subject: Re: [volt-nuts] 732A and Prologix received Bill, I have convinced myself that the problem I an seeing is due to thermals. If I move the cables (with gold-plated banana plugs) using a small towel rather than letting my hand touch the plugs, it is much more stable. If I then hold the banana plug with my hand after the reading has stabilized, the reading drifts rapidly upward. I am trying to check the stability of the reading but I haven't figured out the MATH function yet. I assume this is a programmed function using GPIB only? The stability I am seeing by manually recording readings (using NLPC of 100 and 1000) is much greater than what you are measuring on your system. Not sure how to ascertain if it's the 3458A or the 732. The value of the readings are very different between the two - the 3458 reads about 50 uV high on the 10 V output and about 12 uV low on the 1V output. Rather large differences (this is after an ACAL). I need to find some better cables to make sure the errors are not due to thermals again. Randy On Sat, Aug 23, 2014 at 10:21 AM, Bill Gold wpgold3...@att.net wrote: Randy: I get 6 volt 4 amp/hr (or 4.5 amp/hr) batteries and they will fit perfect. Power Sonic PS-640, Genesis NP4-6, Panasonic LC-R064R5C and others that are in this size and package. Order from one of the usual electronics distributors like Allied, Mouser, Digikey. This is a very common battery as it is used in a
Re: [volt-nuts] 732A and Prologix received
Bill, Thanks for the MATH overview. That could be very helpful. I definately will give it a try. Randy On Sun, Aug 24, 2014 at 2:44 PM, Bill Gold wpgold3...@att.net wrote: Todd: I check the batteries every month per the 732A manual. Usually I keep a few used cells from previous packs around that seem to be ok after checking them for capacity just like checking the battery pack. I can usually spot cells going bad with that method. If I don't have a spare set then I just substitute a used cell until I receive a new set. I agree with you that the cheap ones are crap. I have used Power Sonic a lot with some a few EaglePicher and one set of Enersys. The EaglePicher are crap so I will never use them. EaglePicher have had a couple out of 8 that have failed very early. I have never tried Panasonic. So I stick with the Power Sonic's. I am not sure why the 12 volt ones would be better than the 6 volts because 12 volt is just 6 lead acid cells while the 6volt are 3 lead acid cells. If one of the 6 cells in the 12 volt battery go bad then the whole battery has to be changed. So you better buy good quality 12 volt batteries. I just can't seem to source batteries locally easily at a reasonable price. So I order them from Allied usually. Bill - Original Message - From: Todd Micallef tmical...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Sunday, August 24, 2014 8:13 AM Subject: Re: [volt-nuts] 732A and Prologix received Bill, I use a lot of the 12v 7ah batteries for my UPS backups and 732B. But yes, I was mistaken. The 12V 5ah batteries are the ones that I am using in one of my 732A. There is more play inside the tray with the 12v batteries by several mm as compared to the 6v which only has a 2-3mm. The 12v conversion is not difficult, but it is easier if the battery tray has already been machined for the 12v batteries. The battery tabs don't line up well with the existing holes and need to be widened. Two additional holes must also be added. Sourcing the batteries locally is more of a convenience than waiting for the delivery. The el-cheapo 6v batteries are a waste of money and I have 8 batteries so far to prove it. They died the first time I had a 6hr outage and would not hold a charge after that. Todd On Sat, Aug 23, 2014 at 1:21 PM, Bill Gold wpgold3...@att.net wrote: Randy: I get 6 volt 4 amp/hr (or 4.5 amp/hr) batteries and they will fit perfect. Power Sonic PS-640, Genesis NP4-6, Panasonic LC-R064R5C and others that are in this size and package. Order from one of the usual electronics distributors like Allied, Mouser, Digikey. This is a very common battery as it is used in a lot of EXIT signs so they are lighted when the power goes out. I don't see how the 12V 7AH will fit as they are too large. I guess you could use a 12V 5AH (PS1250) as it is the same size as 2 x 6 volt 4 AH but the terminals are in the wrong place so you will have to nibble out the aluminum plate that holds them in the 732A battery pack. You have to be careful if you use the 12v 5AH as you will have 4 extra battery connection leads to deal with and connect correctly. I would stick with the 6V 4AH. New batteries will last around 12 to 14 hours before the CAL light goes out when AC power is not applied. So shipping to Cal Lab can be a problem if it is a distance away, or you have to use a shipper like UPS or FEDEX and you ship the night before and then use their Morning delivery and the Cal Lab is expecting your 732A. Same on the way back to you. Of course you could always strap another battery on the 732A and hook it up to the ext power plug to last longer. I have seen it done. The issue is to get the Cal Lab to charge the extra battery before they ship the 732A back to you. When you remove and work on the battery pack always have the AC power plugged in. The CAL led will stay on because the 18.6 v regulated supply is working. The CAL light is to indicate that power has not been lost to the Reference Amp or other associated circuits. When the raw supply (battery) voltage drops below about 21 volts the CAL light will go out. Below that voltage the heater circuits will not work correctly and the 18.6 volt regulated supply will not regulate. The requirement is that the Reference Amp be kept alive at all times to maintain the output voltage that was measured at the time of the most recent Calibration or Certification. When the semiconductor junctions are unbiased and cool off when power is lost, and then power is restored the result will be a different 10 volts than before the power failure. My experience is that after all of the years that these units have been powered up, this won't happen and when power is lost
Re: [volt-nuts] 732A and Prologix received
Bill, I am trying to figure out the MATH function without much success. The 3458 On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold wpgold3...@att.net wrote: Randy: The MATH function is accessible from the keypad. I don't have an IEEE interface right now that works. You can also program the numeric keypad keys to have preprogrammed functions. DEFKEY I have made my own low thermal measurement leads from Pomona #4892 banana plugs and Belden #9272 wire. Why 9272, because it was handy at the time. It is tin plated copper, shielded twisted pair 20 ga. I have plans to do custom cables with 16 ga. bare copper wire that I will twist and then put a braided shield over it. I simply cannot find what I want so I will build my own cable. I have done something like this before and it worked fine. When I get a round toit. I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I have used in the past to verify my homemade low thermal leads as described above. Frankly I cannot see any difference between using the 1756 cables and my homemade cables once I give them a few minutes for the thermals to go away. As far as I can tell and measure the differences, if any, are below 0.1 ppm at 10 volts. Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A are all adjustable you may be seeing a misadjusted 1 volt from the 732A. As far as the instability of the readings it is hard to determine which is causing the problem. I have programed (DEFKEY) a numeric keypad key #1 with the following code. MATH 14;NRDGS 40;TRIG 4;TRIG ; So what this does is set the MATH to Statistics (store high reading/low reading/ and mean of the readings) in the registers, the number of readings to 40, the trigger to hold (which keeps the meter from triggering until I press ENTER and then trigger the sequence of 40 readings when I push the ENTER button. You can do all of this manually from the keypads but since I use this sequence a lot I have preprogrammed it. This is after I set digits to 8 and PLC to 100. Once those 40 readings are finished then you can access the various MATH statistic registers, using the menu, by entering MATH and then a 2 for low, a 4 for mean, and 13 for high. Of course you could do all of this through the IEEE also. The 3458A has a very rich set of measurement commands. I am still learning all of them. It depends upon what I am trying to accomplish. Since the 1.018 and 1.0 volt outputs are passive and derived from resistive dividers from the 10 volt, I don't see how they could contribute to the varying readings you are measuring. I think I would put a short on the input of the 3458A and manually set the range to 1 volt and then observe the variations that way without the 732A involved. When I do this I see a variation from low reading to high reading of 0.125 uVolts and then another 40 I get 0.155 uVolts. This is without the GUARD connected to the low side of the measurment terminals, GUARD connected doesn't seem to affect the readings. So that is the base noise of the 3458A without the 732A, somewhere below .2uVolts. When hooked up to the 732A 1.0 volt output I got a variation of 0.159 uVolts using the same 40 reading method above. I would use this to determine where your problem might exist. Just having the meter input shorted will point you in the right direction. Meter, cables or 732A. Sorry for the long dissertation. Friends get mad at me for being so detailed sometimes. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Sunday, August 24, 2014 7:22 AM Subject: Re: [volt-nuts] 732A and Prologix received Bill, I have convinced myself that the problem I an seeing is due to thermals. If I move the cables (with gold-plated banana plugs) using a small towel rather than letting my hand touch the plugs, it is much more stable. If I then hold the banana plug with my hand after the reading has stabilized, the reading drifts rapidly upward. I am trying to check the stability of the reading but I haven't figured out the MATH function yet. I assume this is a programmed function using GPIB only? The stability I am seeing by manually recording readings (using NLPC of 100 and 1000) is much greater than what you are measuring on your system. Not sure how to ascertain if it's the 3458A or the 732. The value of the readings are very different between the two - the 3458 reads about 50 uV high on the 10 V output and about 12 uV low on the 1V output. Rather large differences (this is after an ACAL). I need to find some better cables to make sure the errors are not due to thermals again. Randy On Sat, Aug 23, 2014 at 10:21 AM, Bill Gold wpgold3...@att.net wrote: Randy: I get 6 volt 4 amp/hr (or 4.5 amp/hr) batteries and they will fit
Re: [volt-nuts] 732A and Prologix received
Bill, I am trying to figure out the MATH function without much success. I input the sequence you said (I looked up the instructions to understand what you did - seems logical), BLUE DEFKEY BLUE F1 MATH 14;NRDGS 40;TRIG 4;TRIG; and it shows up on the display when I input BLUE F1. I hit ENTER and it takes the 40 measurements and the MATH symbol shows on the display during the measurements. After the SMPL symbol no longer blinks I hit MATH 2 and I get a MATH ERR symbol on the display. I tried it a couple of times and the same result so I am doing something wrong. Is there a better source for explaining how to do front panel masurements than the User Guide, which seems oriented at programming automatic rather than manual measurements. Randy On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold wpgold3...@att.net wrote: Randy: The MATH function is accessible from the keypad. I don't have an IEEE interface right now that works. You can also program the numeric keypad keys to have preprogrammed functions. DEFKEY I have made my own low thermal measurement leads from Pomona #4892 banana plugs and Belden #9272 wire. Why 9272, because it was handy at the time. It is tin plated copper, shielded twisted pair 20 ga. I have plans to do custom cables with 16 ga. bare copper wire that I will twist and then put a braided shield over it. I simply cannot find what I want so I will build my own cable. I have done something like this before and it worked fine. When I get a round toit. I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I have used in the past to verify my homemade low thermal leads as described above. Frankly I cannot see any difference between using the 1756 cables and my homemade cables once I give them a few minutes for the thermals to go away. As far as I can tell and measure the differences, if any, are below 0.1 ppm at 10 volts. Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A are all adjustable you may be seeing a misadjusted 1 volt from the 732A. As far as the instability of the readings it is hard to determine which is causing the problem. I have programed (DEFKEY) a numeric keypad key #1 with the following code. MATH 14;NRDGS 40;TRIG 4;TRIG ; So what this does is set the MATH to Statistics (store high reading/low reading/ and mean of the readings) in the registers, the number of readings to 40, the trigger to hold (which keeps the meter from triggering until I press ENTER and then trigger the sequence of 40 readings when I push the ENTER button. You can do all of this manually from the keypads but since I use this sequence a lot I have preprogrammed it. This is after I set digits to 8 and PLC to 100. Once those 40 readings are finished then you can access the various MATH statistic registers, using the menu, by entering MATH and then a 2 for low, a 4 for mean, and 13 for high. Of course you could do all of this through the IEEE also. The 3458A has a very rich set of measurement commands. I am still learning all of them. It depends upon what I am trying to accomplish. Since the 1.018 and 1.0 volt outputs are passive and derived from resistive dividers from the 10 volt, I don't see how they could contribute to the varying readings you are measuring. I think I would put a short on the input of the 3458A and manually set the range to 1 volt and then observe the variations that way without the 732A involved. When I do this I see a variation from low reading to high reading of 0.125 uVolts and then another 40 I get 0.155 uVolts. This is without the GUARD connected to the low side of the measurment terminals, GUARD connected doesn't seem to affect the readings. So that is the base noise of the 3458A without the 732A, somewhere below .2uVolts. When hooked up to the 732A 1.0 volt output I got a variation of 0.159 uVolts using the same 40 reading method above. I would use this to determine where your problem might exist. Just having the meter input shorted will point you in the right direction. Meter, cables or 732A. Sorry for the long dissertation. Friends get mad at me for being so detailed sometimes. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Sunday, August 24, 2014 7:22 AM Subject: Re: [volt-nuts] 732A and Prologix received Bill, I have convinced myself that the problem I an seeing is due to thermals. If I move the cables (with gold-plated banana plugs) using a small towel rather than letting my hand touch the plugs, it is much more stable. If I then hold the banana plug with my hand after the reading has stabilized, the reading drifts rapidly upward. I am trying to check the stability of the reading but I haven't figured out the MATH function yet. I assume this is a programmed function using GPIB only? The stability I am
Re: [volt-nuts] 732A and Prologix received
Hi Randy, You can use the NPLC command to change the A/D converter's'integration time. Set it to 1000 if you want full resolution. It sets the hp3458a's NMR. Charlie On 8/24/2014 6:04 PM, Randy Evans wrote: Bill, I am trying to figure out the MATH function without much success. I input the sequence you said (I looked up the instructions to understand what you did - seems logical), BLUE DEFKEY BLUE F1 MATH 14;NRDGS 40;TRIG 4;TRIG; and it shows up on the display when I input BLUE F1. I hit ENTER and it takes the 40 measurements and the MATH symbol shows on the display during the measurements. After the SMPL symbol no longer blinks I hit MATH 2 and I get a MATH ERR symbol on the display. I tried it a couple of times and the same result so I am doing something wrong. Is there a better source for explaining how to do front panel masurements than the User Guide, which seems oriented at programming automatic rather than manual measurements. Randy On Sun, Aug 24, 2014 at 4:46 PM, Bill Gold wpgold3...@att.net wrote: Randy: The MATH function is accessible from the keypad. I don't have an IEEE interface right now that works. You can also program the numeric keypad keys to have preprogrammed functions. DEFKEY I have made my own low thermal measurement leads from Pomona #4892 banana plugs and Belden #9272 wire. Why 9272, because it was handy at the time. It is tin plated copper, shielded twisted pair 20 ga. I have plans to do custom cables with 16 ga. bare copper wire that I will twist and then put a braided shield over it. I simply cannot find what I want so I will build my own cable. I have done something like this before and it worked fine. When I get a round toit. I have 6 ea. Pomona 1756-48 spade lug low thermal leads that I have used in the past to verify my homemade low thermal leads as described above. Frankly I cannot see any difference between using the 1756 cables and my homemade cables once I give them a few minutes for the thermals to go away. As far as I can tell and measure the differences, if any, are below 0.1 ppm at 10 volts. Since the 10 volt, 1.0 volt and 1.018 volt outputs on the 732A are all adjustable you may be seeing a misadjusted 1 volt from the 732A. As far as the instability of the readings it is hard to determine which is causing the problem. I have programed (DEFKEY) a numeric keypad key #1 with the following code. MATH 14;NRDGS 40;TRIG 4;TRIG ; So what this does is set the MATH to Statistics (store high reading/low reading/ and mean of the readings) in the registers, the number of readings to 40, the trigger to hold (which keeps the meter from triggering until I press ENTER and then trigger the sequence of 40 readings when I push the ENTER button. You can do all of this manually from the keypads but since I use this sequence a lot I have preprogrammed it. This is after I set digits to 8 and PLC to 100. Once those 40 readings are finished then you can access the various MATH statistic registers, using the menu, by entering MATH and then a 2 for low, a 4 for mean, and 13 for high. Of course you could do all of this through the IEEE also. The 3458A has a very rich set of measurement commands. I am still learning all of them. It depends upon what I am trying to accomplish. Since the 1.018 and 1.0 volt outputs are passive and derived from resistive dividers from the 10 volt, I don't see how they could contribute to the varying readings you are measuring. I think I would put a short on the input of the 3458A and manually set the range to 1 volt and then observe the variations that way without the 732A involved. When I do this I see a variation from low reading to high reading of 0.125 uVolts and then another 40 I get 0.155 uVolts. This is without the GUARD connected to the low side of the measurment terminals, GUARD connected doesn't seem to affect the readings. So that is the base noise of the 3458A without the 732A, somewhere below .2uVolts. When hooked up to the 732A 1.0 volt output I got a variation of 0.159 uVolts using the same 40 reading method above. I would use this to determine where your problem might exist. Just having the meter input shorted will point you in the right direction. Meter, cables or 732A. Sorry for the long dissertation. Friends get mad at me for being so detailed sometimes. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: Discussion of precise voltage measurement volt-nuts@febo.com Sent: Sunday, August 24, 2014 7:22 AM Subject: Re: [volt-nuts] 732A and Prologix received Bill, I have convinced myself that the problem I an seeing is due to thermals. If I move the cables (with gold-plated banana plugs) using a small towel rather than letting my hand touch the plugs, it is much more stable. If I then hold the banana plug with my hand after the reading has stabilized, the reading drifts rapidly upward. I am trying to check the stability of the
Re: [volt-nuts] 732A and Prologix received
On Sun, Aug 24, 2014 at 1:46 PM, Don@True-Cal truecalservi...@gmail.com wrote: Randy all, You have correctly concluded that some (maybe not all) of your measurement problem is thermal EMF being added or subtracted in series within your measurement interconnect. This thermal EMF is generated at the junction of dissimilar metals when accompanied with thermal gradients between the test lead and device terminals. You have to eliminate both the dissimilarity of the metal junctions as well as minimize the thermal differences. The terminals of the 3458A as well as the 732A are Beryllium Copper so you want to use the same test lead terminals. Forget the typical Tin plated lugs or even Gold plated as both are not Beryllium Copper and constitute dissimilar metals. The best solution (as usually the most expensive) is to use a set of Fluke 5440A-7005 (48) cables. I also have just as good results using the much more flexible Pomona 11174A (lugs end always stay connected to the 732A) or 11058A with more convenient shielded banana plugs. The Fluke cable has the added Guard built in but be sure to also use a Guard lead with the Pomona cabled. The Guard lead does not need to be low thermal EMF. DIY cables is usually not a good idea because the lead wire to terminal also constitutes just as critical of junction. The above cables use Tellurium Copper wire which is usually hard to find and hard to crimp properly and NEVER solder. 11058A and 11174A are discontinued at Keysight. However, Pomona 5295 spade to banana cables are available (5295-36 at Mouser et al) and claim that they are designed to minimize thermal EMFs. Datasheet is here: http://www.mouser.com/ds/2/159/d5295_1_01-51722.pdf Any comments on these as an alternative? Orin. ___ 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.
