Re: [volt-nuts] Fluke 732A themistor reading
well, re. the resistor, question is how stable it is, not so much absolute value. if not very good, your 3458a may be more stable that your reference. vpg hermetic foil 4 wire resistors are very stable (1ppm pa) and are cheap (50usd). re the wire, you should use twisted shielded pair. there are good teflon tsp wires with kapton isolation (as used in satellites) on sale on ebay. use copper gold plated terminals, around one usd and crimp them. pure copper wire is not needed. cheers adrian Gesendet: Montag, 18. August 2014 um 01:03 Uhr Von: Randy Evans randyevans2...@gmail.com An: Discussion of precise voltage measurement volt-nuts@febo.com Betreff: Re: [volt-nuts] Fluke 732A themistor reading I do have an ESI SR1 10Kohm standard, but I'm not sure its accurate enough...time to look around I suppose. BTW, I understand that TV twin lead, the copper wire type, makes a good test lead for the 3458 measurements. It seems reasonable, although the leakage resistance might be questionable. Randy On Sun, Aug 17, 2014 at 1:36 PM, Todd Micallef tmical...@gmail.com wrote: Randy, Next thing you know, you will be looking at a 10K standard resistor to go with that 3458A and possible 732A. Todd On Sun, Aug 17, 2014 at 3:51 PM, Randy Evans randyevans2...@gmail.com wrote: Todd and Bill, Thanks for the input. The 3.6 K thermistor reading seems viable and i will pursue it further. I may have over committed myself to modifying the HP-419A, the Fluke 845A, buying the 3458A and looking at buying a Fluke 732A. So much to do and so little time. Thanks again, Randy On Sun, Aug 17, 2014 at 11:48 AM, Bill Gold wpgold3...@att.net wrote: Randy: I have 6 ea Fluke 732A instruments. The results of being an over the edge and deeply obsessed Volt Nut, they just kept adding (reproducing?) over the years. My readings for the themistors range from 3.407K OHMS to 4.514K OHMS and all work just fine. 3.6K OHMS would seem just fine to me. It really depends upon the final inside temp of the oven assembly. The one with 3.407K OHMS measures around 47.5 degrees C while the others are around 45 C. It is the stability of this reading over time that is very important. Fluke says that it could change as much as 10 ohms per month but mine are rock solid for years and years. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: volt-nuts@febo.com Sent: Sunday, August 17, 2014 11:08 AM Subject: [volt-nuts] Fluke 732A themistor reading Can anyone tell me what value to expect for a Fluke 732A thermistor reading? I am looking to get a used 732A and one of the things I was told to look for is to measure the thermistor reading after the unit has heated up for at least an hour. I saw in one of the posts that a typical reading was 4950 ohms. One vendor I asked said he measured about 3600 ohms after a two hour warmup. I was concerned that this is too low. What do you guys think? Thanks, Randy ___ 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. ___ 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] Fluke 732A themistor reading
Randy, Two of mine read in the 3.7-3.8K range, another reads in the 4.2K range. It is a good sign if the reading dropped in a few hours after turn-on. I believe the lower thermistor readings indicate the older 732A oven. Some minor changes were made and both manuals are available on Didier's site. Verify that the 1V and 1.018V outputs are functioning as well as the 10V obviously. There have been a few sold recently on eBay with one or both of the 1V outputs reading low or dead. Todd On Sun, Aug 17, 2014 at 2:08 PM, Randy Evans randyevans2...@gmail.com wrote: Can anyone tell me what value to expect for a Fluke 732A thermistor reading? I am looking to get a used 732A and one of the things I was told to look for is to measure the thermistor reading after the unit has heated up for at least an hour. I saw in one of the posts that a typical reading was 4950 ohms. One vendor I asked said he measured about 3600 ohms after a two hour warmup. I was concerned that this is too low. What do you guys think? Thanks, Randy ___ 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] Fluke 732A themistor reading
Randy: I have 6 ea Fluke 732A instruments. The results of being an over the edge and deeply obsessed Volt Nut, they just kept adding (reproducing?) over the years. My readings for the themistors range from 3.407K OHMS to 4.514K OHMS and all work just fine. 3.6K OHMS would seem just fine to me. It really depends upon the final inside temp of the oven assembly. The one with 3.407K OHMS measures around 47.5 degrees C while the others are around 45 C. It is the stability of this reading over time that is very important. Fluke says that it could change as much as 10 ohms per month but mine are rock solid for years and years. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: volt-nuts@febo.com Sent: Sunday, August 17, 2014 11:08 AM Subject: [volt-nuts] Fluke 732A themistor reading Can anyone tell me what value to expect for a Fluke 732A thermistor reading? I am looking to get a used 732A and one of the things I was told to look for is to measure the thermistor reading after the unit has heated up for at least an hour. I saw in one of the posts that a typical reading was 4950 ohms. One vendor I asked said he measured about 3600 ohms after a two hour warmup. I was concerned that this is too low. What do you guys think? Thanks, Randy ___ 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] Fluke 732A themistor reading
Todd and Bill, Thanks for the input. The 3.6 K thermistor reading seems viable and i will pursue it further. I may have over committed myself to modifying the HP-419A, the Fluke 845A, buying the 3458A and looking at buying a Fluke 732A. So much to do and so little time. Thanks again, Randy On Sun, Aug 17, 2014 at 11:48 AM, Bill Gold wpgold3...@att.net wrote: Randy: I have 6 ea Fluke 732A instruments. The results of being an over the edge and deeply obsessed Volt Nut, they just kept adding (reproducing?) over the years. My readings for the themistors range from 3.407K OHMS to 4.514K OHMS and all work just fine. 3.6K OHMS would seem just fine to me. It really depends upon the final inside temp of the oven assembly. The one with 3.407K OHMS measures around 47.5 degrees C while the others are around 45 C. It is the stability of this reading over time that is very important. Fluke says that it could change as much as 10 ohms per month but mine are rock solid for years and years. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: volt-nuts@febo.com Sent: Sunday, August 17, 2014 11:08 AM Subject: [volt-nuts] Fluke 732A themistor reading Can anyone tell me what value to expect for a Fluke 732A thermistor reading? I am looking to get a used 732A and one of the things I was told to look for is to measure the thermistor reading after the unit has heated up for at least an hour. I saw in one of the posts that a typical reading was 4950 ohms. One vendor I asked said he measured about 3600 ohms after a two hour warmup. I was concerned that this is too low. What do you guys think? Thanks, Randy ___ 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.
Re: [volt-nuts] Fluke 732A themistor reading
I do have an ESI SR1 10Kohm standard, but I'm not sure its accurate enough...time to look around I suppose. BTW, I understand that TV twin lead, the copper wire type, makes a good test lead for the 3458 measurements. It seems reasonable, although the leakage resistance might be questionable. Randy On Sun, Aug 17, 2014 at 1:36 PM, Todd Micallef tmical...@gmail.com wrote: Randy, Next thing you know, you will be looking at a 10K standard resistor to go with that 3458A and possible 732A. Todd On Sun, Aug 17, 2014 at 3:51 PM, Randy Evans randyevans2...@gmail.com wrote: Todd and Bill, Thanks for the input. The 3.6 K thermistor reading seems viable and i will pursue it further. I may have over committed myself to modifying the HP-419A, the Fluke 845A, buying the 3458A and looking at buying a Fluke 732A. So much to do and so little time. Thanks again, Randy On Sun, Aug 17, 2014 at 11:48 AM, Bill Gold wpgold3...@att.net wrote: Randy: I have 6 ea Fluke 732A instruments. The results of being an over the edge and deeply obsessed Volt Nut, they just kept adding (reproducing?) over the years. My readings for the themistors range from 3.407K OHMS to 4.514K OHMS and all work just fine. 3.6K OHMS would seem just fine to me. It really depends upon the final inside temp of the oven assembly. The one with 3.407K OHMS measures around 47.5 degrees C while the others are around 45 C. It is the stability of this reading over time that is very important. Fluke says that it could change as much as 10 ohms per month but mine are rock solid for years and years. Bill - Original Message - From: Randy Evans randyevans2...@gmail.com To: volt-nuts@febo.com Sent: Sunday, August 17, 2014 11:08 AM Subject: [volt-nuts] Fluke 732A themistor reading Can anyone tell me what value to expect for a Fluke 732A thermistor reading? I am looking to get a used 732A and one of the things I was told to look for is to measure the thermistor reading after the unit has heated up for at least an hour. I saw in one of the posts that a typical reading was 4950 ohms. One vendor I asked said he measured about 3600 ohms after a two hour warmup. I was concerned that this is too low. What do you guys think? Thanks, Randy ___ 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. ___ 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.
