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Calibration Of Electronic Equipment In The Home Workshop
On Wed, 07 Mar 2007 06:25:48 GMT, Robert Baer
Gave us: I gave up responding to him a while back as being a useless waste of time. Ahh... so you're a double posting dope too! This dope is still running windows 98! |
Calibration Of Electronic Equipment In The Home Workshop
On Wed, 7 Mar 2007 02:45:32 -0600, "Anthony Fremont"
Gave us: Anthony Fremont wrote: 50nA you idiot. DO THE MATH! BTW, I'm surprised you didn't have anything to say about my Extech/Micronta Shootout thread? I did some resistance measurements and the Micronta is right on with way less than 1% difference. Drifted to another plane, ha ha ha 15 years old and still within 1% on most functions. HA HA HA HA Wrong again DM. How would you know without a reliable device to check it against, dip****? I'll clue you... the extech ain't it. Bwuahahahahahaahah! |
Calibration Of Electronic Equipment In The Home Workshop
MassiveProng wrote:
On Wed, 7 Mar 2007 02:45:32 -0600, "Anthony Fremont" Gave us: Anthony Fremont wrote: 50nA you idiot. DO THE MATH! BTW, I'm surprised you didn't have anything to say about my Extech/Micronta Shootout thread? I did some resistance measurements and the Micronta is right on with way less than 1% difference. Drifted to another plane, ha ha ha 15 years old and still within 1% on most functions. HA HA HA HA Wrong again DM. How would you know without a reliable device to check it against, dip****? I'll clue you... the extech ain't it. Bwuahahahahahaahah! Oh really? And just how do you figure that? It's brand new and it was available with an NIST certificate (though I didn't opt for it). I guess I need to send it to you so you can verify it against your Protek? |
Calibration Of Electronic Equipment In The Home Workshop
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Calibration Of Electronic Equipment In The Home Workshop
On Wed, 7 Mar 2007 07:06:35 -0600, "Anthony Fremont"
Gave us: MassiveProng wrote: On Wed, 7 Mar 2007 02:45:32 -0600, "Anthony Fremont" Gave us: Anthony Fremont wrote: 50nA you idiot. DO THE MATH! BTW, I'm surprised you didn't have anything to say about my Extech/Micronta Shootout thread? I did some resistance measurements and the Micronta is right on with way less than 1% difference. Drifted to another plane, ha ha ha 15 years old and still within 1% on most functions. HA HA HA HA Wrong again DM. How would you know without a reliable device to check it against, dip****? I'll clue you... the extech ain't it. Bwuahahahahahaahah! Oh really? And just how do you figure that? It's brand new and it was available with an NIST certificate (though I didn't opt for it). I guess I need to send it to you so you can verify it against your Protek? I told you, dumbass, I have a calibrated HP 3478A. The protek is ANOTHER meter I have, and I use the HP to verify it. Your NON NIST traceable and certified Extech is calibrated by an assembler that was working enough years to end up in the production test lab. Their prime pass yields are likely far less than 90%, and 96% is considered poor. Yes, you'll have to look that one up. I'll say it again... Bwuahahahahahahaha! |
Calibration Of Electronic Equipment In The Home Workshop
MassiveProng wrote:
On Wed, 7 Mar 2007 07:06:35 -0600, "Anthony Fremont" Gave us: MassiveProng wrote: On Wed, 7 Mar 2007 02:45:32 -0600, "Anthony Fremont" Gave us: Anthony Fremont wrote: 50nA you idiot. DO THE MATH! BTW, I'm surprised you didn't have anything to say about my Extech/Micronta Shootout thread? I did some resistance measurements and the Micronta is right on with way less than 1% difference. Drifted to another plane, ha ha ha 15 years old and still within 1% on most functions. HA HA HA HA Wrong again DM. How would you know without a reliable device to check it against, dip****? I'll clue you... the extech ain't it. Bwuahahahahahaahah! Oh really? And just how do you figure that? It's brand new and it was available with an NIST certificate (though I didn't opt for it). I guess I need to send it to you so you can verify it against your Protek? I told you, dumbass, I have a calibrated HP 3478A. The protek is ANOTHER meter I have, and I use the HP to verify it. Your NON NIST traceable and certified Extech is calibrated by an assembler that was working enough years to end up in the production test lab. At least you didn't touch it. Their prime pass yields are likely far less than 90%, and 96% is considered poor. Yes, you'll have to look that one up. I'll say it again... Bwuahahahahahahaha! Funny how it can be sent in and certified after the sale. I wonder how they know who to send the good ones to. These meters you have at home, what do you use them for? I mean I never see a schematic from you or hear of you tinkering with some kind of experiment. Why is that? |
Calibration Of Electronic Equipment In The Home Workshop
On Wed, 7 Mar 2007 20:27:58 -0600, "Anthony Fremont"
Gave us: Funny how it can be sent in and certified after the sale. Anything can, you ****in' retard. |
Calibration Of Electronic Equipment In The Home Workshop
On Mar 8, 10:57 am, MassiveProng
wrote: On Wed, 7 Mar 2007 07:06:35 -0600, "Anthony Fremont" Gave us: MassiveProng wrote: On Wed, 7 Mar 2007 02:45:32 -0600, "Anthony Fremont" Gave us: Anthony Fremont wrote: 50nA you idiot. DO THE MATH! BTW, I'm surprised you didn't have anything to say about my Extech/Micronta Shootout thread? I did some resistance measurements and the Micronta is right on with way less than 1% difference. Drifted to another plane, ha ha ha 15 years old and still within 1% on most functions. HA HA HA HA Wrong again DM. How would you know without a reliable device to check it against, dip****? I'll clue you... the extech ain't it. Bwuahahahahahaahah! Oh really? And just how do you figure that? It's brand new and it was available with an NIST certificate (though I didn't opt for it). I guess I need to send it to you so you can verify it against your Protek? I told you, dumbass, I have a calibrated HP 3478A. The protek is ANOTHER meter I have, and I use the HP to verify it. You don't even know when you are being made fun of! Your NON NIST traceable and certified Extech is calibrated by an assembler that was working enough years to end up in the production test lab. At this price and accuracy level it is almost certain that every unit would be automatically factory tested to be in-spec, so the NIST cert is worth the paper it's written on. You can bet the farm that Anthony's new meter meets the published specs. Dave :) |
Calibration Of Electronic Equipment In The Home Workshop
On 8 Mar 2007 01:02:52 -0800, "David L. Jones"
Gave us: At this price and accuracy level it is almost certain that every unit would be automatically factory tested to be in-spec, so the NIST cert is worth the paper it's written on. You can bet the farm that Anthony's new meter meets the published specs. Idiot! His meter is NOT certified. Learn to read. |
Calibration Of Electronic Equipment In The Home Workshop
MassiveProng wrote:
On 8 Mar 2007 01:02:52 -0800, "David L. Jones" Gave us: At this price and accuracy level it is almost certain that every unit would be automatically factory tested to be in-spec, so the NIST cert is worth the paper it's written on. You can bet the farm that Anthony's new meter meets the published specs. Idiot! His meter is NOT certified. Learn to read. It comes with specs, they always apply. Wasn't it you that said that certs were often just a check not necessarily turning screws? If the meter said Agilent or Fluke on it, would you even be mentioning this? How come you didn't say anything about the RMS convertor behaving the way I described? I thought you were knowledgeable on this stuff. |
Calibration Of Electronic Equipment In The Home Workshop
"Anthony Fremont" wrote in
: MassiveProng wrote: On 8 Mar 2007 01:02:52 -0800, "David L. Jones" Gave us: At this price and accuracy level it is almost certain that every unit would be automatically factory tested to be in-spec, so the NIST cert is worth the paper it's written on. You can bet the farm that Anthony's new meter meets the published specs. Idiot! His meter is NOT certified. Learn to read. It comes with specs, they always apply. Wasn't it you that said that certs were often just a check not necessarily turning screws? If the meter said Agilent or Fluke on it, would you even be mentioning this? How come you didn't say anything about the RMS convertor behaving the way I described? I thought you were knowledgeable on this stuff. Cal Certificates just state the instrument was calibrated using known standards traceable to NIST,the date the work was done,temp and humidity conditions,and the recommended cal interval.They may list the standards used and their expiration dates. -- Jim Yanik jyanik at kua.net |
Calibration Of Electronic Equipment In The Home Workshop
Finding the keyboard operational
MassiveProng entered: On 8 Mar 2007 01:02:52 -0800, "David L. Jones" Gave us: At this price and accuracy level it is almost certain that every unit would be automatically factory tested to be in-spec, so the NIST cert is worth the paper it's written on. You can bet the farm that Anthony's new meter meets the published specs. Idiot! His meter is NOT certified. Learn to read. Youu do realize that calibrated and certified are not the same thing, don't you? You could have your HP 3478A certified to +/- 10% VDC. Bob -- -- Coffee worth staying up for - NY Times www.moondoggiecoffee.com |
Calibration Of Electronic Equipment In The Home Workshop
Dear friend :
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Calibration Of Electronic Equipment In The Home Workshop
Jim Yanik wrote:
After reading all this,I checked the $3 DMM I bought at a Harbor Freight sidewalk sale,and it turns out the *input Z is only ONE megohm*. YUK! My first meter cost five times that, was analog, and only had 20K ohms per volt. For those young folk who aren't familiar with that, yes, the meter input impedance changed depending on the range you set the meter to. -- Martians drive SUVs! http://oregonmag.com/MarsWarm307.html |
Calibration Of Electronic Equipment In The Home Workshop
clifto wrote:
Jim Yanik wrote: After reading all this,I checked the $3 DMM I bought at a Harbor Freight sidewalk sale,and it turns out the *input Z is only ONE megohm*. YUK! My first meter cost five times that, was analog, and only had 20K ohms per volt. For those young folk who aren't familiar with that, yes, the meter input impedance changed depending on the range you set the meter to. My first meter (a cheapie my dad's friend gave me when I was about 10) was in that range (could it have been 10k?). The better meters I had in my younger days were a whopping 50k ohms/volt. |
Calibration Of Electronic Equipment In The Home Workshop
clifto wrote:
Jim Yanik wrote: After reading all this,I checked the $3 DMM I bought at a Harbor Freight sidewalk sale,and it turns out the *input Z is only ONE megohm*. YUK! My first meter cost five times that, was analog, and only had 20K ohms per volt. For those young folk who aren't familiar with that, yes, the meter input impedance changed depending on the range you set the meter to. Check; the neatthing is that on higher voltage scales, the input resistance exceeds that of a DMM. Which is why i built a voltmeter/currentmeter around a 5 microamp movement giving 200K per volt sensitivity. |
Calibration Of Electronic Equipment In The Home Workshop
Anthony Fremont wrote:
clifto wrote: Jim Yanik wrote: After reading all this,I checked the $3 DMM I bought at a Harbor Freight sidewalk sale,and it turns out the *input Z is only ONE megohm*. YUK! My first meter cost five times that, was analog, and only had 20K ohms per volt. For those young folk who aren't familiar with that, yes, the meter input impedance changed depending on the range you set the meter to. My first meter (a cheapie my dad's friend gave me when I was about 10) was in that range (could it have been 10k?). The better meters I had in my younger days were a whopping 50k ohms/volt. I do remember seeing one of those 50K/V meters whan i was young; what the heck has happened to them? |
Calibration Of Electronic Equipment In The Home Workshop
"clifto" wrote in message ... My first meter cost five times that, was analog, and only had 20K ohms per volt. Mine was 2K IIRC. I still have it. |
Calibration Of Electronic Equipment In The Home Workshop
Robert Baer wrote:
Anthony Fremont wrote: clifto wrote: Jim Yanik wrote: After reading all this,I checked the $3 DMM I bought at a Harbor Freight sidewalk sale,and it turns out the *input Z is only ONE megohm*. YUK! My first meter cost five times that, was analog, and only had 20K ohms per volt. For those young folk who aren't familiar with that, yes, the meter input impedance changed depending on the range you set the meter to. My first meter (a cheapie my dad's friend gave me when I was about 10) was in that range (could it have been 10k?). The better meters I had in my younger days were a whopping 50k ohms/volt. I do remember seeing one of those 50K/V meters whan i was young; what the heck has happened to them? Here's a couple of beauts: http://www.bkprecision.com/www/np_se...og+Multimeters |
Calibration Of Electronic Equipment In The Home Workshop
Robert Baer wrote in
ink.net: clifto wrote: Jim Yanik wrote: After reading all this,I checked the $3 DMM I bought at a Harbor Freight sidewalk sale,and it turns out the *input Z is only ONE megohm*. YUK! My first meter cost five times that, was analog, and only had 20K ohms per volt. For those young folk who aren't familiar with that, yes, the meter input impedance changed depending on the range you set the meter to. Check; the neatthing is that on higher voltage scales, the input resistance exceeds that of a DMM. Which is why i built a voltmeter/currentmeter around a 5 microamp movement giving 200K per volt sensitivity. Then there's the Fluke differential voltmeters,that have nearly infinite impedance at null. ISTR a HP diff VM that had a 100Meg Z on it's off-null mode.Then there are Keithley hi-Z meters,with gigohm input Zs. -- Jim Yanik jyanik at kua.net |
Calibration Of Electronic Equipment In The Home Workshop
Anthony Fremont wrote:
Robert Baer wrote: Anthony Fremont wrote: clifto wrote: Jim Yanik wrote: After reading all this,I checked the $3 DMM I bought at a Harbor Freight sidewalk sale,and it turns out the *input Z is only ONE megohm*. YUK! My first meter cost five times that, was analog, and only had 20K ohms per volt. For those young folk who aren't familiar with that, yes, the meter input impedance changed depending on the range you set the meter to. My first meter (a cheapie my dad's friend gave me when I was about 10) was in that range (could it have been 10k?). The better meters I had in my younger days were a whopping 50k ohms/volt. I do remember seeing one of those 50K/V meters whan i was young; what the heck has happened to them? Here's a couple of beauts: http://www.bkprecision.com/www/np_se...og+Multimeters That 114B is the best one.. |
Calibration Of Electronic Equipment In The Home Workshop
Jim Yanik wrote:
Robert Baer wrote in ink.net: clifto wrote: Jim Yanik wrote: After reading all this,I checked the $3 DMM I bought at a Harbor Freight sidewalk sale,and it turns out the *input Z is only ONE megohm*. YUK! My first meter cost five times that, was analog, and only had 20K ohms per volt. For those young folk who aren't familiar with that, yes, the meter input impedance changed depending on the range you set the meter to. Check; the neatthing is that on higher voltage scales, the input resistance exceeds that of a DMM. Which is why i built a voltmeter/currentmeter around a 5 microamp movement giving 200K per volt sensitivity. Then there's the Fluke differential voltmeters,that have nearly infinite impedance at null. ISTR a HP diff VM that had a 100Meg Z on it's off-null mode.Then there are Keithley hi-Z meters,with gigohm input Zs. Wouldn't be neat to have a handheld differential voltmeter? |
Calibration Of Electronic Equipment In The Home Workshop
On Thu, 8 Mar 2007 07:24:18 -0600, "Anthony Fremont"
Gave us: Wasn't it you that said that certs were often just a check not necessarily turning screws? NO! I said that when you get your gear calibrated, it is typically ONLY a verification of a good instrument. Being off cal usually means something is awry. What you are paying for is a VERY nice standard and a comparison check against it. Of the hundreds of calibration sessions that we have had done IN our lab, as opposed to sending the gear out, it was done without them ever opening a single instrument. |
Calibration Of Electronic Equipment In The Home Workshop
On Thu, 08 Mar 2007 13:34:45 -0600, clifto Gave us:
My first meter cost five times that, was analog, and only had 20K ohms per volt. For those young folk who aren't familiar with that, yes, the meter input impedance changed depending on the range you set the meter to. Lemmie guess... An RCA Master Volt Ohmist? I still have one of those as well. Have a couple Heathkit MMs around too. |
Calibration Of Electronic Equipment In The Home Workshop
MassiveProng wrote:
On Thu, 8 Mar 2007 07:24:18 -0600, "Anthony Fremont" Gave us: Wasn't it you that said that certs were often just a check not necessarily turning screws? NO! I said that when you get your gear calibrated, it is typically ONLY a verification of a good instrument. Pretty close to the same thing to me. Being off cal usually means something is awry. What you are paying for is a VERY nice standard and a comparison check against it. Of the hundreds of calibration sessions that we have had done IN our lab, as opposed to sending the gear out, it was done without them ever opening a single instrument. IOW you didn't turn any screws, you just checked it. |
Calibration Of Electronic Equipment In The Home Workshop
Robert Baer wrote:
Anthony Fremont wrote: Here's a couple of beauts: http://www.bkprecision.com/www/np_se...og+Multimeters That 114B is the best one.. Yeah, but it's not as good looking as the other one though. I just recently saw another really nice, big analog meter that someone sells. It wasn't cheap either, but I can't recall where I saw it. I was thinking it was in my Jameco catalog, but I can't seem to find it in there. It looked allot like the older ones. |
Calibration Of Electronic Equipment In The Home Workshop
On Thu, 8 Mar 2007 20:10:09 -0600, "Anthony Fremont"
Gave us: MassiveProng wrote: On Thu, 8 Mar 2007 07:24:18 -0600, "Anthony Fremont" Gave us: Wasn't it you that said that certs were often just a check not necessarily turning screws? NO! I said that when you get your gear calibrated, it is typically ONLY a verification of a good instrument. Pretty close to the same thing to me. Being off cal usually means something is awry. What you are paying for is a VERY nice standard and a comparison check against it. Of the hundreds of calibration sessions that we have had done IN our lab, as opposed to sending the gear out, it was done without them ever opening a single instrument. IOW you didn't turn any screws, you just checked it. That is 99.999% of the time ALL they do. That would be worldwide practice. |
Calibration Of Electronic Equipment In The Home Workshop
Robert Baer wrote in
link.net: Jim Yanik wrote: Robert Baer wrote in ink.net: clifto wrote: Jim Yanik wrote: After reading all this,I checked the $3 DMM I bought at a Harbor Freight sidewalk sale,and it turns out the *input Z is only ONE megohm*. YUK! My first meter cost five times that, was analog, and only had 20K ohms per volt. For those young folk who aren't familiar with that, yes, the meter input impedance changed depending on the range you set the meter to. Check; the neatthing is that on higher voltage scales, the input resistance exceeds that of a DMM. Which is why i built a voltmeter/currentmeter around a 5 microamp movement giving 200K per volt sensitivity. Then there's the Fluke differential voltmeters,that have nearly infinite impedance at null. ISTR a HP diff VM that had a 100Meg Z on it's off-null mode.Then there are Keithley hi-Z meters,with gigohm input Zs. Wouldn't be neat to have a handheld differential voltmeter? why do you need that accuracy in a handheld instrument? -- Jim Yanik jyanik at kua.net |
Calibration Of Electronic Equipment In The Home Workshop
"Anthony Fremont" wrote in
: MassiveProng wrote: On Thu, 8 Mar 2007 07:24:18 -0600, "Anthony Fremont" Gave us: Wasn't it you that said that certs were often just a check not necessarily turning screws? NO! I said that when you get your gear calibrated, it is typically ONLY a verification of a good instrument. Pretty close to the same thing to me. Being off cal usually means something is awry. What you are paying for is a VERY nice standard I would say "accurate,traceable standard". and a comparison check against it. Of the hundreds of calibration sessions that we have had done IN our lab, as opposed to sending the gear out, it was done without them ever opening a single instrument. IOW you didn't turn any screws, you just checked it. If it meets all specs,then there is no need for adjustment. In fact,you might make it worse by tweaking on adjustments. (some pots or trim caps on older instruments freeze in place and turning them breaks them or they become noisy) Instruments that have been adjusted have to be rechecked,as some adjustments interact with others.Trying to "optimize" a range may throw another range or ranges out of spec. -- Jim Yanik jyanik at kua.net |
Calibration Of Electronic Equipment In The Home Workshop
Jim Yanik wrote:
Robert Baer wrote in link.net: Jim Yanik wrote: Robert Baer wrote in ink.net: clifto wrote: Jim Yanik wrote: After reading all this,I checked the $3 DMM I bought at a Harbor Freight sidewalk sale,and it turns out the *input Z is only ONE megohm*. YUK! My first meter cost five times that, was analog, and only had 20K ohms per volt. For those young folk who aren't familiar with that, yes, the meter input impedance changed depending on the range you set the meter to. Check; the neatthing is that on higher voltage scales, the input resistance exceeds that of a DMM. Which is why i built a voltmeter/currentmeter around a 5 microamp movement giving 200K per volt sensitivity. Then there's the Fluke differential voltmeters,that have nearly infinite impedance at null. ISTR a HP diff VM that had a 100Meg Z on it's off-null mode.Then there are Keithley hi-Z meters,with gigohm input Zs. Wouldn't be neat to have a handheld differential voltmeter? why do you need that accuracy in a handheld instrument? I don't *need* a Ferrari, but it would be neat to have one. -- Martians drive SUVs! http://oregonmag.com/MarsWarm307.html |
Calibration Of Electronic Equipment In The Home Workshop
On 9 Mar 2007 17:24:20 GMT, Jim Yanik Gave us:
"Anthony Fremont" wrote in : MassiveProng wrote: On Thu, 8 Mar 2007 07:24:18 -0600, "Anthony Fremont" Gave us: Wasn't it you that said that certs were often just a check not necessarily turning screws? NO! I said that when you get your gear calibrated, it is typically ONLY a verification of a good instrument. Pretty close to the same thing to me. Being off cal usually means something is awry. What you are paying for is a VERY nice standard I would say "accurate,traceable standard". and a comparison check against it. Of the hundreds of calibration sessions that we have had done IN our lab, as opposed to sending the gear out, it was done without them ever opening a single instrument. IOW you didn't turn any screws, you just checked it. If it meets all specs,then there is no need for adjustment. In fact,you might make it worse by tweaking on adjustments. (some pots or trim caps on older instruments freeze in place and turning them breaks them or they become noisy) Instruments that have been adjusted have to be rechecked,as some adjustments interact with others.Trying to "optimize" a range may throw another range or ranges out of spec. All great reasons to abide 100% with my original reply. So there, Too Much Toolessness!, you ****ing RETARD!. |
Calibration Of Electronic Equipment In The Home Workshop
clifto wrote in :
Jim Yanik wrote: Robert Baer wrote in link.net: Jim Yanik wrote: Robert Baer wrote in ink.net: clifto wrote: Jim Yanik wrote: After reading all this,I checked the $3 DMM I bought at a Harbor Freight sidewalk sale,and it turns out the *input Z is only ONE megohm*. YUK! My first meter cost five times that, was analog, and only had 20K ohms per volt. For those young folk who aren't familiar with that, yes, the meter input impedance changed depending on the range you set the meter to. Check; the neatthing is that on higher voltage scales, the input resistance exceeds that of a DMM. Which is why i built a voltmeter/currentmeter around a 5 microamp movement giving 200K per volt sensitivity. Then there's the Fluke differential voltmeters,that have nearly infinite impedance at null. ISTR a HP diff VM that had a 100Meg Z on it's off-null mode.Then there are Keithley hi-Z meters,with gigohm input Zs. Wouldn't be neat to have a handheld differential voltmeter? why do you need that accuracy in a handheld instrument? I don't *need* a Ferrari, but it would be neat to have one. well,precision lab instruments are used in lab conditions,with at least 15 minute warmup times to allow the unit to stabilize,and to expect that accuracy in a handheld that would be used in non-lab conditions....it doesn't make sense. BTW,when calibrating precision instruments,the unit under test has to warm up and stabilize for 20 minutes minimum,and the lab has a controlled temperature and humidity,usually 73+/-2 degF. Of course,your lab standards have already been powered up and stabilized for the proper time. Insturments used outside of specified temps were derated in accuracy. I worked in a USAF depot-level primary standards lab.(PMEL) (before repairing and calibrating for Tektronix for 21.5 yrs.) My lab (L.G. Hanscom Fld) did the MIT-Lincoln Labs instruments,besides the usual USAF stuff,covered Pease,Otis,and other military bases. -- Jim Yanik jyanik at kua.net |
Calibration Of Electronic Equipment In The Home Workshop
Jim Yanik wrote:
Robert Baer wrote in link.net: Jim Yanik wrote: Robert Baer wrote in thlink.net: clifto wrote: Jim Yanik wrote: After reading all this,I checked the $3 DMM I bought at a Harbor Freight sidewalk sale,and it turns out the *input Z is only ONE megohm*. YUK! My first meter cost five times that, was analog, and only had 20K ohms per volt. For those young folk who aren't familiar with that, yes, the meter input impedance changed depending on the range you set the meter to. Check; the neatthing is that on higher voltage scales, the input resistance exceeds that of a DMM. Which is why i built a voltmeter/currentmeter around a 5 microamp movement giving 200K per volt sensitivity. Then there's the Fluke differential voltmeters,that have nearly infinite impedance at null. ISTR a HP diff VM that had a 100Meg Z on it's off-null mode.Then there are Keithley hi-Z meters,with gigohm input Zs. Wouldn't be neat to have a handheld differential voltmeter? why do you need that accuracy in a handheld instrument? Someone asked the same question about a pocket scope. I guess there are times and conditions when such "esoteric" equipment would be nice to have. |
Calibration Of Electronic Equipment In The Home Workshop
MassiveProng wrote:
On Thu, 8 Mar 2007 07:24:18 -0600, "Anthony Fremont" Gave us: Wasn't it you that said that certs were often just a check not necessarily turning screws? NO! I said that when you get your gear calibrated, it is typically ONLY a verification of a good instrument. Being off cal usually means something is awry. What you are paying for is a VERY nice standard and a comparison check against it. Of the hundreds of calibration sessions that we have had done IN our lab, as opposed to sending the gear out, it was done without them ever opening a single instrument. - Odd, I've been working in a cal lab for the last few years, and I'd say a good 10% of what we get has something wrong with it. Some of it is designed-in problems, but most of the rest is due to impact damage or contamination. Our customers are largely the petrochemical industries along the Gulf Coast, and they apparently believe that if a piece of gear can't survive a 1 meter fall onto concrete, or being rained on and rattling around in the back of a pickup truck for a few weeks, than there's obviously something wrong with it anyway. It makes for a good business in replacing switching, connectors and cracked LCDs. |
Calibration Of Electronic Equipment In The Home Workshop
On Sat, 10 Mar 2007 08:41:44 GMT, Robert Baer
Gave us: Jim Yanik wrote: Robert Baer wrote in link.net: Jim Yanik wrote: Robert Baer wrote in rthlink.net: clifto wrote: Jim Yanik wrote: After reading all this,I checked the $3 DMM I bought at a Harbor Freight sidewalk sale,and it turns out the *input Z is only ONE megohm*. YUK! My first meter cost five times that, was analog, and only had 20K ohms per volt. For those young folk who aren't familiar with that, yes, the meter input impedance changed depending on the range you set the meter to. Check; the neatthing is that on higher voltage scales, the input resistance exceeds that of a DMM. Which is why i built a voltmeter/currentmeter around a 5 microamp movement giving 200K per volt sensitivity. Then there's the Fluke differential voltmeters,that have nearly infinite impedance at null. ISTR a HP diff VM that had a 100Meg Z on it's off-null mode.Then there are Keithley hi-Z meters,with gigohm input Zs. Wouldn't be neat to have a handheld differential voltmeter? why do you need that accuracy in a handheld instrument? Someone asked the same question about a pocket scope. I guess there are times and conditions when such "esoteric" equipment would be nice to have. Ahhhh... the "nice" factor. I think it would be nice to have a nice Agilent spectrum analyser, or network analyser, but I don't have $60+k for each right now. Maybe after I win the lottery. |
Calibration Of Electronic Equipment In The Home Workshop
On Sat, 10 Mar 2007 10:38:04 -0600, Palinurus
Gave us: MassiveProng wrote: On Thu, 8 Mar 2007 07:24:18 -0600, "Anthony Fremont" Gave us: Wasn't it you that said that certs were often just a check not necessarily turning screws? NO! I said that when you get your gear calibrated, it is typically ONLY a verification of a good instrument. Being off cal usually means something is awry. What you are paying for is a VERY nice standard and a comparison check against it. Of the hundreds of calibration sessions that we have had done IN our lab, as opposed to sending the gear out, it was done without them ever opening a single instrument. - Odd, I've been working in a cal lab for the last few years, and I'd say a good 10% of what we get has something wrong with it. Some of it is designed-in problems, but most of the rest is due to impact damage or contamination. Our customers are largely the petrochemical industries along the Gulf Coast, and they apparently believe that if a piece of gear can't survive a 1 meter fall onto concrete, or being rained on and rattling around in the back of a pickup truck for a few weeks, than there's obviously something wrong with it anyway. It makes for a good business in replacing switching, connectors and cracked LCDs. Which distinctly falls under the category of REPAIR, NOT calibration. |
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