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Calibration Of Electronic Equipment In The Home Workshop
I have a well stocked test bench at home containing a range of analog,
digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? Links to recommended circuits, pictures and sources would be appreciated. Since this is a need for anyone who has test equipment, I hope to see a good discussion on this subject. Thanks TMT |
Calibration Of Electronic Equipment In The Home Workshop
Tim Shoppa wrote:
On Feb 28, 9:27 pm, "Too_Many_Tools" wrote: I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? It depends entirely on what you need the equipment for. If for any legal reason you need NBS traceability, then the question of how and how often is already answered by your regulatory agencies. If you don't, then I cannot imagine that a couple off-the-shelf precision resistors, voltage references, and frequency references (total cost: $10) would not be good enough for sanity checking for almost any pedestrian uses. If you're the sort who keeps equipment on your bench just to calibrate equipment on your bench just to calibrate equipment on your bench, then any rational argument about traceability is pointless because you've already set yourself up in an infinite circular loop. Tim. A lot of good points have been made already so I'll just add a small one. Don't mess with calibration of quality equipment unless you have reason to believe the calibration is off AND THAT IS ADVERSELY AFFECTING YOUR WORK PRODUCTS. An amazing amount of electronics work has been done using equipment with non-current calibration stickers, some of which was out of calibration. If metrology is something that interests you as a hobby, then jump into it and have fun. Tim's last paragraph ought to be printed and framed. Chuck ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
Calibration Of Electronic Equipment In The Home Workshop
On 28 Feb 2007 18:27:45 -0800, "Too_Many_Tools"
Gave us: I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? Links to recommended circuits, pictures and sources would be appreciated. Since this is a need for anyone who has test equipment, I hope to see a good discussion on this subject. If you have used test gear, and you do not intend to PAY to have it calibrated, you be best off leaving it all the **** ALONE! |
Calibration Of Electronic Equipment In The Home Workshop
Too_Many_Tools wrote:
I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? Links to recommended circuits, pictures and sources would be appreciated. Since this is a need for anyone who has test equipment, I hope to see a good discussion on this subject. Thanks TMT What sort of equipment are you trying to calibrate? You can do a search online for various voltage reference sources. Accurate frequency reference can be picked up off the airwaves from transmitters such as WWV. What methods you use depend on what the equipment is and how accurate you need it to be. |
Calibration Of Electronic Equipment In The Home Workshop
On Feb 28, 9:50 pm, MassiveProng
wrote: If you have used test gear, and you do not intend to PAY to have it calibrated, you be best off leaving it all the **** ALONE! As alone as you on a Friday night? |
Calibration Of Electronic Equipment In The Home Workshop
"Too_Many_Tools" wrote in
s.com: I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? Links to recommended circuits, pictures and sources would be appreciated. Since this is a need for anyone who has test equipment, I hope to see a good discussion on this subject. Thanks TMT Wavetek and Fluke both make nice all-in-one calibrators for voltmeters and scopes,they do V,I,R,timing and bandwidth checks.Not cheap,though. There's plenty of older,used cal standards on the market,too. Getting them certified may be a problem due to their age. For F-counters,you need a WWV or GPS-based receiver. high-end stuff,you send out to a lab. (consider them your "primary standards") A warning;calibration procedures of some TEK gear may be written to use their recommended list of standards,and difficult or impossible to do fully with substitutes. Especially their video test gear. -- Jim Yanik jyanik at kua.net |
Calibration Of Electronic Equipment In The Home Workshop
In article m,
Too_Many_Tools wrote: I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? For frequency, you can use WWV. You need: A short wave radio with an audio output. Perhaps an audio filter tuned to about 1KHz. A generator you wish to calibrate near the WWV frequency. A frequency counter that is not too far off. Procedu Tune in WWV. Put wire on generator and set it to WWV-1KHz Listen for tone and move stuff around until it sounds good. Feed tone into the filter. Place the counter on the output of the filter. The number on the counter is X Hz away from 1KHz when the generator is XHz off from WWV-1KHz. -- -- forging knowledge |
Calibration Of Electronic Equipment In The Home Workshop
"Too_Many_Tools" wrote in message s.com... ** Groper alert ! I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? ** A few 0.1% precision resistors does the first job for DMMs. A Natsemi " LH0070 " 10.000 volt ( +/- 0.02% ) voltage reference IC with 0.1 % resistor divider chain giving 1.000 & 0.1000 volts for the DC volts ranges DMMs and scopes does the second. For AC volts, a scope screen with internal graticule is used to establish the p-p amplitude of a sine wave - then it can be used to check then AC ranges DMMs etc - to a 1% accuracy. A 12MHz crystal oscillator ( 11.99993 MHz @ 25C ) checks the DFM - calibrated using an off air standard frequency transmission picked up on a scanner. ........ Phil |
Calibration Of Electronic Equipment In The Home Workshop
On Mar 1, 12:27 pm, "Too_Many_Tools" wrote:
I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? Links to recommended circuits, pictures and sources would be appreciated. Since this is a need for anyone who has test equipment, I hope to see a good discussion on this subject. If you've got that sort of gear at home then usually you have better (and calibrated) gear at work as well, in which case most of us would simply bring in our gear from home and spot check it against the good gear. In the absense of this gear, you can simply use precision components. Voltage reference chips with 0.05% or better are cheap and readilly available. 0.01% resistors are available too. If you have multiple meters for example, you can also keep an eye on them by comparison. Using any old component, if all three meters read the same then you can be pretty confident they haven't drifted. Checking scope horizontal timebases is easy with a crystal oscillator and divider. There are various methods for getting an accurate frequency standard, but one of the newst methods is using a GPS derived reference. Second hand Rubidium standards can also be had on eBay. Generally though, good quality test gear does not drift out of spec, so the need for regular calibration is minimal. Dave :) |
Calibration Of Electronic Equipment In The Home Workshop
If you have used test gear, and you do not intend to PAY to have it calibrated, you be best off leaving it all the **** ALONE! LOL You're a real ray of sunshine, aren't you? Now go out and play in traffic while we adults talk about serious stuff.. TMT On Feb 28, 8:50 pm, MassiveProng wrote: On 28 Feb 2007 18:27:45 -0800, "Too_Many_Tools" Gave us: I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? Links to recommended circuits, pictures and sources would be appreciated. Since this is a need for anyone who has test equipment, I hope to see a good discussion on this subject. If you have used test gear, and you do not intend to PAY to have it calibrated, you be best off leaving it all the **** ALONE! |
Calibration Of Electronic Equipment In The Home Workshop
On Feb 28, 8:27 pm, "Too_Many_Tools" wrote:
I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? Links to recommended circuits, pictures and sources would be appreciated. Since this is a need for anyone who has test equipment, I hope to see a good discussion on this subject. Thanks TMT Thanks for the (positive) comments so far. I look forward to any more you might want to offer. Any circuits or examples others have done? Any cal boxes that anyone have built? TMT |
Calibration Of Electronic Equipment In The Home Workshop
Too_Many_Tools wrote:
I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? Links to recommended circuits, pictures and sources would be appreciated. Since this is a need for anyone who has test equipment, I hope to see a good discussion on this subject. Thanks TMT You left many things unsaid: (a) Traceable to NBS/NTIS or not; (b) if not, how many reliable digits; (c) at what cost. You can make a 5V "standard" that any loading will not damage with error better than 0.5mV and runs for at least 6 months with no observable change - and the cost is only a few dollars (uses off-the-shelf parts). You can buy thru DigiKey, resistors rated at 0.05% and at 0.1% - rather decent as references. You can buy a Fluke bench meter rated at 6.5 digits and even pay a bit more for traceability. |
Calibration Of Electronic Equipment In The Home Workshop
David L. Jones wrote:
On Mar 1, 12:27 pm, "Too_Many_Tools" wrote: I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? Links to recommended circuits, pictures and sources would be appreciated. Since this is a need for anyone who has test equipment, I hope to see a good discussion on this subject. If you've got that sort of gear at home then usually you have better (and calibrated) gear at work as well, in which case most of us would simply bring in our gear from home and spot check it against the good gear. In the absense of this gear, you can simply use precision components. Voltage reference chips with 0.05% or better are cheap and readilly available. 0.01% resistors are available too. If you have multiple meters for example, you can also keep an eye on them by comparison. Using any old component, if all three meters read the same then you can be pretty confident they haven't drifted. Checking scope horizontal timebases is easy with a crystal oscillator and divider. There are various methods for getting an accurate frequency standard, but one of the newst methods is using a GPS derived reference. Second hand Rubidium standards can also be had on eBay. Generally though, good quality test gear does not drift out of spec, so the need for regular calibration is minimal. Dave :) True, 0.01% resistors are available, *but* they are extremely expensive (over $100 each) and they are made when and if the manufacturer sees fit to do so. |
Calibration Of Electronic Equipment In The Home Workshop
"Too_Many_Tools" wrote in message oups.com... I look forward to any more you might want to offer. If it was me, I would start by reading Scroggie's Radio Laboratory Handbook. -- .. -- .. .. .. .. .. .. .. .. -- |
Calibration Of Electronic Equipment In The Home Workshop
On Feb 28, 9:47 pm, "Too_Many_Tools" wrote:
If you have used test gear, and you do not intend to PAY to have it calibrated, you be best off leaving it all the **** ALONE! LOL You're a real ray of sunshine, aren't you? Now go out and play in traffic while we adults talk about serious stuff.. TMT On Feb 28, 8:50 pm, MassiveProng wrote: On 28 Feb 2007 18:27:45 -0800, "Too_Many_Tools" Gave us: I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? Links to recommended circuits, pictures and sources would be appreciated. Since this is a need for anyone who has test equipment, I hope to see a good discussion on this subject. If you have used test gear, and you do not intend to PAY to have it calibrated, you be best off leaving it all the **** ALONE! I agree with Prong on this one. I've worked in repair and broadcast for 35 years. Unless you have a compelling reason to change it, leave it alone. Of course, this assumes it's good stuff to begin with like Fluke and Tek. The only time I altered a Fluke 8060 was an eBay purchase. When testing some new boards, I was reading 4.998 on the 5 volt ref. Never saw any boards that far off and then tried the other Fluke which was as expected. The eBay meter got a little 'tweak' but that was very unusual. BTW, the 5V ref on the boards was an ADI AD588 which is almost good enough for the 8060. I would use it to cal a 3.5 digit meter with no qualms. GG |
Calibration Of Electronic Equipment In The Home Workshop
On Mar 1, 5:09 pm, Robert Baer wrote:
David L. Jones wrote: On Mar 1, 12:27 pm, "Too_Many_Tools" wrote: I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? Links to recommended circuits, pictures and sources would be appreciated. Since this is a need for anyone who has test equipment, I hope to see a good discussion on this subject. If you've got that sort of gear at home then usually you have better (and calibrated) gear at work as well, in which case most of us would simply bring in our gear from home and spot check it against the good gear. In the absense of this gear, you can simply use precision components. Voltage reference chips with 0.05% or better are cheap and readilly available. 0.01% resistors are available too. If you have multiple meters for example, you can also keep an eye on them by comparison. Using any old component, if all three meters read the same then you can be pretty confident they haven't drifted. Checking scope horizontal timebases is easy with a crystal oscillator and divider. There are various methods for getting an accurate frequency standard, but one of the newst methods is using a GPS derived reference. Second hand Rubidium standards can also be had on eBay. Generally though, good quality test gear does not drift out of spec, so the need for regular calibration is minimal. Dave :) True, 0.01% resistors are available, *but* they are extremely expensive (over $100 each) and they are made when and if the manufacturer sees fit to do so. Not so. RS Components have 0.01% resistors for AU$34.50 (US$26) Farnell have 0.02% for as little as AU$20 Dave :) |
Calibration Of Electronic Equipment In The Home Workshop
Ken Smith wrote:
In article m, Too_Many_Tools wrote: I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? For frequency, you can use WWV. You need: A short wave radio with an audio output. Perhaps an audio filter tuned to about 1KHz. A generator you wish to calibrate near the WWV frequency. A frequency counter that is not too far off. Procedu Tune in WWV. Put wire on generator and set it to WWV-1KHz Listen for tone and move stuff around until it sounds good. Feed tone into the filter. Place the counter on the output of the filter. The number on the counter is X Hz away from 1KHz when the generator is XHz off from WWV-1KHz. This works if you only need about 1 part in a million. The movement of the ionosphere makes wwv useless for real calibration. This was, of course, wonderful when we had nothing else. It is far better to get a gps standard (they are used on cell sites and show up on ebay) and just use it for the timebase all the time. Alternately, use a Rb source. They were also used in cell sites and are available easily. They cannot move more than about a part in 100 million and they make excellent time bases for frequency counters. |
Calibration Of Electronic Equipment In The Home Workshop
On 28 Feb 2007 22:45:45 -0800 "David L. Jones" wrote
in Message id: .com: On Mar 1, 5:09 pm, Robert Baer wrote: [...] True, 0.01% resistors are available, *but* they are extremely expensive (over $100 each) and they are made when and if the manufacturer sees fit to do so. Not so. RS Components have 0.01% resistors for AU$34.50 (US$26) Farnell have 0.02% for as little as AU$20 You guys are paying *way* too much. We use Riedon .01% precision resistors in our A/D products, and pay about 5 bucks apiece. Their site is down at the moment, but even Digikey has .01% resistors for around the same price: http://www.digikey.com/scripts/DkSea...S&Cat=34342147 |
Calibration Of Electronic Equipment In The Home Workshop
On 28 Feb 2007 21:50:49 -0800 "Too_Many_Tools"
wrote in Message id: .com: I look forward to any more you might want to offer. Any circuits or examples others have done? For a cheap voltage reference, I would look into Analog device's AD780 series. The AD780BN has an initial error of +-1mV and is available in a plastic 8 pin DIP for easy assembly. Download the data sheet and you'll find sample circuit diagrams. Be sure to use a nice clean power supply and use good decoupling practices around the device. For resistance, see my post with a link to Digikey. |
Calibration Of Electronic Equipment In The Home Workshop
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Calibration Of Electronic Equipment In The Home Workshop
MassiveProng wrote:
On 28 Feb 2007 18:27:45 -0800, "Too_Many_Tools" Gave us: I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? Links to recommended circuits, pictures and sources would be appreciated. Since this is a need for anyone who has test equipment, I hope to see a good discussion on this subject. If you have used test gear, and you do not intend to PAY to have it calibrated, you be best off leaving it all the **** ALONE! You're amazing. You don't even know what equipment, qualifications or needs he has, yet you're right there with THE answer. Lets take an example. I have a 20 year old Hitachi scope as you know, the voltage cal is way off (~20%) in a couple of ranges. Are you suggesting that I should drag it across town, spend $200 and be without it for 2 weeks just to get it adjusted by some obstinate, E-1 grade line tech, instead of using a brand new DMM w .03% accuracy to tweak it myself? I'm quite sure that my Micronta is up to the task to be honest. If someone doesn't need traceable calibration, then why should they pay for it? Especially if they have the resources to do it themselves. I'm thinking of buying a cheap used Rb time base from e-bay so I can cal my old Protek freq counter and adjust the timebase on my Hitachi scope, it's certainly cheaper than having it done. Using a PIC driven by an ordinary can xtal, and a quartz wris****ch of known accuracy, I was able to tweak the xtal to within about 1-2ppm over the course of a week or two. Of course you know that's impossible, don't you? |
Calibration Of Electronic Equipment In The Home Workshop
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Calibration Of Electronic Equipment In The Home Workshop
On 28 Feb 2007 21:47:49 -0800, "Too_Many_Tools"
Gave us: If you have used test gear, and you do not intend to PAY to have it calibrated, you be best off leaving it all the **** ALONE! LOL You're a real ray of sunshine, aren't you? Now go out and play in traffic while we adults talk about serious stuff.. TMT Serious? Look, dumb****, if you are concerned with calibration, then you should be concerned enough to do it right. Asking here the way you did means that you are beyond your depth to start with. If you are too stupid to take your device to a place where freshly calibrated devices are, and check it against them, you are too stupid to be attempting to do it with some patched up method in the home without cal manuals from the makers of all those devices. Far too stupid. So **** you, pops. You prove that numeric age does not an adult make. The traffic I play in runs at 30GHz, so you are screwed with that presumption as well. I had calibrated meters back in 1970, and knew more then than you do know. |
Calibration Of Electronic Equipment In The Home Workshop
On 28 Feb 2007 21:50:49 -0800, "Too_Many_Tools"
Gave us: Thanks for the (positive) comments so far. I look forward to any more you might want to offer. Any circuits or examples others have done? Any cal boxes that anyone have built? TMT All the circuits suggested here, while appearing good on the surface, are all likely to introduce more error into your instruments than correct. THAT IS WHY REAL calibration services are used, and why I suggested that if you do not intend to have it professionally calibrated, you... YOU IN PARTICULAR, should just leave the gear alone, as you are too ****ing stupid to do it without introducing the aforementioned error. In other words, they are better off UNcalibrated and still reliable, than after any futzing around a twit like you will do with them. You LACK the competence. You want to attack my adulthood, fine, little boy. You are BRAINLESS for this task. I have worked in cal labs and in QA for years. You lose, sonny. |
Calibration Of Electronic Equipment In The Home Workshop
On Thu, 01 Mar 2007 06:09:35 GMT, Robert Baer
Gave us: David L. Jones wrote: On Mar 1, 12:27 pm, "Too_Many_Tools" wrote: I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? Links to recommended circuits, pictures and sources would be appreciated. Since this is a need for anyone who has test equipment, I hope to see a good discussion on this subject. If you've got that sort of gear at home then usually you have better (and calibrated) gear at work as well, in which case most of us would simply bring in our gear from home and spot check it against the good gear. In the absense of this gear, you can simply use precision components. Voltage reference chips with 0.05% or better are cheap and readilly available. 0.01% resistors are available too. If you have multiple meters for example, you can also keep an eye on them by comparison. Using any old component, if all three meters read the same then you can be pretty confident they haven't drifted. Checking scope horizontal timebases is easy with a crystal oscillator and divider. There are various methods for getting an accurate frequency standard, but one of the newst methods is using a GPS derived reference. Second hand Rubidium standards can also be had on eBay. Generally though, good quality test gear does not drift out of spec, so the need for regular calibration is minimal. Dave :) True, 0.01% resistors are available, *but* they are extremely expensive (over $100 each) and they are made when and if the manufacturer sees fit to do so. Or if the order is large enough. |
Calibration Of Electronic Equipment In The Home Workshop
On Thu, 1 Mar 2007 06:05:56 -0600, "Anthony Fremont"
Gave us: You're amazing. You don't even know what equipment, qualifications or needs he has, yet you're right there with THE answer. Lets take an example. I have a 20 year old Hitachi scope as you know, the voltage cal is way off (~20%) in a couple of ranges. Are you suggesting that I should drag it across town, spend $200 and be without it for 2 weeks just to get it adjusted by some obstinate, E-1 grade line tech, instead of using a brand new DMM w .03% accuracy to tweak it myself? I'm quite sure that my Micronta is up to the task to be honest. You are to be disappointed. The scale dial on that scope is likely fitted with resistors, and one of them has shifted, which shifts all the dividers on the dial below it. It is not a calibration issue. It is a repair issue. So shove it up your ass, you E-1 grade dip****. Your micronta? Bwuahahahahahah! |
Calibration Of Electronic Equipment In The Home Workshop
MassiveProng wrote:
On Thu, 1 Mar 2007 06:05:56 -0600, "Anthony Fremont" Gave us: You're amazing. You don't even know what equipment, qualifications or needs he has, yet you're right there with THE answer. Lets take an example. I have a 20 year old Hitachi scope as you know, the voltage cal is way off (~20%) in a couple of ranges. Are you suggesting that I should drag it across town, spend $200 and be without it for 2 weeks just to get it adjusted by some obstinate, E-1 grade line tech, instead of using a brand new DMM w .03% accuracy to tweak it myself? I'm quite sure that my Micronta is up to the task to be honest. You are to be disappointed. The scale dial on that scope is likely fitted with resistors, and one of them has shifted, which shifts all the dividers on the dial below it. Given that the symptom is not as you describe, then I figure you are probably wrong, again. If so, I imagine I can fix it. It is not a calibration issue. It is a repair issue. You just know it all don't you? So shove it up your ass, you E-1 grade dip****. Just had to get that anal jab in there, huh? Your micronta? Bwuahahahahahah! Since 3% accuracy is considered good in the scope world, I think it would do fine. |
Calibration Of Electronic Equipment In The Home Workshop
On Feb 28, 9:27 pm, "Too_Many_Tools" wrote:
I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? It depends entirely on what you need the equipment for. If for any legal reason you need NBS traceability, then the question of how and how often is already answered by your regulatory agencies. If you don't, then I cannot imagine that a couple off-the-shelf precision resistors, voltage references, and frequency references (total cost: $10) would not be good enough for sanity checking for almost any pedestrian uses. If you're the sort who keeps equipment on your bench just to calibrate equipment on your bench just to calibrate equipment on your bench, then any rational argument about traceability is pointless because you've already set yourself up in an infinite circular loop. Tim. |
Calibration Of Electronic Equipment In The Home Workshop
In article , doug doug@doug wrote:
Ken Smith wrote: In article m, Too_Many_Tools wrote: I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? For frequency, you can use WWV. You need: A short wave radio with an audio output. Perhaps an audio filter tuned to about 1KHz. A generator you wish to calibrate near the WWV frequency. A frequency counter that is not too far off. Procedu Tune in WWV. Put wire on generator and set it to WWV-1KHz Listen for tone and move stuff around until it sounds good. Feed tone into the filter. Place the counter on the output of the filter. The number on the counter is X Hz away from 1KHz when the generator is XHz off from WWV-1KHz. This works if you only need about 1 part in a million. One PPM is enough for almost all the test equipment you will find on places like ebay. You can do better if you average over longer periods. [.....] just use it for the timebase all the time. Alternately, use a Rb source. They were also used in cell sites and are available easily. They cannot move more than about a part in 100 million and they make excellent time bases for frequency counters. I thing someone messed up a decimal. You just made a Rb clock 100 times worse that WWV. -- -- forging knowledge |
Calibration Of Electronic Equipment In The Home Workshop
Dr. Anton T. Squeegee wrote in
: In article m, (known to some as Too_Many_Tools) scribed... I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. snippety I could post pictures... ;-) Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? Hmm. Excellent question. For frequency, I actually have three different references, all GPS- locked. One is my primary reference, an HP Z3801, as retired from a cellphone site. The second and third ones are both combination clocks and freq-references, one from Trak Systems (now Trak Microwave) and the other from Odetics/Zypher. All three use a very stable OCXO that is constantly disciplined by the GPS receiver. Long-term accuracy is on the order of 1E10 -11th or so. In other words, about as good as you can get without being NIST certified. I don't have good primary voltage or current references as yet. That's on the 'Acquire' list for scrounging this year. For resistance, simple Pomona plugs with 0.01% tolerance resistors work pretty well for 2-wire. For anything more, I will probably have to rent one of the Fluke all-in-ones. I'm just beginning to gather the goodies I need for calibrating my O-scope collection. That will eventually consist of Tektronix leveled sine-wave generators, and one of their CG5xxx series calibration generators. Keep the peace(es). TEK sold their TM500/5000 line to TEGAM years ago,they may still make some calibration products. www.tegam.com -- Jim Yanik jyanik at kua.net |
Calibration Of Electronic Equipment In The Home Workshop
chuck wrote in
: Tim Shoppa wrote: On Feb 28, 9:27 pm, "Too_Many_Tools" wrote: I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? It depends entirely on what you need the equipment for. If for any legal reason you need NBS traceability, then the question of how and how often is already answered by your regulatory agencies. If you don't, then I cannot imagine that a couple off-the-shelf precision resistors, voltage references, and frequency references (total cost: $10) would not be good enough for sanity checking for almost any pedestrian uses. If you're the sort who keeps equipment on your bench just to calibrate equipment on your bench just to calibrate equipment on your bench, then any rational argument about traceability is pointless because you've already set yourself up in an infinite circular loop. Tim. reminds me of the local TV station techs who insisted that the video gear of theirs I serviced and calibrated was off,and it turned out their 75 Ohm termination was 87ohms.Other techs double-terminated monitors and complained of low brightness,tried to tweak it in,screwed it all up. Or they would have a "reference" generator at the end of 100's of feet of coax and complain it was a few percent off. A lot of good points have been made already so I'll just add a small one. Don't mess with calibration of quality equipment unless you have reason to believe the calibration is off AND THAT IS ADVERSELY AFFECTING YOUR WORK PRODUCTS. An amazing amount of electronics work has been done using equipment with non-current calibration stickers, some of which was out of calibration. If metrology is something that interests you as a hobby, then jump into it and have fun. Tim's last paragraph ought to be printed and framed. Chuck this is good advice,because without a service manual and cal procedure,you have no way of knowing what adjustments INTERACT with others. Adjust a power supply,and gain and timing goes out the window. Freq.response tweaks can affect more than one area of the signal. for example, TEK 475s have multiple vertical gain adjustments,and different adjustments for the 2/5-10mv ranges.And the gain affects F-response. -- Jim Yanik jyanik at kua.net |
Calibration Of Electronic Equipment In The Home Workshop
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Calibration Of Electronic Equipment In The Home Workshop
Ken Smith wrote:
In article m, Too_Many_Tools wrote: I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? For frequency, you can use WWV. You need: A short wave radio with an audio output. Perhaps an audio filter tuned to about 1KHz. A generator you wish to calibrate near the WWV frequency. A frequency counter that is not too far off. Procedu Tune in WWV. Put wire on generator and set it to WWV-1KHz Listen for tone and move stuff around until it sounds good. Feed tone into the filter. Place the counter on the output of the filter. The number on the counter is X Hz away from 1KHz when the generator is XHz off from WWV-1KHz. I believe the color subcarrier in a color TV is phase locked to the transmitted signal and, for network studio transmissions, is derived from a cesium clock. From what I have read it is more accurate than WWV and doesn't require extra equipment other than a TV displaying an image with a studio source. Frequency is 3.579545 MHz. -- bud-- |
Calibration Of Electronic Equipment In The Home Workshop
In message , MassiveProng
writes Joe Kane's audio video set up discs on Laser Disc, and DVD, and now HD DVD are the bee's knees for a lot of audio spectrum sine wave tones. DVD $20, Player $40 TV and Audio gear already owned. Aren't you reliant on the stability of the DVD player reference clock for the stability of the test tones? I would suspect a GPS reference would be considerably better. Of course, I could be wrong! Catching it off some transmission has to be far more inaccurate. Short wave receiver worth having $100 plus. Then add in audio gear? Catching you thinking old is better than new after your brow beating of BAH... priceless. Hehehe... just kidding... -- Clint Sharp |
Calibration Of Electronic Equipment In The Home Workshop
Ken Smith wrote:
In article , doug doug@doug wrote: Ken Smith wrote: In article m, Too_Many_Tools wrote: I have a well stocked test bench at home containing a range of analog, digital and RF test equipment as I am sure most of you also do. Well the question I have is how do you handle the calibration of your equipment? What do you use for calibration standards for resistance, voltage, current and frequency? For frequency, you can use WWV. You need: A short wave radio with an audio output. Perhaps an audio filter tuned to about 1KHz. A generator you wish to calibrate near the WWV frequency. A frequency counter that is not too far off. Procedu Tune in WWV. Put wire on generator and set it to WWV-1KHz Listen for tone and move stuff around until it sounds good. Feed tone into the filter. Place the counter on the output of the filter. The number on the counter is X Hz away from 1KHz when the generator is XHz off from WWV-1KHz. This works if you only need about 1 part in a million. One PPM is enough for almost all the test equipment you will find on places like ebay. You can do better if you average over longer periods. [.....] just use it for the timebase all the time. Alternately, use a Rb source. They were also used in cell sites and are available easily. They cannot move more than about a part in 100 million and they make excellent time bases for frequency counters. I thing someone messed up a decimal. You just made a Rb clock 100 times worse that WWV. No. One part in 100 million (10^-8) is 100 times better than wwv (10^-6). There is lots of excellent equipment on ebay that can take advantage of this level of accuracy. The main point is that you do not have to think about it very often. The low cost counters that have uncompensated or poorly compensated timebases are basically useless for any serious work. The other nice part about the high stability references is that you can distribute it to all the synthesizers on your bench and everything is coherent. Of course it depends on what you do. For my ham work, one ppm is fine. I do other work where the Rb source is not good enough. |
Calibration Of Electronic Equipment In The Home Workshop
Glenn Gundlach wrote:
I agree with Prong on this one. I've worked in repair and broadcast for 35 years. Unless you have a compelling reason to change it, leave it alone. Of course, this assumes it's good stuff to begin with like Fluke and Tek. A few years ago I got stuck with the Telequipment scope, the last junk available. It was sadly out of calibration. I whipped up a few voltage dividers and took other stuff and spent an hour calibrating the vertical channels and horizontal timebase. I got my work done. The head tech wanted to know how, and I told him, and he hit the ceiling, ran to the other room, grabbed the scope and sent it out for calibration. He was strangely silent when the scope came back. When I asked him outright about it, he didn't look up from his work when he mumbled something about the vertical being 0.4% off reference. Mission-critical? Send it out. Need for extreme precision? Send it out. But if 2-5% is good enough and you've got some time and imagination, you can get it awfully close to where you need it. -- "...global warming is an apocalyptic faith whose preachers demand sacrifices of others that they find far too painful for themselves." -- Andrew Bolt, in Australia's Herald Sun |
Calibration Of Electronic Equipment In The Home Workshop
Bud-- wrote:
I believe the color subcarrier in a color TV is phase locked to the transmitted signal and, for network studio transmissions, is derived from a cesium clock. From what I have read it is more accurate than WWV and doesn't require extra equipment other than a TV displaying an image with a studio source. Frequency is 3.579545 MHz. I've seen that discussed elsewhere, and although it would take me a week to find the particulars, (1) the frequency can be off as much as 10 Hz by FCC standards, (2) from what I've read it's frequently off by more than that, even on network feeds, (3) IIRC they don't even use the good clocks on the networks any more, (4) NIST clocks are going to be a couple of orders of magnitude better than the best a network would buy for the purpose of meeting FCC regulations, (5) IIRC the frequency should actually be 3,579,545.454545454545..... Hz, and (6) Doppler shift on the incoming television signal could potentially cause the subcarrier frequency to vary up and down. -- "...global warming is an apocalyptic faith whose preachers demand sacrifices of others that they find far too painful for themselves." -- Andrew Bolt, in Australia's Herald Sun |
Calibration Of Electronic Equipment In The Home Workshop
Anthony Fremont wrote:
If someone doesn't need traceable calibration, then why should they pay for it? Especially if they have the resources to do it themselves. I'm thinking of buying a cheap used Rb time base from e-bay so I can cal my old Protek freq counter and adjust the timebase on my Hitachi scope, it's certainly cheaper than having it done. Using a PIC driven by an ordinary can xtal, and a quartz wris****ch of known accuracy, I was able to tweak the xtal to within about 1-2ppm over the course of a week or two. Of course you know that's impossible, don't you? I don't think the oscillator on a PIC would be good to 2ppm absolute accuracy even with a very good xtal, unless you FIRST calibrate it against something that has already been calibrated, therefore it doesn't get you far. It will however be good enough to calibrate your scope since that would only need 1% or so, and any old crystal should achieve that, even with a fairly primitive oscillator. For frequency calibration, your best bet is to receive an off-air standard, for example GPS or in many countries there are low frequency standard transmissions (50kHz, 60kHz, 77.5kHz or others, look up which ones are available in your country). It is quite feasible to build your own receiver for these. These transmitters are maintained to a higher accuracy than any piece of hardware that a hobbyist could afford (e.g. 2 parts in 10^12). http://www.npl.co.uk/time/msf/ctm001v05.pdf Chris |
Calibration Of Electronic Equipment In The Home Workshop
On Mar 1, 9:20 pm, JW wrote:
On 28 Feb 2007 22:45:45 -0800 "David L. Jones" wrote in Message id: .com: On Mar 1, 5:09 pm, Robert Baer wrote: [...] True, 0.01% resistors are available, *but* they are extremely expensive (over $100 each) and they are made when and if the manufacturer sees fit to do so. Not so. RS Components have 0.01% resistors for AU$34.50 (US$26) Farnell have 0.02% for as little as AU$20 You guys are paying *way* too much. We use Riedon .01% precision resistors in our A/D products, and pay about 5 bucks apiece. Their site is down at the moment, but even Digikey has .01% resistors for around the same price:http://www.digikey.com/scripts/DkSea...ria?Ref=3107&S... It's not too much when you only want a couple, and you can have it within the hour. If you want volume and price matters, sure, you shop around. Dave :) |
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