Before it messes with the accuracy of the 5520A? I have not done this in a long time but I remember techs doing this when I was with Transcat many moons ago...
Depends on what function/range/accuracy of the meter. Low accuracy meters like Fluke 77, you can do about 3 for DC volts and DC current. I don't like paralleling/seriesing them for AC functionality as the inoput impedance is lower already. And resistance, 1 at a time. I haven't really done that since the old Fluke 5102B days calibrating Simpson 260's.
I think when I did it I put 3 together and took all my readings that way except for Ohms. Obviously you have to move the leads when your doing the amps but I do not remember any of them ever reading different that way.
I'm just shaking my head!!!OMG
Mid 80's in the Army we fielded the Simpson 467 I think it was, a digital dmm. Anyway at Ft Hood a guy on our team designed and laid out the diagram, I did the assembly of the "Ganger Banger" It allowed us to connect up 10 of them and each one had a switch on the box that allowed us to change them from parallel (voltage) to series (current). We could run voltage OK but the series current connection had too much resistance for the calibrator to overcome if you did more than 2 or 3 (compliance voltage). This was on older equipment, Fluke 332 for DCV, HP 745A for ACV and Fluke 760A for current. I sometimes wonder what became of that thing, our old shop is now a vacant lot at Hood.
Why are you shaking your head RF cal?? If your doing no data it makes it go a heck of a lot faster. You never daisy chained a couple attenuators?? Just put like 3 of them together (same type like 20 DB) get your reding figure out the difference divide by 3 and BOOM calibrated 3 in the time it takes to do one!!
3 attenuators in a daisy chain ? How many issues can I state that
will happen because of this , Mismatch of impedance , VSWR , one being high
one being low , pin depth ect ect . To many errors in that philosophy I hope that was just a joke
you where doing . Because it made me laugh and think horrible thoughts of traceability.
You've never daisy chained attenuators? It works great, especially on a PNA! Always try to do 4 20db ones at the same time, they always read spot on :-o
/end sarcasm
OK.. I am going to chime in here..
Yes.. They read spot on because you are getting a average.
Metrology is about comparing an unknow to a know. Not the average of 4 unknows to a know. Of course they most likely going to be spot on.
And that is not the same as daisy chaining DMM's. The Fluke calibrators will typically trip when they can't provide the source required. Voltage can be done in parallel but the lab should know the errors or repeatability of their cables this can be done with an R&R Study. Same thing with Current except in series. Resistance has to be tested one UUT at a time.
We automated one of our customer's labs to do DMM's in bulk they can calibrate 8 Fluke 87's in 2 hours. With data it was $85 dollars each if you do the math that's over $300 per hour. The only problem is feeding the monster.
Mike
Mike
Thanks for the chime in . Yep a auditor would have a field day with
this practice . And Yes on the 5520A daisy chain they are not understanding
about the impendance of the daisy chain and what that will do to ACV freq response .
And Yes loading effects will cause possible issue with the 5520A or whatever calibrator
you are using . Saving time and doesn't result in quality and proper traceability.
But I guess if they want to do these practices so be it , Im not the auditor .
I agree with cal lab solutions wholeheartedly.. OMG!!
I forgot I had to write "sarcasm" ayt the end of that.... :evil:
Hey, you're doing this wrong! You're in a production line, not a calibration lab.
Real kalibraters daisy chain spec ans
There is certainly a place for daisy chaining handhelds. It's a legitimate practice used in every lab I've ever worked in, including Air Force Type IIA. Top Gun is overstating the AC effects. We are talking low frequencies here, practically DC in the grand scheme of things. The proof is in the pudding. Daisy chain 4 Fluke 87s and take the data, then do one at a time. No discernible difference. I'm not saying that there aren't some additional uncertainties associated with this method, I'm just saying they are negligible for all intents and purposes. We are talking about a handheld DMM for the love of God. Use some common sense. The calibration only has to be "good enough" for the situation at hand. That's why we don't use 3458As to calibrate power supplies. Not every cal requires the best that you've got. If somebody told you different, someone done told you wrong. Oh, and no, I would not daisy chain attenuators under any circumstances. But that's a whole different ball of wax.
Man can't have any fun around here anymore......
And no, you can't daisy chain attenuators..... on a PNA or elsewhere. If you had ever used a PNA you would have gotten the joke, -80 db puts the trace at the bottom of the screen.... looks perfect...... but if you have to explain it, well guess that kinda kills the joke......
Ok, back to daisy chaining dmms and spec ans.....
I love the impedance check where you use an assortment of T connectors and an HP 909A 50 Ohm termination. You can do up to three network analyzers simultaneously (for those who don't understand - kidding).
you know, every lab I worked in did not allow this practice. I must have worked in legit labs--US NAVY, DOD,HP,Agilent,etc.
I never do that any more, really. In an ISO17025 world, besides the practical implications of loading the output of the calibrator, you would need to account for the uncertainty introduced, and of course what procedure you use that allows multiple meters (none). Matter of fact, I believe it was the Datron 4808 that I used a number of years ago, that when you connect it to lower input impedance meters (such as a Simpson 260), it would not adequately regulate and you would get erroneous out of tolerance readings. So even simple handheld DMM's might get erroneous results.
Accreditation and the infiltration of metrology by the mathematicians has ruined this once great career field. Listen to yourselves. WE ARE TALKING ABOUT HANDHELD DMMS FOR CHRIST'S SAKE! WAKE THE HELL UP! Microvolts of uncertainty on the 200 mVAC range of a Fluke 87 is not even worthy of consideration. You guys are really overthinking this. And what good is data on a handheld DMM? No one has been able to offer me a legitimate explanation yet.
Quote from: Duckbutta on 04-21-2015 -- 20:46:55
Accreditation and the infiltration of metrology by the mathematicians has ruined this once great career field. Listen to yourselves. WE ARE TALKING ABOUT HANDHELD DMMS FOR CHRIST'S SAKE! WAKE THE HELL UP! Microvolts of uncertainty on the 200 mVAC range of a Fluke 87 is not even worthy of consideration. You guys are really overthinking this. And what good is data on a handheld DMM? No one has been able to offer me a legitimate explanation yet.
Since when do we judge how important a piece of equipment is? I have no idea what the use is of a piece of equipment is. Ill give my customer the best cal I can provide at a reasonable cost.
It may be "Just a Fluke 87" but I was a part of a a Fluke 77 fiasco back in the early 90's at Pearl HArbor in which a submarine was sent back to port because a technician was concerned that the reactor may not have been started properly because of a simple Fluke 77. It cost the Navy millions and it was not fun calibrating a meter in front of the Admiral. But it was "Just a HandHeld Meter" right...
I think your missing the point. It is not that we "judge" how important the meter is. It is that there is almost no change to the accuracy of the 5520A when doing this. When they said it is not important they meant it does not change the accuracy enough that you would EVER see it on the handheld DMM. That being said I would not recommend daisy chaining a 34401A or higher accuracy instruments together because it is much closer to a 4 to 1 ratio and it might actually change some readings there. Although I would love to see some actual data instead of just opinions. Anyone done any actual tests to see if this changes anything??
ck - If there was a problem with the Fluke 77 I assure you that it wasn't because it was daisy chained during cal. I stand by my comment, no matter what the end use of the item is, the standards only have to be "good enough" (4:1). You take yourself to seriously. Get over yourself.
Quote from: USMCPMEL on 04-22-2015 -- 06:48:50
there is almost no change to the accuracy of the 5520A when doing this.
"there is almost no change" is not a measurement. though there are too many mathematicians, our job is still to know what and how we are measuring everything. will 3 take the calibrator out of tolerance? 4? 10? as long as it resettles is the accuracy the same? there are a lot of variables there. could i gang together 300 pressure gauges?
The Fluke 77-4 is accurate to +-2% +-2 counts. The fluke 5520A is accurate to .012%. Unless someone is going to go out and do some type of study to show me that it will make a difference I will never believe that the accuracy would degrade enough. As I had stated I would only do that when we were calibrating no data. I have a very hard time believing that it would make a difference even if you were calibrating with data.
Unless the uncertainty's have been done for a " Daisy Chain "
Then as Metrologist you follow the proper way of doing things.
Not the unknown variable UNTIL YOU HAVE PROVEN IT .
We are test and measurement people . Standards and practices
need to be followed. If we all decided it " Good Enough " then what
is Bad and what is good ??? What is your standard of thinking .
Until there is proof with the calculations then I say do it the tried and true
method . But if you want to play with Fire and the Auditors and the consequences
behind this practice so be it. We adhere to procedures and specs and calculations.
Please don't teach these practices to the new people , they need proper guidance .
I've found that in the time wasted in the set up for daisy chaining handhelds, I could probably have calibrated 2 or 3 already, they're not exactly rocket science. I never really saw much of an advantage in daisy chaining. The things you might daisy chain are usually so simple, it's usually faster to just do the damn thing.
Guys Im done with this email chain , and I understand the
reasoning that people have with the Daisy Chain on DVM
ect . Its a harsh commercial environment and Time equals
money . I understand the pressure of the Cal Techs to produce and
meet quotas and have a 3-1 ration of billings to pay , at a minimum .
Recommendation to eliminate all this and stick to High End Cal and then
spend the time to do it right (I wish) . At least in a perfect world , LOL
But I understand the pressure is to produce and bill . So be it .
What would you guys say is the Quota of Billing to salary ??
3-1 on average ???
If the company you work for actually has a quota, I would say you are working for a poorly managed lab. Your salary should reflect the expertise you bring to the lab along with the production you can generate. Having said that, I would say that if you are primarily a technician in the commercial field, and you can not generate enough production to cover 3 times your yearly salary, your lab does not charge enough or you do not work efficiently enough (organize, automate, upgrade standards & technique, etc.).
Just wanted the general feeling of the ratio SD Metrol .
What would you say the average ratio is ? Im sorry if I offended you
with that question. And Im a repair guy . I like to keep separate from
cal to give the repair a unbiased judgment in cal. AKA no fudge factor .
But Im a Lowry 1983 grad . So I do know cal pretty good , but not physical
dimensional as I believe you are . Strickly a RF guy and various calibrators
in the calibration realm. So please don't feel offended when I say ratios .
I know a lot of Cal Labs work as such and I do agree that it shouldn't matter.
But also 3 rd Party Calibration is a business and has to be profitable in order to survive.
Just was curios what the rate was out there for seasoned cal techs . And its
best to state a ratio without people giving actual salary or hourly numbers .
So I hope your following me about my question and why it was stated as such .
When I was at Transcat years ago they wanted you to bill like $1500 per day at onsites. I had just started out and I think that year I billed about 10 times my pay but back then I was making $12 an hour.
I'm with sdmetrol, if you work for a company with a quota, you are working for the wrong company. I worked commercial calibration for a few years but would never do it again. It really soured me on the whole accreditation process and the quality of calibration services that are available commercially. These were accredited labs with a national footprint. If you look at their scope on their websites it looks impressive but I know what goes on behind the scenes. It's a joke and definitely not metrology, but not because they daisy chain multimeters, but because they are selling their customers a bill of goods.
I have discussed this with management. The answer is all of them.
Duckbutta
Almost every compeny I have worked for has had some sort of a quata usually it is not directly spoken but if you fall behind a certain amount they would mention it to you. That being said I do not think it compromised quality. We followed procedures. I even changed some of the Fluke handhelds to military procedures becuase I felt that the frequency response was not being checked in the Manufacturers procedures. Now you are always going to have people that just check a few points and throw a sticker on but I have never worked for a company that I was pushed to the point that I felt I had to do that. If I had been I would have quit.
I too worked for Transcat and know how they operate. Does anyone think it even remotely possible to calibrate thirty network analyzers manually in two days? I've seen guys do it. It's like stealing money. I think they were getting like $850 apiece or something for each one. Not bad for two guys and two days of work. No wonder management looked the other way. They knew what side their bread was buttered on. Even though we worked for them we all used to call the company Transcam. A very apt description.
Quote from: Top Gun Test on 04-22-2015 -- 21:32:05
Just wanted the general feeling of the ratio SD Metrol .
What would you say the average ratio is ? Im sorry if I offended you
with that question. And Im a repair guy . I like to keep separate from
cal to give the repair a unbiased judgment in cal. AKA no fudge factor .
But Im a Lowry 1983 grad . So I do know cal pretty good , but not physical
dimensional as I believe you are . Strickly a RF guy and various calibrators
in the calibration realm. So please don't feel offended when I say ratios .
I know a lot of Cal Labs work as such and I do agree that it shouldn't matter.
But also 3 rd Party Calibration is a business and has to be profitable in order to survive.
Just was curios what the rate was out there for seasoned cal techs . And its
best to state a ratio without people giving actual salary or hourly numbers .
So I hope your following me about my question and why it was stated as such .
No offense taken. I was just voicing my opinion about the ratio because I have been on both sides of that equation. Sometimes the ratio is very high for technicians that are not really performing adequate work (the fault of the tech in my opinion), and sometimes the tech is performing excellent work but has a low ratio because the pricing is not adequate (fault of the lab in my opinion).
I received my initial training in Physical/Dimensional but now have over 25 years experience in DC/LF and consider myself well enough versed in RF/Microwave to know the actual work involved and related costs of performing it correctly.
In the commercial world, we are performing verification (performance testing/comparing to a known standard) much more than actual calibration (adjusting to a known standard) so it is difficult to compare the two. Our lab is setup so the performance testing techs are adequately equipped to test their workload in the field and get the gear back into use quickly (something you better be prepared to do if you want to be successful in the commercial world) and they bring the rejected items back to the lab where a calibration tech can take the time to make necessary adjustments/repairs without having the time constraints of a production oriented environment impeding the quality of the work. Of course there are some exceptions to this (easily adjusted in the field, unmovable objects, etc.).
In our case, the performance testing techs usually have a higher ratio than the bench calibration techs, but we do not place that much weight on their respective ratios when determining performance.
SDMETROL
Well done explanation !!! That was very clear and made a lot of sense .
Business , calibration , quality and methodology. Very well done .
I appreciate the explanation .
specs of an item are based on "normal conditions" a meter calibration is expecting xxx impedance for any given range or function. when you change that (as in high temp conditions) you must do the math. that is why labs are kept within fairly close temp/humidity. now maybe you can externally monitor, say the sensing internally will compensate from y to z, but you should be able to prove everything.
THANK YOU Jimmy!! That actually at least has some input into my original question. I understand this is not a good practice i am not recomending technicians start doing it. I was just trying to get a feel for how it would actually effect the output of the 5520A. Most people on this thread are just telling me it is wrong do not do it but not actually making any kind of valid argument why. I understand it might change the output MIGHT so prove it to me. Give me actual evidence to supoort your argument for a few days there I thought I was talking to people from an Oboma rally!! All arguments with not true evidence to back anything up.
Duckbutta! You da man. As for daisy chaining. As you were saying, it depends on what is being daisy chained and how the item is being used. I have daisy chained up to 6 fluke 27, 77, 87, PSM45, sperry 61-609, snap on EEDM586D and such. The only thing is the resistance checks, obviously. Like you stated earlier, "they are just DMMs." Now if they were being used to measure something down to the 6th decimal then obviously a good calibrator would not do such a thing as daisy chain. Most of these models are used to check battery voltage or the voltage of an alternator/generator. Even in the Army TMDE diasy chain is frowned upon but used often. DEPENDING on the item being tested and its use.
I guess the best way to find out how many COULD be tested would be to contact Fluke and have them prove it. Seeing that most DMMs in this discussion were flukes and a 5520A is being used. We have the 5720/5725 setup and the 5520A. I would prefer using the 5520A any day of the week. Love that 20A option. As stated before. The voltage drop is so minimal in comparison to the DMM being tested that it doesn't really matter. Now if testing say a 3458A or an 8508 then one would be more apt to use proper procedure.
That's right. I said Army TMDE. :-D
If I would not do it with an auditor (QA, A2LA, ACLASS, ISO, FBI, CIA, or my supervisor) standing over my shoulder then I don't do it anytime. We forget sometimes that in this small field all we have is our name. I know every time I put a label on a piece I am saying it is tested to be within the specs provided in the applicable procedure. If I do not know what the effects are, I'm not going to do it. The effects of daisy chaining may be negligible, but until I sit down and waste days proving that it is irrelevant, it is relevant. Days? Yes, considering the umpteen thousand models of handheld DMMs out there.
Besides, in the time it takes the average Joe to setup a daisy chain, he probably could be at least halfway through the stack of meters, if not more.
I agree with you CalibratorJ. Daisy chaining has never been something I cared to do. The first time I tried it, one of the meters had a bad solder joint in the input connector and it screwed up all the readings and I needed to check each one individually anyway.
Quote from: CalibratorJ on 04-25-2015 -- 19:24:55
If I would not do it with an auditor (QA, A2LA, ACLASS, ISO, FBI, CIA, or my supervisor) standing over my shoulder then I don't do it anytime.
This... :mrgreen:
Good Answer Griff..
And yes... I would do it in front of an auditor.
Wow griff, your last post smacks of racism and I'm surprised that is tolerated here. Grow up and join the 21st century please.
Did I miss something?
Quote from: sdmetrol on 04-27-2015 -- 20:23:05
Wow griff, your last post smacks of racism and I'm surprised that is tolerated here. Grow up and join the 21st century please.
Please, elaborate.
Quote from: griff61 on 04-27-2015 -- 22:53:30
Quote from: sdmetrol on 04-27-2015 -- 20:23:05
Wow griff, your last post smacks of racism and I'm surprised that is tolerated here. Grow up and join the 21st century please.
Please, elaborate.
Ill take a stab. :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen:
Gimme a f'n break.
Quote from: ck454ss on 04-28-2015 -- 05:37:57
Quote from: griff61 on 04-27-2015 -- 22:53:30
Quote from: sdmetrol on 04-27-2015 -- 20:23:05
Wow griff, your last post smacks of racism and I'm surprised that is tolerated here. Grow up and join the 21st century please.
Please, elaborate.
Ill take a stab. :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen:
Gimme a f'n break.
So, you don't like Mr. Green? Perhaps you should take it up with Hoopty.
Mr Green is racist? I am really confused now.
Quote from: USMCPMEL on 04-28-2015 -- 11:17:04
Mr Green is racist? I am really confused now.
You're probably less confused than some here.
Perhaps he's offensive to the bald emoticons?
Sorry, I should have said "Follicle challenged"
I like Mr. Green :mrgreen:
And I don't see anything wrong w/ griff using him in his post either. He was agreeing w/ the quoted text and added Mr. Green as one would a smiley face emoticon at the end.
That being said, I just knew that when I saw the tweets updating this thread for as many days as I have, that there had to be something going on and that it would probably require intervention. Thankfully it wasn't anything major, but c'mon guys, let's just stick to the topic and keep it from getting personal.
Thanks!
Maybe I misunderstood? I actually read his reply as disagreeing with the post and commenting as "this (insert n word)"
I know not of this Mr. Green but if I saw something that wasn't intended, I will give the benefit of the doubt. Btw, the emoticon reads as "afro", which can easily offend if taken wrong.
Quote from: sdmetrol on 04-28-2015 -- 20:29:36
Maybe I misunderstood? I actually read his reply as disagreeing with the post and commenting as "this (insert n word)"
I know not of this Mr. Green but if I saw something that wasn't intended, I will give the benefit of the doubt. Btw, the emoticon reads as "afro", which can easily offend if taken wrong.
I don't require your benefit, beucause you were wrong, presumptuous and insulting.
An apology would be appropriate.
'mrgreen' Is the 'code' behind the emoticon.
It's pretty much across the top of the message box.
Sort of like :)
The more you know...
BTW an Afro is a legitimate name for a type of haircut. Assuming it is a derogatory reference about a type of person says volumes more about you than me.
Also means you probably never lived through the 70's, a time when is seemed like everyone had that or the Farah Fawcett hairdo, with or without the Ron Burgundy mustache.
You should be clear about a subject before you decide to throw around insults and also have the integrity and good manners to properly to apologize when you're wrong.
You have a nice day.
Put four calibrators on any problem and you will get 4 different ways to solve said problem. Key is to not kill each other on the way to agreeing on a solution.
But griff, I know you would look good sportin an afro..... I tried, but stringy hair + saltwater = no bueno. Just end up looking like every other beach bum out here :-o
Quote from: CalibratorJ on 04-28-2015 -- 23:55:24
But griff, I know you would look good sportin an afro..... I tried, but stringy hair + saltwater = no bueno. Just end up looking like every other beach bum out here :-o
My hair wouldn't do the Afro thing, came close to the Farrah look back in high school...scary really. Had a firend who just sort of woke up with the perfect 'fro every day, hope he's bald now, that'll teach him. Now my hair's pretty much translucent, so I get the old high and tight and pretend it's not gray...it's just really short
Quote from: griff61 on 04-28-2015 -- 23:07:29
Quote from: sdmetrol on 04-28-2015 -- 20:29:36
Maybe I misunderstood? I actually read his reply as disagreeing with the post and commenting as "this (insert n word)"
I know not of this Mr. Green but if I saw something that wasn't intended, I will give the benefit of the doubt. Btw, the emoticon reads as "afro", which can easily offend if taken wrong.
I don't require your benefit, beucause you were wrong, presumptuous and insulting.
An apology would be appropriate.
'mrgreen' Is the 'code' behind the emoticon.
It's pretty much across the top of the message box.
Sort of like :)
The more you know...
BTW an Afro is a legitimate name for a type of haircut. Assuming it is a derogatory reference about a type of person says volumes more about you than me.
Also means you probably never lived through the 70's, a time when is seemed like everyone had that or the Farah Fawcett hairdo, with or without the Ron Burgundy mustache.
You should be clear about a subject before you decide to throw around insults and also have the integrity and good manners to properly to apologize when you're wrong.
You have a nice day.
Let's look at this logically:
When you hover over the object, it says "Afro".
It appears you replied sarcastically to the previous post and stated "This (Afro Emoticon)"
It has been stated here that the code says "Mr. Green"
Conclusions:
You were calling into question something about the character of the poster by saying "This Afro", or This Mr. Green". Since I have no knowledge of this Mr. Green, I assumed that you were making a racist comment. Please explain how "This Mr. Green" applies to a character description and I will indeed offer my apologies.
OK sdmetrol,
This is how it works, let me translate a little better than I did before.
Griff quoted a previous post where someone said "If I wouldn't do it in front of an auditor, I wouldn't do it any time." (I'm paraphrasing) Griffs response was "This..." Which in forum speak... means that he (Griff) agrees with the quoted statement. Very much akin to the +1. He put an emoticon on the end. It's a standard emoticon. It wasn't meant as a character description. It's groovy. Whatever. Could have been a smiley face, could have been the devilish face, it happened to be Mr. Green the guy with the afro. It wasn't racist, it was just a cool emoticon at the end of his post.
Standard forum posting.
Case closed. Thread Closed.