Re: [volt-nuts] HP 3457A
Orin wrote: They send a calibration certificate which claims that their standards are traceable to NIST. I have no reason to doubt that. Owning standards and instruments with traceable calibrations is necessary but not sufficient for making traceable calibrations with them. For a calibration to be traceable, the lab that did the calibration must be accredited. If the lab is accredited, the calibration certificate would certainly identify the accrediting body. Does the certificate you received identify an accrediting body? Best regards, Charles ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP 3457A
Joe, I looked at the listing you posted. The unit looks very nice. However, the units are selling in the $150 - $250 range, although I note some of the units you linked to have sold for the price asked. There has been considerable discussion on the list about the 3457A and some differences between units, depending on serial number, having to do with the circuitry about the backup battery for the RAM. I would recommend you search the archives about that. Also, there are various options for the rear compartment that may or may not be useful so being able to see the back of the unit to see what is installed and what the serial number is would be useful. I prefer to use the original manufacturer's calibration services when it comes to Agilent or Fluke just to be able to eliminate the 'trust uncertainty' with 'outside labs', since I have little experience in using various calibration labs. Therefore, my choice would be to look for a desirable 'used' unit then clean it up myself, check the date on the backup battery and possibly change it (with the need to keep voltage applied to the unit while unsoldering the battery lest losing the CAL data - careful there - 'Danger, Danger, Will Robinson') then send it to Agilent for calibration ($204.22 for the Agilent Calibration). If you are looking for a currently supported unit, I would consider the Fluke 8846A. Can be had for under $1000. A bit more expensive but currently available and currently supported. Good luck. Joe -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of Joseph Gray Sent: Saturday, August 10, 2013 9:20 PM To: Discussion of precise voltage measurement Subject: [volt-nuts] HP 3457A If I want to buy a used 3457A, is it better to buy one as-is and send it for calibration, or perhaps spend a bit more and get one already calibrated? Just one example: http://www.ebay.com/itm/HP-3457A-6-5-Digit-Lab-Quality-Front-Terms-Fully-Ref urbished-NIST-Cal-/300928374155 Joe Gray W5JG ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP 3457A
I think the statement is awkward English, but what I think he is trying to say is that: 1) the instrument will be recalibrated 2) after the instrument is verified, by the calibration lab, to be working within specs, 3) a NIST traceable calibration certificate will be mailed. -Chuck Harris Charles Steinmetz wrote: Orrin wrote: Well, lets discuss the 3456A I got from goldenrubi, calibrated. They send a calibration certificate which claims that their standards are traceable to NIST. I have no reason to doubt that. I happened upon one of the seller's auctions, so I checked that one and several others. In the boilerplate of each one I found this: WE WILL RE-CALIBRATED THE UNIT BEFORE SHIPPING AND A NIST TRACEABLE CALIBRATION CERTIFICATE, WILL BE PROVIDED AFTER ITEM IS RECEIVED AND IS ACCEPTED AS WORKING WITH IN SPECS. WE WILL MAIL OUT THE CERTIFICATE. If I understand this correctly, I buy an instrument, the seller calibrates it before shipment, but doesn't send the calibration certificate with the item. He mails it to me after I accept[] [the instrument] as working within specs. So, I have to verify the calibration myself, and then this seller will send me a NIST traceable calibration certificate??? Words cannot express how irregular that sounds to me. I'd be interested to hear about any other NIST traceable calibration facility that works this way. Best regards, Charles ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP 3457A
They shipped the certificate with the 3456A I got from them. The cal certificate is from AAA Calibration Equipment Specialist Inc. at a SW Albuquerque address and is issued to AAA Equipment Resources Inc. at a NW Albuquerque address. I suspect some internal accounting reason or a defense against dishonest buyers for this. BTW, they don't list any accreditation on the certificate. I did once ask if they could cal an 8484A and they said no. As for the local labs here, I'm not happy with the local Tek lab that I sent my TDS210 to in its original packaging. They returned it in a small box with two layers of bubble wrap. The Fluke HQ and cal lab is twenty miles from here... I think that's about as good as it gets, so they might be getting my business in the future. Orin. On Sun, Aug 11, 2013 at 5:57 AM, Charles Steinmetz csteinm...@yandex.comwrote: Orrin wrote: Well, lets discuss the 3456A I got from goldenrubi, calibrated. They send a calibration certificate which claims that their standards are traceable to NIST. I have no reason to doubt that. I happened upon one of the seller's auctions, so I checked that one and several others. In the boilerplate of each one I found this: WE WILL RE-CALIBRATED THE UNIT BEFORE SHIPPING AND A NIST TRACEABLE CALIBRATION CERTIFICATE, WILL BE PROVIDED AFTER ITEM IS RECEIVED AND IS ACCEPTED AS WORKING WITH IN SPECS. WE WILL MAIL OUT THE CERTIFICATE. If I understand this correctly, I buy an instrument, the seller calibrates it before shipment, but doesn't send the calibration certificate with the item. He mails it to me after I accept[] [the instrument] as working within specs. So, I have to verify the calibration myself, and then this seller will send me a NIST traceable calibration certificate??? Words cannot express how irregular that sounds to me. I'd be interested to hear about any other NIST traceable calibration facility that works this way. Best regards, Charles __**_ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/volt-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP 3457A
On 11 August 2013 03:19, Joseph Gray jg...@zianet.com wrote: If I want to buy a used 3457A, is it better to buy one as-is and send it for calibration, or perhaps spend a bit more and get one already calibrated? Just one example: http://www.ebay.com/itm/HP-3457A-6-5-Digit-Lab-Quality-Front-Terms-Fully-Refurbished-NIST-Cal-/300928374155 Joe Gray W5JG If you look at the feedback for the seller, you will find this auction# http://www.ebay.com/itm/221234066046 He bought one of the meters for $305. At first I see best offer accepted and no price. But if you print the auction to a PDF file, then look at the PDF, you will find the actual cost it sold at !! Funny thing was, after doing that I could see the price anyway, so perhaps I was mistaken first time I thought the price was a best offer. Anyway, he seems happy to buy at $305. so it might be worth sending him a mesage with a lower offer. Dave ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] HP 3457A
Orin wrote: The cal certificate is from AAA Calibration Equipment Specialist Inc. at a SW Albuquerque address and is issued to AAA Equipment Resources Inc. at a NW Albuquerque address. Those are both the seller: http://www.bizapedia.com/nm/AAA-CALIBRATION-EQUIPMENT-SPECIALIST-INC.html https://aaaequipmentresources.3dcartstores.com/crm.asp?action=contactus BTW, they don't list any accreditation on the certificate. As I suspected. So it is vanishingly unlikely that they do traceable calibrations, contrary to their claim. The Fluke HQ and cal lab is twenty miles from here... I think that's about as good as it gets, so they might be getting my business in the future. It's hard to do better than that. The Sandia Primary Standards Lab is right up there, too. Best regards, Charles ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Calibration and Certification - Trust and detail
On 11 August 2013 15:39, Robert Atkinson robert8...@yahoo.co.uk wrote: On a related issue to the 3457A calibration, I was asked to review an item at work last week (sorry can't say what or why). Looking at compliance certification by two fully qualified, internationally recognised labs, all looked well until I looked at the detail. Things like ..all RELEVANT requirements of.. (my capitals) with no list of what was relevant or any test report., details of only one test when the standard needed a number under different conditions, no record of the part or serial numbers of the unit tested. Others had accepted the certification at face value. I think it depens why you want the cal certificate. 1) If it to keep the BSI person happy to keep your ISO 9001 acreditation, then I guess as long as it has a cal certificate that is ok, so use the cheapest dodgy cal lab. 2) If the purpose of the cal certificate is to get the highest price when selling something, then a cal certificate by some dodgy cal lab is probably all you need. 99% of buyers are not going to question who did the cal, and their ability to do it. 3) If you want to know the instrument works correctly, and have it adjusted for best performance, then it is a very different matter. One is probably better sending it to the manufacturer in many cases. I want to know my VNA works properly, so that is going to Agilent this week. The cal cost on my VNA is about 5% of what I paid for the VNA. It would be much more difficult to justify sending my 3457A to Agilent, when the cal cost will probably be more than what I paid for the instrument. How useful is this http://www.ebay.com/itm/281149723636 ? On the fact of it, the device would give one a reasonly high confidence something is working readlably well. I wonder if that is good enough for a 3457A. Unfortunatly if the test house customer says just do this bit and the test house is happy to put weasely words on the certifcate, then user beware. As I wrote earlier, I think there is a very cosy relationship between cal labs and test equipment dealers. It is in both their interests to get cal certificates on items even if they are not 100%. A T+M dealer is not likely to use a cal lab that keeps sending items back marked Out of specification or similar. A cal lab does not want to lose a customer. Robert G8RPI. Dave, G8WRB. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Calibration and Certification - Trust and detail
David wrote: How useful is this http://www.ebay.com/itm/281149723636 ? On the fact of it, the device would give one a reasonly high confidence something is working readlably well. I wonder if that is good enough for a 3457A. Let's assume that it is still working exactly the same as it was when it was calibrated. The calibration values are recorded to 4-1/2 digits. So the uncertainty is greater than the two LSDs of a 3457A. Of course, it is almost certainly not working exactly the same as it was when it was calibrated, which is going to put at least the third LSD of a 3457A in question. So it is good enough for a 3457A only if one is content with a 3-1/2 digit verification on a 6-1/2 digit instrument. Best regards, Charles ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
