Regarding Jon's last comments about the use of un-calibrated equipment. CDS has an internal Metrology department which handles almost all of my periodic calibration (I send out my antennas, current probes & LISN's). Every year, we have a long discussion about their need to minimize calibration costs. (I have to provide them with a budget to cover all of my predicted calibration costs.)
One thing I have done to minimize costs is to put all of my power supplies, amplifiers, pulse generators and function generators on a "No Periodic Calibration; User Verified" status. My rationale is that I never trusted these devices to actually create what you set them for, so I always use a calibrated DMM or oscilloscope to verify and monitor any settings. (All of this NPC equipment carries a bright label warning of its status.) Of course, I still keep all oscilloscopes, meters, spectrum analyzers, measurement pre-amps, attenuators and probes on normal periodic calibration. I also keep any signal sweepers, signal generators and AF/RF synthesizers also on calibration, since I like to be able to use them "stand-alone" for some testing. Also, having calibrated RF signal sources allows me to informally cross-check my meters and analyzers. Using this system, I have moved from 100% calibrated equipment to only about 30% calibrated equipment. Considering that I have about 300 capital equipment items, this has resulted in a pretty decent cost reduction in the past few years. Regards, Ed Ed Price [email protected] Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military & Avionics EMC Services Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis -----Original Message----- From: Jon D. Curtis [mailto:[email protected]] Sent: Monday, February 26, 2001 10:48 AM To: Flinders, Randall Cc: [email protected]; [email protected]; [email protected]; [email protected] Subject: Re: Calibration of test equipment As I understand it the interpretation to have tracibility to your national authority through equipment used only for calibration originated with NAMAS. Some other accreditors have picked it up since then. The requirement need not be that onerous. You can calibrate your own equipment traceably to your national authority using equipment that you send out for calibration. Where the instrument is cheap (multimeter) we buy an extra and use it only for calibration. Where it is expensive (oscope, receiver), we use it for calibration only directly after it returns from outside calibration (or inside tracible cal) and after we have calibrated our secondary equipment with it we put it into regular service for the year. If you manage your yearly calibration cycle well this shouldn't crimp your style too much. The key is not to have equipment in your calibration chain back to the national authority that has been used for non-calibration purposes between the time of its calibration and that of the secondary calibration. The idea is to have high confidence that the tracibilty chain is intact. If a piece of equipment in the chain has been used daily in regular rough and tumble testing it is seen as having a much higher probability of operating outside of its tolerances. In my experience the outside cal houses are pretty tough on their gear too, so I am not sure that much is gained. I personally think this interpretation is overly severe, but we comply with it because we want our test reports to be accepted by authorities who think this process is reasonable. To directly answer your specific question about a signal generator used in immunity: If it is being used as an uncalibrated signal source in the measurement and you are using a power meter or receiver for tracibility then you can use that signal generator, even if it went off a cliff the day before. If you are relying on the calibrated output level that the signal generator says it is putting out, then you should not have used that instrument in non-calibration use since its last calibration. Jon. "Flinders, Randall" wrote: > Does this mean that a signal generator that is used for Radiated > Immunity testing should not be used to calibrate Pre-Amps and Cables? > How about Antenna Calibration? Can you use the same receiver you use on > the OATS to calibrate those? I know this is a common practice with > Commercial Test Labs. > > Is there guidance as to what types of equipment can be used for both lab > use and for the calibration of other equipment? > > [email protected] wrote: > > > > I think there is a special requirement to keep the calibration equipment > > separate from the EMC equipment. In other words the calibration equipment > > can only be used for the calibration process and not for testing EMC. > > > > > Michael Sundstrom > > > Product Test Technician EMC > > > Nokia Mobile Phones, Dallas PCC > > > > > > * Email [email protected] > > > % Desk (972) 374-1462 > > > *Mobile (817) 917-5021 > > > * Fax (972) 374-0901 > > amateur call: KB5UKT > > > > ------------------------------------------- > > This message is from the IEEE EMC Society Product Safety > > Technical Committee emc-pstc discussion list. > > > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > > > To cancel your subscription, send mail to: > > [email protected] > > with the single line: > > unsubscribe emc-pstc > > > > For help, send mail to the list administrators: > > Michael Garretson: [email protected] > > Dave Heald [email protected] > > > > For policy questions, send mail to: > > Richard Nute: [email protected] > > Jim Bacher: [email protected] > > > > All emc-pstc postings are archived and searchable on the web at: > > http://www.rcic.com/ click on "Virtual Conference Hall," > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Michael Garretson: [email protected] > Dave Heald [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > http://www.rcic.com/ click on "Virtual Conference Hall," -- Jon D. Curtis, P.E. Director of Engineering Curtis-Straus LLC One Stop Laboratory for NEBS, EMC, Product Safety, and Telecom Testing. 527 Great Road Littleton, MA 01460 USA Voice 978-486-8880 Fax 978-486-8828 email: [email protected] WWW.CURTIS-STRAUS.COM ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: [email protected] Dave Heald [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall," ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: [email protected] Dave Heald [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
