Re: OK, what's going on?
Hi Earl and the gang, I may be atypical, but I have a shortwave radio in the same room (on the same desk with much of it) with 4 computers, a unix server, a print server, fax machine, large copy machine, and several printers, the hub equipment of a good sized ethernet network (for 8 computers, a unix server, and print server) and I expect to be able to hear WWV to set my clocks and occasionally listen in on the Ham bands. The only thing that bothered the radio was parallel port printing. But now that I print over my 100 Mbit network, no problem. The TV in this room (13 inch) seems to cause more interference than the rest of it! Doug Morse, Earl (E.A.) wrote: Amen! I had 15 years of computer EMC when I left the PC sector this year. This was a never ending source of frustration. I won't even get into the shortcomings of the measurement standards. The emigration of PC manufacturing to the PAC rim is being followed by emigration of the design and validation teams also. Many PC manufacturers have completely outsourced their EMC testing to the OEM PC manufacturers even when they own several 10 meter semi anechoic chambers. This is akin to having the fox watch over the hen house. Management says it is more economical that way. When every test is compliant and product passes the first time every time then I guess it is. Besides, it isn't compliance that anyone is really after anymore but rather a piece of paper that says it is compliant. (Neville Chamberlain effect) Maybe it doesn't matter anyway. Most customers don't care if it meets EMC requirements. Most only relate features to price and EMC is not a feature they would pay for. An EMC engineer can't tell whether a PC passes or fails without an expensive test site chock full of equipment so how is a consumer supposed to tell? A few commercial and government customers perform audit tests before entering into contracts but most don't seem to care. I seem to remember an FCC employee speaking at a conference somewhere stating that they don't get computer interference complaints. Mostly telephone interference complaints but never computer interference. Most of the field complaints I worked on were immunity related. Customers care and complain about that. In today's computer industry the companies that aggressively pursue EMC are penalized by adding more cost while the companies that ignore it are able to produce a more inexpensive product. The vigilant companies will not be able to compete. I agree, enforce the emissions standards or drop them. Earl Morse ex-Major PC Company EMC guru .. -- ___ _ Doug Smith \ / ) P.O. Box 1457 = Los Gatos, CA 95031-1457 _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-( ) | o |Email: d...@dsmith.org \ _ /]\ _ / Website: http://www.dsmith.org 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
high immunity
With the advent of E-weapons we might need some new immunity specs. I read that they can output several GW. Testing for equipment survival at over 5000 V/m should be fun (and profitable to some). Dave Cuthbert Micron Technology 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
New EMC RTTE standards list
New reference lists for EMC and RTTE standards were published in the OJ today. http://europa.eu.int/eur-lex/en/oj/2003/c_07420030326en.html Richard Woods Sensormatic Electronics Tyco International 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: OK, what's going on?
Most of the stuff I worked on was global. The same box went everywhere with the appropriate language pack installed. There are some companies that are NA sales only and we did have a few consumer products that were marketed that way. From: Stone, Richard A (Richard) [mailto:rsto...@lucent.com] Sent: Wednesday, March 26, 2003 11:44 AM To: 'Morse, Earl (E.A.)'; 'Grasso, Charles'; 'lfresea...@aol.com'; emc-p...@majordomo.ieee.org Subject: RE: OK, what's going on? thats true Earl, good point on company B, not caring but selling with a higher profit, less EMC..company A busting butt to pass and comply with integrity. as for immunity... do any PC makers manufacturer any PC's strictly for sales in USA...only need Emissions here. that would save 1000's in emc costs, never mind engineering to fix the problems.. of course you would need diff. p/n's then. and sales,manuals, compliance certs..etc would be altered. has anyone ever done a cost estimate based on building a USA vs. EU chassis? curious to see if its worth the time. From: Morse, Earl (E.A.) [mailto:emo...@ford.com] Sent: Wednesday, March 26, 2003 11:10 AM To: 'Grasso, Charles'; 'lfresea...@aol.com'; emc-p...@majordomo.ieee.org Subject: RE: OK, what's going on? Amen! I had 15 years of computer EMC when I left the PC sector this year. This was a never ending source of frustration. I won't even get into the shortcomings of the measurement standards. The emigration of PC manufacturing to the PAC rim is being followed by emigration of the design and validation teams also. Many PC manufacturers have completely outsourced their EMC testing to the OEM PC manufacturers even when they own several 10 meter semi anechoic chambers. This is akin to having the fox watch over the hen house. Management says it is more economical that way. When every test is compliant and product passes the first time every time then I guess it is. Besides, it isn't compliance that anyone is really after anymore but rather a piece of paper that says it is compliant. (Neville Chamberlain effect) Maybe it doesn't matter anyway. Most customers don't care if it meets EMC requirements. Most only relate features to price and EMC is not a feature they would pay for. An EMC engineer can't tell whether a PC passes or fails without an expensive test site chock full of equipment so how is a consumer supposed to tell? A few commercial and government customers perform audit tests before entering into contracts but most don't seem to care. I seem to remember an FCC employee speaking at a conference somewhere stating that they don't get computer interference complaints. Mostly telephone interference complaints but never computer interference. Most of the field complaints I worked on were immunity related. Customers care and complain about that. In today's computer industry the companies that aggressively pursue EMC are penalized by adding more cost while the companies that ignore it are able to produce a more inexpensive product. The vigilant companies will not be able to compete. I agree, enforce the emissions standards or drop them. Earl Morse ex-Major PC Company EMC guru -Original Message- From: Grasso, Charles [mailto:charles.gra...@echostar.com] Sent: Tuesday, March 25, 2003 7:38 PM To: 'lfresea...@aol.com'; emc-p...@majordomo.ieee.org Subject: RE: OK, what's going on? Hi Derek - Go Reds!! This is not a surprise to me. I have railed at much length a couple of years ago as to the latest FCC changes to the emissions qualification. I am sure you are familiar with it so I won't belabour the point. Fundementally the FCC PC emissions procedure has rendered the EMC discipline almost irrelevent. The new procedures coupled with the lack of enfocement makes it difficult to justify the increased costs of EMC design test. It also makes the whole measurement uncertainty push ridiculous. After all if the procedures allow for prodcut that 20dB out of spec why bother with a couple of dB of error?? Lets give the emissions standards some teeth or eliminate it all together. Best Regards Charles Grasso Senior Compliance Engineer Echostar Communications Corp. Tel: 303-706-5467 Fax: 303-799-6222 Cell: 303-204-2974 Email: charles.gra...@echostar.com; mailto:charles.gra...@echostar.com; Email Alternate: chasgra...@ieee.org From: lfresea...@aol.com [mailto:lfresea...@aol.com] Sent: Tuesday, March 25, 2003 1:05 PM To: emc-p...@majordomo.ieee.org Subject: OK, what's going on? Hi all, This e-mail has been prompted because of a number of things that have all come together. This may take a little reading, but please stick with it. Last note... this is not intended to pick on any individuals, or organization, but I do want to stir the pot. I operate an engineering lab, helping clients harden their designs to meet EMC requirements. In this particular instance, I was working for a small client, on a card that goes in the PC
Re: OK, what's going on?
Hi Ken and the group, Thanks for the information. The common mode current was in the 100 MHz region and WAY over what would be enough to exceed just about any limits of radiation, and this was on the power cord (and therefore any other leads to some extent). Doug Ken Javor wrote: I have seen the same kind of thing, but I believe there is a simple explanation. The input leads must meet CE102, but the output leads need only meet RE102, so they shield the output leads running to a dummy load in a control chamber. The fact that the customer can't shield the leads is another problem for another day. This doesn't happen when equipment is procured by an integrator and designed per the integrator's definition, but it is common with off-the-shelf gear. for a son 3/26/03 1:38 AM, Doug Smith at d...@emcesd.com wrote: Hi All, Just wanted to put my 2 cents worth in. The same thing may be happening in Mil-spec testing. Recently, I was at a client's site for a purpose unrelated to this story. I noticed interference to the measurement I was trying to make on a piece of equipment. The equipment had enough common mode current on its leads to fail emissions, even though it was turned off! There was a military battery charger for small batteries on their bench so I connected my current probe to its power cord and noticed enough common mode current to cause a 30 dB+ failure of emissions over a broad frequency range. I would suppose the battery charger had been tested to mil-specs. If so there is a problem here, even accounting for the repeatability problems in mil-spec testing. Doug Grasso, Charles wrote: Hi Derek - Go Reds!! This is not a surprise to me. I have railed at much length a couple of years ago as to the latest FCC changes to the emissions qualification. I am sure you are familiar with it so I won't belabour the point. Fundementally the FCC PC emissions procedure has rendered the EMC discipline almost irrelevent. The new procedures coupled with the lack of enfocement makes it difficult to justify the increased costs of EMC design test. It also makes the whole measurement uncertainty push ridiculous. After all if the procedures allow for prodcut that 20dB out of spec why bother with a couple of dB of error?? Lets give the emissions standards some teeth or eliminate it all together. ... -- ___ _ Doug Smith \ / ) P.O. Box 1457 = Los Gatos, CA 95031-1457 _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-( ) | o |Email: d...@dsmith.org \ _ /]\ _ / Website: http://www.dsmith.org 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: OK, what's going on?
thats true Earl, good point on company B, not caring but selling with a higher profit, less EMC..company A busting butt to pass and comply with integrity. as for immunity... do any PC makers manufacturer any PC's strictly for sales in USA...only need Emissions here. that would save 1000's in emc costs, never mind engineering to fix the problems.. of course you would need diff. p/n's then. and sales,manuals, compliance certs..etc would be altered. has anyone ever done a cost estimate based on building a USA vs. EU chassis? curious to see if its worth the time. From: Morse, Earl (E.A.) [mailto:emo...@ford.com] Sent: Wednesday, March 26, 2003 11:10 AM To: 'Grasso, Charles'; 'lfresea...@aol.com'; emc-p...@majordomo.ieee.org Subject: RE: OK, what's going on? Amen! I had 15 years of computer EMC when I left the PC sector this year. This was a never ending source of frustration. I won't even get into the shortcomings of the measurement standards. The emigration of PC manufacturing to the PAC rim is being followed by emigration of the design and validation teams also. Many PC manufacturers have completely outsourced their EMC testing to the OEM PC manufacturers even when they own several 10 meter semi anechoic chambers. This is akin to having the fox watch over the hen house. Management says it is more economical that way. When every test is compliant and product passes the first time every time then I guess it is. Besides, it isn't compliance that anyone is really after anymore but rather a piece of paper that says it is compliant. (Neville Chamberlain effect) Maybe it doesn't matter anyway. Most customers don't care if it meets EMC requirements. Most only relate features to price and EMC is not a feature they would pay for. An EMC engineer can't tell whether a PC passes or fails without an expensive test site chock full of equipment so how is a consumer supposed to tell? A few commercial and government customers perform audit tests before entering into contracts but most don't seem to care. I seem to remember an FCC employee speaking at a conference somewhere stating that they don't get computer interference complaints. Mostly telephone interference complaints but never computer interference. Most of the field complaints I worked on were immunity related. Customers care and complain about that. In today's computer industry the companies that aggressively pursue EMC are penalized by adding more cost while the companies that ignore it are able to produce a more inexpensive product. The vigilant companies will not be able to compete. I agree, enforce the emissions standards or drop them. Earl Morse ex-Major PC Company EMC guru -Original Message- From: Grasso, Charles [mailto:charles.gra...@echostar.com] Sent: Tuesday, March 25, 2003 7:38 PM To: 'lfresea...@aol.com'; emc-p...@majordomo.ieee.org Subject: RE: OK, what's going on? Hi Derek - Go Reds!! This is not a surprise to me. I have railed at much length a couple of years ago as to the latest FCC changes to the emissions qualification. I am sure you are familiar with it so I won't belabour the point. Fundementally the FCC PC emissions procedure has rendered the EMC discipline almost irrelevent. The new procedures coupled with the lack of enfocement makes it difficult to justify the increased costs of EMC design test. It also makes the whole measurement uncertainty push ridiculous. After all if the procedures allow for prodcut that 20dB out of spec why bother with a couple of dB of error?? Lets give the emissions standards some teeth or eliminate it all together. Best Regards Charles Grasso Senior Compliance Engineer Echostar Communications Corp. Tel: 303-706-5467 Fax: 303-799-6222 Cell: 303-204-2974 Email: charles.gra...@echostar.com; mailto:charles.gra...@echostar.com; Email Alternate: chasgra...@ieee.org From: lfresea...@aol.com [mailto:lfresea...@aol.com] Sent: Tuesday, March 25, 2003 1:05 PM To: emc-p...@majordomo.ieee.org Subject: OK, what's going on? Hi all, This e-mail has been prompted because of a number of things that have all come together. This may take a little reading, but please stick with it. Last note... this is not intended to pick on any individuals, or organization, but I do want to stir the pot. I operate an engineering lab, helping clients harden their designs to meet EMC requirements. In this particular instance, I was working for a small client, on a card that goes in the PC . In order to test I need a host PC. So, to save money, the card maker supplies 2 clones. Neither of the two PCs passed emissions testing with the card, in fact, above 100 MHz, they fail even the Class A limit: badly! So, before calling my client, I pull his card, the PC is no different, I pull the monitor, then the keyboard, then the mouse... No different. I test just the PC chassis one at a time. On their own, booted and then the peripherals removed. Not even close
Re: OK, what's going on?
I have seen the same kind of thing, but I believe there is a simple explanation. The input leads must meet CE102, but the output leads need only meet RE102, so they shield the output leads running to a dummy load in a control chamber. The fact that the customer can't shield the leads is another problem for another day. This doesn't happen when equipment is procured by an integrator and designed per the integrator's definition, but it is common with off-the-shelf gear. for a son 3/26/03 1:38 AM, Doug Smith at d...@emcesd.com wrote: Hi All, Just wanted to put my 2 cents worth in. The same thing may be happening in Mil-spec testing. Recently, I was at a client's site for a purpose unrelated to this story. I noticed interference to the measurement I was trying to make on a piece of equipment. The equipment had enough common mode current on its leads to fail emissions, even though it was turned off! There was a military battery charger for small batteries on their bench so I connected my current probe to its power cord and noticed enough common mode current to cause a 30 dB+ failure of emissions over a broad frequency range. I would suppose the battery charger had been tested to mil-specs. If so there is a problem here, even accounting for the repeatability problems in mil-spec testing. Doug Grasso, Charles wrote: Hi Derek - Go Reds!! This is not a surprise to me. I have railed at much length a couple of years ago as to the latest FCC changes to the emissions qualification. I am sure you are familiar with it so I won't belabour the point. Fundementally the FCC PC emissions procedure has rendered the EMC discipline almost irrelevent. The new procedures coupled with the lack of enfocement makes it difficult to justify the increased costs of EMC design test. It also makes the whole measurement uncertainty push ridiculous. After all if the procedures allow for prodcut that 20dB out of spec why bother with a couple of dB of error?? Lets give the emissions standards some teeth or eliminate it all together. Best Regards Charles Grasso Senior Compliance Engineer Echostar Communications Corp. Tel: 303-706-5467 Fax: 303-799-6222 Cell: 303-204-2974 Email: charles.gra...@echostar.com; mailto:charles.gra...@echostar.com; Email Alternate: chasgra...@ieee.org mailto:chasgra...@ieee.org -Original Message- From: lfresea...@aol.com [mailto:lfresea...@aol.com] Sent: Tuesday, March 25, 2003 1:05 PM To: emc-p...@majordomo.ieee.org Subject: OK, what's going on? Hi all, This e-mail has been prompted because of a number of things that have all come together. This may take a little reading, but please stick with it. Last note... this is not intended to pick on any individuals, or organization, but I do want to stir the pot. ... -- Ken Javor EMC Compliance Huntsville, Alabama 256/650-5261 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: EN61000-4-3 Radiated Immnuity Product Monitoring
I read in !emc-pstc that Alex McNeil alex.mcn...@ingenicofortronic.com wrote (in 5685ADDE2285D511925200508BB9F5031EC41C@FORT2) about 'EN61000-4-3 Radiated Immnuity Product Monitoring' on Wed, 26 Mar 2003: My problem is I bought a Teseo RF proofed camera that cannot zoom in on the display at a distance of 2m (from the corner of the chamber). Can you get a telephoto adapter for the camera? -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: OK, what's going on?
Hi All, Just wanted to put my 2 cents worth in. The same thing may be happening in Mil-spec testing. Recently, I was at a client's site for a purpose unrelated to this story. I noticed interference to the measurement I was trying to make on a piece of equipment. The equipment had enough common mode current on its leads to fail emissions, even though it was turned off! There was a military battery charger for small batteries on their bench so I connected my current probe to its power cord and noticed enough common mode current to cause a 30 dB+ failure of emissions over a broad frequency range. I would suppose the battery charger had been tested to mil-specs. If so there is a problem here, even accounting for the repeatability problems in mil-spec testing. Doug Grasso, Charles wrote: Hi Derek - Go Reds!! This is not a surprise to me. I have railed at much length a couple of years ago as to the latest FCC changes to the emissions qualification. I am sure you are familiar with it so I won't belabour the point. Fundementally the FCC PC emissions procedure has rendered the EMC discipline almost irrelevent. The new procedures coupled with the lack of enfocement makes it difficult to justify the increased costs of EMC design test. It also makes the whole measurement uncertainty push ridiculous. After all if the procedures allow for prodcut that 20dB out of spec why bother with a couple of dB of error?? Lets give the emissions standards some teeth or eliminate it all together. Best Regards Charles Grasso Senior Compliance Engineer Echostar Communications Corp. Tel: 303-706-5467 Fax: 303-799-6222 Cell: 303-204-2974 Email: charles.gra...@echostar.com; mailto:charles.gra...@echostar.com; Email Alternate: chasgra...@ieee.org mailto:chasgra...@ieee.org -Original Message- From: lfresea...@aol.com [mailto:lfresea...@aol.com] Sent: Tuesday, March 25, 2003 1:05 PM To: emc-p...@majordomo.ieee.org Subject: OK, what's going on? Hi all, This e-mail has been prompted because of a number of things that have all come together. This may take a little reading, but please stick with it. Last note... this is not intended to pick on any individuals, or organization, but I do want to stir the pot. .. -- ___ _ Doug Smith \ / ) P.O. Box 1457 = Los Gatos, CA 95031-1457 _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-( ) | o |Email: d...@dsmith.org \ _ /]\ _ / Website: http://www.dsmith.org 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: OK, what's going on?
In a message dated 3/25/2003 8:49:04 PM Central Standard Time, cgrassospri...@earthlink.net writes: So the next obvious question is: Are the majority of the PC failures clones?? So far, from what I've seen... no. Derek.
Re: OK, what's going on?
What no one checks -- no one does. Got an OLD PC? One certified under the old rules, with an ID number? Try THAT. A local computer store (of a national chain) is selling computer chassis' with plastic sides. No complaints, no problems. It appears no one is CHECKING. Cortland 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: OK, what's going on?
Hi Ken, I remember that thread. I think I even started it!! There is no way that FCC + FCC = FCC but the current rules and regs allow that to happen. its no surprise that Derek is finding PCs that fail. Question to Derek: Do the PCs have the infamous assembled from FCC compliant components label?? From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Ken Javor Sent: Tuesday, March 25, 2003 6:19 PM To: lfresea...@aol.com; emc-p...@majordomo.ieee.org Subject: Re: OK, what's going on? All, I would suggest a little literature survey and analysis before approaching the FCC. Answers to the following questions would be helpful to have in hand before approaching authorities: What bands were the outages in? I don't mean a list of frequencies vs. dB above limit, but outage frequencies vs. spectrum usage. If not many people are trying to use the spectrum where the outages occur, then you don't get many complaints. For instance, the broadcast television band extends from 54-87 MHz, and then picks up again from 174-216, and then from 470-890, except maybe the cell bands overlap the last part nowadays. But how many people in fringe TV reception areas in the USA are still trying to receive broadcast, vs. satellite or cable distribution? How many of this subset would operate their PC and also need their TV to receive on a channel that encompasses a problem frequency? The FCC responds to consumer complaints, or the potential for such. If the answers to these questions fall a certain way, it might make more sense to relax the limits... Related to the above: What does 20 dB above the limit mean? Look at the derivation of FCC Class A/B RE limits and it is tied to received signal quality. But how far are you from a transmitter before the broadcast signal is low enough that a 20 dB outage would cause a problem? Finally, I know Derek and am fully confident he is making accurate measurements, and is smart enough to differentiate an ambient from an EUT-sourced signal. But what anyone needs to know, before running to the FCC, is what is the configuration of the PC you tested, relative to the golden unit that was qualified to Class B. How did the design change between qualification and mass production? How many vendor changes were made, how many vendors changed parts but didn't change part numbers? I think this is most likely the root of the problem, but you will find the FCC very unwilling to crack down here, because the implication of enforcing this level of configuration control would be to kill the PC peripheral market. There was a thread here some time ago, about FCC + FCC = FCC? It is a very real EMC problem, but the economic forces here are very strong. I think that all these issues need to be addressed before making a case to the FCC. I don't believe the test houses are the weak link. -- Ken Javor EMC Compliance Huntsville, Alabama 256/650-5261 on 3/25/03 3:05 PM, lfresea...@aol.com at lfresea...@aol.com wrote: Hi all, This e-mail has been prompted because of a number of things that have all come together. This may take a little reading, but please stick with it. Last note... this is not intended to pick on any individuals, or organization, but I do want to stir the pot. I operate an engineering lab, helping clients harden their designs to meet EMC requirements. In this particular instance, I was working for a small client, on a card that goes in the PC . In order to test I need a host PC. So, to save money, the card maker supplies 2 clones. Neither of the two PCs passed emissions testing with the card, in fact, above 100 MHz, they fail even the Class A limit: badly! So, before calling my client, I pull his card, the PC is no different, I pull the monitor, then the keyboard, then the mouse... No different. I test just the PC chassis one at a time. On their own, booted and then the peripherals removed. Not even close to passing. Disgruntled, I get my office PC... Fail. I get my kids PC.. over 20 dB over the limit! So, I think so much for clones... I buy 2 Dell ( sorry, no point trying to hide names... ) desktops, both fail, quite badly. However, they have very similar noise profiles... Can 5 PC's all fail? I think my measuring system is set -up wrong. So I verify this. I am within 1 dB of what I expect when I inject a signal from a signal generator and account for antenna factors. Here lies the question: why can I not find a PC that passes? Worse, since they don't pass, who is chasing them down to enforce the requirements? I'm unhappy, because I am taking a clients money to make him meet the requirements, when it seems no one else is. Now, what's making this worse for me, is that I am an EMC Lab assessor. So, I go to labs and make them jump through hoops so that they produce, as consistently as possible, data the characterizes a product. Exercises, like those performed by USCEL, show that labs can have very consistent results.
RE: OK, what's going on?
So the next obvious question is: Are the majority of the PC failures clones?? From: lfresea...@aol.com [mailto:lfresea...@aol.com] Sent: Tuesday, March 25, 2003 7:32 PM To: cgrassospri...@earthlink.net; ken.ja...@emccompliance.com; emc-p...@majordomo.ieee.org Subject: Re: OK, what's going on? In a message dated 3/25/2003 8:28:40 PM Central Standard Time, cgrassospri...@earthlink.net writes: Question to Derek: Do the PCs have the infamous assembled from FCC compliant components label?? The clones do, the others do not. Little more news.. 2 laptops, an older Micron, 350 MHz, looks good. Brand new Prostar 2.8 GHz, looks good... If I could only get my PCI card in a laptop! Cheers, Derek.
