RE: Awards for Worst EMC/PS qualities
Regulatory Management Humor from a past employer. Like most companies, the Regulatory department was considered a bottleneck in the development cycle. Our Director (that's right, we had a Director of Regulatory Compliance) always fought to get prototypes into our lab as soon as possible to speed things along. One day, our Director was in a design review meeting where a new product was discussed. In the center of the large conference table was a prototype of the design. Wanting to get this unit in to the Regulatory Lab as soon as possible, the Directory TOOK the demo unit after the meeting (without asking) and brought it over to the Lab for testing. His instructions were to TEST IT NOW! The EMC Technicians jumped right on it. The unit was placed into the chamber and turned on. Though the indicator lights on the front was blinking, the unit just didn't seem to function properly. On the bright side, the RF Emissions were EXTREMELY low. It looks as if Engineering finally designed something that would pass Radiated Emissions right out of the gate. After the EMC Technicians returned from a short break, they discovered that the prototype unit had disappeared. A frantic search of the build found the unit in the office of the Industrial Design Engineer. When asked Why did you take the prototype?, he replied, This unit is only a mock-up. It is an empty box with a 555 timer circuit to make the lights blink and a 9 volt battery. Good thing we found out before we generated the FCC submittal. Is this what you would call a Queen Unit? Brian -- From: bma b...@namg.us.anritsu.com (Bailin Ma) Sent: Monday, March 08, 1999 8:03 AM To: emc-pstc emc-p...@ieee.org Subject:Awards for Worst EMC/PS qualities Hi Group, We have already seen awards for the most misleading ads, worst attire, worst films, . Why not awards for worst EMC and PS qualities? Barry Ma Morgan Hill, CA 95037 - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Awards for Worst EMC/PS qualities
Most of the stories are stories about EMC fixes. I've got one that is not and won't be fixed. I just live with it! It involves my '96 Honda Accord, bought new. I'm in San Diego, about 100 miles south of Los Angeles. I noticed that 50 kW Los Angeles AM stations such as KFI and KNX were really quite noisy on my car radio. So, too, are some of the local, San Diego AM stations. When I pull into my garage (in my stucco home with chicken-wire EMC shielding), the signals disappear into the noise. I chalked it up to poor AM design of the radio, or to the rear window antenna. (No whip antenna on this Honda!) One day, upon arriving at work, I turned off the ignition, but left it in the accessory position. The radio noise disappeared and the radio was clear! I repeated the same thing as I pulled into my garage. While there was some noise, most of it disappears when the ignition is turned off. The noise appears as soon as the ignition is turned on, and before the engine is started. Starting the engine has no effect on the noise. The AM radio is almost useless except for the strongest stations! Unless the iginition is off. Best regards, Rich - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Awards for Worst EMC/PS qualities
Ed, now THAT is a good one. it should win. It's not that unusual though. It happens quite often just like you said, specially the part about the VP getting promoted. The tester gets blamed if the room fails. They dont want you to find leaks, they want you to do something and then write a report saying that it passes. It's no joke though. When that classified data leaks out and runs down the hillside it can, and occasionally DOES, get someone's kid killed. If he or she is the right age and wearing a uniform, it might be YOUR kid. Lou At 08:59 AM 3/11/99 -0800, you wrote: Subject: Awards for Worst EMC/PS qualities Author: b...@namg.us.anritsu.com (Bailin Ma) at Internet Date:03/08/1999 8:03 AM Hi Group, We have already seen awards for the most misleading ads, worst attire, worst films, . Why not awards for worst EMC and PS qualities? Barry Ma Morgan Hill, CA 95037 OK, I'll submit just one more entry, even though this will need a new category (which I'll call Stupid Construction). Many years ago, a very large defense contractor decided that a black program needed multiple shielded enclosures within their SCIF so as to keep their classified data from leaking out and running down the hillside. So, the Program Manager talked to the Facilities Engineer, and together they said We can build our own TEMPEST shielded room. We will even do it cheaper and faster than any of these dumb quotes we have. So it came to be that they ordered much chicken wire, and beryllium copper fingerstock, and lumber, and drywall panels, and oh yes, very very many 2 long drywall screws. And a three phase powerline filter. And the facilities laborers then labored mightily for what may have been months; no one really knows. But finally, it was completed. It was painted, and carpeted, and even had plywood veneer paneling on the walls. It also had fluorescent lights in each room. And telephones in each room (but alas, no telephone line filters). And the program occupied the area, setting up their computers and test equipment and their other stuff. After a while, the more troublesome technicians began to wonder why their pagers had no problem functioning within the rooms, and that workers could enjoy FM broadcast radio at their workstations. Wasn't this supposed to be an RF shielded facility? I arrived on site, with spectrum analyzer and trusty loop antenna (three turns of the extended coax center conductor formed into a loop). I'd find those leaks and plug 'em fast. The first thing I noticed was that the room doors were ordinary steel office doors, with painted frames. The fingerstock had been screwed over the painted surfaces. Many of the fingers were broken, bent or missing. And the steel door frame was mounted to the drywall. The RF shield consisted of chicken wire, a wide-mesh, twisted steel wire construction. The name should tell you what it was good for. The average chicken cannot be forced through a chicken wire barrier (at least without significant distortion). AM broadcast radio uses a wavelength long enough that the barrier yields a certain amount of shielding. But FM broadcast slips through like a mosquito. So I started to probe one of the rooms. I just tuned the SA to one of the many convenient signals around 100 MHz, and started to sweep the room. Not only did the mesh screen leak like crazy, but it also turned out that most of those many thousands of drywall screws went right through the wall without touching the mesh. So EACH of these little conductive rods acted as a path for RF in and out of the screen barrier. There were no leaky points; it was like playing laser tag in an infinite hall of mirrors. And, just to show that none of the basics of proper shielding technique had been followed, I found that the powerline filter was located about 75 feet away from the shielded rooms. The filtered power was run to the room in PVC conduit, and the filter was grounded by a six foot long #00 pigtail. After wandering the facility for about two hours, I was approached by the Program Manager, who inquired about my corrective actions. I told him something to the effect that I hadn't been able to find any shielded rooms, but that if we stripped this area clear to the concrete, we could build some right here. I went on to detail that I had seen just about every shielding mistake you could make, all concentrated in one place. This site could qualify only as a museum of inverse shielding. Bad report, bad career action. I went back to testing noisy gadgets that smelled vaguely of ozone. The customer wouldn't let them use the rooms for classified work. A year later, the PM became a VP. -- Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 Date: 03/11/1999 Time: 08:59:26 -- - This message is coming from the emc-pstc discussion list. To cancel your subscription, send
RE: Awards for Worst EMC/PS qualities
February 1999: There we were sitting in the delivery room waiting for the baby to come The TV is on in the room (to distract the wife in between contractions...it didn't work but that's a different story). Attached to my wife is an automated rather new and high tech looking blood pressure machine (manufacturer name withheld to protect the guilty). Every 10 minutes it auto inflates the cuff and takes the BP readings making a nice little table and graphs on the display screen. Every time the thing goes on, without fail, the TV picture and sound go berserk. Major static on both regardless of channel. Hm... And you thought these problems were all back in the dark days of early electronics. I would have written down the model and manufacturer, tried to find their EMC engineer if possible and sent him/her a very sarcastic note, but soon after that I was distracted for some reason. Mom and baby are doing fine, but the long term effects of broadband 50 to 800Mhz (broadcast TV freqs) will remain to be seen. ;-) Richard Cass -Original Message- From: b...@namg.us.anritsu.com (Bailin Ma) at internet Sent: Monday, March 08, 1999 2:22 PM To: emc-p...@ieee.org at INTERNET Subject: Awards for Worst EMC/PS qualities Hi Group, We have already seen awards for the most misleading ads, worst attire, worst films, . Why not awards for worst EMC and PS qualities? Barry Ma Morgan Hill, CA 95037 - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: Awards for Worst EMC/PS qualities
Ed, if there is a grand prize to be awarded here for the most amusing account ... you've got it hands down with this one... and your closing statement, is a gem ! george -Original Message- From: ed.pr...@cubic.com [SMTP:ed.pr...@cubic.com] Sent: Thursday, March 11, 1999 11:59 AM To: EMC-PSTC Subject: Re: Awards for Worst EMC/PS qualities Subject: Awards for Worst EMC/PS qualities Author: b...@namg.us.anritsu.com (Bailin Ma) at Internet Date:03/08/1999 8:03 AM Hi Group, We have already seen awards for the most misleading ads, worst attire, worst films, . Why not awards for worst EMC and PS qualities? Barry Ma Morgan Hill, CA 95037 OK, I'll submit just one more entry, even though this will need a new category (which I'll call Stupid Construction). Many years ago, a very large defense contractor decided that a black program needed multiple shielded enclosures within their SCIF so as to keep their classified data from leaking out and running down the hillside. So, the Program Manager talked to the Facilities Engineer, and together they said We can build our own TEMPEST shielded room. We will even do it cheaper and faster than any of these dumb quotes we have. So it came to be that they ordered much chicken wire, and beryllium copper fingerstock, and lumber, and drywall panels, and oh yes, very very many 2 long drywall screws. And a three phase powerline filter. And the facilities laborers then labored mightily for what may have been months; no one really knows. But finally, it was completed. It was painted, and carpeted, and even had plywood veneer paneling on the walls. It also had fluorescent lights in each room. And telephones in each room (but alas, no telephone line filters). And the program occupied the area, setting up their computers and test equipment and their other stuff. After a while, the more troublesome technicians began to wonder why their pagers had no problem functioning within the rooms, and that workers could enjoy FM broadcast radio at their workstations. Wasn't this supposed to be an RF shielded facility? I arrived on site, with spectrum analyzer and trusty loop antenna (three turns of the extended coax center conductor formed into a loop). I'd find those leaks and plug 'em fast. The first thing I noticed was that the room doors were ordinary steel office doors, with painted frames. The fingerstock had been screwed over the painted surfaces. Many of the fingers were broken, bent or missing. And the steel door frame was mounted to the drywall. The RF shield consisted of chicken wire, a wide-mesh, twisted steel wire construction. The name should tell you what it was good for. The average chicken cannot be forced through a chicken wire barrier (at least without significant distortion). AM broadcast radio uses a wavelength long enough that the barrier yields a certain amount of shielding. But FM broadcast slips through like a mosquito. So I started to probe one of the rooms. I just tuned the SA to one of the many convenient signals around 100 MHz, and started to sweep the room. Not only did the mesh screen leak like crazy, but it also turned out that most of those many thousands of drywall screws went right through the wall without touching the mesh. So EACH of these little conductive rods acted as a path for RF in and out of the screen barrier. There were no leaky points; it was like playing laser tag in an infinite hall of mirrors. And, just to show that none of the basics of proper shielding technique had been followed, I found that the powerline filter was located about 75 feet away from the shielded rooms. The filtered power was run to the room in PVC conduit, and the filter was grounded by a six foot long #00 pigtail. After wandering the facility for about two hours, I was approached by the Program Manager, who inquired about my corrective actions. I told him something to the effect that I hadn't been able to find any shielded rooms, but that if we stripped this area clear to the concrete, we could build some right here. I went on to detail that I had seen just about every shielding mistake you could make, all concentrated in one place. This site could qualify only as a museum of inverse shielding. Bad report, bad career action. I went back to testing noisy gadgets that smelled vaguely of ozone. The customer wouldn't let them use the rooms for classified work. A year later, the PM became a VP. -- Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 Date: 03/11/1999 Time: 08:59:26 -- - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr
RE: Awards for Worst EMC/PS qualities
Well . . . from what I read so far . . .I think Ed's experience ranks right 'up there'! (Pun intended!) Seriously though . . . I think we've got a winner there! John A. Juhasz Product Qualification Compliance Engr. Fiber Options, Inc. 80 Orville Dr. Suite 102 Bohemia, NY 11716 USA Tel: 516-567-8320 ext. 24 Fax: 516-567-8322 -Original Message- From: ed.pr...@cubic.com [mailto:ed.pr...@cubic.com] Sent: Thursday, March 11, 1999 11:22 AM To: EMC-PSTC Subject: Re: Awards for Worst EMC/PS qualities Subject: Awards for Worst EMC/PS qualities Author: b...@namg.us.anritsu.com (Bailin Ma) at Internet Date:03/08/1999 8:03 AM Hi Group, We have already seen awards for the most misleading ads, worst attire, worst films, . Why not awards for worst EMC and PS qualities? Barry Ma Morgan Hill, CA 95037 OK, I'll submit my entry for both the EMC and PS categories! Years ago, whilst working at a large defense contractor, we re-built 5 UH-1 Huey helicopters to act as test beds for a large synthetic aperture radar system. All major mechanical and electrical systems were stripped out and then replaced (at the mid-point of the job, the Hueys looked like a wire-frame model). When we got everything back together, we had to go through flight worthiness testing. After that, we installed the electronics racks and started a set of platform EMC integration tests. So, I found myself hovering for hours at about 500 feet, while we ran through various operational modes of both the electronics payload and the vehicle systems. Everything checked out fine, until we found an accidental, uhhh, feature. Suddenly, just like an elevator to heaven, we started to climb straight up. I mean wide open throttle and full positive collective pitch! Well, I don't know how fast a heavily loaded Huey can climb, but it was impressive! I don't even want to think about how far those rotors deflected. After the pilot got things stabilized, and we all started breathing again, we started to sort things out. The problem turned out to be that the pilot had his autopilot engaged (I didn't know Hueys even had one), and then decided to key the UHF radio. We found that, out of twenty thousand or so UHF channels, about a dozen would cause the Vertical Speed Indicator to deflect full negative when the radio was keyed. And that instrument told the autopilot that the Huey was going down, so the autopilot cranked in as much pitch correction as possible, and also opened to full throttle. The result was; key radio on a magic channel and you get a penthouse express. (Actually, not too bad a result, considering what the result would have been if the VSI had been deflected full POSITIVE!) After a little snooping, we found that the VSI cable harness had an improperly assembled backshell, which degraded the shielding effectiveness of that cable and allowed RF into the indicator. Ed -- Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 List-Post: emc-pstc@listserv.ieee.org Date: 03/11/1999 Time: 08:21:48 -- - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Awards for worst EMC/PS qualities
While not quite as bad as the disaster Ed Price described, I once had to fix a shielded room built to the specifications of a self-described RF expert. This gentleman had convinced his management that he could build a cheap and easy facility. The intended site was an unused loft on the fourth floor of the building, a 100+ year old former hat factory. They started by removing most of the inch-thick dust and all of the dead bird carcasses. They never stopped to wonder why there were so many dead birds - more on that later. Sheet metal workers brought in a load of galvanized steel and dumped it onto the somewhat clean floor. The expert had them butt the (still oily) sheets together and screw them down over the beat up wooden floor. Then, three inch wide strips were fastened over the joints, with screws every foot or so. One of the mechanical techs was a carpentry expert, so he convinced the RF expert to hire him instead of a building contractor to install the frame for the screening. He framed the cage using two-by-fours on the flat, on four foot centers, to save on lumber. Then he ran one-by-fours horizontally to provide some support for the copper screening stapled over the whole mess. He used a cheap hollow-core door because it was easier to carry up the narrow stairs. The door, of course, was wrapped in copper screening. The screening on the outside wall was left with several horizontal seams over the windows. The first hint of trouble was that AM reception was pretty fair inside the room due to the long unsecured seams. The carpentry expert had given up by that point, so I was asked to solder the window seams by my boss, the RF expert. Anyway, to make a long story short, I eventually used several thousand sheetmetal screws, several cartons of staples, several rolls of three-inch copper tape, and over a dozen pounds of solder before the room was more or less usable. I worked on that nightmare for weeks, finally having to solder the seams between floor and walls to plug some of the worst leaks. The room was finally quiet enough to use for pre test site scans and diagnostic use. My boss demonstrated his gratitude by sulking for weeks. We soon learned to cover the equipment with plastic when it was not in use. Birds often flew into their former roost/toilet. None of the experts involved had bothered to check for access holes before starting work. There were several holes, some of them in inaccessible locations above the screen room, which was framed in such a flimsy manner that no one dared to climb onto it. It is amazing how effectively steel wool sprayed with instant foam can plug leaks when it is inserted using a long pole with a frustrated test engineer at the other end. Never, ever, again! Scott - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re[2]: Awards for Worst EMC/PS qualities
In one of my past lives, there was a safety inspector (agency not divulged here) that adamantly defended his interpretation of the 94V marking on PWBs as a voltage rating of the PWB. He even wrote us up for this for not having a high enough voltage rating. This guy, too, is still in the safety field. BTW Monty, did that guy you were referring to have a multiple personality? :-) Best regards, Ron Pickard ron_pick...@hypercom.com __ Reply Separator _ Subject: RE: Awards for Worst EMC/PS qualities Author: Griffith Monty mgrif...@ingr.com at INTERNET List-Post: emc-pstc@listserv.ieee.org Date:3/11/99 10:39 AM I once had a Safety Engineer tell me that a class 2 transformer had opened during the overload test. He was measuring resistance primary to secondary (Duh!!!). This guy is still in the Safety Field but they don't work here thank God!!! Monty Griffith Senior Product Safety Engineer EMC Quality Manager Intergraph Compliance Services Ph. (256) 730-6017 Fx. (256) 730-6239 http://mecsrv.b29.ingr.com -Original Message- From:brian_kunde [SMTP:brian_ku...@leco.com] Sent:Thursday, March 11, 1999 9:48 AM To:emc-pstc; bma Subject:RE: Awards for Worst EMC/PS qualities In the early 1980's, I worked for a company that manufactured PCs and peripherals. I worked in a Functional Testing Lab where we ran functional tests on our new designs before allowing them to go to production. I was testing a dot matrix printer which our company purchased the electronics and incorporated it into our mechanical. The printer was setting on a printer table about six feet away from the computer which was on a computer table. I would start up the exercise program on the PC, then quickly roll my wheeled lab chair over to the printer to observe its function. When I would roll by the printer on my chair, the printer would start failing in the most destructive ways. The print head would slam back and forth against its stops, the paper would shoot out, stop, then reverse causing a major jam, the display would flash some type of hieroglyphics. Engineering could not find a test, including ESD, that could duplicate this failure. So, the problem was debugged, in our lab, (that's right) while I rolled back and forth on my lab chair. It took several days, but the problem was eventually fixed. Then I went on vacation. Brian -- From: bma b...@namg.us.anritsu.com (Bailin Ma) Sent: Monday, March 08, 1999 8:03 AM To: emc-pstc emc-p...@ieee.org Subject:Awards for Worst EMC/PS qualities Hi Group, We have already seen awards for the most misleading ads, worst attire, worst films, . Why not awards for worst EMC and PS qualities? Barry Ma Morgan Hill, CA 95037 - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Awards for Worst EMC/PS qualities
Subject: Awards for Worst EMC/PS qualities Author: b...@namg.us.anritsu.com (Bailin Ma) at Internet Date:03/08/1999 8:03 AM Hi Group, We have already seen awards for the most misleading ads, worst attire, worst films, . Why not awards for worst EMC and PS qualities? Barry Ma Morgan Hill, CA 95037 OK, I'll submit just one more entry, even though this will need a new category (which I'll call Stupid Construction). Many years ago, a very large defense contractor decided that a black program needed multiple shielded enclosures within their SCIF so as to keep their classified data from leaking out and running down the hillside. So, the Program Manager talked to the Facilities Engineer, and together they said We can build our own TEMPEST shielded room. We will even do it cheaper and faster than any of these dumb quotes we have. So it came to be that they ordered much chicken wire, and beryllium copper fingerstock, and lumber, and drywall panels, and oh yes, very very many 2 long drywall screws. And a three phase powerline filter. And the facilities laborers then labored mightily for what may have been months; no one really knows. But finally, it was completed. It was painted, and carpeted, and even had plywood veneer paneling on the walls. It also had fluorescent lights in each room. And telephones in each room (but alas, no telephone line filters). And the program occupied the area, setting up their computers and test equipment and their other stuff. After a while, the more troublesome technicians began to wonder why their pagers had no problem functioning within the rooms, and that workers could enjoy FM broadcast radio at their workstations. Wasn't this supposed to be an RF shielded facility? I arrived on site, with spectrum analyzer and trusty loop antenna (three turns of the extended coax center conductor formed into a loop). I'd find those leaks and plug 'em fast. The first thing I noticed was that the room doors were ordinary steel office doors, with painted frames. The fingerstock had been screwed over the painted surfaces. Many of the fingers were broken, bent or missing. And the steel door frame was mounted to the drywall. The RF shield consisted of chicken wire, a wide-mesh, twisted steel wire construction. The name should tell you what it was good for. The average chicken cannot be forced through a chicken wire barrier (at least without significant distortion). AM broadcast radio uses a wavelength long enough that the barrier yields a certain amount of shielding. But FM broadcast slips through like a mosquito. So I started to probe one of the rooms. I just tuned the SA to one of the many convenient signals around 100 MHz, and started to sweep the room. Not only did the mesh screen leak like crazy, but it also turned out that most of those many thousands of drywall screws went right through the wall without touching the mesh. So EACH of these little conductive rods acted as a path for RF in and out of the screen barrier. There were no leaky points; it was like playing laser tag in an infinite hall of mirrors. And, just to show that none of the basics of proper shielding technique had been followed, I found that the powerline filter was located about 75 feet away from the shielded rooms. The filtered power was run to the room in PVC conduit, and the filter was grounded by a six foot long #00 pigtail. After wandering the facility for about two hours, I was approached by the Program Manager, who inquired about my corrective actions. I told him something to the effect that I hadn't been able to find any shielded rooms, but that if we stripped this area clear to the concrete, we could build some right here. I went on to detail that I had seen just about every shielding mistake you could make, all concentrated in one place. This site could qualify only as a museum of inverse shielding. Bad report, bad career action. I went back to testing noisy gadgets that smelled vaguely of ozone. The customer wouldn't let them use the rooms for classified work. A year later, the PM became a VP. -- Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 List-Post: emc-pstc@listserv.ieee.org Date: 03/11/1999 Time: 08:59:26 -- - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: Awards for Worst EMC/PS qualities
I once had a Safety Engineer tell me that a class 2 transformer had opened during the overload test. He was measuring resistance primary to secondary (Duh!!!). This guy is still in the Safety Field but they don't work here thank God!!! Monty Griffith Senior Product Safety Engineer EMC Quality Manager Intergraph Compliance Services Ph. (256) 730-6017 Fx. (256) 730-6239 http://mecsrv.b29.ingr.com -Original Message- From: brian_kunde [SMTP:brian_ku...@leco.com] Sent: Thursday, March 11, 1999 9:48 AM To: emc-pstc; bma Subject: RE: Awards for Worst EMC/PS qualities In the early 1980's, I worked for a company that manufactured PCs and peripherals. I worked in a Functional Testing Lab where we ran functional tests on our new designs before allowing them to go to production. I was testing a dot matrix printer which our company purchased the electronics and incorporated it into our mechanical. The printer was setting on a printer table about six feet away from the computer which was on a computer table. I would start up the exercise program on the PC, then quickly roll my wheeled lab chair over to the printer to observe its function. When I would roll by the printer on my chair, the printer would start failing in the most destructive ways. The print head would slam back and forth against its stops, the paper would shoot out, stop, then reverse causing a major jam, the display would flash some type of hieroglyphics. Engineering could not find a test, including ESD, that could duplicate this failure. So, the problem was debugged, in our lab, (that's right) while I rolled back and forth on my lab chair. It took several days, but the problem was eventually fixed. Then I went on vacation. Brian -- From: bma b...@namg.us.anritsu.com (Bailin Ma) Sent: Monday, March 08, 1999 8:03 AM To: emc-pstc emc-p...@ieee.org Subject:Awards for Worst EMC/PS qualities Hi Group, We have already seen awards for the most misleading ads, worst attire, worst films, . Why not awards for worst EMC and PS qualities? Barry Ma Morgan Hill, CA 95037 - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: Awards for Worst EMC/PS qualities
In the early 1980's, I worked for a company that manufactured PCs and peripherals. I worked in a Functional Testing Lab where we ran functional tests on our new designs before allowing them to go to production. I was testing a dot matrix printer which our company purchased the electronics and incorporated it into our mechanical. The printer was setting on a printer table about six feet away from the computer which was on a computer table. I would start up the exercise program on the PC, then quickly roll my wheeled lab chair over to the printer to observe its function. When I would roll by the printer on my chair, the printer would start failing in the most destructive ways. The print head would slam back and forth against its stops, the paper would shoot out, stop, then reverse causing a major jam, the display would flash some type of hieroglyphics. Engineering could not find a test, including ESD, that could duplicate this failure. So, the problem was debugged, in our lab, (that's right) while I rolled back and forth on my lab chair. It took several days, but the problem was eventually fixed. Then I went on vacation. Brian -- From: bma b...@namg.us.anritsu.com (Bailin Ma) Sent: Monday, March 08, 1999 8:03 AM To: emc-pstc emc-p...@ieee.org Subject:Awards for Worst EMC/PS qualities Hi Group, We have already seen awards for the most misleading ads, worst attire, worst films, . Why not awards for worst EMC and PS qualities? Barry Ma Morgan Hill, CA 95037 - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Awards for Worst EMC/PS qualities
Some years ago, I carted a prototype down to a Maryland area test lab for an EMI scan. What I didn't realize was that the lab technician who built the prototype crossed the power and earth lines to the power supply, resulting in a hot chassis. Well, as might be expected, there was some problem meeting the conducted emissions requirement. In fact, a plot of the spectrum was prominently displayed on the lab's shield room wall for many months afterward as an example of the worst emissions that they had ever found. It was a dubious honor, at best. Now, the guy who runs this lab is pretty sharp, and figured that something had to be wrong. Taking out his trusty Fluke DVM, he proceeded to probe around in the power supply. Why he didn't expect the chassis he was steadying his hands on to be at 120 volts is beyond me. The resulting sequence went something like this: ZAP - YIKES!!! - recoil - stab - OUCH!! - @#%$#*#@ We still joke about the two holes he poked in his brand new shirt. __ Reply Separator _ Subject: Awards for Worst EMC/PS qualities Author: b...@namg.us.anritsu.com (Bailin Ma) at Internet List-Post: emc-pstc@listserv.ieee.org Date:03/08/1999 8:03 AM Hi Group, We have already seen awards for the most misleading ads, worst attire, worst films, . Why not awards for worst EMC and PS qualities? Barry Ma Morgan Hill, CA 95037 - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Awards for Worst EMC/PS qualities
Some time ago, in a far-away land, I saw a product that was on the lab bench for some initial functionality testing (1-st rev. of the device). A radio was close by, plugged to the same power circuit. The test engineer could not listen to the radio due to the interference with the noise coming from the device. He switched the radio off and, in that moment - the device reset. Neven Disclaimer: I was not involved (of course) in that design :) At 08:03 AM 3/8/99 PST, bma (Bailin Ma) wrote: Hi Group, We have already seen awards for the most misleading ads, worst attire, worst films, . Why not awards for worst EMC and PS qualities? Barry Ma Morgan Hill, CA 95037 - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: Awards for Worst EMC/PS qualities
Along the same lines, the old VW Beatles would put out so much noise that you could pick them up on your FM receiver a hundred yards down the road. Daniel W. Mitchell Product Safety Associate Engineer EOS Corp. -- From: Hans Mellberg[SMTP:emcconsult...@yahoo.com] Sent: Wednesday, March 10, 1999 11:14 AM To: emc-p...@ieee.org Subject:Re: Awards for Worst EMC/PS qualities A certain German sports car using a certain German fuel injection system could be made to malfunction in an amuzing way (not to the sports car operator though!) such as backfire, sputter, smoke, flames from exhaust pipe, etc., by tractor-trailer operators with their CB lin-amps when keying on and off. This was a popular thing to do by truckers in the late 70's. This susceptibility problem was addressed and corrected by the sports car manufacturer. Other manufacturers may have had similar problems. At 08:03 AM 3/8/99 PST, bma (Bailin Ma) wrote: Hi Group, We have already seen awards for the most misleading ads, worst attire, worst films, . Why not awards for worst EMC and PS qualities? Barry Ma Morgan Hill, CA 95037 - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). _ DO YOU YAHOO!? Get your free @yahoo.com address at http://mail.yahoo.com - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Awards for Worst EMC/PS qualities
Hi Douglas, What you described is very interesting! But I cannot understand Jingling change in a ziplock bag produces very high levels of super fast transients up into the GHz range. It seems to me that jingling coins, jangling keys, and slamming metal door would certainly produce acoustic waves. How come they also produced electromagnetic waves? If do, under what conditions? What is the mechanism to produce very high level of transient EM waves? Did that company incorporate those kinds of Jingling change in a ziplock bag tests into regular ESD tests for their thereafter products? What is the lessen we all should learn from this particular example? Hopefully you don't think it's offensive to ask above questions. I am just very curious. Thank you. Best Regards, Barry Ma (408)778-2000 x 4465 - Original Text From: Douglas McKean dmck...@corp.auspex.com, on 3/10/99 2:55 PM: At 08:03 AM 3/8/99 PST, Bailin Ma wrote: Hi Group, We have already seen awards for the most misleading ads, worst attire, worst films, . Why not awards for worst EMC and PS qualities? Barry Ma Morgan Hill, CA 95037 Long ago in another company, I was completing the testing for a large rack mounted device, i.e. emissions, immunity, safety, some parts of Bellcore. We got a call from one of our customers complaining about how sensitive our equipment was and how susceptible it was to ESD events during their own testing of our equipment. This was deemed unacceptable by them. This decision of theirs jeopardized a sale of several million dollars. The finger was duly pointed by everyone right to yours truly. My head was literally in no uncertain terms put on the block. I contested producing repeatable and acceptable ESD test results that were BELOW the BER levels specified by Bellcore with ESD test levels ABOVE that specified by the test standard. I wanted as much margin as possible for our product. Well, it ended up that if you stood three to four feet in front of the rack and jingled change in your pocket or jangled a set of keys in front of it, the product would RESET. Jingling change in a ziplock bag produces very high levels of super fast transients up into the GHz range. Worse, slamming the metal door to the lab in which the equipment was setup would also reset the product. The lab door was say 20 or so feet from our equipment under test. It took six months of a redesign cycle to straighten out that one, but it was finally done. I always wanted to find out who in God's name could have come up with such an insidious ESD test by simply putting some change in a zip lock bag and jingling it in front of equipment. But, I figured he, whoever he was, was lost in time. And wouldn't you know it? ... I now work for that man. - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Awards for Worst EMC/PS qualities
A certain German sports car using a certain German fuel injection system could be made to malfunction in an amuzing way (not to the sports car operator though!) such as backfire, sputter, smoke, flames from exhaust pipe, etc., by tractor-trailer operators with their CB lin-amps when keying on and off. This was a popular thing to do by truckers in the late 70's. This susceptibility problem was addressed and corrected by the sports car manufacturer. Other manufacturers may have had similar problems. At 08:03 AM 3/8/99 PST, bma (Bailin Ma) wrote: Hi Group, We have already seen awards for the most misleading ads, worst attire, worst films, . Why not awards for worst EMC and PS qualities? Barry Ma Morgan Hill, CA 95037 - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). _ DO YOU YAHOO!? Get your free @yahoo.com address at http://mail.yahoo.com - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Awards for Worst EMC/PS qualities
At 08:03 AM 3/8/99 PST, Bailin Ma wrote: Hi Group, We have already seen awards for the most misleading ads, worst attire, worst films, . Why not awards for worst EMC and PS qualities? Barry Ma Morgan Hill, CA 95037 Long ago in another company, I was completing the testing for a large rack mounted device, i.e. emissions, immunity, safety, some parts of Bellcore. We got a call from one of our customers complaining about how sensitive our equipment was and how susceptible it was to ESD events during their own testing of our equipment. This was deemed unacceptable by them. This decision of theirs jeopardized a sale of several million dollars. The finger was duly pointed by everyone right to yours truly. My head was literally in no uncertain terms put on the block. I contested producing repeatable and acceptable ESD test results that were BELOW the BER levels specified by Bellcore with ESD test levels ABOVE that specified by the test standard. I wanted as much margin as possible for our product. Well, it ended up that if you stood three to four feet in front of the rack and jingled change in your pocket or jangled a set of keys in front of it, the product would RESET. Jingling change in a ziplock bag produces very high levels of super fast transients up into the GHz range. Worse, slamming the metal door to the lab in which the equipment was setup would also reset the product. The lab door was say 20 or so feet from our equipment under test. It took six months of a redesign cycle to straighten out that one, but it was finally done. I always wanted to find out who in God's name could have come up with such an insidious ESD test by simply putting some change in a zip lock bag and jingling it in front of equipment. But, I figured he, whoever he was, was lost in time. And wouldn't you know it? ... I now work for that man. - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Awards for Worst EMC/PS qualities
Some time ago, in a far-away land, I saw a product that was on the lab bench for some initial functionality testing (1-st rev. of the device). A radio was close by, plugged to the same power circuit. The test engineer could not listen to the radio due to the interference with the noise coming from the device. He switched the radio off and, in that moment - the device reset. Neven Disclaimer: I was not involved (of course) in that design :) At 08:03 AM 3/8/99 PST, bma (Bailin Ma) wrote: Hi Group, We have already seen awards for the most misleading ads, worst attire, worst films, . Why not awards for worst EMC and PS qualities? Barry Ma Morgan Hill, CA 95037 - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: Awards for Worst EMC/PS qualities
I would agree is the scope was narrowed to worst standards. Dave George -Original Message- From: b...@namg.us.anritsu.com [mailto:b...@namg.us.anritsu.com] Sent: Monday, March 08, 1999 11:04 AM To: emc-p...@ieee.org Subject: Awards for Worst EMC/PS qualities Hi Group, We have already seen awards for the most misleading ads, worst attire, worst films, . Why not awards for worst EMC and PS qualities? Barry Ma Morgan Hill, CA 95037 - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Awards for Worst EMC/PS qualities
Hi Group, We have already seen awards for the most misleading ads, worst attire, worst films, . Why not awards for worst EMC and PS qualities? Barry Ma Morgan Hill, CA 95037 - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
