unsubscribe
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: emc_p...@symbol.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: CDMA Product Approvals
So now I'm curious, which came first Ethernet or cell phone. CDMA is also used on Ethernet. At least the original simplex versions - triple shielded coax, then cheaper net - essentially phone cables. It wasn't needed with full duplex PTP transmission, which some might argue isn't true Ethernet. I remember seeing those old brick sized cell (mobile?) phones but thought they were slightly behind LAN's and the precursor to the Internet ARPANET (probably have wildly misspelled that) seems to have been around much longer than that. So I'm curious what was CDMA originally designed for? Anybody know. Gary
Re: Temperature effects on conducted emissions?
As the componets warm from room to operating temp you may see a small change, but I've never seen anything that big - except when I had a metallic grouding clamp that expanded and quit making contact. But as components come up to temp some of them do change value so you may want to look at those characteristics on the individual components. Having said that I would agree with Ed that it seems to be too large for a component value and confirm your set up and equipment. Gary 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: emc_p...@symbol.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: Clayton Pauls - Thanks all, obviously I messed up and Paul was correct
Well, I knew I could expose my inadequacies in public. I hear this loud - WHAT AGAIN! coming through the Ether at me from the group :)This was obviously as good a way as any. I'm going to blame my calculator as a face saving effort. Ron after I got your note (and some others thanks) I went back at it again and within reason I know, almost magically, get the same answer. When stumped I usually right the result of each step in the equation down. The only place I didn't do that was the conversion between mu and mu relative - same for conductivity. So I must have screwed those up. (Not sure why it only becomes obvious after I ask the question - heavy sigh. Gary
Clayton Pauls - Intro to EMC - an error or two? for those that have the text
My anal-retentive self is having some trouble with an occasional example in the text and I need either a confirmation or a slap in the forehead. I was just fiddling around with the text and reviewing some of the examples and in section 6.4 he presents a table of skin depth for copper, but then in question 6.2 he asks for the skin depth of steel - and the numbers for the skin depth are the same. My calculations say otherwise and makes sense to me since the permeability is different between the materials. copper = 1 and steel is 1000, that and the conductivity is different between the two. If you have the text and little or nothing else to do could you give me the number you come up with? ( in mm's or mils) When I'm trying to learn or relearn stuff and I'm at odds with the various references it just drives me wild and I don't have anyone else to confer with up here. One is torn between the I'm right response and the author's obvious authority on the subject. Thanks Befuddled (Gary)
Re: Number of Terminations on a Ground Stud?
John, I'm certainly not as familiar with as many standards as you are, but isn't the requirement, not so much that the PEC, must be on its own stud, but rather than this connection must be the first, and then a double locking nut to secure it? If there is remaining post length grounds could then be attached above that with their own fasteners? The goal of which is to insure that the PEC connection isn't removed while servicing the other subsections of the equipment and hopefully means that service personnel won't forget to replace it since it wasn't necessary to remove this important connection. I could see it both ways. Gary
Re: Boston Symposium
Unfortunately I can't be there, but if on the way to get a brew you stop by a post office or other federal building you may be able to see my picture hanging up - but I didn't do all of the things they say, and even some of those that I did do were more of a misunderstanding kind of thing. :) Gary
Re: MRI-safe test lab
Certainly a reasonable and timely request. Not sure the location other than here in the US, but recently a death resulted from a patient being hit in the head during an MRI buy something metallic that was inadvertently brought into the imaging room. Believe that it was something on the order of a fire extinguisher which was sucked into the machine and struck the patient. Gary
Re: Need cheap hotel close to EMC show
The last time I went to one of these and was found in a cheap motel it cost me my house and half of everything I owned :) So I'm betting you'll want to get someone else to give you a recommendation. Gary
Re: ESD - not applicable ?
Agree with Don. May not be necessary but maintenance type ESD testing is a very good idea. In fact part of the NEBS (Telecommunications test suite) has circuit card ESD tests specifically for maintenance and production handling. They do have a product ESD test but they are in different documents. I think the maintenance ESD testing is actually under GR-78 (Some RBOCS include this some do not in their acceptance criteria) Gary
Re: (mis)spelling humor
Once let spell check do its thing while having my brain on empty and not paying to much attention to what it was suggesting. So I sent a company wide memo that changed a name from Hugh Hagel to Huge Bagel. Gary
Re: PCB marked for UL 94V-0
First of all I would update the note to say the board manufacturer must be a recognized printed wiring manufacturer, and then call out the flame rating you need on the board. You'll need the manufactures name or trademark, board model (single or multilayer), and the flame ratings stamped on the board. This is consistent with what UL requires for a recognized assembly anyway, so you aren't asking the vendor to do anything different for you than he has to do for any of their customers. That way you have UL running through their plant confirming their process and ratings. That will also give you some backhanded insurance that the board traces will stay on the board along with a host of other things checked by UL. There is no cost difference and you have bazillions of vendors to choose from. Just the flame rating itself can be a little hazardous because the flame rating of any material is dependent on the material thickness. Too thin and its no longer V0. Can the vendor still screw it all up - yes. But if you don't have any reasonable trust from them you shouldn't be using them anyway, unless you are going to test each and every lot that comes into the factor. Gary
Re: Bellcore SR-3580: Update to reflect the new GR-63 Issue 2 and GR- 1089 Is...
Each of the RBOC's has its own requirements for NEBS levels - Verizon -naturally being the most different. You may want to go out to the WEB sites for each and pull down their documentation to calculate your strategy on this. Unfortunately, I'm not where I can access my web links and URL's for them. Gary
Re: FDA registration of laser
Nope, you are absolutely correct on the GBIC's or the new smaller pluggable LC connector optics. You are just a distributor of those under the laser guidelines. Again, its a fully contained module that you make no changes to, and they have no controls or failure modes that you could induce to change the output of the laser. Gary
Re: FCC and Hi Temp operation
The first thing to do is to check the component temperature ratings to see if you will even meet the parts manufacturers operating limits. Many commercial components are rated at 70C, meaning that the parts vendors only guarantee the operation up to that point, after that you are on you own. They will likely have some level of safety margin, but I wouldn't be betting my equipment and company reputation on what the vendor's sales guys told you. If the equipment hasn't been designed for that kind of ambient it may well pass the relatively short duration screening test but you will see a sharp reduction in the life of the product. The major stress on integrated circuits, etc., is temperature. As the ambient and component temperatures increase the failure rate increases exponentially and conversely life, and reliability decrease exponentially. Screening the parts by the vendor will only tell you that these particular units made it for an extremely short time (compared to expected product life). How they play with the rest of the system and there associated variables is nothing but a crap shoot, and its going to be a new risk for every lot the vendor produces. The last time I checked the FCC mainly identified the test ambient as between 50F and 100F (but I'm fuzzy on the upper limit), and that the equipment be in a well warmed condition. That implies that the testing done under a normal test site condition would be acceptable. However, I have had a couple of instances when increased temperatures changed, and indeed failed, some equipment. The components and impedances change somewhat, but the problem I encountered was more mechanical in nature. There were some spring tension components that were used for grounding of flex PCB's etc, that expanded under the higher temperatures and they lost there ground contact. I would at least confirm the emissions compliance at the higher temperatures. Gary McInturff
Re: EMC Friendly PC Platforms.
I don't know if they sell them commercially or just onsey-twosey. But Itronix, here in Spokane Wa sells a line of ruggedized laptops that are exceptionally quiet. Gary McInturff
Re: Safety testing after equipment repair
I agree with Alice on the arrangement of Hi-Pot for new products, but I think the question was returned products for repair, correct. I read John W's note with interest, but I also remember a note from Rich Nute about a test he ran that pretty much pointed out that a simple continuity test served about the same purpose. Rich, I hope I'm not putting words in your mouth -- I apologize in advance if I have. If I remember Rich's much earlier note, he ran the tests with very few of the original PEC wire strands in place. Finally all of this brings up an interesting question about the aging of protective systems. Most of you know that I'm not in favor or writing or even changing standards just because one can do it, there must be some new problem that the old standard doesn't address before it should be changed. Having said all of that, how does the standard address aging of the insulation system, other than mentioning that the system should be in a well warmed condition before hi-pot? Gary 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: emc_p...@symbol.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
