It depends upon the cabinet construction. Cheap cabinets with soft or thin metal is a problem. -----Original Message----- From: Wayne Cooke <[email protected]> To: [email protected] <[email protected]> List-Post: [email protected] Date: Thursday, September 03, 1998 9:09 PM Subject: RE: Recommendations for PCs
>I find this a bit amusing, as we have a desktop PC that we use to test our >modems, and the PC emissions actually go down when we put the monitor on >top of the PC! This is the only way that this PC would pass Class B >emissions. We believe that the monitor puts some weight onto the finger >stock to create a better connection. > >Wayne Cooke >Regulatory Engineer, 3Com Corp. >email: [email protected] > > > > >"Allan, James" <[email protected]> on 09/03/98 01:00:43 PM > >Please respond to "Allan, James" <[email protected]> > >To: "'emc-pstc @ieee.org'" <[email protected]> >cc: (Wayne Cooke/MW/US/3Com) >Subject: RE: Recommendations for PCs > > > > >Funny how the same experience can lead to different conclusions. Like >you, I have found that desktop systems do radiated more with the monitor >on top than with it beside the unit. At that time we did extensive >tests to find out why because our pc was well designed with lots of >conductive fingerstock at strategic points. By carefully substituting >passive weights and non conductive platforms into the test we found that >the problem had nothing to do with seams opening up. The problem was >ordinary old di/dt on the monitor signal cable. As the monitor came into >close proximity to the pc the capacitive coupling between the monitor >and pc increased and thus the common mode current on the video cable >increased. The cable made a real good loop antenna. I'll bet if you >look closely at your results you will find that the problem frequencies >were video dot rate related. I might add that this was several years >ago and things might be different in pc land today. I only present this >to show that popular beliefs may or may not ALWAYS hold up to scientific >examination. >Jim > > -----Original Message----- > From: CTL [SMTP:[email protected]] > Sent: Thursday, September 03, 1998 9:25 AM > To: Mark Briggs; emc-pstc > Subject: Re: Recommendations for PCs > > I have had the same experience with desktops. All desktop >cabinets cannot > support the weight of monitors, especially 15" and larger. > > -----Original Message----- > From: Mark Briggs <[email protected]> > To: emc-pstc <[email protected]> > Date: Wednesday, September 02, 1998 7:48 PM > Subject: RE: Recommendations for PCs > > > >One other point to bear in mind - towers often prove to be >better hosts > >than an equivalent desktop version. The FCC requires that the >monitor be > >placed on top of the PC if it is a desktop unit in order to >re-create a > >typical operating condition (refer fig 11 of ANSI C63.4). I >have seen > >several PCs which are ok UNTIL the monitor is placed on top of >the host > >and causes the chassis to flex, reducing the shielding >effectiveness of > >the host and letting the higher frequencies out. > > > >Mark > > > > > >> -----Original Message----- > >>From: rbusche [SMTP:[email protected]] > >>Sent: Wednesday, September 02, 1998 8:01 AM > >>To: emc-pstc > >>Subject: Recommendations for PCs > >> > >> ---------------------------------------------------- > >>We are in need of a PC to perform EMC testing in support of >FCC and > >>CISPR limits. We are looking for the latest, state of the art, >system > >>with at least 400 MHz processors. Can someone suggest to me >(off line if > >>desired) a good candidate for this application? It is >surprising to me > >>the number of quality systems that fail even BEFORE additional >cards are > >>added. > >> > >>Thanks in advance > >> > >>Rick Busche > >>Evans & Sutherland > >>Salt Lake City, Utah > >>[email protected] > >> > >> --------- > >>This message is coming from the emc-pstc discussion list. > >>To cancel your subscription, send mail to [email protected] > >>with the single line: "unsubscribe emc-pstc" (without the > >>quotes). For help, send mail to [email protected], > >>[email protected], or [email protected] (the list > >>administrators). > >> > >> > >>--------- > >>This message is coming from the emc-pstc discussion list. > >>To cancel your subscription, send mail to [email protected] > >>with the single line: "unsubscribe emc-pstc" (without the > >>quotes). For help, send mail to [email protected], > >>[email protected], or [email protected] (the list > >>administrators). > >> > > > > > >Mark Briggs > >[email protected] > > > > > >--------- > >This message is coming from the emc-pstc discussion list. > >To cancel your subscription, send mail to [email protected] > >with the single line: "unsubscribe emc-pstc" (without the > >quotes). For help, send mail to [email protected], > >[email protected], or [email protected] (the list > >administrators). > > > > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to [email protected] > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to [email protected], > [email protected], or [email protected] (the list > administrators). > >--------- >This message is coming from the emc-pstc discussion list. >To cancel your subscription, send mail to [email protected] >with the single line: "unsubscribe emc-pstc" (without the >quotes). For help, send mail to [email protected], >[email protected], or [email protected] (the list >administrators). > > > > > > > >--------- >This message is coming from the emc-pstc discussion list. >To cancel your subscription, send mail to [email protected] >with the single line: "unsubscribe emc-pstc" (without the >quotes). For help, send mail to [email protected], >[email protected], or [email protected] (the list >administrators). > --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], or [email protected] (the list administrators).
