Re: EMC test table construction plans
I read in !emc-pstc that Michael Taylor wrote (in <7798e57399e3d211b11600902762695205c15...@lvexch1.lvl.hach.com>) about 'EMC test table construction plans', on Mon, 5 Nov 2001: >We successfully used these woods in stands that were subjected to charge >deposition in excess of 6000 micro Coulombs That doesn't sound very big. >and direct lightning strikes of >10.7MV without breakdown. Of course the appropriate design constraints > were >followed for stress equalization and gradient control. As a general rule >(if the wood is properly specified and moisture controlled) a value of > 0.76 >of Teflon can be used for calculation of properties. Value for what? Cost? (;-) -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co..uk Eat mink and be dreary! --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: EMC test table construction plans
Some time ago, in a galaxy far far away at the Rocket Ranch - - - I was involved in a study to determine the dielectric breakdown mechanisms in Solid Rocket Propellant. It was necessary to construct a large number of "stands or Platforms" to hold large blocks of propellant. These blocks were subjected to a variety of charging methods as well as simulated Lightning. As you can surmise these stands were used only ONCE. Because we were consuming these Stands at a high rate we were forced to go to less expensive construction material. Wood was the best 2nd choice. We initiated a detailed study of the dielectric characteristics of various wood types. We found after extensive study that the conductivity of the wood is controlled by both the moisture content (big surprise) and the level of organic salts & minerals contained in the growth ring boundary. We found that the best wood from an insulation standpoint was Balsa. However this wood had no structural strength. The next best was white Poplar or Ash, Triple kiln dried with 2-3 coats of marine varnish. We successfully used these woods in stands that were subjected to charge deposition in excess of 6000 micro Coulombs and direct lightning strikes of 10.7MV without breakdown. Of course the appropriate design constraints were followed for stress equalization and gradient control. As a general rule (if the wood is properly specified and moisture controlled) a value of 0.76 of Teflon can be used for calculation of properties. For what it's worth. Michael Taylor Awaiting winter in Colorado -Original Message- From: Scott Lacey [mailto:sco...@world.std.com] Sent: Friday, November 02, 2001 5:04 PM To: POWELL, DOUG Cc: emc-p...@majordomo.ieee.org Subject: RE: EMC test table construction plans Doug, Wood is ok if you seal it properly to prevent absorbed moisture from causing inconsistancies from one test to the next. Most clear resins do not cause RF problems whereas the metallic pigments in paints often do. If you can, covering the top with laminate (Formica) increases durability and provides a low friction surface. The best design is to make a sturdy table using the following criteria: 4 X 4 or doubled 2 X 4 legs. Top of 2 layers of 3/4" plywood or particle board. Apron to support legs of at least 2 X 4 or 3/4 X 6 cross section. Pivoting top overlay of 3/4" plywood or particle board with a piece of 1 1/2" PVC pipe for a pivot. What you do is either cover the table surfaces (top & bottom) with laminate or sand, seal (multiple coats) and sand again plus wax to allow easy rotation. Drill matching holes through the center of the 3/4" overlay and the tabletop for the stub (4" long or so) of pipe. glue the pipe flush with the top of the overlay (it will protrude from the bottom). You just drop the overlay with pipe onto/into the tabletop with hole. During testing the table is rotated (1/4 turn) manually between tests. If you doubt that laminate can provide a low friction bearing, try this test - turn one table upside down on top of an identical table, rotate the top table, and then try rotating the table with a coworker standing on it. If you find too much friction apply some automotive paste wax. Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of POWELL, DOUG Sent: Thursday, November 01, 2001 12:38 PM To: EMC-PSTC (E-mail) Subject: EMC test table construction plans Hello all, I plan to construct my own insulated EMC test table for a 5 meter chamber. Seems simple enough to do and I could easily come up with something. I thought I might first ask for input from those of you in the discussion group who have experience or maybe even construction plans. Here are some features I want: 1) I will be testing products that weight up to 200 Lbs (91 kg). 2) I want to minimize metalic fastners. 3) I would like to make it a pivoting table (not motorized). 4) Height is 80 cm. 5) The surface should be replacable if it gets badly worn or scarred. I'm thinking of using hardboard. 6) Suggestions on length & width? -doug --- Douglas E. Powell, Compliance Engineer Advanced Energy Industries, Inc. Mail stop: 203024 1626 Sharp Point Drive Ft. Collins, CO 80525 970.407.6410 (phone) 970-407.5410 (fax) mailto:doug.pow...@aei.com --- _ This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. --- 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/
RE: EMC test table construction plans
I agree that wood and other high density materials are a problem as one approaches 1 GHz. I have data (taken in a previous life) that clearly shows the effect of a wooden table with a "Formica" top. This was done by placing an isotropic field sensor (ok, close to isotropic) at the center of a table and illuminating it from three meters away in a semi-anechoic chamber. Field strength was measured at each ten degrees of rotation at several frequencies up to 1 GHz. The effect at 1 GHz was in excess of 6 dB difference. The interesting part is that what appeared to be happening was low angle (below the "critical angle") dielectric reflection. The signal was strongest when aligned with the corners of the rectangular table. Brent DeWitt Datex-Ohmeda Louisville, CO -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Sundstrom Michael (NMP-RD/Dallas) Sent: Friday, November 02, 2001 7:09 AM To: 'Pommerenke, David'; 'POWELL, DOUG'; EMC-PSTC (E-mail) Subject: RE: EMC test table construction plans We use a styrofoam table here at our lab, it is a round plug of styrofoam 80cm tall and 1m across. This has worked the best for us, and it has the least reflections at any frequency we can reliably test at. I would guess that some form of hard material on top of this type of table would support 200lBs. Michael Sundstrom NOKIA TCC Dallas / EMC ofc: (972) 374-1462 cell: (817) 917-5021 amateur call: KB5UKT -Original Message- From: ext Pommerenke, David [mailto:davi...@ece.umr.edu] Sent: Thursday, November 01, 2001 3:16 PM To: 'POWELL, DOUG'; EMC-PSTC (E-mail) Subject: RE: EMC test table construction plans Doug, For emissions and immunity you should not use any wood in the table. It will significantly (+/-2 dB up to 1 GHz for emissions , more above, +/-10 dB for immunity up to 1 GHz) change the test result. My experience has shown that Styrofoam is basicly the best material. There are a couple of published papers on this issue. As surface material the following worked out fine: - Foamed PVC (rather stiff, low dielectric constant due to the foamed nature), maybe 4 mm thick. - PE sheet, maybe 2 mm thick. David Pommerenke -Original Message- From: POWELL, DOUG [mailto:doug.pow...@aei.com] Sent: Thursday, November 01, 2001 11:38 AM To: EMC-PSTC (E-mail) Subject: EMC test table construction plans Hello all, I plan to construct my own insulated EMC test table for a 5 meter chamber. Seems simple enough to do and I could easily come up with something. I thought I might first ask for input from those of you in the discussion group who have experience or maybe even construction plans. Here are some features I want: 1) I will be testing products that weight up to 200 Lbs (91 kg). 2) I want to minimize metalic fastners. 3) I would like to make it a pivoting table (not motorized). 4) Height is 80 cm. 5) The surface should be replacable if it gets badly worn or scarred. I'm thinking of using hardboard. 6) Suggestions on length & width? -doug --- Douglas E. Powell, Compliance Engineer Advanced Energy Industries, Inc. Mail stop: 203024 1626 Sharp Point Drive Ft. Collins, CO 80525 970.407.6410 (phone) 970-407.5410 (fax) mailto:doug.pow...@aei.com --- _ This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. --- 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: Michael Garretson:pstc_ad...@garretson.org
RE: EMC test table construction plans
Doug, Wood is ok if you seal it properly to prevent absorbed moisture from causing inconsistancies from one test to the next. Most clear resins do not cause RF problems whereas the metallic pigments in paints often do. If you can, covering the top with laminate (Formica) increases durability and provides a low friction surface. The best design is to make a sturdy table using the following criteria: 4 X 4 or doubled 2 X 4 legs. Top of 2 layers of 3/4" plywood or particle board. Apron to support legs of at least 2 X 4 or 3/4 X 6 cross section. Pivoting top overlay of 3/4" plywood or particle board with a piece of 1 1/2" PVC pipe for a pivot. What you do is either cover the table surfaces (top & bottom) with laminate or sand, seal (multiple coats) and sand again plus wax to allow easy rotation. Drill matching holes through the center of the 3/4" overlay and the tabletop for the stub (4" long or so) of pipe. glue the pipe flush with the top of the overlay (it will protrude from the bottom). You just drop the overlay with pipe onto/into the tabletop with hole. During testing the table is rotated (1/4 turn) manually between tests. If you doubt that laminate can provide a low friction bearing, try this test - turn one table upside down on top of an identical table, rotate the top table, and then try rotating the table with a coworker standing on it. If you find too much friction apply some automotive paste wax. Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of POWELL, DOUG Sent: Thursday, November 01, 2001 12:38 PM To: EMC-PSTC (E-mail) Subject: EMC test table construction plans Hello all, I plan to construct my own insulated EMC test table for a 5 meter chamber. Seems simple enough to do and I could easily come up with something. I thought I might first ask for input from those of you in the discussion group who have experience or maybe even construction plans. Here are some features I want: 1) I will be testing products that weight up to 200 Lbs (91 kg). 2) I want to minimize metalic fastners. 3) I would like to make it a pivoting table (not motorized). 4) Height is 80 cm. 5) The surface should be replacable if it gets badly worn or scarred. I'm thinking of using hardboard. 6) Suggestions on length & width? -doug --- Douglas E. Powell, Compliance Engineer Advanced Energy Industries, Inc. Mail stop: 203024 1626 Sharp Point Drive Ft. Collins, CO 80525 970.407.6410 (phone) 970-407.5410 (fax) mailto:doug.pow...@aei.com --- _ This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: EMC test table construction plans
We use a styrofoam table here at our lab, it is a round plug of styrofoam 80cm tall and 1m across. This has worked the best for us, and it has the least reflections at any frequency we can reliably test at. I would guess that some form of hard material on top of this type of table would support 200lBs. Michael Sundstrom NOKIA TCC Dallas / EMC ofc: (972) 374-1462 cell: (817) 917-5021 amateur call: KB5UKT -Original Message- From: ext Pommerenke, David [mailto:davi...@ece.umr.edu] Sent: Thursday, November 01, 2001 3:16 PM To: 'POWELL, DOUG'; EMC-PSTC (E-mail) Subject: RE: EMC test table construction plans Doug, For emissions and immunity you should not use any wood in the table. It will significantly (+/-2 dB up to 1 GHz for emissions , more above, +/-10 dB for immunity up to 1 GHz) change the test result. My experience has shown that Styrofoam is basicly the best material. There are a couple of published papers on this issue. As surface material the following worked out fine: - Foamed PVC (rather stiff, low dielectric constant due to the foamed nature), maybe 4 mm thick. - PE sheet, maybe 2 mm thick. David Pommerenke -Original Message- From: POWELL, DOUG [mailto:doug.pow...@aei.com] Sent: Thursday, November 01, 2001 11:38 AM To: EMC-PSTC (E-mail) Subject: EMC test table construction plans Hello all, I plan to construct my own insulated EMC test table for a 5 meter chamber. Seems simple enough to do and I could easily come up with something. I thought I might first ask for input from those of you in the discussion group who have experience or maybe even construction plans. Here are some features I want: 1) I will be testing products that weight up to 200 Lbs (91 kg). 2) I want to minimize metalic fastners. 3) I would like to make it a pivoting table (not motorized). 4) Height is 80 cm. 5) The surface should be replacable if it gets badly worn or scarred. I'm thinking of using hardboard. 6) Suggestions on length & width? -doug --- Douglas E. Powell, Compliance Engineer Advanced Energy Industries, Inc. Mail stop: 203024 1626 Sharp Point Drive Ft. Collins, CO 80525 970.407.6410 (phone) 970-407.5410 (fax) mailto:doug.pow...@aei.com --- _ This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old me
RE: EMC test table construction plans
In our OATS dome, we use a pair of large antistatic plastic Rubbermaid wheeled carts with a sheet of plywood laid across the tops. A tabletop host pc is set on that. How's that effecting the measurements? Should these effects be part of the 'uncertainty'? Kyle Ehler KCØIQE <mailto:kyle.eh...@lsil.com> Assistant Design Engineer LSI Logic Storage Systems Div. 3718 N. Rock Road U.S.A. Wichita, Kansas 67226 Ph. 316 636 8657 Fax 316 636 8321 -Original Message- From: umbdenst...@sensormatic.com [mailto:umbdenst...@sensormatic.com] Sent: Thursday, November 01, 2001 4:12 PM To: doug.pow...@aei.com; emc-p...@ieee.org; davi...@ece.umr.edu Subject: RE: EMC test table construction plans David, On a similar note I had heard that an EUT shelter might demonstrate a 6 dB variation between wet and dry conditions, or dirty vs. clean (pressure cleaned) condition. Did the papers comment on wood properties? Perhaps identifying soft wood vs. hard wood, minerals absorbed during growth, wet vs. dry, or other "conditioning" situations? I have only seen a handful of labs, but they all had wooden tables (defacto standard for the times -- past?). I wonder if the standards were written around the convention of wooden tables? You've raised an interesting issue. Best regards, Don Umbdenstock Sensormatic > -- > From: Pommerenke, David[SMTP:davi...@ece.umr.edu] > Reply To: Pommerenke, David > Sent: Thursday, November 01, 2001 4:15 PM > To: 'POWELL, DOUG'; EMC-PSTC (E-mail) > Subject: RE: EMC test table construction plans > > > Doug, > > For emissions and immunity you should not use any wood in the table. It > will > significantly (+/-2 dB up to 1 GHz for emissions , more above, +/-10 dB > for > immunity up to 1 GHz) change the test result. My experience has shown that > Styrofoam is basicly the best material. There are a couple of published > papers on this issue. As surface material the following worked out fine: > > - Foamed PVC (rather stiff, low dielectric constant due to the foamed > nature), maybe 4 mm thick. > > - PE sheet, maybe 2 mm thick. > > David Pommerenke > > > > -Original Message- > From: POWELL, DOUG [mailto:doug.pow...@aei.com] > Sent: Thursday, November 01, 2001 11:38 AM > To: EMC-PSTC (E-mail) > Subject: EMC test table construction plans > > > > Hello all, > > I plan to construct my own insulated EMC test table for a 5 meter chamber. > Seems simple enough to do and I could easily come up with something. I > thought I might first ask for input from those of you in the discussion > group who have experience or maybe even construction plans. Here are some > features I want: > > 1) I will be testing products that weight up to 200 Lbs (91 kg). > > 2) I want to minimize metalic fastners. > > 3) I would like to make it a pivoting table (not motorized). > > 4) Height is 80 cm. > > 5) The surface should be replacable if it gets badly worn or scarred. I'm > thinking of using hardboard. > > 6) Suggestions on length & width? > > -doug > > --- > Douglas E. Powell, Compliance Engineer > Advanced Energy Industries, Inc. > Mail stop: 203024 > 1626 Sharp Point Drive > Ft. Collins, CO 80525 > > 970.407.6410 (phone) > 970-407.5410 (fax) > mailto:doug.pow...@aei.com > --- >
RE: EMC test table construction plans
From: Douglas Beckwith@MITEL on 11/02/2001 08:21 AM Sorry guys, finger trouble here with a mouse, didn't mean to send a reply. Regards Doug Beckwith --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: EMC test table construction plans
David, or anyone else, would you please site any papers that cover the error issue with emissions or immunity testing below 1 GHz? Richard Woods Sensormatic Electronics -Original Message- From: Pommerenke, David [mailto:davi...@ece.umr.edu] Sent: Thursday, November 01, 2001 4:16 PM To: 'POWELL, DOUG'; EMC-PSTC (E-mail) Subject: RE: EMC test table construction plans Doug, For emissions and immunity you should not use any wood in the table. It will significantly (+/-2 dB up to 1 GHz for emissions , more above, +/-10 dB for immunity up to 1 GHz) change the test result. My experience has shown that Styrofoam is basicly the best material. There are a couple of published papers on this issue. As surface material the following worked out fine: - Foamed PVC (rather stiff, low dielectric constant due to the foamed nature), maybe 4 mm thick. - PE sheet, maybe 2 mm thick. David Pommerenke -Original Message- From: POWELL, DOUG [mailto:doug.pow...@aei.com] Sent: Thursday, November 01, 2001 11:38 AM To: EMC-PSTC (E-mail) Subject: EMC test table construction plans Hello all, I plan to construct my own insulated EMC test table for a 5 meter chamber. Seems simple enough to do and I could easily come up with something. I thought I might first ask for input from those of you in the discussion group who have experience or maybe even construction plans. Here are some features I want: 1) I will be testing products that weight up to 200 Lbs (91 kg). 2) I want to minimize metalic fastners. 3) I would like to make it a pivoting table (not motorized). 4) Height is 80 cm. 5) The surface should be replacable if it gets badly worn or scarred. I'm thinking of using hardboard. 6) Suggestions on length & width? -doug --- Douglas E. Powell, Compliance Engineer Advanced Energy Industries, Inc. Mail stop: 203024 1626 Sharp Point Drive Ft. Collins, CO 80525 970.407.6410 (phone) 970-407.5410 (fax) mailto:doug.pow...@aei.com --- _ This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: EMC test table construction plans
John, You are arguing "Should the test conditions not reflect the actual environment in use of the product, rather than employ these unusual materials?" The problem is that we do not know the actual conditions. So we need to define the test conditions. If everyone use be using the SAME wooden table, it would be fine. But that is not the case and there are large variations between different wooden tables, surface materials etc. So if one uses a wooden table, its influence must be taken into the uncertainty calculation. This adds a few more dBs, much more above 1 GHz. In radiated immunity it is even worse, as there is no maximization done. David Pommerenke -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Friday, November 02, 2001 1:34 AM To: emc-p...@majordomo.ieee.org Subject: Re: EMC test table construction plans I read in !emc-pstc that Pommerenke, David wrote (in <9da8d24b915bd1118911006094516eaf0ba31...@umr-mail02.cc.umr.edu>) about 'EMC test table construction plans', on Thu, 1 Nov 2001: >For emissions and immunity you should not use any wood in the table. It will >significantly (+/-2 dB up to 1 GHz for emissions , more above, +/-10 dB for >immunity up to 1 GHz) change the test result. My experience has shown that >Styrofoam is basicly the best material. You mean that it gives the worst-case results? >There are a couple of published >papers on this issue. As surface material the following worked out fine: > > - Foamed PVC (rather stiff, low dielectric constant due to the foamed >nature), maybe 4 mm thick. > > - PE sheet, maybe 2 mm thick. Should the test conditions not reflect the actual environment in use of the product, rather than employ these unusual materials? -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Eat mink and be dreary! --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: EMC test table construction plans
Doug, You might want to look at a paper that was presented at the Montreal IEEE EMC Symposium by HP on measurements that they made on a table when starting to test above 1 GHz. As you know, the FCC (ANSI C63.4) and CISPR 22 requirements simply call out that the table should be non-conducting. That's about all that is said. Measurements made by HP in Vancouver, WA show that this might just be an inadequate specification for the table due to reflections from the table/air boundary. Their table was wood with no metal fasteners of any kind, with a plastic sheet on the top. It meets the "non-conducting" requirement, but demonstrated that this minimal standard is inadequate to ensure accurate and repeatable results. I am certain that the results of their tests will cause some interesting discussions in various standards bodies over the next few years. That said, a wood or fiberglass table should meet your needs quite nicely. I've seen a number of construction techniques over the years that have all had minimal metal content (our tables have two swivel casters under the legs at one end and metal axels for the wheels at the other end as their total metal content). These range from all wood, to PCV pipe frame with a wood top to fiberglass construction. All are sturdy enough to hold 200 pounds and all are "non-conductive". I'm not sure what to suggest for your swivel mount, but I have seen turntables built with a single metal pivot in the middle with a race of pool balls used for ball bearings further out on the table. Quick, simple and elegant. Non-conductive, except for the pivot in the middle. Good luck and have fun. Based on HP's paper, I suspect that a lot of us will be building new tables of a yet to be determined material in the next few years. Should make for some interesting conversations. Ghery Pettit Intel -Original Message- From: POWELL, DOUG [mailto:doug.pow...@aei.com] Sent: Thursday, November 01, 2001 9:38 AM To: EMC-PSTC (E-mail) Subject: EMC test table construction plans Hello all, I plan to construct my own insulated EMC test table for a 5 meter chamber. Seems simple enough to do and I could easily come up with something. I thought I might first ask for input from those of you in the discussion group who have experience or maybe even construction plans. Here are some features I want: 1) I will be testing products that weight up to 200 Lbs (91 kg). 2) I want to minimize metalic fastners. 3) I would like to make it a pivoting table (not motorized). 4) Height is 80 cm. 5) The surface should be replacable if it gets badly worn or scarred. I'm thinking of using hardboard. 6) Suggestions on length & width? -doug --- Douglas E. Powell, Compliance Engineer Advanced Energy Industries, Inc. Mail stop: 203024 1626 Sharp Point Drive Ft. Collins, CO 80525 970.407.6410 (phone) 970-407.5410 (fax) mailto:doug.pow...@aei.com --- _ This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. --- This message is from the IEEE EMC Society Pro
Re: EMC test table construction plans
John, Your point is well taken with regard to testing a unit while closely matching the testing environment to the environment it will be used in. However, we don't sell a lot of equipment to people who have 40 meters of ground plane, either. It is my understanding a reasonable "false" environment is an attempt to control the testing environment and obtain repeatable results. Controlling the table material so it does not appreciably affect the outcome of the test seems to be consistent with that goal. - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: John Woodgate To: emc-p...@majordomo.ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Friday, November 02, 2001 2:30 AM Subject: Re: EMC test table construction plans > >I read in !emc-pstc that Pommerenke, David wrote >(in <9da8d24b915bd1118911006094516eaf0ba31...@umr-mail02.cc.umr.edu>) >about 'EMC test table construction plans', on Thu, 1 Nov 2001: >>For emissions and immunity you should not use any wood in the table. It will >>significantly (+/-2 dB up to 1 GHz for emissions , more above, +/-10 dB for >>immunity up to 1 GHz) change the test result. My experience has shown that >>Styrofoam is basicly the best material. > >You mean that it gives the worst-case results? > >>There are a couple of published >>papers on this issue. As surface material the following worked out fine: >> >> - Foamed PVC (rather stiff, low dielectric constant due to the foamed >>nature), maybe 4 mm thick. >> >> - PE sheet, maybe 2 mm thick. > >Should the test conditions not reflect the actual environment in use of >the product, rather than employ these unusual materials? >-- >Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk > --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: EMC test table construction plans
I read in !emc-pstc that Pommerenke, David wrote (in <9da8d24b915bd1118911006094516eaf0ba31...@umr-mail02.cc.umr.edu>) about 'EMC test table construction plans', on Thu, 1 Nov 2001: >For emissions and immunity you should not use any wood in the table. It will >significantly (+/-2 dB up to 1 GHz for emissions , more above, +/-10 dB for >immunity up to 1 GHz) change the test result. My experience has shown that >Styrofoam is basicly the best material. You mean that it gives the worst-case results? >There are a couple of published >papers on this issue. As surface material the following worked out fine: > > - Foamed PVC (rather stiff, low dielectric constant due to the foamed >nature), maybe 4 mm thick. > > - PE sheet, maybe 2 mm thick. Should the test conditions not reflect the actual environment in use of the product, rather than employ these unusual materials? -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Eat mink and be dreary! --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: EMC test table construction plans
David, On a similar note I had heard that an EUT shelter might demonstrate a 6 dB variation between wet and dry conditions, or dirty vs. clean (pressure cleaned) condition. Did the papers comment on wood properties? Perhaps identifying soft wood vs. hard wood, minerals absorbed during growth, wet vs. dry, or other "conditioning" situations? I have only seen a handful of labs, but they all had wooden tables (defacto standard for the times -- past?). I wonder if the standards were written around the convention of wooden tables? You've raised an interesting issue. Best regards, Don Umbdenstock Sensormatic > -- > From: Pommerenke, David[SMTP:davi...@ece.umr.edu] > Reply To: Pommerenke, David > Sent: Thursday, November 01, 2001 4:15 PM > To: 'POWELL, DOUG'; EMC-PSTC (E-mail) > Subject: RE: EMC test table construction plans > > > Doug, > > For emissions and immunity you should not use any wood in the table. It > will > significantly (+/-2 dB up to 1 GHz for emissions , more above, +/-10 dB > for > immunity up to 1 GHz) change the test result. My experience has shown that > Styrofoam is basicly the best material. There are a couple of published > papers on this issue. As surface material the following worked out fine: > > - Foamed PVC (rather stiff, low dielectric constant due to the foamed > nature), maybe 4 mm thick. > > - PE sheet, maybe 2 mm thick. > > David Pommerenke > > > > -Original Message- > From: POWELL, DOUG [mailto:doug.pow...@aei.com] > Sent: Thursday, November 01, 2001 11:38 AM > To: EMC-PSTC (E-mail) > Subject: EMC test table construction plans > > > > Hello all, > > I plan to construct my own insulated EMC test table for a 5 meter chamber. > Seems simple enough to do and I could easily come up with something. I > thought I might first ask for input from those of you in the discussion > group who have experience or maybe even construction plans. Here are some > features I want: > > 1) I will be testing products that weight up to 200 Lbs (91 kg). > > 2) I want to minimize metalic fastners. > > 3) I would like to make it a pivoting table (not motorized). > > 4) Height is 80 cm. > > 5) The surface should be replacable if it gets badly worn or scarred. I'm > thinking of using hardboard. > > 6) Suggestions on length & width? > > -doug > > --- > Douglas E. Powell, Compliance Engineer > Advanced Energy Industries, Inc. > Mail stop: 203024 > 1626 Sharp Point Drive > Ft. Collins, CO 80525 > > 970.407.6410 (phone) > 970-407.5410 (fax) > mailto:doug.pow...@aei.com > --- > > > > _ > > This message, including any attachments, may contain information that is > confidential and proprietary information of Advanced Energy Industries, > Inc. > The dissemination, distribution, use or copying of this message or any of > its attachments is strictly prohibited without the express written consent > of Advanced Energy Industries, Inc. > > --- > 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: > Michael Garretson:pstc_ad...@garretson.org > Dave Healddavehe...@mediaone.net > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > All emc-pstc postings are archived and searchable on the web at: > No longer online until our new server is brought online and the old > messages are imported into the new server. > > --- > 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: > Michael Garretson:pstc_ad...@garretson.org > Dave Healddavehe...@mediaone.net > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > All emc-pstc postings are archived and searchable on the web at: >
Re: EMC test table construction plans
I read in !emc-pstc that POWELL, DOUG wrote (in ) about 'EMC test table construction plans', on Thu, 1 Nov 2001: >1) I will be testing products that weight up to 200 Lbs (91 kg). No problem > >2) I want to minimize metalic fastners. No problem > >3) I would like to make it a pivoting table (not motorized). Do you mean rotatable? > >4) Height is 80 cm. No problem > >5) The surface should be replacable if it gets badly worn or scarred. I'm >thinking of using hardboard. It needs support at intervals of 50 cm in one direction to safely support 200 lb. > >6) Suggestions on length & width? Bigger than the biggest unit you want to put on it? 1 m by 0.5 m might be convenient. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Eat mink and be dreary! --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: EMC test table construction plans
Doug, For emissions and immunity you should not use any wood in the table. It will significantly (+/-2 dB up to 1 GHz for emissions , more above, +/-10 dB for immunity up to 1 GHz) change the test result. My experience has shown that Styrofoam is basicly the best material. There are a couple of published papers on this issue. As surface material the following worked out fine: - Foamed PVC (rather stiff, low dielectric constant due to the foamed nature), maybe 4 mm thick. - PE sheet, maybe 2 mm thick. David Pommerenke -Original Message- From: POWELL, DOUG [mailto:doug.pow...@aei.com] Sent: Thursday, November 01, 2001 11:38 AM To: EMC-PSTC (E-mail) Subject: EMC test table construction plans Hello all, I plan to construct my own insulated EMC test table for a 5 meter chamber. Seems simple enough to do and I could easily come up with something. I thought I might first ask for input from those of you in the discussion group who have experience or maybe even construction plans. Here are some features I want: 1) I will be testing products that weight up to 200 Lbs (91 kg). 2) I want to minimize metalic fastners. 3) I would like to make it a pivoting table (not motorized). 4) Height is 80 cm. 5) The surface should be replacable if it gets badly worn or scarred. I'm thinking of using hardboard. 6) Suggestions on length & width? -doug --- Douglas E. Powell, Compliance Engineer Advanced Energy Industries, Inc. Mail stop: 203024 1626 Sharp Point Drive Ft. Collins, CO 80525 970.407.6410 (phone) 970-407.5410 (fax) mailto:doug.pow...@aei.com --- _ This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: EMC test table construction plans
Hi Doug, The following expresses some of my experiences. >I plan to construct my own insulated EMC test table for a 5 meter chamber. >Seems simple enough to do and I could easily come up with something. I >thought I might first ask for input from those of you in the discussion >group who have experience or maybe even construction plans. Here are some >features I want: > >1) I will be testing products that weight up to 200 Lbs (91 kg). Standard 2x2 or 2x4 and 1/2" plywood should suffice. >2) I want to minimize metalic fastners. What I've used in the past are wood dowels and wood glue. This takes some time, but the table is extremely durable. >3) I would like to make it a pivoting table (not motorized). I have used a large lazy-susan mechanism (very low profile and w/ball bearings). Teflon pads were used to provide rotational stability and ease of rotation. >4) Height is 80 cm. Just cut the wood to fit. >5) The surface should be replacable if it gets badly worn or scarred. I'm >thinking of using hardboard. A round piece of 1/2" plywood should suffice (they can come pre-cut in 36" and 48" diameters). I've never had to replace a table top. >6) Suggestions on length & width? I would not recommend any horizontal dimension greater than 60" for table stability. All this material is commonly available and can be purchased at places like Home Depot, Lowes, your local lumber retailer, etc. As a convenience for measurement repeatability, I placed angular markings on the table top in 10 and 45 degree increments. I hope this helps. Best regards, Ron Pickard rpick...@hypercom.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: EMC test table construction plans
Doug, I am not sure what you mean by pivoting. We created a table that has the features listed below and include knock-down for flat storage. For a small square table, we used 3/4" plywood for top and legs. The legs were slotted and hollowed, and fit together in a perpendicular slot to slot fashion. A full size table uses the legs for the small square table plus one more long leg. For both the square table and full size table, the table is guided into position by glued-on blocks. We typically don't test 200 lb devices; but I have stood on the table. You might feel more comfortable with 1" plywood. See crude sketch below for a better concept. <> We place this table on a flush-mount turn-table for the rotational requirements. This table is light weight, easily stored, takes up minimal space in storage, strong, and is built with no metallic parts. Best regards, Don Umbdenstock Sensormatic > -- > From: POWELL, DOUG[SMTP:doug.pow...@aei.com] > Reply To: POWELL, DOUG > Sent: Thursday, November 01, 2001 12:37 PM > To: EMC-PSTC (E-mail) > Subject: EMC test table construction plans > > > Hello all, > > I plan to construct my own insulated EMC test table for a 5 meter chamber. > Seems simple enough to do and I could easily come up with something. I > thought I might first ask for input from those of you in the discussion > group who have experience or maybe even construction plans. Here are some > features I want: > > 1) I will be testing products that weight up to 200 Lbs (91 kg). > > 2) I want to minimize metalic fastners. > > 3) I would like to make it a pivoting table (not motorized). > > 4) Height is 80 cm. > > 5) The surface should be replacable if it gets badly worn or scarred. I'm > thinking of using hardboard. > > 6) Suggestions on length & width? > > -doug > > --- > Douglas E. Powell, Compliance Engineer > Advanced Energy Industries, Inc. > Mail stop: 203024 > 1626 Sharp Point Drive > Ft. Collins, CO 80525 > > 970.407.6410 (phone) > 970-407.5410 (fax) > mailto:doug.pow...@aei.com > --- > > > > _ > > This message, including any attachments, may contain information that is > confidential and proprietary information of Advanced Energy Industries, > Inc. > The dissemination, distribution, use or copying of this message or any of > its attachments is strictly prohibited without the express written consent > of Advanced Energy Industries, Inc. > > --- > 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: > Michael Garretson:pstc_ad...@garretson.org > Dave Healddavehe...@mediaone.net > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > All emc-pstc postings are archived and searchable on the web at: > No longer online until our new server is brought online and the old > messages are imported into the new server. > Table sketch.doc Description: MS-Word document
RE: EMC test table construction plans
Doug, You might want to look at a paper that was presented at the Montreal IEEE EMC Symposium by HP on measurements that they made on a table when starting to test above 1 GHz. As you know, the FCC (ANSI C63.4) and CISPR 22 requirements simply call out that the table should be non-conducting. That's about all that is said. Measurements made by HP in Vancouver, WA show that this might just be an inadequate specification for the table due to reflections from the table/air boundary. Their table was wood with no metal fasteners of any kind, with a plastic sheet on the top. It meets the "non-conducting" requirement, but demonstrated that this minimal standard is inadequate to ensure accurate and repeatable results. I am certain that the results of their tests will cause some interesting discussions in various standards bodies over the next few years. That said, a wood or fiberglass table should meet your needs quite nicely. I've seen a number of construction techniques over the years that have all had minimal metal content (our tables have two swivel casters under the legs at one end and metal axels for the wheels at the other end as their total metal content). These range from all wood, to PCV pipe frame with a wood top to fiberglass construction. All are sturdy enough to hold 200 pounds and all are "non-conductive". I'm not sure what to suggest for your swivel mount, but I have seen turntables built with a single metal pivot in the middle with a race of pool balls used for ball bearings further out on the table. Quick, simple and elegant. Non-conductive, except for the pivot in the middle. Good luck and have fun. Based on HP's paper, I suspect that a lot of us will be building new tables of a yet to be determined material in the next few years. Should make for some interesting conversations. Ghery Pettit Intel -Original Message- From: POWELL, DOUG [mailto:doug.pow...@aei.com] Sent: Thursday, November 01, 2001 9:38 AM To: EMC-PSTC (E-mail) Subject: EMC test table construction plans Hello all, I plan to construct my own insulated EMC test table for a 5 meter chamber. Seems simple enough to do and I could easily come up with something. I thought I might first ask for input from those of you in the discussion group who have experience or maybe even construction plans. Here are some features I want: 1) I will be testing products that weight up to 200 Lbs (91 kg). 2) I want to minimize metalic fastners. 3) I would like to make it a pivoting table (not motorized). 4) Height is 80 cm. 5) The surface should be replacable if it gets badly worn or scarred. I'm thinking of using hardboard. 6) Suggestions on length & width? -doug --- Douglas E. Powell, Compliance Engineer Advanced Energy Industries, Inc. Mail stop: 203024 1626 Sharp Point Drive Ft. Collins, CO 80525 970.407.6410 (phone) 970-407.5410 (fax) mailto:doug.pow...@aei.com --- _ This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
