Ralph: Good question. I don't know, but for a very reasonable fee, I'll be happy to look into that! As usual, all the best questions and answers result in positive cash flow!
Ed Price [email protected] WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military & Avionics EMC Is Our Specialty > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf > Of Ralph McDiarmid > Sent: Friday, August 21, 2009 11:00 AM > To: [email protected] > Subject: RE: 28 volt Linear Power Supply > > A low impedance near DC, but what of 100KHz or so? > > > Ralph McDiarmid, AScT > Compliance Engineering Group > Xantrex Technology Inc > > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf > Of Price, Edward > Sent: Friday, August 21, 2009 10:33 AM > To: Derek Walton > Cc: [email protected] > Subject: RE: 28 volt Linear Power Supply > > Derek: > > I think the comments about using batteries were aimed at the > fact that a battery has very low impedance, and can serve as > a big "capacitor", smoothing out the noise from a noisy > supply. Also, with the battery supplying some of the load, > the supply is not working as hard, so maybe it would be > contributing less noise too. > > You mentioned that LISN and facility powerline filter > impedances were too high to allow starting of your EUT. You > could temporarily jumper around the LISN path, or even the > facility filter path, in order to start the EUT, and then > remove the jumpers during testing. > > Finally, you could look around (eBay?) for some old brute > force linear supplies, like the old Sorenson that I use. A > couple of these in parallel could get you a much quieter > source. Even a single linear in parallel with your noisy > switcher could allow the switcher to contribute less noise. > > > Ed Price > [email protected] WB6WSN > NARTE Certified EMC Engineer > Electromagnetic Compatibility Lab > Cubic Defense Applications > San Diego, CA USA > 858-505-2780 > Military & Avionics EMC Is Our Specialty > > > > -----Original Message----- > > From: [email protected] [mailto:[email protected]] On > Behalf Of Derek > > Walton > > Sent: Friday, August 21, 2009 10:00 AM > > To: Ken Javor > > Cc: [email protected] > > Subject: Re: 28 volt Linear Power Supply > > > > Hi Everyone, > > > > thanks for the constructive comments so far. > > > > I'm not really in a position to use batteries, my voltage > spec is very > > tight at +- 0.5 volts. > > > > I have tried running through the facility filters, they are 100 amp > > rated, but I think a combination of that impedance and the LISN > > impedance is too much for the EUT starting current. It seems I can > > start the EUT with just the LISN's, but then I have too much noise > > from my power source. > > > > I swapped the room filters for some 10 uF caps, same ones that are > > called out in MIL std testing, and I almost get quiet enough. > > > > Ideally, I'd like to find a quieter source rather than try to > > filter..... > > > > Sincerely, > > > > Derek Walton - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
