http://www.ieee-pses.org/symposium http://www.emc2004.org/ -------------------------------------------------- http://www.ieee-pses.org/symposium http://www.emc2004.org/ --------------------------------------------------
I agree with Ken. However, note that if the pre-amp is not overloaded, inserting a 3 dB attenuator will decrease the signal by 3 dB. If the pre-amp is overloaded, the decrease will be somewhere between 0 and less than 3 dB depending upon the amount of overload. John Shinn, P.E. Sanmina-SCI From: [email protected] mailto:[email protected]] On Behalf Of Ken Javor Sent: Thursday, August 05, 2004 8:37 AM To: [email protected]; [email protected] Subject: Re: Pre-amp overload That works but you certainly don't need that power rating and 3 dB would work better as a low-level signal would not then get buried in the noise - with a 10 dB pad you had to have better than 16 dB S+N/N ratio to be able to make a decent measurement after putting 10 dB in-line. From: [email protected] List-Post: [email protected] Date: Thu, 5 Aug 2004 11:23:04 -0400 To: [email protected] Subject: Pre-amp overload http://www.ieee-pses.org/symposium http://www.emc2004.org/ -------------------------------------------------- EMC Gurus, We use a pre-amplifier for Radiated Emissions measurements going back to the spectrum analyzer. I wonder if anyone has a good standard method to verify that the pre-amp is not being overloaded? My thoughts are to use a 10dB, 50W in-line attenuator. To first take a measurement without and then with the attenuator in-line. I would then conclude the following: If the measurement stays the same we have an overload If the measurement drops by 10dB we are fine If the measurement drops by more than 10dB I assume we have an overload at other frequencies that need to be checked. Does this process sound good to everyone? (pulling out the old college day experiments here) Rob Kado EMC Engineer VWS - Auburn Hills, USA Tel: 248-340-3828 / Fax: 248-340-3316 Internal Location 3M2 ------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. IEEE PSES Main Website: http://www.ieee-pses.org/ To post a message send your e-mail to [email protected] Instructions for use of the list server: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc _____________________________________________________________________________ Scanned by Sanmina-SCI eShield ________ ____________________________________________________________________ ------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. IEEE PSES Main Website: http://www.ieee-pses.org/ To post a message send your e-mail to [email protected] Instructions for use of the list server: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. IEEE PSES Main Website: http://www.ieee-pses.org/ To post a message send your e-mail to [email protected] Instructions for use of the list server: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
