http://www.ieee-pses.org/symposium http://www.emc2004.org/ -------------------------------------------------- Rob, your test tests the preamp for compression. There is more to it than this. There is mixing going on in any amplifier. The third order products are usually the issue. For example: 1000 kHz and 1.001 kHz will mix to produce the third order products of 999 kHz and 1002 kHz. Anyway, the third order products will increase 3 dB for every 1 dB of increase in signal. So, adding the 10 dB attenuator will decrease the desired signal by 10 dB and the 3rd order products by 30 dB. To be safe you might want to use as much attenuation as possible while maintaining a signal-to-noise ratio of 10 dB or more. Dave Cuthbert Micron Technology
From: [email protected] mailto:[email protected]] On Behalf Of [email protected] Sent: Thursday, August 05, 2004 9:23 AM 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 ------------------------------------------- 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
