John, Yes, that is true and made much more sense than using a 50 ohm amp, but still depends on having a good injection probe. We ended up using an audio amp from 10kHz to 100kHz, but that was after the GR1089 spec lowered the 10kHz test level by about 30dB. Never could get a good answer why the original test level existed in the first place, nor why it was decided to lower it by 30dB. The way an early version of the spec read, you met the requirements if you could put 50 watts into the clamp. So, we experimented with trying to get 50 watts net power into the clamp, which was not easy, either. Then, we asked the Bellcore folks about that, and they said we only needed to put 50 watts "forward" power into the clamp. Ok, 50w forward power from a 50 ohm amp into clamp X may inject 20dB less current than 50w forward power into clamp Y. The spec had no mention of required clamp characteristics. A client could go to a lab that had a cheesy clamp and get a pass, or go to a lab with a really good clamp and fail. Not a good situation. The amplifier we ended up using was a Radio Shack 250w rack mounted audio amp. :-) Bob Richards, NCT
John Woodgate <j...@jmwa.demon.co.uk> wrote: Not a great problem for a good *audio* amplifier, of quite modest specification. ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: 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: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org 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: http://www.ieeecommunities.org/emc-pstc
