Dear All, Thank you very much for many members who has replied online and offline. I value your expert comments. So far, I have learned that antenna's VSWR, cable loss (at high frequency), and 80% AM modulation are the factors to count on. The new requirements from the third edition of IEC61000-4-3 are important factors too.
Many members suggest to choose an amplifier triple times' power as calculated (i.e. 500W for 80-1000MHz), which I agree with. However, two sales representatives from two amplifier manufacturers suggest a 150W for 80-1000MHz. I get lost. Kindest regards, Grace On 6/10/06, Bob Richards <b...@toprudder.com> wrote: Mac, Yeah, good point, I forgot to mention that. The the old 15dB requirement may not be enough. At a lab where I used to work, we tested down to 26 MHz regularly. The difference in antenna factors between 26 and 52 MHz were terrible. When calibrating at 26 MHz at only 1/3 the rated power of the amp, the signal level at 52 MHz dominated. This was with a very common 500w amplifier, at 10v/m level. We ended up using an Amplifier Research 2500w amp for the 10v/m test. Way overkill, but it points out the fact that you can't just calculate the power required to generate a desired field strength and use that figure to size your amp. You may need to double or even triple that figure just to meet the harmonics requirement. Bob Richards, NCT. Elliott Mac-FME001 <fme...@motorola.com> wrote: Grace, I agree that trying a demonstrator before you buy is the best approach. One thing that you want to take into consideration besides the compression points that Bob mentioned is the harmonic / distortion requirements mentioned in section 6 of 61000-4-3. The 2006 version of IEC 61000-4-3 is a bit different than the current version of EN 61000-4-3. IEC 61000-4-3:2006 [expected to be published as EN this year] requires that harmonics in the uniform field area field be at least 6 dB below the fundamental. There is a lot of good info in Annex D about how to accomplish / measure this. The current EN 61000-4-3 requires that the amplifier not produce harmonics > 15 dB below carrier. Whichever amp you choose, make sure that you take these considerations into account as well. Good luck! Mac Elliott - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: <http://www.ieee-pses.org/> 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/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 <mailto:mcantw...@ieee.org> mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: <mailto:emc-p...@daveheald.com> emc-p...@daveheald.com 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. 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/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: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
