Eric - I used the numbers from the January 2009 QST tests, where the ARRL measured -136 dBm MDS with the internal preamp on, and either -130 dBm in a 400 Hz bandwidth or -128 dBm in a 500 Hz bandwidth with the preamp off.
using MDS = -174 dBm + Noise Figure + 10*log(Bandwidth) Noise Figure = 174 + MDS -10*log(Bandwidth) QST measured an MDS of -136 dBm in a 400 Hz bandwidth with the preamp on, which gives a noise figure of NF = 174 -136 -10*log(400) = 11.98 dB Which I rounded up to 12 dB in my note. Is there an error in my methodology? The -133 dBm to -135 dBm you quote as typical would only make the noise figure worse than the 12 dB NF I calculated from the ARRL data. Did I miss something? I don't think I ever referred to MDS in the mid -120s. - Duffey -- James Duffey KK6MC DM65tc Cedar Crest NM < [email protected] > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
