Arie Kleingeld PA3A-2 wrote: > > I have no lab equipment but I have a K3 with dBV measurements, XG2 and > the stepped attenuator from elecraft. >
Arie I believe you may have some measurement error. I'm sure you know that noise can only be measured correctly with a True RMS responding meter...which is not what is in the K3 dBV meter. This is the only way I can reconcile any difference based on N1EU's measurements: > I just ran a spectral analysis of the current firmware versus the very > first > APF implementation (mcu 4.17 dsp 2.65) from 11/3/10 AND THE PLOTS ARE > ABSOLUTELY CONGRUOUS! The APF implementation hasn't changed a bit (or a > byte). > > Have a look: http://n1eu.com/k3apf.gif If the APF filter responses are identical, your S/N measurements should also be identical. http://vk1od.net/measurement/noise/multimeter.htm "Conclusions The model and the experimental results both suggest that these and similar multimeter are not capable of single high resolution relative measurements of narrowband audio noise such as measuring S/N ratios or Y factor for noise figure measurement due mainly to the short integration time in combination with narrow bandwidth. It may be possible to improve resolution by taking multiple measurements and calculating the root of the mean of the squares of the measurements, but errors in the summary process and in temporal drift become an issue." 73, Bill -- View this message in context: http://elecraft.365791.n2.nabble.com/APF-tp5963894p5967466.html Sent from the [K3] mailing list archive at Nabble.com. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
