Thanks a lot guys for all the input! The nist articles was a very interesting read. I have ordered the minicircuits ZRPD-1 and will try to build the 2N2222A mixer to to see how far that will take it. I probably also will build a low noise jfet preamp to see if that will reduce the noise. But I probably have to go to build myself a crosscorrelation system to be able to <-180dBc with confidence. Is there any cheap way into cross correlation measurement, using high quality soundcard for example? Or do I have to buy one of these big old expensive dual FFT analyzers? /Anders
On Fri, Nov 23, 2012 at 4:42 PM, Anders Time <anderst...@gmail.com> wrote: > I have been using an minicircuits mixer as a phase detector for measuring > low frequency(5-10MHz) and it is usually good enough. But when I want to > measure 100MHz the sensitivity of the mixer decreases a lot, so when I want > to measure some really low noise 100MHz(Pascall -178dBc floor with 18dBm > out) oscillators the sensitivity is not good enough. I read in an old > article by Walls, Stein et al(Design considerations in state-of-the-art > signal processing and phase noise measurement system) that one can use two > diodes in series in the double balanced mixer to increase the sensitivity. > I tried this with some standard 1n5711 Schottky and the sensitivity is now > 1V/rad, but is there a easier way to do this? /Anders > > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.