Macom also do NLTL comb generators which are much quieter than SRDs: https://www.macom.com/products/product-detail/MLPNC-7100-SMA850
Bruce > On 16 May 2020 at 09:14 Gerhard Hoffmann <g...@hoffmann-hochfrequenz.de> > wrote: > > > No, no, no, it's not that bad :-) I should not post here in the middle > of the night. Sorry to cause that confusion. > > Minimum is -90 dBc @ 50 Hz, or let's say @100 Hz @ 10 GHz. > that would equal -110 dBc@1 GHz, or -130 dBc @100 MHz, BTDT. > > And then, the ~4 MHz difference between TX and RX frequency could be > done by a SSB mixer with a non-multiplied crystal. We would have some > common mode noise, but the RX-TX difference would be fairly constant. > It would not de-correlate over the 10 mm run length, not at low > offsets where it counts. > > The -110 was only meant for "Don't care about multiplied white noise > floor", not in the sense of a spec but in the sense of "guaranteed > harmless". It's not such a great relaxation after all, it could be > 20 dB looser. > > The question was really only about a _simple_ multiplier chain. The > style used in ham radio 10 GHz transverters has too many stages, > GaAS-Fets with 1/f and pipe cap filters. Too complicated. > > Macom still make a SRD diode, but probably it is easiest to phaselock > a ceramic puck or an on-chip VCO to a 100+ MHz crystal. The offset- > mixing removes the need for a low reference frequency or fractional > voodoo. > > cheers, Gerhard > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.