Hi Mike, On 9/19/10, Mike Feher <mfe...@eozinc.com> wrote: > Frank - > > Great idea, so obvious I did not think of it. If you mix the 20 and 22 you > will only get 3 dB degradation or still very close to the -131 dBc/Hz > relative to the 10811A. As I mentioned before the architecture is relevant. > I have found that mixing does not cause any noticeable degradation, and I > used to go all the way up to 45 GHz on military programs where it was very > critical. At the frequencies you are talking about I doubt if the amplifiers > will have any appreciable degradation either. Of course you have to keep > levels in perspective, as you will not do better than kT. I also do not > believe that dividers will have much impact. After all, a DDS is a > divider/counter and accumulator, and PN is usually considered to be very > close to 20logN better at the output than the reference, however, DDS does > have spurious at most frequencies, but that is a discussion for another > time. I still think your original thought is your best approach. Fast, easy > and less than $100, even if you do use a used 10811A. 73 - Mike
this approach as I said has a lot of unkown to me, for example, how to divide by 5 (ttl or cmos or maybe synchronous or something else?), then there's the doubler (diodes? jfet?), then the mixers: need them to be diode mixers (a classic double balanced? can be homebrewed or better use ready-made?) or I can get away with something cheaper like fet mixer or something else? Finally the xtal filters, those need to be ordered, where? what exactly do I need as filter here in terms of poles or number of xtals? Not to mention I need to "reuse" many of the signals, this means a few isolation amplifiers with good isolation. After posing myself these questions I thought I might evaluate other approaches :-) Best regards Frank _______________________________________________ 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.