You're right Matt. The basic PN performance of the LO chain in the IC-7800 is not too good. Measurememnts of the IMDR confirm this. So I personally think looking for a lower phase noise OCXO would be a fruitless exercise. It would be far more valuable to figure out what features of the design of the 7800 contribute to the problem. The IC7800 is a 'strong' receiver in terms of IP3 and IP2 - one of the best in ham terms, but I am not sure that without drastic internal surgery you are going to do any better.
Of course, if someone would like to send me an IC7800 I would be happy to experiment on it! John At 01:19 PM 7/7/2006, Matt Ettus wrote: > > > > Does anyone have any suggestions as a replacement OCXO with excellent phase > > noise approaching -160 dBc @ 1 kHz? Are there any special precautions or > > other alignments required when dropping in a replacement OCXO? Thanks! > > > >Paul, > >It is very likely that the close-in phase noise of the ICOM is >determined more by the dividers in the PLL than by the phase noise of >the reference oscillator, especially at such low levels. Assuming >that the ICOM divides the 10 MHz down to at least 100 kHz, the phase >noise of the OCXO would be divided down to -200 dBc, which is well >below the internal divider noise of the PLL. Thus even an OCXO with >absolutely no phase noise would not improve things. > >Matt > >_______________________________________________ >time-nuts mailing list >[email protected] >https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
