Wayne Burdick, N6KR, of Elecraft let us know that there was an error in the QST article about the KSYN3A Synthesizer Upgrade. The original graph in the QST article showed an improvement in phase noise at close-in frequencies, but it also showed a significant worsening of the phase noise beyond 10 kHz. THIS CHART WAS INCORRECT. The Upgrade does, in fact, improve the phase noise performance as shown in the corrected graph above. A corrected version of the article appears here:
Pete and I will continue our study and discussion of phase noise; as synthesizers make their way into more and more of our hombrew rigs it is important for us to understand the significance of this parameter.