For the low noise nuts, here are some modern techniques . At the moment I am looking at 1/f noise , or better how to keep it low. I am supervision an dissertation on this topic and I am happy to get some input. 73 de Ulrich U. L. Rohde and A. K. Poddar, “Method Minimizes Noise in VCXOs”, Microwave & RF, Nov 2011. U. L. Rohde and A. K. Poddar, “Techniques Minimize the Phase Noise in Crystal Oscillators”, 2012 IEEE FCS, pp. 01-07, May 2012 U. L. Rohde and A. K. Poddar, “'Electromagnetic Interference and Start-up Dynamics in High Frequency Crystal Oscillator Circuits,”, 2010 IEEE International Frequency Control Symposium, June 01-04, 2010, California, USA. U. L. Rohde and A. K. Poddar, “Impact of Radiated EMI in High Frequency Crystal Oscillator”, IEEE MTT-S Digest, May 2010. In a message dated 12/3/2014 4:38:04 P.M. Eastern Standard Time, paulswedb@gmail.com writes: What a pleasant surprise to see Ulrich post on Time-nuts. We spoke many years ago on radio on as I recall an opening on 2 meters FM. I have to agree with Azelio for many of us it is the other way around. We would learn as we do from many of the other excellent Time-nuts mentors. Best regards Ulrich Paul WB8TSL