I did dig into this a bit more the other day and learned that the "main RF can" is the cesium oscillator module. The history there was pretty interesting! The

I did dig into this a bit more the other day and learned that the "main RF can" is the cesium oscillator module. The history there was pretty interesting! The early ones I found were the Symmetricom Quantum SA.45s[1,2] which included a pretty entertaining thread here[3]. There were several levels of quality and function in the family of products which have been discontinued in favor of the MAC-SA55[4], and I wish I could find where I saw that recommendation... It's a rubidium, instead of cesium oscillator, not that I know enough about these things to concluded one should be better than the other but my impression was cesium was higher precision. [1] https://www.gpsworld.com/wirelesstimingnewssymmetricom-offers-gps-disciplined-atomic-oscillator-modules-and-high-frequency/ https://www.gpsworld.com/wirelesstimingnewssymmetricom-offer... [2] https://www.si.edu/object/symmetricom-chip-scale-atomic-clock-csac%3Anmah_1419239 https://www.si.edu/object/symmetricom-chip-scale-atomic-cloc... [3] https://febo.com/pipermail/time-nuts_lists.febo.com/2021-January/thread.html#102605 https://febo.com/pipermail/time-nuts_lists.febo.com/2021-Jan... [4] https://www.microchip.com/en-us/product/mac-sa55 https://www.microchip.com/en-us/product/mac-sa55