Comments have been that the Shortt clock is not a phase locked loop because of the infrequent checking but if you were to cast your mind back to the early days of PLLs in VHF rigs, typically the 145MHz signal was crystal mixed down to a few hundred kHz before being phase checked, and you can't get more infrequent than 1 in 1000, which is really slow compared to the 1 in 30 check rate of the Shortt clock!
- posted
6 years ago