Chris wrote:
I have always wondered why we build our "standard" with such a low frequency. Why not a 100MHz GPSDO? Why 10MHz
Quartz crystals work better at lower frequencies, predominantly because they have higher Q. 10MHz was chosen because it is low enough for excellent performance but high enough to be directly useful (since an accident of biology gave us ten fingers, we've created a base-10 world and powers of 10 are favored in almost everything).
In prior times, 5MHz crystals held this position, and before that, 1MHz. There is a good argument even today that the best 2.5MHz or 5MHz crystals are better than the best 10MHz crystals, but not by enough to make 2.5MHz or 5MHz standards popular any longer.
One lonely data point, which proves nothing: My best crystal oscillator is a Symmetricom clone of the double-oven HP 10811s (it came out of an HP GPSDO, so apparently HP at one time used them interchangeably with the 10811). That OCXO uses a 5MHz crystal and a frequency doubler to produce its 10MHz output.
Best Regards, Charles _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
