I too use the Z3801A. It's tied to a UPS and looks like it been on for almost 13 years now. Even back then I don't remember them selling for a whole lot. I have an antenna located in the attic of the house for it. Modified mine to use an internal supply and enabled the RS-232. I thought the 10MHz reference was was 10-9, so 1hz/GHz. Also thought this was not very good compared to what they had at the time.
Looking in the manual, "Frequency Accuracy: < 1 x 10-9, one day average" Certainly good enough for 1ppm.
Looking in the manual, "Frequency Accuracy: < 1 x 10-9, one day average"
We have smiled with this specification many times. But, they do not lie.
It is better.
Need also remember there was time when they change SA status in GPS system for civil use.
But some 3801 is much better than some other. Also depending if OWEN is drifted out from optimal temperature discipline or perhaps in manufacturing phase they have not done it perfectly for every individual XTALS)
It fun that some (old) Trimble (not Tb but model what looks like just as Z3801A
specify:
Frequency accuracy - <2E-12 one day average and <2E-10 any interval.
Perhaps Trimble NTPX26 what have also used years ago parallel with Z3801
(At this time I have 2x Z3801A and this Trimble NTPX26 and also Trimble Tb (with good OCXO)
And I need say I get best with Z3801A's
But Trimble Tb can be very good if environment temp do not change so much and parameters are carefully set for accurate frequency (default is more like fast find accurate time and this leads to more wide freq changes when it discipline. Discipline Parameters (and also receiver parameters depending local things) need find optimum for individual Trimble)