FTS 1050A OCXOI have an FTS 1050A quartz oscillator that is better, except for one parameter, than any other quartz unit I've seen. I don't have the capacity (yet) to absolutely measure its short term performance, but by comparing it to several other oscillators, I can determine a worst-case performance curve (see my short term comparison page for further details):
The one place where this standard falls down is in phase noise performance. While it exceeds its published specification of -116 dBc/Hz at 1 Hertz offset, its floor is only around -140 dbC/Hz, and its noise at spacings closer than 1 Hertz also seems high:
There is clearly something wrong, since the published noise floor is -160dBc. Given how quickly the floor is reached (at only 10 Hz), it looks to me like there's a broadband noise that extends from the carrier all the way out; 10 Hz is the place where the normal noise curve meets this other noise source.
However, this standard has such superb stability that I don't want to mess with it and possibly break something else. So, I'm going to live with the phase noise.