>Does anyone have actual measurements with and without the outer oven >controlled by a PID? see plot: <http://www.febo.com/pipermail/time-nuts/attachments/20100223/c94d5eec/attachment-0001.gif> on posting <http://www.febo.com/pipermail/time-nuts/2010-February/045279.html> > To avoid misunderstanding could you clarify which of those specifications > you can get 10 to 100+ better performance? a) Aging Rate spec <5e-10, easy to find ones that are 100 times better b) Temp TC for small changes, easy to find/Made them 100 times better with outer oven c) Load change 5e-10, easy to make them 500 + times better (add a good buffer) d) Allan at 1 sec, 5e-12, Not so easy, but you can find them >10 times better. ws ********************** Tom Van Baak tvb at LeapSecond.com >>Q) None of the hp/Agilent bench test equipment that uses these >>oscillators uses insulation. Perhaps that's a clue. > a) It is not much of a clue, considering that a patent & knowledgeable > time-nuter can get 10 to 100 + better performance out of them. The spec page for the 10811A is here: http://www.leapsecond.com/museum/10811a/10811a-spec.jpg To avoid misunderstanding could you clarify which of those specifications you can get 10 to 100+ better performance? > Look inside a HP Z3801 GPS. Right, that's why I wrote "bench test equipment". None of the hp test & measurement products use insulation around the 10811. The Z3801A is unique; that was a 1st generation telecom unit; the only piece of hp gear with a custom heat blanket wrapped around a stock OCXO. The outer oven was a hack so Z3801A could meet telecom cell tower cold weather warm-up specs. In other words, the better performance they were looking for in that case was warm-up time; not a tempco or frequency stability spec. The external blanket is reminiscent of the 115 VAC fast warmup heater in the vintage 00105 brick oscillators (a predecessor of the 10544 and 10811). But unlike the 00105 the Z3801A reportedly uses PID control on the blanket. For that reason I would expect that the outer shell could improve the tempco of the oscillator, but I haven't seen data on that. Does anyone have actual measurements? A long run with, and without, the outer oven circuit connected would tell the story nicely. /tvb

WarrenS wrote: > > a) Aging Rate spec <5e-10, easy to find ones that are 100 times better That is news to me, having looked at 100's of 10811's. > b) Temp TC for small changes, easy to find/Made them 100 times better with > outer oven I'm surprised, but haven't detailed knowledge. The outer oven was supposed to be good for 10X > d) Allan at 1 sec, 5e-12, Not so easy, but you can find them >10 times > better. Agreed. The measurement system for Allan wasn't all that great itself, so we never really knew how good they might get, but 5e-13 certainly was achieved by some units. Rick Karlquist N6RK