[time-nuts] HP10811 vs 00105 OCXO

Tom Van Baak tvb at LeapSecond.com
Fri Aug 7 08:36:04 EDT 2015

Hi Luciano,

Thanks for that plot. In general an ADEV plots shows more succinctly the differences between oscillators than the raw phase and frequency plots that you posted earlier. The jitter and wander of your phase plots give a hint, but an ADEV plot neatly summarizes all this with statistics.

About the 00105 vs. 10811 -- it's nearly impossible to make solid claims about one vs. the other. Oscillators of the same make/model vary a lot. Oscillators that are 20 or 30 or 40 years old may not behave the same way they did when they left the manufacturing line. A ham fest or eBay buy adds its own special mystery, for better or worse.

The SC-cut 10811 warms up quickly. But that feature is irrelevant for a frequency standard that you power up once and then leave running the rest of your life. Low daily frequency drift is important, unless you use the oscillator as part of a 5065 or 5061 or GPSDO. Then even drift rate is irrelevant.

The simple answer is -- just measure it. Don't rely on the name or make or model. It may be an order of magnitude better than original spec. Or it might be an order of magnitude worse.

My dream would be to solicit a hundred ADEV plots of 00105 and 10811 from all time nuts and then make an informative plot or histogram. But still even that plot would not predict the performance of a random OCXO that you pick up from a ham fest.


----- Original Message ----- 
From: <timeok at timeok.it>
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Sent: Thursday, August 06, 2015 8:37 PM
Subject: Re: [time-nuts] HP10811 vs 00105 OCXO

here the ADEV of the two oscillator. I have added the Super performance of an HP105B (old oscillator) bought in an Ham fest.


On Fri 07/08/15 03:37 , Bob Camp <kb8tq at n1k.org> wrote:

> Hi
> HP 10811’s vary over almost a 100:1 range in terms of ADEV performance
> at short tau. The standard model is un-sealed so it has some issues
> with humidity when it is in storage for a long time. In both the case of
> the 10811 and the 105, their stability will improve as they are
> on power. In the case of long term storage, they both may continue to
> improve for more than a month.
> All of this makes any sort of comparison between the two models a bit
> difficult. About all you can say is that on a given day, this example of
> one
> was (or was not) more stable than that example of the other model.
> Bob
> > On Aug 6, 2015, at 5:03 AM, timeok at timeok.it wrote:
> >
> >
> >
> > Hi,
> >
> > I have done some measurement comparing two HP OCXO, the HP10811 and the
> 105.
> >
> > These two oscillator are mounted in the HP5065A rubidium Standard, the
> 105 in the old models, the 10811 in newer, and for this purpose they are
> selected units.
> >
> > I have two HP5065A use the different oscillators. For the stability test
> I have set the two 5065A in Open loop so the OCXO are free running .
> > I have done the measurements using as reference a third HP5065A in
> closed loop operation.
> >
> > Here the files show the frequency and phase difference.
> >
> > The 00105-6034 appear to be more stable as frequency than the 10811.
> >
> > comments?
> >
> >
> > Luciano

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