[time-nuts] Question for any HP105 owners

Mark Spencer mspencer12345 at yahoo.ca
Tue Aug 30 11:00:03 EDT 2011

Thanks Tom, the reference oscilator is a Datum FTS 1050.  I've used both a HP 5370B and my Tek 2252 scope as time interval counter and looked at the data files with Plotter and Time Lab.  The results are all more or less the same for ADEV at 100 seconds.

With regards to the sqrt(2) removal I'm not familiar with that phrase but the measurements I was making were for ADEV.  Using Plotter I also removed the small ammount of drift but the ADEV values didn't change much.

My HP105B has the older style (non 10811) oscilator.   It does out perform all the 10811's that I own (especially with regards to longer term stability.)  

Mark Spencer

--- On Tue, 8/30/11, Tom Van Baak <tvb at LeapSecond.com> wrote:

> From: Tom Van Baak <tvb at LeapSecond.com>
> Subject: Re: [time-nuts] Question for any HP105 owners
> To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
> Received: Tuesday, August 30, 2011, 2:09 AM
> Hi Mark,
> What reference oscillator and measurement system did you
> use?
> Is that with or without a sqrt(2) removed? Is your HP105
> the older
> style with the 00105 brick oscillator or a newer one?
> The modern HP105 is essentially a well engineered wrapper
> around
> a 10811 oscillator so the performance you see will be that
> of the
> 10811. Your 3e-12 measurement beats the spec for a 10811
> (1e-11
> at tau 100 s) by a wide margin.
> It is possible that the 10811 used in HP105 met some higher
> spec
> or were hand selected. I don't know. Perhaps someone from
> HP
> (Rick?) could clarify this for us. We do know there are a
> number
> of different grades of 10811.
> One lesson you learn if you test many 10811 is that they
> can vary
> by quite a lot (an order of magnitude or more), even those
> with the
> same part number in the same instrument model.
> For example, see the tau 100 second point of a dozen
> 10811's:
> http://leapsecond.com/pages/z3801a-osc/z3801a-13-adev-m.gif
> Notice they all are under the 1e-11 at 100s spec, but some
> are
> much better than others. It's the luck of the draw. And one
> reason
> why some of us troll eBay for old or cheap 10811 hoping to
> find
> one that's better than the previous best.
> /tvb
> ----- Original Message ----- From: "Mark Spencer" <mspencer12345 at yahoo.ca>
> To: <time-nuts at febo.com>
> Sent: Saturday, August 27, 2011 4:53 PM
> Subject: [time-nuts] Question for any HP105 owners
> > Just curious what a typical ADEV figure is for the
> HP105 ?  Mine seems to be approx 3X10-12 at 100
> seconds.  Just curious what results any other HP105
> owners have seen in practice.
> > 
> > Thanks in advance
> > Mark VE7AFZ
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