[time-nuts] Question for any HP105 owners

Paul A. Cianciolo paulc at snet.net
Tue Aug 30 15:24:08 UTC 2011


Is there an assumption that is normally made when referring to ADEV.

For example I looked at your image and see that you the chart begins at  .1
seconds, so I am assuming that the sample rate was .1 sec to acquire these
But Mark  does not specify a sample time in his ADEV number.

Right now after I am testing a Rakon double oven oscillator and I see the
Using a HP5370, z3801 reference for both the LO and the ref input on HP

Using .1 sec sample rate:

4.18 x 10 -11  @ 1sec
7.04 x 10 -12  @ 10 sec
1.11 x 10 -11 @  100  sec.

Using a 1 second sample rate

3.85 x 10 -11 @ 1sec
4.01 x 10 -12 @ 10 sec.
9.60 x 10 -13 @ 100 sec.

This oscillator has been running now for barely 20 hours.  The z3801a has
been running for about a year 

Am I doing something wrong?

Thank you

Paul A. Cianciolo
Our business computer network is  powered exclusively by solar and wind
Converting Photons to Electrons for over 20 years

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Tom Van Baak
Sent: Tuesday, August 30, 2011 2:09 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Question for any HP105 owners

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

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:
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


----- 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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