# [time-nuts] Cesium DOES Drift, not

Bill Hawkins bill at iaxs.net
Wed Apr 20 14:29:29 EDT 2005

```How about this:

Brooke is watching the last of his cesium evaporate.

Bill Hawkins

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
Behalf Of Brooke Clarke
Sent: Wednesday, April 20, 2005 11:33 AM
To: Discussion of precise time and frequency measurement;
richard at karlquist.com
Subject: Re: [time-nuts] Cesium DOES Drift, not

Hi Rick:

I agree.

It's just that my FTS4060 IS drifting.
The Excel equation and fit for a month of data as of this morning are:
y = -1.2954x2 + 243.1x - 10631
R2 = 0.9607
Where y is in ns, x is the Day of Year and R2 is the quality of the fit
(very good).

The first derivative (after dividing by 86400) gives:
Offset = -3E-14 * X + 243
i.e. minus 3E-14 per day.

I'll keep watching and post from time to time, maybe this will stabilize???

Have Fun,

Brooke Clarke, N6GCE

--
w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com

Richard (Rick) Karlquist (N6RK) wrote:

>My understanding from talking to the experts is
>that no aging, or environmental effects are observable
>on the 5071A, and measurements have been made into
>the 10^-15 range.  Also, no systematic frequency offset
>has been observed down to at least 1x10^-14.  IE,
>frequency offset between different 5071A's is randomly
>distributed with a mean within 10-14 of laboratory
>standards, such as Cs fountains.  Knowing the way we
>overdesigned the 5071A, I am not surprised that it
>is this good.
>
>Rick Karlquist
>(member of 5071A design team)
>
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>time-nuts at febo.com
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