[time-nuts] HP 5061Cs reference question

paul swed paulswedb at gmail.com
Sat Dec 6 13:49:41 EST 2014


OK Tom
Some things for me to look at.
The Zeeman freq method never worked for me. I tried high and low drive and
several generators that are very accurate.
But will take a look.
Thanks

On Sat, Dec 6, 2014 at 1:18 PM, Tom Van Baak <tvb at leapsecond.com> wrote:

> > Now if the device was on one of those side peaks what would that make
> the offset at 5 MHz be?.
> > I think something like 1 Khz divided by 9192631770. I am sure 5 MHz
> comes into the calculation.
> > Pretty small. But may guess thats what I see. Its 44ns slow over 27
> minutes as of yesterday.
> > The systems been on 4 days.
>
> Paul,
>
> 40 kHz / 9192 MHz is 4e-6, so you're obviously not locked to one of the 6
> wrong peaks.
>
> 1 kHz / 9192 MHz is 1e-7, or 100 ns per second, so I don't think you're
> locked to one of the 2 side peaks either. A 1e-7 error translates to 0.5 Hz
> out of 5 MHz.
>
> 44 ns / 27 minutes time drift = 2.7e-11 frequency offset. Maybe all you
> need to do is adjust the C-field dial. As a quick test measure the 5061A
> output frequency at min C-field and max C-field to get an idea of your
> tuning range. HP used two different ranges on the 5061A. Or measure at each
> turn of the dial, as I did here:
> http://www.leapsecond.com/pages/hp-5065a-cfield/
>
> If you want, perform the Zeeman calibration as described in the 5061A
> manual. It says "an error of 1% in the Zeeman frequency causes an error of
> 3.6 parts in 10^12 in the 5 MHz output".
>
> /tvb
>
> ----- Original Message -----
> From: "Tom Van Baak" <tvb at LeapSecond.com>
> To: "Discussion of precise time and frequency measurement" <
> time-nuts at febo.com>
> Sent: Saturday, December 06, 2014 9:04 AM
> Subject: Re: [time-nuts] HP 5061Cs reference question
>
>
> Paul,
>
> There are 7 peaks total, about 40 kHz apart (on my 5061A). If you're
> talking about just the central peak, there are two smaller peaks on either
> side, about 1 kHz apart. The exact value depends on internal magnetic
> field, which is specific to each beam tube design.
>
> For some measurements of all the peaks, have a look at:
> http://leapsecond.com/pages/cspeak/
>
> You can play with the C-field in addition to playing with peaks:
> http://leapsecond.com/images/cfield.gif  (578 x 4610 pixels)
>
> For more details search the archives for the word Zeeman. For example:
> https://www.febo.com/pipermail/time-nuts/2005-April/018171.html
>
> A nice description from hp how a cesium beam standard works:
> http://leapsecond.com/museum/hp5062c/theory.htm
>
> /tvb
>
>
> ----- Original Message -----
> From: "paul swed" <paulswedb at gmail.com>
> To: "Time-nuts" <time-nuts at febo.com>
> Sent: Saturday, December 06, 2014 6:11 AM
> Subject: [time-nuts] HP 5061Cs reference question
>
>
> >I have a curious question that really applies to all Cs references.
> > Its possible to set them on to the wrong peak.
> > Typically in the literature it will speak to at least 3 peaks and you
> want
> > to select the highest central peak.
> > However if you select the wrong peak, how much would the output frequency
> > be off?
> > I had read a tech note for the airforce that seems to indicate its pretty
> > easy to get on to the wrong peak.
> > Regards
> > Paul
> > WB8TSL
>
>
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