[time-nuts] FE-5680 frequency jump

[Magnus Danielson]

On 04/06/2013 02:22 AM, EB4APL wrote:
> Thank you for the info, I used to attach a magnetic mount surface
> thermometer to my FRS-C to check its operating temperature after
> installing it in a box. I think it is time to power it up and after some
> days check it against the GPS.

Ehm. Rubidiums is tweaked by magnetic field adjustments, and you have 
my-metal shields to shield of ambient fields as they go in the wrong 
direction typically, change, etc.

Use the C-field EFC input and not magnets to tweak it...

Please keep magnets away!

Cheers,
Magnus

> Regards,
> Ignacio EB4APL
>
>
> On 05/04/2013 20:59, Bob Quenelle wrote:
>> I found the cause of the 4 mHz frequency jump. I have an LPRO-101, an
>> FE-5680, power supplies and a Motorola M12T GPS board in a surplus case.
>> When I put the case away to work on another project I piled the hockey
>> puck antenna and lead in the case and it happened to land on the
>> FE-5680. I noticed the antenna stuck firmly to the FE-5680 case when I
>> got the project back out. I found I could get a 6 mHz (0.6 ppb) shift
>> comparing the frequency with residual magnetism from the magnet stuck on
>> the FE-5680 case to the frequency after demagnetizing the FE-5680 case.
>> Unintentional C field adjustment. Dope slap, live and learn.
>> Bob
>>
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