[time-nuts] FE-5680 frequency jump

[Don Latham]

Actually, mumetal easily loses permeability, hence shielding ability, 
by mechanical stress or heat. Some mumetals are made to bend for boxes
and the like, sheets available from electronics goldmine, I think.
Ed Palmer
> There's something in the back of my mind that MuMetal is easily
> magnetized.  If that's true, and if the FRS-C and/or FE-5680 cases are
> made of MuMetal (seems like a good chance), they should be demagnetized
> anytime they come in contact with a magnet.
>
> Ed
>
> On 4/5/2013 6:22 PM, 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.
>>
>> 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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-- 
"Neither the voice of authority nor the weight of reason and argument
are as significant as experiment, for thence comes quiet to the mind."
De Erroribus Medicorum, R. Bacon, 13th century.
"If you don't know what it is, don't poke it."
Ghost in the Shell


Dr. Don Latham AJ7LL
Six Mile Systems LLP
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