[Elecraft] Re: magnetic fields and phase noise?

[Stephen W. Kercel]

I've seen several mentions of mu metal in this discussion. I offer a few 
thoughts for what they are worth.

Some years back, when I worked in the Electromagnetic Compatibility Group 
at Oak Ridge National Laboratory, we occasionally used mu-metal. The idea 
is that it directly suppresses magnetic field independent of electric 
field, and is thus supposed to be an effective shield for near-field 
situations where the constrained relationship between the electric and 
magnetic field breaks down. (Magnetic shielding of propagating waves is not 
a problem; kill off the electric field, and the magnetic field vanishes for 
free.)

Mu metal is expensive, difficult to find, hard to work with if you can find 
it, and if subjected to mechanical shock, it can lose its mu-ness.

Personally, I would only use it as a last desperate measure.

73,

Steve Kercel
AA4AK



At 01:54 PM 3/20/2005 -0500, you wrote:
>Earl W Cunningham wrote:
>
>>It has been suggested that mu-metal shielding might alleviate the
>>problem.  I'm considering making mu-metal bottom and side covers for my
>>K2.
>
>If I were having that problem, I'd be thinking about shielding the 
>*source*...because it would likely affect other equipment in my shack.
>
>  73 de Maggie K3XS