[time-nuts] Noise and non-linear behaviour of ferrite transformers

Chuck Harris cfharris at erols.com
Sun Jul 20 21:10:10 EDT 2014

I'm not sure what you are saying.

skin depth = (2.6/sqrt(fhz))inches for copper.

So, at 60Hz,   skin depth = 0.336 inches.
and at 100KHz, skin depth = 0.008 inches.
and at 1MHz,   skin depth = 0.0026 inches.

Are you saying that at 60Hz, because the
skin depth is deeper than the coax shield is
thick, that current passing through the outside
of the shield will induce voltage inside of
the shield, and that at say, 100KHz where the
skin depth is a little less than the shield
thickness, or at 1 MHz, where the skin depth
is only a small fraction of the thickness of
the shield that it won't?

Or something else?

-Chuck Harris

Bob Camp wrote:
> Hi
> The “coax is an antenna” problem comes in well before you get to DC. Even with no
> transformer involved, the skin depth of the coax shield gives up well above 60 Hz
> (and likely well above 100 KHz). If you want to do full isolation over a very wide
> range you need some combination of shielding and balanced lines.
> Bob

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