Johnny WATT,
I designed / built medical instrumentation, once upon a time,
and one device picked up A.M. radio stations.
I could tune between three stations by adjusting the grounding / shielding,
by altering the capacitance and inductance accumulating in these sub-systems.
For the video coax,
the Video signal itself tops out at 4 MHz,
and the channel 4 band is about 60 MHz.
So, a high pass filter (capacitive) looks good for the video signal.
Faraday shielding grounded at one end (Capacitive mode) helps.
Pi-network filtering is good (in hi-pass mode).
Ferrite Cores are Not recommended (Inductive Impedance).
Xl = (2 pi F L ) and
Xc = 1 / ( 2 pi F C ) I think,
so do not add inductance in the video system.
Or so my memory goes.
To relate that to the usual Electrician's experience,
recall that a GEC passed through metal conduit
must be grounded at BOTH ends. :smile:
This is the Faraday shield in "Capacitive Mode",
which allows the High Frequency Lightning pulse
to pass through to the earth ground,
which is Lightnings reference back up to the clouds (like a big capacitor).
If, forbid it, you connect only the top end of the metal conduit
(to the Meter Box), and NOT the Ground ROD,
then you have setup a Faraday shield in "Inductive Mode",
which will inhibit the High Frequency Lightning pulse,
and push the pulse throughout the residence wiring.
This inhibition is also called 'choking', 'quenching', 'clamping',
and is the same as passing the GEC through a ferrite core (toroid).
The inductance of this single ended connection
will soak up the Lightning pulse to build its magnetic field,
thus inhibiting the Lightning pulse from traveling down to the earth ground, which is Lightnings reference back up to the clouds (like a big capacitor).
Hope that helps.
Gar can probably do a better job at this.
