Tag changed to EE.  This is certainly more appropriate than the source code
control drivel we have been enduring on EE in the last day.


Manu Abraham wrote:
> Ah, yes. true. They are not simply there to avoid dangling and
> vandalism.

Actually that was a joke in the first place.  When Russell was wondering wh=
y
there were coils, I thought he meant as apposed to the cable being cut
shorter.  My answer implying the alternative was to let the cables dangle
was meant to be funny.  Jokes suck when you have to explain them.

As for what they are there for, we don't know just by looking at the
picture.  That only tells us there are coils.  We can only guess why.  It
could be something as mundane as the installation wasn't finished and they
left coils up there to continue the next day.  At best we can come up with
reasons that leaving coils might be beneficial.

In any case, coax cable is sometimes deliberately coiled to make a balun or
common mode choke.  The differential mode currents, which is what carries
the wanted signals, are equal and opposite and therefore don't cause any
magnetic field outside the coax.  To them, the coil is just a longer length
of coax and doesn't matter whether it is straight or coiled.  The common
mode signals however flow in the same direction.  They add to form a
magnetic field, which is another way of saying there is a inductor there.
This inductance will attenuate the common mode signals.


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