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Terminating a cable with a metallic braid


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The metalic braid you are refering to is the shield of the cable and is generally connected to earth or ground. If you are talking about a cable designed for audio then you can comb the strands out and twist them together. This and the centre conductor form an un-balanced cable. You terminate it in what ever way is required in the circuit.

Now, if the cable is an RF cable then it is a slightly different matter. The metalic braid is still a shield and is always connected to ground and is also an unbalanced cable. BUT, because of the frequency of the signal the impedence of the cable and any termination will affect the amount of signal that is passed (this is also true about the audio cable but is less critical). As such any termination must be very good and the use of specific connectors is required.

Also as I have called these unbalanced cables I guess I should explain what this is. An unbalanced cable implies that the 2 conductors are at different potentials and the shield is nearly always at gound potential. A balanced cable implies that the 2 conductors are balanced and at the same potential. Although a balanced cable doesn't have a shield they still do not radiate as much as one would expect. This is because the current flow in each conductor (when terminated in the cables characteristic impedence) is equal and opposite and tends to cancel the radiation.

WOW. Now that hurts the memory cells. I could go a lot deeper but I will avoid that for now.

More than willing to continue if anyone would like.

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