67 a comprises a layer of shielding material 35 as described above that covers but is not in contact with the conductor portions 75 located between the adjacent segments of electrical wire 25 u2032 and a capacitor 70 provided between each such conductor 75 and the layer of shielding material 35 in addition in the shielded rf choke 67 a an inductor 33 is provided between each conductor 75 and the segment of electrical wire 25 u2032 that is electrically upstream in terms of current flow from the point at which the capacitor 70 is connected to the conductor 75 in the embodiment shown in fig9 a the capacitors 70 are tuned the electrical lead 65 b shown in fig9 b is similar to the electrical lead 65 a except that in the electrical lead 65 b an inductor 33 is provided between each conductor 75 and the segment of electrical wire 25 u2032 that is electrically downstream in terms of current flow from the point at which the capacitor 70 is connected to the conductor 75 in the electrical lead 65 b the capacitors 70 are short at relatively high frequencies on the order of 100 mhz and therefore no signal is transmitted by the electrical lead 65 b and therefore no signal is provided to the location 20 such.