TS450S.4 If it is a ribbon cable, it will be very difficult to tap into it. You can lift one end of choke L106 instead, and run wires from the lead and the empty hole to the switch. You can snake the wires out through a hole in the cabinet somewhere, or you could mount the switch on the rear panel immediately behind the antenna tuner. (I was told that it contains a small, replaceable piece of metal.) Remember, close the switch for MARS operation immediately above 4.000 MHz, and leave it open for all other operation. Disclaimer: Perform this modification at your own risk, and be aware that it may void the warranty on the radio. (To the best of my knowledge, Kenwood does not currently authorize this modification.) I assume no responsibility for any consequences of performing the mod, although I do know of one case in which it was done and operation was satisfactory. --WA8MCQ, 29 May 1993