I used a through deck connector with a 90 degree connector on the inside. When the mast is down there is a cap that goes on both connectors. Ran the wire down the compresion post along with the other one already there and through the floor pan. I used the same sort of connector from BoatUS it was about a quarter of an inch longer. ANCOR MARINE PL-258 Coax Connector -Dbl Female Allows two PL-259 connectors to be connected. WM Model #: 110148 Manuf. Part #: 99M 200258

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This is the one I used. Info is from the West Marine website. Replaced mine three years ago and have not had to mess with it since.AQUA-SIGNAL 80100-7 315168 Only $28.99 These 5-pole plug connectors are watertight (double sealed by O-rings) and made of impact-resistant, glass- reinforced polycarbonate. Horizontal mounting minimizes interference with sheets, sails, etc. Wire-inlet size 3/8