Vern, I suggest using some of the practices I employed in several control and repeater stations I have installed on the Pacific Coast, subject to corrosive salt air and runoff. First off, use genuine Military Specification RG-214/U silver-plated coaxial cable, and not any ersatz cable that has the word "type" in its identification. Second, use only silver-plated type N connectors with gold-plated center pins. Crimp connectors made by RF Industries are very good, when installed with the proper tools. Waterproof all connectors with self-vulcanizing rubber splicing tape, with an over-wrap of Scotch Super 88 plastic tape.
To prevent the cable from whipping back and forth inside the mast, use spacers that support the cable at regular intervals. Use marine cable entry ports that seal around the cable, wherever the cable passes from a wet to a dry environment. Make certain that the antenna base is solidly connected to the mast, and that the mast is properly grounded for lightning protection. A surge arrestor should be placed at the radio, to protect it from lightning surges. Needless to say, a boat with a metal mast tends to attract lightning, so all radio equipment should be protected. 73, Eric Lemmon WB6FLY -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Vernon Densler Sent: Tuesday, November 24, 2009 8:18 AM To: [email protected] Subject: [Repeater-Builder] Best coax for marine use I have been in a big discussion with the guys on my boat list about the right coax for running up the mast for VHF marine radio. Keeping in mind that we are talking about a 70' or so run going up the center of an aluminum mast, in a salt water environment, and the radio is limited to 25 watts. Also keep in mind that when off shore this is a life line and the best possible send and receive is needed in an emergency situation. So given the criteria what is the best possible coax to use knowing that thickness matters and bend radiuses may be tight? Others on the list are saying "just grab any old 8X type cable and you will be fine". I say use something with very low loss and suggested small heliax. Any suggestions? Vern s/v Nirvelli KI4ONW
