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Old 05-14-2010, 08:09 PM   #1
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Default Antenna Extension question

I want to add an extension to my VHF Antenna to see if I can get better reception. To do this, I'll need to cut off the PL259 connector, rethread the coax, and put a new connector back on. Will doing this (effectively shortening the cable) affect the performance of the antenna? Is there any additional tuning (i.e. SWR on a CB) I'll need to verify?

Thanks for any advice

b
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Old 05-15-2010, 04:09 AM   #2
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You can. Is it adviseable? Yes, and no. Every additional foot of RG-58/U cable, along with the necessary connectors, will result in transmitted signal loss. Unless you are going to increase the height of the antenna significantly, you may gain nothing.
You will need: a PL-259 connector, with UG-58 inserts, to re-install on your antenna cable once you get it in place, a PL-258 "barrel" connector, and two more PL-259 conenctors for the extension cable. Use ONLY the shortest amount of cable needed for the extension. And, make sure it is a good quality RG-58 cable. RG-59, the type commonly used for cable TV runs, is a different impedence and will also result in loss. If you are not comfortable with soldering the connectors in place (I advise against using the crimp type connectors), find a ham radio operator in your area. He'll likely be more than happy to assist, as long as you do all the "leg work" and manual labor. He can also look at your boat and wil likely be able to tell you if the extra height you are gaining will offset the loss of the longer cable and connectors. Every foot of cable AND the addition of three connectors (two PL-259's and the PL-258) have losses.
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Old 05-15-2010, 06:50 AM   #3
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Antenna height is the most important factor in getting better range. The loss of using additional cable and connectors is insignificant. I would suggest male and female BNC connectors or Mini-UHF connectors. Easier to install, much lower profile, no need for a barrel adapter. If you go with PL259,s. the reducing adapter for RG58 is a UG/175 and for RG8X it's a UG/176. Installed properly and with the proper crimp tool, crimp connectors are just as good as soldered ones.

Eric

Last edited by fairbank56; 05-15-2010 at 08:14 AM.
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Old 05-15-2010, 02:55 PM   #4
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Thanks for the hints!

I actually have plenty of original coax to add the antenna extension without adding additional cable. Right now I'm using a base loaded 3' shakespeare antenna. it' about 3 feet from my radio, and directly behind my right shoulder as I'm at the helm. Adding a 2' extension will get the load of the antenna over the windshield and my head, and still allow me to get my cover on the boat when I trailer it. I've only got a 19' runabout and run in rivers and lakes in the midwest. I use my radio to check with the tows on which side they want me to pass, and to get a hold of my fellow boaters. As a result, I'm rarely on high power, but I'm betting that getting the antenna above all the rest of the crap (me included) in the boat will get clearer reception.
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Old 05-17-2010, 06:53 AM   #5
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You can shorten the cable as long as it's still three feet or more in length. The shorter the cable (up to that point), the less loss in the cable. You don't have to tune anything but you do have to know how to attach the PL 59 plug correctly.

Moving the antenna away from your head is good for your health.
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