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Author Topic: Antenna feed wire: Length important?  (Read 400 times)
KC0LPV
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« on: September 06, 2003, 10:52:18 PM »


Just finished installing a radio in my car, and while I was putting things together I cut the coax to about the length I needed plus a foot or two.  Total length probably comes out to five feet.

A more experienced ham in the area said that the mobile antenna connectors usually come with about 17 feet of coax, and that there is some special reason why it should be that length.  Unfortunately, I didn't talk with him until after I had done the install.

My SWR checks out.  So, do I need to extend my coax back out to the full length and just coil up the excess, or am I okay as is?

Thanks,

Jim
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AA4PB
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Posts: 12905




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« Reply #1 on: September 07, 2003, 09:01:06 AM »

It's an "old ham's tale".  Unless your antenna is not close to 50 ohms and you are trying to use a length of coax for impedance transformation, there is no special length for the coax run. Even if you did use it for impedance transformation, it would have to be a different length for different bands. Use whatever it takes to reach the rig.
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KA5S
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Posts: 229




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« Reply #2 on: September 19, 2003, 01:31:08 PM »

Manufactured antenna mounts come with a long enough coax to fit most cars. That is the only significance of "17" foot feedlines.


Cortland

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