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VHF to close to antenna?

Old 04-21-2008, 10:11 AM
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Default VHF to close to antenna?

Mounted a VHF on a small center console, not a lot of room. Ended up mounting it pretty close to the antenna (long white Shakespeare, not the small metal whip). VHF manual says to mount the unit at least 3 feet from antenna, but I just don't have the space for that. Why does it need to be three feet away? Interference?

Appreciate any advice.


Joe
Old 04-21-2008, 05:43 PM
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Default Re: VHF to close to antenna?

you shouldn't have any problems
Old 04-21-2008, 09:43 PM
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Default Re: VHF to close to antenna?

I have the same issue with having the radio and antenna mounted very close. I left about 6 feet of cable, and ignored every warning and coiled it up in a nice neat bundle under the console. It looked real pretty, but my radio performance sucked. I uncoiled the cable, and made a couple big loops around the inside of the console, but reversed the loop every turn so I never ended up with a circle (how do I describe this, kind of like reverse figure 8's.)

Solved my problem and have had good performance since, coiling the cable creates an rf choke, imparing your signal.
Old 04-22-2008, 06:33 AM
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Default Re: VHF to close to antenna?

Thanks guys, I appreciate it.
Old 04-23-2008, 05:49 AM
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Default Re: VHF to close to antenna?

Jim_Arndt - 4/21/2008 9:43 PM

...coiling the cable creates an rf choke, imparing your signal.
Nonsense. On a coaxial transmission line the radio frequency signals flowing inside the transmission line cannot tell if it is coiled or not. Only radio frequency signals flowing on the outside of the transmission line are affected by coiling. Coiling the transmission line is a good practice to prevent the flow of RF current on the outside of the line, which is not desirable.

The recommendation to separate the transmitter from its antenna by several feet is to prevent RF feedback during transmission.

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