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Author Topic: AH-4 antenna tuner & Motorhome  (Read 413 times)
N7GCO
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Posts: 144




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« on: February 14, 2005, 09:32:25 PM »

I have a Icom 706 MKIIG & AH-4 antenna tuner mounted on my motorhome. The antenna and tuner are mounted on the front drivers side. The antenna is attached to a metal base stand that is then bolted to the fiberglass front end of the motorhome and stands about 12" away from the fiberglass front cap. Both the mount and the tuner are grounded to the motorhome frame. I use a 12 ft antenna.

I am not getting very good performance and wondered if the problem is that the antenna mount is not connected to the frame. Does the antenna base need to be attached to metal that is connected to the frame?

I actually get better coverage on my tow vehicle using a hustler antenna. Not sure what to try next to get better coverage.

Thanks
Mel
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AA4PB
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Posts: 12841




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« Reply #1 on: February 15, 2005, 05:27:18 AM »

Only the tuner needs to be grounded to the vehicle frame. The antenna actually begins at the connection to the tuner, regardless of what combination of whip length and feed wire length you have. That's why it is important not to have a long feed wire runing inside the vehicle or against metal.

The tuner ground needs to be a good RF ground. The ground wire needs to be as short as possible. A metal strap works best because RF tends to flow on the surface, so give it as much surface area as possible.

Performance tends to be better if you can mount the antenna higher up on the vehicle, away from the ground. Of course you can't always do that from a practical standpoint.
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N8BOA
Member

Posts: 90




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« Reply #2 on: February 17, 2005, 06:44:53 PM »

I have a 26 foot RV with a AH-4 and it works great....
I made 6 18" fiberglass rod stand-offs and placed them at each corner and two in the middle then run 14ga wire to make a 58' horizonal loop. (tunes 75m to 6m)I ground the "return" side of the loop to elimilate static. I also have a 33' fiberglas telliscoping rod when parked I open the loop and feed a wire going up the 33' rod giving me 91' feet end fed all of it on top of the Rv. Also I have four radials that plug into the frame of the RV same point that I ground the AH-4. I also lost my first AH-4 due to water making it's way in so I bought a NEMA 4x electrical fiberglass box to keep the water out..good tip.
P.Sean
N8BOA
 
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