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Author Topic: 75/40M mobile ant for 4x4 desert offroading  (Read 394 times)
KG6VFN
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Posts: 5




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« on: June 09, 2004, 07:33:00 PM »

Who has experience with a decent 75 meter/40 meter HF mobile antenna sturdy enough for offroading? I offroad a lot in the Mojave desert in a Ford Ranger 4x4 truck, and am skeptical about the survivabiltiy of any screwdriver-style or bugcatcher-style antenna against hard heavy pounding.  Said antenna will probably be side-mounted, so it will also be swiped by shrub branches, the same as what makes 'desert pinstriping' paint scratches.

Hamsticks look indestructable but are poor radiators.  So what do you think?

Thanks,
Brian
KG6VFN
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AA4PB
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Posts: 12836




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« Reply #1 on: June 09, 2004, 10:34:57 PM »

I'd probably go with an antenna tuner and a military surplus whip and heavy duty insulator. I don't think the Hamstick will survive for very long with the treatment you propose to give it. The scraping will soon peal the outer coating exposing the wire to the elements and the constant whipping will soon cause the wire to break near the base.
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KG6VFN
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« Reply #2 on: June 11, 2004, 10:24:14 PM »

Thanks AA4PB!

To follow this train of thought, what do you think about fabing a mount welded to the truck frame to ensure a sturdy ground for one of those 16-foot or 32-foot surplus whips?

It makes me wonder though about height restrictions ...
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AA4PB
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« Reply #3 on: June 12, 2004, 08:52:58 AM »

I think the on-road height limit for most states is 13-feet. You can always pull it over with a tie-down for on-road use or have more than one whip available.

I recall seeing some antenna and mount info on some sites dedicated to off-road vehicles when doing some Internet searches a while back. It might have been some Hummer sites.

The key to running a whip and tuner is to locate the tuner very close to the base of the whip and connect it with a short (a few inches max) length of well insulated, unshielded wire. Especially on the lower bands you need to minimize the capacitance between the base of the whip and the metal vehicle. Mounting the whip higher up on the vehicle helps as well but you may have to compromise there.

Be sure to get a good RF ground connection between the tuner and the vehicle.

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VE3VBO
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Posts: 14




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« Reply #4 on: July 04, 2004, 04:30:06 PM »

Hi,

I too do a fair bit of off-roading (http://www.landroveradventure.com) and have been looking for something sturdy enough to take the punnishment.

I am using a Yaesu ATAS 120 on a Diamond K400 on the hatch of my Land Rover Discovery. As you might have guessed, the ATAS is way too fragile for off-road, so I take it off. No HF on the trail.

The only solution I have seen that seems to make sense is some of the stuff from Australia. They have an HF network called RFDS especially for 4x4 users in the outback. (General info here: http://www.exploroz.com/Feature/HFRadio/Default.asp)

An example of what's available can be seen at: http://www.web-counting.com/cgi-bin/outbacker/scan/fi=products/st=db/co=yes/sf=category/se=Outbacker%20HF%20Mobile/sf=prod_group/se=ANTENNA/va=banner_image=/va=banner_text=.html

Hope this helps.

Victor
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