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Author Topic: HF Install in Rental Car  (Read 1045 times)
AA8RF
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Posts: 67




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« on: September 16, 2003, 10:56:17 PM »

I have an IC-706MKIIG and a screwdriver antenna. I end up with rental cars for 5 days to two weeks and would like to do some HF. Any suggestions on install shortcuts that are still reasonable?

One I have considered is using my Diamond K400 trunk lip mount (holds a small screwdriver surprisingly well!) and clipping a good braided ground lead from the mount down under the car to the front bumper as a quick but possibly effective counterpoise.

Another is renting large GM cars with the battery under the back seat (just lift the cushion) for easy, short battery connections.

Any other ideas?

-Jim
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K0BG
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Posts: 9868


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« Reply #1 on: September 17, 2003, 09:35:43 AM »

With some fear of sounding negative, forget about it. Here is why:

First, there is a great difference between DC ground and groundplane. In basic terms, proper matching requires the former, effeciency requires the latter.

Secondly, ANY temporary installation is an accident waiting to happen. Using magnets, velcro, bungie cords and the like to attached rigs and antennas to vehicles is a dangerous practice enjoyed by many, but for all the wrong reasons.

Lastly, you have no control over the ignition and/or electrical noise, and there is no temporary fix for these types of problems.

Instead, use a handheld and enjoy VHF.

Alan, KØBG
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AA4PB
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Posts: 12857




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« Reply #2 on: September 18, 2003, 11:09:41 AM »

I tend to agree with Alan. Quick install mobile on HF is a tall order, especially on the lower bands. You might consider a "portable" operation from the car (i.e. not in motion). For example, you could use a portable dipole such as the buddypole that could be set on a mast or attached temporarily to the car. I've had good luck on 40M using a pair of Hustler resonators and a custom made "break-down" dipole assembly. I used a small magnet mount to attach it to lamp poles, etc. Even worked great with 5 watts.
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KA5S
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Posts: 229




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« Reply #3 on: September 19, 2003, 01:25:58 PM »

I've used a Bug Catcher coil on a 5 inch mag-mount, with an AT-271A folding military whip. I used a clip lead to select the number of turns needed for resonance. By mounting on the trunk, it was mostly out of the wind and didn't blow over. I ran coax through the back door closure (find a spot that doesn't pinch it). The mount itself I grounded with a piece of braid and an alligator clip to a trunk hinge attaching bolt. You could get a better ground with under the bolt. **This ground is required**. If you use a trunk lip mount the retaining setcrews may make one for you - though possibly not quite as good as grounding to the car's body.

An IC706 requires rather high current, so with that rig I put crocodile clips on a power cord, and ran it from the battery past the hood closure and through the front door closure (same as coax, make sure it does not pinch) inside the car to the rig. Fuses are at the battery end!

The rig grounded with an alligator clip. A cigar lighter plug is enough with an FT817 and probably with an FT897 at 20 watts.

Audio is often a problem.  A small mobile speaker of the 2 inch cube type can be stuck behind the driver's ehard under the headrest, or clipped onto the visor.

By the way, AT-271's, while convenient to pack and for portable use, aren't really suitable for mobiles, as the mating sections deform with wind and vibration. I'd suggest instead a thin stainless whip such as the one Superantennas sells with its mobile kit; it can pack curved inside a checked suitcase.

Cortland
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WM8R
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Posts: 3




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« Reply #4 on: September 30, 2003, 05:59:33 PM »

IN 1996 I installed a temporary HF and VHF/UHF station in  rented Ford Expedition.  The HF rig was a DX70 and the dual band was an FT5100.  I mounted an SG230 tuner in a metal box, attached a marine antenna mount for the HF antenna fed by the tuner.  I also attached NMO mount 6 meter and 2 meter/440 MHz antennas to the box.  The box mounted to the roof with 4 large magnets and was also securred with a strap across the luggage rack.  The abox monted towards the rear of the roof, allowing me to run a 1 foot braid into the tailgate where I attached it under the plastic trim after scraping the paint a little.  Power connections were taken directly from the battery.

It worked great, nothing like an 8-foot antenna on top of a 7-foot vehicle.  We drove from SLC Utah to Seattle, then over to Spokane, into British Columbia and over to Alberta, down to Glacier Nat'l Park and back to SLC to fly back to Cincinnati.

Mark WM8R
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WM8R
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Posts: 3




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« Reply #5 on: September 30, 2003, 06:02:22 PM »

One additional note to my previous: the bottom cover of the box held the radios in their original brackets and this cover was strapped to the front of the seat and the trans. hump with a small ratchet strap.
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AA8RF
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Posts: 67




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« Reply #6 on: October 10, 2003, 10:59:35 PM »

I knew after we got past the comments about how it wouldn't work, someone would have some good ideas. Thanks!

-Jim
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