[TowerTalk] Mobile antenna for SUV

Bill Turner dezrat at copper.net
Sun Mar 25 18:21:43 EST 2007


ORIGINAL MESSAGE:

On Sun, 25 Mar 2007 03:02:56 -0400, "K8RI" <K8RI-on-TowerTalk at tm.net>
 wrote:

>Thing is, I don't know what to do about an HF antenna. 

------------ REPLY FOLLOWS ------------

A screwdriver type is good on most vehicles, but not if the coil has
to be near the vehicle's body, which it probably would on a SUV unless
you mount it on the front. If the XYL will tolerate a front mount, you
have an excellent XYL. :-)

My choice would be a roof mount right in the center of the vehicle and
to use Hamsticks. I know Hamsticks get a bad rap on 75 meters,
probably deserved, but I can testify they work well an 40 meters and
higher frequencies. On 20 meters and higher, they are as good as
anything short of a custom made bugcatcher. Install a quick disconnect
on each one and you're all set.

For the mount, I would use one of the triple magnet types such as that
made my Iron Horse. I have used one of those for years with a Hamstick
and never a problem. Hamsticks are about seven feet long, so unless
your SUV is exceedingly tall, you should be under the 13'6" height
limit, which I believe is standard in most states. Please correct me
on this if I'm wrong, someone.

One caution however: On 40 meters and lower frequencies the
capacitance of the mag mount to the roof may not be enough to achieve
a low SWR. Simply drill (ouch, I know) a tiny hole next to the mag
mount and run a short ground wire using a sheet metal screw. Problem
solved, and the hole is easily plugged when it's time to sell by
painting a screw the same color as the roof and driving it in. Nearly
invisible.

A Hamstick will not cover all of 40 meters without readjusting, but it
will cover all of 20, 15 and the lower part of 10. On 40 it's good for
about 60 kHz at a 2:1 SWR. They work well, give 'em a try.

Bill W6WRT


 


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