On 24 Mar 2004 14:12:07 -0800, Patrick Gardella wrote:
I'm stumped on a problem I've been having with a Comet UHV-4 quad band
antenna (10m/6m/2m/70cm). It's mounted to a Comet CP-5M mobile mount
on my Saturn SL1. The problem I have is that I cannot get it to
tune. I figure that it's an insufficient RF ground. I've tried
running braid from a good ground location in the trunk to the mount
(good metal to metal contact on the "car" end of the braid). Still
nothing.

Those Saturn's are plastic panelled aren't they? There is 80% of your
answer right there! If I were you I would try to run a thick braid
directly to the car FRAME from your antenna ground point, as there is
probably little real metal in that trunk. The frame would connect all
large pieces of metal in your car to your antenna ground.

I would also do the same at the rig end, directly to the engine block
and firewall panel.


So I was wondering if there would be a way to tune the antenna off the
car. I was thinking of creating a ground plane with several 1/4
wavelength wires on each of the bands, and then adjusting the antenna
to bring it into tune. That way I would know if the ground braid I
put into the car is working well enough.

Tuning the antenna away from the car would only prove that the antenna
is tuneable, in the very unlikely chance there is something wrong with
it. That I doubt very much.

Patrick, I'm afraid that with that car, despite doing the above, that
you might never get as good a ground or signal as someone with a metal
panelled car. But then I have heard some good signals from mobile
antennas mounted to fiberglass recreational vehicles, so you never know!

Good luck with your efforts.

Larry Gagnon VE7EA

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