High SWR - Cobra 29LX w/ magnetic mount antenna

Nope, not down there, I wish but I am here in the great state of denial - Michigan.

I just know there is a HF there. Used to live off of 17 down by Charleston almost 27 years ago.

That's good.

That's where I think your problem is, I just checked a couple of mag mounts and peeled the rubbery thing away and they all conduct from the ground of the cable to the foil on the bottom.

The tool box doesn't matter at this point, but I know what Illillil (or what ever his handle is) said, I would still see about putting something that connects the foil to the ground side of the antenna.

 

I'm headed up that way. Going to visit my folks for a few days and help dad install AC in his '57 Buick.

I lived there for a long time... now I'm an outsider with my Alabama tag.

That's the way I figured it worked. I just wasn't willing to sacrifice mine for the team.

 

Are you absolutely positive that the top stud and bottom stud are not connected? And that the bottom stud is connected to the shielding?

Ground strap is available at any auto parts store.

 

Shielding is the metal braid that's just underneath the outer plastic jacket of the coax. It is connected electrically to the barrel nut that screws on to your radio and also to ground on the antenna end.

Below the shielding is a foam insulation material and then in the middle is your center conductor.

The center conductor carries the RF power to your antenna where it can be radiated into the air.

At no point should the center conductor and the shielding ever touch. It's like letting your positive battery cable touch the negative... sparks are going to fly.

A magnetic mount antenna does not have a physical connection to ground from the shielding. It's like putting two disks of metal very close to each other. It doesn't exactly happen like this, but if it helps you to conceptualize it, think of the electricity flowing from the shielding to the foil, jumping the gap from the foil plate in the base of the antenna, through a super thin layer of paint, to the body of your truck, back to the negative terminal of your battery.

What you are trying to do has a bunch of breaks in the circuit. The coax shielding is no longer connected to the foil. The electricity can't get through a gob of Rhino lining and the toolbox is electrically isolated from the truck.

Think of it this way, you're taking a trip to Key West, but a ferry and two of the bridges are out.

 

The bottom stud at the antenna end to the top stud... no beep on your meter.

The bottom stud to the barrel nut should beep.

The top stud to the center conductor should beep.

 

Try this, just to see what's what.

Take a peice of wire and short out those two studs. Then check the connector end just like rabbis image shows you, you should get a zero reading. If you don't then we may have an issue.