I give up....

Running different power wires won't change your SWR. Why do you like Wilson so well you won't use a antenna that works? I have about 5 or 6 Wilsons, but they wouldn't work well on a Freightliner no matter how long of shaft I used. So I went with as long of antenna as I could get by with that is also top loaded. Why do you ask for help than reject it? Trial and error is a good learning tool....unless you "give up", you'll figure it out eventually.

 

Need to urgently find an expert electronics technician the yellow pages would be a good start

 

To the original poster, I understand why you grounded the radio to the battery. BUT, grounding the antenna directly to the chassis or battery could have your antenna ground wire acting like another antenna.
.
.When your SWR reading on an external meter reads 3 or higher, that is an indication of a faulty antenna ground plane [some people refer to it as a counter poise]. What you need to do is interconnect the large metal portions of the truck into one large antenna ground plane. There are 2 options.
.Option 1 - What you do is called BONDING. It has nothing to do with grounding or electrical power. You do bonding by running short ground straps from the antenna mount to the door, door to the cab door frame and the cab to the chassis. These short straps interconnect the large metal components into one large antenna ground plane. Do not run one long strap from the antenna all the way to the chassis or battery.
.Option 2 - install a second antenna mount upside down next to your existing antenna mount so that the second antenna will be pointing to the ground. Mount an antenna, pointing to the ground, without the gasket. This will act as your antenna ground plane.
.
.Finally, I do not advise using 18 feet of coax unless you really need that length to connect the antenna to the radio. Excessive coax that is bundled in a small tight loop can cause problems. If you have a large excess of coax, form it into the shape of a figure 8 that is about 10-12 inches in length. Secure it with tape so that is maintains that figure 8 shape. Also keep in mind, the longer the length of coax the more signal loss you get.
.
.If someone tells you that you need 18 feet of coax because it is the half wave length of the CB frequency; just smile, say thank you for that and walk away. It is not worth your time to argue with someone that misinformed.

 

2009 freightliner classic here, cobra 29 with wilson 2000 having exactly the same problems you mentioned and I finally got my ground ran to the frame from the radio and the positive to the battery. Also, grounded the antenna bracket during my process of elimination. I had a feeling the factory positive was the problem and, of course, the last thing I changed was in fact the problem.

 

How does one get a .2 or .3 swr?

For those who don't know, swr isn't everything, you can have a high swr ratio and have a good setup.

 

Im not sure I agree with that statement, a high swr 2-3 will eventally make that CB a paperweight when it gets over heated.

if your not getting out on the CB either the ground is not good or the SWR is going the wrong way, adjustments are made in 1/8's good swr is 1.2-.1.5 on the meter. if you have a multi meter you can check your grounding.