CB ground & cobra 29 LX questions.

Iv only been driving a tractor trailer about 6 months on my own, when I was with my mentor his cb & some drivers saved me from locking my brakes if not crashing when I came over a hill going 68 mph fully loaded to cars at a dead stop about 100-150 yards once I could have even reacted. A lot of new drivers don't really use them, but that definitely stuck with me. So about a month ago I got the cobra 29 LX with the LCD screen... I'm normally good with most electronics's but these things threw me for a whole new loop. How they work, how radio waves work, all the buttons, & knobs how you could fry the thing if your not careful. Any how I got that package at the TA with a 4ft fiberglass antenna with the small mounting bracket and a 9ft coax cord, I used the spot where the curb mirror use to bolt on top of the passenger door, and made a bracket so that's where it is now leaning slightly forward. Now about the grounding, I understand when you bolt this thing on to your steel truck, it grounds it, like how your car battery grounds to the block or the body of your car?, but is there a way to assure it's grounded, as like maybe running and actual ground wire from a ground to the the antenna it's self somewhere to be 100% that it's getting a ground? my mounting bracket is over paint, but where the bolts go in are threaded studs in the door its self, also iv heard if the SWR is higher on one it's too short, higher on 40 it's too long correct? So when I hold the PTT channels 1- 20- 40 all sit on the 3rd smallest calibration line (in SWR mode), if I had to guess I'd be like .3 or .4 but now I'm confused does the antenna need to go up, or down?? Or could it be coax cord problems, ground problems? When you hold down the PTT the SWR if it's tuned correctly should jump to CAL I believe? I got it to 3.0 one time, that's as close as iv got? I know I could pay to get it done at a cb shop somewhere but I'd like to see if I can figure it out with yalls help , so I would be able to do it again if need be, and understand it a little more. Sorry for all the rookie questions I got haha, I'm sure yall hear the same ones all the time. Any help at all I appreciate though

 

Okay thanks for that, I didn't know the swr was so sensitive, that even changing the channel could make it act different. I have watched a lot of videos on this. What iv seen no one really has a video of some one taking this exact cb and mounting an antenna and then going to the cb and tweaking it to match and showing how the two meters are acting when tuned correctly. There all showing you how to calibrating the swr with the swr knob, I get that part, but then I'm like okay so what else did he do too everything else to do that, when I check the swr on 1&40 they are both on 2.5 when holding down the PTT. My coax cord is a problem the way I have it too probably. Iv got it going under the weather striping, which iv hear is probably not good. That's just temporary till I get home, but do you have any solutions or experience going to a freightliner cascadia door, the antenna is mounted where the "curb mirror" what I call the mirror that use to hang off the top side off the passenger door looking down at the line of travel on your passenger side. & Iv got about 2 extra feet of hanging coax that would have to go somewhere. I probably do need to go to a cb shop, and let him do it the first time and just have a list of questions, so if I decide to change something I can tune it back. 1 last thing any word on what this new digital cobra is supposed to reach out to, distance wise? I'm sure it all depends on what antenna and coax and etc, but just a rough estimate with it bone stock with a cheap $30 4ft antenna ad on?

I appreciate your time and thoughts, thanks