Excessive SWR causes

Short answer: yes.

I suspect coax. One way, and maybe this isn't the best way because I'm a newbie myself, is to accomplish a process of elimination. Replace one component in the system at a time, starting with the most suspect and the cheapest thing to try. In this case both the most suspect and cheapest thing to try is coax.

 

coax could be getting pinched when the door is closed...Or could be a loose coax connection and when you shut the door it pulls on the coax till it quits making a good connection...Or maybe the coax is just a bit too tight and when the doors closed its pulling something loose?

Get another coax jumper (like maybe 10') and hook to radio and antenna (disconnecting the factory stuff) and see if the SWR spikes when the doors shut using the jumper coax instead of the factory coax...

Least that way you can narrow down the problem to being the coax or something else.

 

It would be interesting to connect an antenna analyzer and drive down the interstate and see if the SWR fluctuates as you're driving.

 

I thought you did this already?

 

I'm not the one having problems.

 

I think many of you put too much credence in swr.

 

SWR values change as you go down the road. Drivers often do not notice because they have to be transmitting and watching the SWR meter at the same time to see it happen, which can be tricky when trying to drive too.

I've seen the SWR values change as vehicles pass closely on the highway or when I drive close to other such obstacles. I'm sure the SWR also can vary to some degree by an antenna that is swaying in the wind and the transmitted signal is being reflected back as the antenna momentarily "points" towards the vehicle's body on which it is planted.

As Ridgeline implies, such SWR vagaries are not important. IMHO, the best one can do is to adjust the antenna while the vehicle is in a stationary position without large obstacles close by that can influence the SWR values, and then quit worrying about it as the scenario changes when traveling on the road. However, I do think it is good to occasionally check the SWR to make sure something hasn't changed, such as a loosened connector or a damaged coax.

 

Meteor, swr while moving is useless.

There are a number of complex things going on when a vehicle going down the road, the relationship of the vehicle and the earth measured in capacitance. The reactance of the vehicle with relationship of the earth and so on. Even ground resistance has something to do with it.

It is just like this myth that the lowest swr is where the antenna is resonating.