Antenna issues

Some volvo versions come without multiplexor.

The left antenna has a direct coaxial to the CB,
The right antenna has a direct coaxial to the radio.

I think the better configuration is to use a only one antenna for the CB. (no multiplex = less loss)

I have see some trucks with a paint job, and the painters cut the cable at the mirror site and after the paint, their insntall a "PL coaxial adaptor/extensor" to the cable.

 

Loss per foot in cable is negligible in comparison to ground losses due to bad mounting locations.

 

I had a Volvo that had the same box, one for the stereo and the other for the CB. How I rand my cb was I unscrewed the coax that went to the junction box. Bought a 3' extension line of coax. I used that line from the Cb radio directly to the Coax that was attached to the juction box by a barrel connector thus leaving the juction box out of the equation . Cb radio+3' jumper line attached by a barrel connector to coax cable that was going to the juction box. Tuning your antenna...that is where a lot of mistakes are made . You can take a chance with a fiberglass antenna OR use a metal antenna. I use a Metal type antenna since most of them are " trim to tune" simply put. the lower SWR you have the better your radio will work. The less chance your going to experience bleed over into your trucks ECM , So since the radio works better , you will more than likely use it more than ever.