FM antenna saga

When I brought the truck home I was less than impressed with the FM radio reception. Later, when I started working on the truck I found the FM radio antenna was connected to Volvo's antenna splitter system. The CB antennae connect to a box under the dash that splits the signals to the CB and FM stereo. There was a problem. The truck didn't have any CB antennae mounted. No wonder the reception sucked. There was no antenna to speak of other than what little antenna function the coax itself provided.

I had no use for the splitter setup so I unscrewed the coax connections to the mirrors and chucked the splitter. I put an antenna on the driver's side mirror and adapted the driver's side coax to the FM radio. The radio reception was still marginal.

Later I installed an amplified external TV antenna which also included a lead for an FM stereo. It took a 17-foot and a 10-foot extension to reach the stereo. The radio reception was okay if you turned on the amplifier that is mounted on the back of the TV. Not very handy. With the amplifier off the FM stereo reception sucks.

After installing my chrome bumper I stood and pondered the FM reception situation. I grabbed a multimeter and checked the continuity between the driver's side CB coax and the antenna on the driver's side mirror. continuity whatsoever. No wonder the reception sucked before.

A few days earlier I had watched a video on YouTube of Leon Kirby replacing the coax in his Volvo mirror. He did a great job showing how the filler piece between the hood and door is removed to get to the coax. He also showed how to disassemble the mirror, but my truck seems to have a non-standard set of mirrors.

I dug through my supplies and found another 10-foot FM antenna extension cable I had purchased for the external antenna project but not needed. I decided to run a new cable for the FM stereo antenna.

After some experimentation I was able to remove the mirror. On the normal Volvo mirrors you push the mirror up then pull it forward to remove it. On mine it 'pops' out of a center hole in the power mirror mechanism. With the mirror removed I could safely remove the mirror cap. If you don't do it correctly the mounting tabs can easily break.

When the cables (coax and mirror controls) enter the body they go through a plastic grommet. When I removed the grommet to access the hole I found the reason for the lack of continuity. The coax from the mirror wasn't connected to the coax inside the truck. Did this happen when the Kenworth dealer changed the mirror?

I stripped out all the factory coax and replaced it with the FM antenna extension. Now I had a new, unmolested, single piece of cable between the antenna and the radio. Center conductor continuity...perfect. Ground continuity...perfect. Center conductor to A scan of the radio band revealed a multitude of clear FM stations. Another project finished and a mystery solved.

Update November 2021 - I ran new coax from the other mirror. Its antenna mount was very loose so I tightened it up.

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