The one under the seat is yer A M F M radio. Should you have a C B radio It's mounted under the trunk. You need a wiring schematic. But the fuse panel and all the associated wiring is under the right side cover. The A M F M antenna is on the right rear corner stock position as yer sittin in the saddle. And as I've never pulled my trunk I have zero idea where the connection plug if there are one is located. Good luck on the project!

And a belated welcome from The Missouri Ozarks. RIDE SAFE.
Thanks, that clears up the CB situation. Having the CB antenna (left side) was a bit confusing since PO said he never had a CB. I didn't think they came with the second antenna, could be wrong though. Thanks for the welcome. It's been a while since I was here. Sold my last Valk(Tourer) in 2010. Good to be back.