I'm having a bear of a time tuning my CB install, and was hoping you guys might be able to point me in the right direction. I'm getting a very high SWR (3.5+) on all channels, and my radio's range is about 100 feet before it drops off completely. Obviously this is no fun. My setup is a Uniden Pro505XL mounted in the dash. It's not the most high end radio but it has great reviews pretty much everywhere, and should certainly perform better than this.
It's powered off of a clean wire behind the radio, and has a short ~6" ground to the dash behind the radio. I've checked both with a multimeter and the power is constant and the ground is solid.
From there I have a 12' coax that runs from behind the dash, down the doorsill and out the back of the cab. There's about a ~6 foot coil of it under the seat, but everything I've googled tells me that it's normal to have some overlap wrapped up. There are no kinds/bends/cuts in the wire. I have good ground on both ends, and no continuity between the center pin and the sleeve (which I believe is the way it should be), so the cable isn't grounding out.
From there is runs out to the bed corner behind the cab. Here's my mount. The cable is tight and the mount itself has solid ground, as do both coax connectors. There's an additional ground wire with an eye connector on it (you can see the wire coming off of it) that connects to the underside of the mount between the lock washer and the mount.
That ground wire runs down to the frame, where I wire-wheeled it off and fired a screw into it. I've checked it with the meter as well and there's continuity between my battery negative terminal and the mount on both sides.
I've gone through two antennas so far - one's a Firestik 3' that's not tuneable, which I initially thought was the problem. I swapped it out with a 4' K40 tuneable, and ended up with the exact same readings.
Then I tried the meter with NO antenna attached, and the reading is the same - 3.5-4 across all channels. Everything I've read tells me that this is usually a bad coax or a bad ground to the mount, but from everything I can tell both my grounds are good and this cable is fine.
Any ideas as to what I can try next? I have the radio custom mounted into my dash and it would be a bit of a PITA to swap it out and try another one, and I don't want to just arbitrarily throw money at it before I've asked around and got some insight from people who know more about this than I do.