Bad CB SWR...Can I keep my current setup but improve my SWR somehow?

[smithytailor]

With my current setup placement I'm getting ~2 SWR on channel 20 and ~2.5 for channels 1 and 40. I pulled the cb out and removed the audio headunit (audio troubles which turned out to be a speaker.......), placed the cb on the dash and was getting a SWR of under 1.5 for channels 1 and 40.

My current setup placement is described below and I'm hoping there might be something I can do to keep it. The SWR to cb cable is the same one that came with the SWR meter. Would a better cable help? The cb power is coming from the same cables that power the headunit. Would a dedicated power line help? Can I shield the cb with some material maybe...or...? Any ideas or maybe there's no way to salvage this location?

I've got a single din cobra cb sitting below my audio headunit. I've also got an inline SWR meter at the bottom of the dash. The cable runs from the antenna inside the cabin on the passenger side, runs over the foot well, up the console, and connects to the SWR meter. From the SWR meter the cable runs up the driver side console and in to the back of the cb.

 

[PhulesAU]

Tune the antenna and ditch the "swr" meter. where you draw power has NO effect on swr. Make sure you don't have coax all wadded up behind dash. make sure The transmitter has a good ground. You failed to mention your antenna setup, which is usually 90% of the reason for SWR difficulties.

 

[smithytailor]

Yeah, the only reason I didn't mention the antenna setup is because I was able to get a good swr by changing the cb location. It's a 4 foot Firefly on top of a firestik spring and a coax termination mount. The mount is hooked to my bumper. The ground is good and the antenna center isn't being grounded.

 

[prerunner1982]

If you moved the radio and the SWR changed I would suspect an issue with the coax, make sure there are no tight bends in it.

 

[comptiger5000]

I'd agree with possible bad coax. Or one mounting location had the radio chassis grounded well and the other doesn't.

 

[smithytailor]

Hmm. So far I've tried two different ground locations and two different "extra coax" bundling methods. Right now the ground should be really good. I've run the extra coax in a big loop around the passenger side cabin area and I've also bundled the extra in a ~1 foot, long, thin loop that's zip tied in the middle. I actually got bad readings while doing both methods.

Mentioning the tight bends, though, made me think of the bends coming out of the radio and the swr meter where the cable presses against whatever is behind the dash. Without the swr meter inline, I was removing the cb and headunit from the dash so I could swap coax connections and was testing swr that way (which shouldn't have had those bends) but was getting bad swr then as well. I'll probably try pulling the cb/headunit out a bit, pull the swr meter out a bit as well, and try testing again to see if something else has changed enough for the bends to be the current issue.

When I did get the good swr reading I did notice that I could move the coax that came with the swr meter and get different swr readings. With everything currently installed, I have pushed and pulled a bit on that cable to see if the swr would change but it's been solid. Maybe that cable is kinda bad?

 

[sonoronos]

placed the cb on the dash and was getting a SWR of under 1.5 for channels 1 and 40.

I could move the coax that came with the swr meter and get different swr readings.

It should be pretty obvious what the problem is

 

[smithytailor]

Bad location and/or bad coax jumper? I agree that the location is bad which is sad because the setup appeals to me for some reason. I've tried poking/prodding both coax cables with everything in the final location and don't really get any swr movement. My guess is the coax jumper isn't shielded very much so is susceptible to noise/power? A nice 3' coax jumper is pretty expensive and might not fix my problem... I might just use what I have and, if my cb destroys itself, switch to a handheld unit later. Bleh.

 

[BigSwede]

I had a Cobra 18 in the dash for years, no problems, so I don't think that is your issue.

 

[comptiger5000]

Personally, I don't bother wrapping up extra coax. I just cut the cable down to the length I need and don't worry about excess.

 

[DaveInDenver]

Personally, I don't bother wrapping up extra coax. I just cut the cable down to the length I need and don't worry about excess.

Trimming and finishing your coax to the length you need is the right thing to do, there's nothing magical about 18' anyway.

 

[smithytailor]

I tried switching out my jumper coax and I'm still getting the same readings. While I was switching it out I also made sure all of the coax was running without tight bends and tested it with the components pulled slightly out from the dash. No change there either.

 

[Ozarker]

Consider this another vote to:

Replace with shielded coax, cut coax to length, additionally check coax connections, solder, check grounds. I assume your battery is good.

I'm not familiar with that Cobra rig, but a bad ground or short in a mic/connection can cause that as well. Your rig, antenna and meter should all be on the same common ground.

Next, what type SWR meter, how is it powered and check its ground and power source.

@noahenholm, in theory an SWR meter isn't frequency specific, however the parts used to build one can be and a meter can be "out of band" due to parts used. Any meter sold for CB should be within the band, in fact a 6 or 10 Meter unit should be fine for 11 Meters.

 

[mep1811]

Is there a truck stop close by? Most have a CB shop that can tune your antenna.

 

[GlennA]

Talk about a thread resurrected from the dead........