Well i moved my main power ground, and grounded my antenna shielding (at the box and at the antenna) and a little more tuning. I managed to pull about a 2.7 across the full spectrum (some channels a little better than others). I would still like to get it better, but I guess it will have to do for now unless someone else has any better Ideas???

 

No....he is correct.....well yes and no. Redneck.......what do you think SO239 and PL259 coax connectors are for? They are so you don't have to directly unwrap the shield away from around the center dielectric as well as from under the coax outer covering. The shield (ground) IS connected to the ground on the coax connector via a CRIMP or SOLDER. And the same with the center (hot) connector. So then, when the coax connector ground is tightend up to the antenna MOUNT and the mount is connected to the body of the vehicle, and the body to the frame, there is absolutely NO difference than manually taking the coax shield (braid) and grounding it to the body or frame. So ideally, if all is well with the coax system, you should be able to touch the outside TIGHTENED up ground connector at the antenna mount on the back of the vehicle with one lead of a continuity tester, and touch the other lead to a bolt on the front bumper, and get a tone. If you don't then your antenna mount is not totally grounded to the frame of the vehicle. Now, I said "yes and no" because if the antenna system doesn't have a SO239, for the PL259 coax connector to connect to, and some are that way, then yes.........you would have to manually ground the coax shield (braid) by itself to the body or frame. And here again, why not to the antenna mount, as long as it's grounded well?

 

That's just it.......if your swrs aren't good enough then you WON'T be "reaching out" as well as you could be. And if you continue transmitting with a high SWR, unless the radio has a built in safety feature, then you risk damaging your radio.

 

Do you have a volt/ohm meter? You might check to see if you have continuity from the ground on your antenna mount all the way down to the frame.
Also, and I don't know how far you want to go with this, but there is something called a "dummy load". It is like a tuned antenna, and what it does is take the place of your antenna to help eliminate the antenna from the system as the problem. You hook it up and then if everything is ok, then you know it's your antenna. You might google search it and read up. It's a real good thing to have, and you may be able to find one somewhere pretty cheap.

 

Well sure, but then, if there's not a seperate ground wire, you're grounding THROUGH the CB. THAT is not a good idea. Hay....yall ground the damn things any way yall want to. I'm just giving my recommendation that's worked for over twenty five years. yeah, there's some new cables and all that have come out, but you need to ground the shield and antenna some way OTHER than just the coax through the radio...and the mount don't need to be it. You don't have to unwrap anything, Dave. I've covered all this before. I'm turnin blue so screw it. I'm done. yall have fun with it.

 

Wrong. Trimming the length of your coax or adjusting or trimming your antenna will trick your SWR meter and you in to believing your SWR is lower. SWR is the ratio of the impedance of your coax to the impedance of the antenna. Standard CB coax is rated at 50 ohms. It has a 50 ohm impedance regardless of whether it is 3 feet long or 1000 feet long. To get a Standing Wave Ratio of "1 : 1" both the antenna and the coax must have an impedance of 50 ohms. If the antenna has an impedance of 100 ohms and the coax has an impedance of 50 ohms then your SWR is 2:1, or put another way the impedance of the antenna is twice the impedance of the coax. Likewise an antenna impedance of 25 ohms and a coax impedance of 50 ohms is STILL a 2:1 SWR because the coax impedance is twice the impedance of the antenna. I don't really know any other way to explain it.

 

Ok, I've got to chime in on this.

There is entirely to much BS being spewed out.

SWR or Standing Wave Ratio is "the ratio of the amplitude of a partial standing wave at an antinode (maximum) to the amplitude at an adjacent node (minimum)" or power out to power reflected back. This has nothing to do with impedance mismatches of the cable or the antenna but with matching the length of the antenna to the wavelength of the frequency being transmitted. Since Citizens Band is 40 channels or 40 different frequencies it is difficult to electrically match the antenna to the varied freq's being transmitted so you compromise by tuning on channels 1 and 40. The SWR curve looks like a halfpipe and ideally you would like to have your lowest SWR at channel 20 with slightly higher SWR's at 1 and 40 (of course getting those as low as possible). If you can get both 1 and 40 to the same SWR channel 20 will most likely be the lowest.

Grounding is very important. I have a K40 Super-flex with a fender mount and with a V/Ohm meter check for low resistance between mount and chassis then connected my coax braid to the mount. With the PL-259 connected to the CB and a short path to ground you have effectively shielded the center conductor from potentially induced voltage and prevented it from radiating prior to the antenna, which could cause some problems tuning. I recommend grounding the ground of the power cable to a chassis connection point nearest the CB radio itself and that it helps with any induced noise.

Some more observable notes: It is a good idea is to have at least 2/3rd of the antenna above the roof line of the rig. DO NOT coil excess COAX cable, cut to length and avoid sharp bends or pinch points. Check for any shorts between the coax's center conductor and shield after install.

And to the fellow that says it's worked fine for 25 years, well your doing it wrong.

 

[QUOTE=el beasto;1069275]......This has nothing to do with impedance mismatches of the cable or the antenna but with matching the length of the antenna to the wavelength of the frequency being transmitted. QUOTE]

I said....." The adjustment of an antenna, ie, to lengthen, or shorten it, is in direct relationship as to how the antenna radiates to the desired frequency. It has EVERYTHING to do with SWR........

I believe that'spretty much the same as what you said......No?

 

Yes, you two are pretty much along the same lines.

To those looking for more info, I recommend reading the info on Firestick's site. It is quite useful, and I say that running a K40 on my truck, so I have no reason to push their info .

All I can say is that reading the info from the people that make this stuff will help you weed out the 25 years of crap that may be posted. h ttp://www.firestik.com/Tech_Docs/swr-intro.htm <== This is just one of many good documents on the site.

Can you get it to work other ways, sure, I recommend just keeping a couple of cans with a line of string between them, one can in each vehicle. If you need to talk, just slow down or speed up to tighten the line, then talk into the can.

 

09 Rubicon, are you in a open area away from trees and buildings when trying to tune it (ie not inside a garage)? Sometimes its the simple things we overlook that cause problems. I probably would have been guilty of this if I hadnt read up on things first.