Help with Antenna tuning

[Kanueh]

So I installed a CB antenna this weekend and when tuning the antenna the SWR meter is maxing out. I am using a FireStick 4 foot antenna, Fire Ring Coax cable, and the antenna mount that bolts onto the spare tire mount. From looking at the bracket its powder coated, do I need to remove some paint from where the fire ring and bolts contact the bracket? I'm going to be grounding the tail gate tonight.

[jeepjones]

Sounds like a grounding issue to me. Ground the antenna to the tail gate & then ground the tail gate to the body. Check and make sure you coax isn't getting pinched or have any severe bends/binds.  Remember you have to be out in the open away from buildings & power lines also if your antenna has a tunable tip start with it all the way down. Are you using a separate SWR meter or are you going of the meter built into the radio? The ones built in aren't known to be accurate. If you are using an external SWR meter make sure the coax from the radio to the meter is as short as possible this will help with the  accuracy of the readings.

[Slewfoot]

So I installed a CB antenna this weekend and when tuning the antenna the SWR meter is maxing out. I am using a FireStick 4 foot antenna, Fire Ring Coax cable, and the antenna mount that bolts onto the spare tire mount. From looking at the bracket its powder coated, do I need to remove some paint from where the fire ring and bolts contact the bracket? I'm going to be grounding the tail gate tonight.

Like jeepjones said, it does sound like a bad ground.
I'm not sure if it will ground through the powder coat, but, personally, I'd shoot for metal-on-metal contact.
You WILL want a ground on the antenna mount (and make sure the mount itself is grounded), but whether it's on the top or bottom of the mount depends on how you mount the coax and antenna stud:
http://www.firestik.com/Catalog/k4-8r18.htm
In either case, I believe it's the ring mount itself that you want to ground, and you want to keep the stud bolt insulated...but study the instructions and diagrams in the link I provided to confirm that.

[Kanueh]

Thanks for the information, I'll give it a try tonight.

[TL-Iguana]

Also double check your mount. The plastic washer needs to be installed correctly if this is the style of mount you are using. And yes, first and foremost check your grounds. This is most often the cause of ridiculously high SWR.

[Kanueh]

So I have a really good ground on the tailgate now but the SWR meter is at 3-3.5 with the antenna tuning screw as low as it will go. If I adjust it all the way up it will go as low as 2.5 but that as low as I can get it not matter how much tuning I try...any other suggestions?

[TL-Iguana]

Weld on an entirely metal hard top, ground that directly to the battery, and you will have a much nicer ground plane Mount the antenna in the center of the new steel roof.

Sounds as though your electrically short for your antenna. You can also try lengthening your coax cable. Dont coil the excess up, just leave it loose and spread out. Comtek sells butt connectors, try an extra 6 feet of cable length, and you can also add a spring to your mount. Both will electrically raise your antenna, and may lower your SWR. Are you higher on channel 1 or 40 for your readings?

[Kanueh]

I have a spring and quick disconnect so it's pretty long and the cable is at full length not coiled. Chanel 1 and 40 are basically the same.

[TL-Iguana]

I have a spring and quick disconnect so it's pretty long and the cable is at full length not coiled. Chanel 1 and 40 are basically the same.

If your SWR is the same on 1 and 40 thats about the best your going to get for your setup... If you make your antenna longer it will raise you on Channel 1 but lower you on 40, and if you make it shorter, it will lower you on 1 and raise you on 40 IIRC.

You have basically got yourself to where your swr will stay unless you start changing antenna length, mount point etc.

If you want more clarification you can PM wsquared on here, as hes a HAM operator. morerpmfred is also very knowledgeable about radio setup. They may also be good resources for you at this point.

[Nootch]

this thread spurred me to tune my Cb because i had borrowed a SWR meter from Stan at Northridge, but hadn't used it.  Got it down to 1.5 on talk, which i am assuming is pretty good. 

[TL-Iguana]

this thread spurred me to tune my Cb because i had borrowed a SWR meter from Stan at Northridge, but hadn't used it.  Got it down to 1.5 on talk, which i am assuming is pretty good. 

1.5 is great! Is that your average? 1.5 on channel 1 may be great, but if your at 4.0 on channel 40 you have issues In a perfect scenario you want to get your SWR to 1.0. However, this is not possible. For a typical setup on a Jeep, if 1.5 is your average on all channels, thats pretty damned good The lower the SWR the better, 1 is perfect, but unless your in space, with no friction through the copper and antenna, its an infinte number that you cannot achieve.