Ground passing to antenna

[orod1]

Hey all,

I am installing a new cb radio, and I have the antenna mount grounded. I have switched the installation multiple ways, but the antenna itself is receiving a ground.

I think it may be the bolt that connects the fire ring that's passing the ground to the stud mount, and that's passing to the spring and the antenna.

I'm at a loss with so many different mounting options, but not being able to stop the antenna from grounding.

The negative on the battery is connected to the inside metal panel near the engine. I ran a daisy chained cable to another petal part that connects to the frame, and I ran that to the stud to connect to the stud mount. I've repositioned the ground in different places, but either it passes the ground through to the antenna, or it doesn't get a ground at all.

I've watched countless videos of how to make sure the antenna is grounded, and to make sure there is no continuity to the antenna, but I have not found any help for when the antenna itself is grounded.

I bought an SWR meter, and it's off the wall with a 10+ reading. I basically set the SWR and flip it from PWR to REF, and it pushes the needle passed the 10 pretty hard. There's clearly a problem, and I am not sure how to solve this. I don't keep the radio on because I'm afraid it will burn out with a short.

Any help or tips on what to look for or what to do, is greatly appreciated.

 

[prcguy]

If its a 3/8-24 stud mount with SO-239 connector on the bottom it will have an insulating shoulder washer that should be on the top of the antenna mount insulating the stud from the grounded mount. The SO-239 side will ground directly to the bottom of the mount.

If the coax attaches directly to the stud then there will be two insulating washers, one on top and one on the bottom of the mount either side of the stud and the coax braid will ground to a screw somewhere on the mount.

Can you post a picture or let us know the make and model of the antenna mount?

 

[orod1]

Pics of most recent attempt. I also tried a plastic washer underneath and one on top. Also tried orings between the bottom mount ant top plastic washer. That didn't work.

The base triggers continuity, but the antenna and the stud mount also trigger continuity. In all the videos I've watched. The base has continuity, but the antenna mount show open/infinite. Not sure what i'm doing wrong because I'm doing exactly what the instructions show. The cb has a self diagnostic, and it shows fail with every attempt.

 

[orod1]

Pic with antenna spring connected. It's mounted on the passenger side of a 3rd gen tacoma.

 

[prcguy]

Pics of most recent attempt. I also tried a plastic washer underneath and one on top. Also tried orings between the bottom mount ant top plastic washer. That didn't work.

The base triggers continuity, but the antenna and the stud mount also trigger continuity. In all the videos I've watched. The base has continuity, but the antenna mount show open/infinite. Not sure what i'm doing wrong because I'm doing exactly what the instructions show. The cb has a self diagnostic, and it shows fail with every attempt.

It appears to be put together right. An ohmmeter should reveal where the problem is and you might have to take the coax off the mount and test separate, then reassemble everything testing for shorts at every step.

 

[orod1]

I think it's the mount. Not certain though.. Right now, with the current set up, the base where the fire ring and the antenna is connected does not show any ohms (OL). However, the stud and stud mount trigger ohms between the two, and trigger ohms when checking against the chasis. So it's reverse. The plate that needs to be grounded is not, and the part that is not supposed to show any ohms is showing ground.

 

[prcguy]

I think it's the mount. Not certain though.. Right now, with the current set up, the base where the fire ring and the antenna is connected does not show any ohms (OL). However, the stud and stud mount trigger ohms between the two, and trigger ohms when checking against the chasis. So it's reverse. The plate that needs to be grounded is not, and the part that is not supposed to show any ohms is showing ground.

Looking at the pictures I notice the black wire (coax?) with the large lug going under the bolt head looks odd for coax, as in where is the ground side? Does the coax enter the black plastic ring that the bolt goes through and is the black wire you are putting under the bolt head the coax ground side? Something just doesn't make sense here.

 

[orod1]

The first wire between the stud and the fire ring is the ground cable, then it's the fire ring. Both are connected to the bottom of the mounting base. It's exactly as the fire stick and the videos that I've watched. I also tried connecting the ground to the where the base is mounted, but that didn't work. I think I've tried every which way possible. Maybe the radio is bad? It picks up the weather without a problem. I did order the radio online from wally world. Here's a pic with the labels of what's connected. The mounting base is connected to the underside of the hood hinge. So my maybe flawed logic thinks the stud is grounded, and the stud is connecting to the stud mount where the spring and antenna connect. The plastic washers are supposed to keep the ground from passing through, but the washers are actually preventing the ground from passing through to the base mount and because the stud is grounded, the ground is passing all the way through to the antenna.

 

[AC9BX]

Coax connects off to the side? What's with the wire under the bolt head? The bolt holds the mount in place, through insulators of both sides of the surface you mount it to.

 

[slowmover]

FireStik Fire-Flex Coax Reference

K-8R18/K-8R9 CABLE

.

 

[orod1]

Yes, coax connects through the fire ring at a 90 degree angle as opposed to screwing in from the bottom. The wire between the fire ring and the stud is a ground. Maybe it's where I'm connecting the ground?

 

[slowmover]

Pic with antenna spring connected. It's mounted on the passenger side of a 3rd gen tacoma.

For testing:

Spring not needed. Plastic washer between stud & spring/antenna not needed. (Leave off).

Leave off “ground wire” for now.

“Simplify” for testing.


Reference for all things mobile as you go along. Lengthy, peruse per subject:

Mobile Radio Install Guide


— My first thought was mount-ground to bed thence bed to frame. (Paint, etc).

— What SWR via another device? Another antenna available?

.

 

[prcguy]

Coax connects off to the side? What's with the wire under the bolt head? The bolt holds the mount in place, through insulators of both sides of the surface you mount it to.

In the ant1 picture it looks like the coax enters the black doughnut thing from the side with a strain relief molded in. I suspect the black wire with large lug is the ground side of the coax and by putting that under the bolt head you short out the mount. I would take everything apart and make sure all parts are understood and the coax hot and ground are positively identified, then put it all together the right way.

 

[G7RUX]

You appear to have an extra wire under the bolt that holds the stud mount to the bracket and I suspect this is a ground wire...it should not be there as the feeder is attached to the antenna through the plastic ring the both passes through.

 

[ramal121]

I am not familiar with that mount, but humor me. Are you making these checks with the coax connected to the radio?

 

[prcguy]

After looking at the specifics of your mount you have it installed in the "Fire Ring below mount" mode, which would be correct for the elevated bracket you are using. The problem is the ground wire you placed under the bolt head, its shorting out the antenna. Two things need to change for it to work which is remove the ground wire under the bolt head and make sure the underside of your bracket has some paint or coating removed so the Firestick mount can ground itself to the underside of the bracket. You should not need a ground wire if the other end of the elevated bracket is bolted into the vehicle body and making a good ground.

If you were needed an additional ground to the mount I would drill a hole in your elevated bracket near the mount and attach a wire that way. You could possibly use a 1/2" ID round lug on top of the mount between the shoulder washer and elevated bracket for a ground but mechanically speaking that would not be a good option.

 

[orod1]

After looking at the specifics of your mount you have it installed in the "Fire Ring below mount" mode, which would be correct for the elevated bracket you are using. The problem is the ground wire you placed under the bolt head, its shorting out the antenna. Two things need to change for it to work which is remove the ground wire under the bolt head and make sure the underside of your bracket has some paint or coating removed so the Firestick mount can ground itself to the underside of the bracket. You should not need a ground wire if the other end of the elevated bracket is bolted into the vehicle body and making a good ground.

If you were needed an additional ground to the mount I would drill a hole in your elevated bracket near the mount and attach a wire that way. You could possibly use a 1/2" ID round lug on top of the mount between the shoulder washer and elevated bracket for a ground but mechanically speaking that would not be a good option.

Thanks!! When I tried placing the ground on the mounting bracket, I placed it on the top of the bracket instead of between the bracket and the hood. I'll install it between the bracket and the hood this afternoon. I think this will fix the issue as I had not tried installing it this way. I'll need to make sure the ground is making a good contact.. might need to scrape some of the paint. Shouldn't be visible though, since the hood hinge would cover it up. Thanks for the tip!

 

[guttapercha]

Hey all,

I am installing a new cb radio, and I have the antenna mount grounded. I have switched the installation multiple ways, but the antenna itself is receiving a ground.

I think it may be the bolt that connects the fire ring that's passing the ground to the stud mount, and that's passing to the spring and the antenna.

I'm at a loss with so many different mounting options, but not being able to stop the antenna from grounding.

The negative on the battery is connected to the inside metal panel near the engine. I ran a daisy chained cable to another petal part that connects to the frame, and I ran that to the stud to connect to the stud mount. I've repositioned the ground in different places, but either it passes the ground through to the antenna, or it doesn't get a ground at all.

I've watched countless videos of how to make sure the antenna is grounded, and to make sure there is no continuity to the antenna, but I have not found any help for when the antenna itself is grounded.

I bought an SWR meter, and it's off the wall with a 10+ reading. I basically set the SWR and flip it from PWR to REF, and it pushes the needle passed the 10 pretty hard. There's clearly a problem, and I am not sure how to solve this. I don't keep the radio on because I'm afraid it will burn out with a short.

Any help or tips on what to look for or what to do, is greatly appreciated.

If this is a DC-grounded antenna type, this is normal behavior. RF does not behave like DC. Look at the spec for the particular FireStik that you have. If not, make sure that your coax isn't shorted.

 

[orod1]

I placed the ground between the mounting plate and the hood. I shaved off the coating where the ground connects, and it is grounding the mounting plate without passing to the antenna. Now the ground is where it should be, but I tested the SWR and it is pushing the limit of the meter. I've screwed and unscrewed the coax several times, so I may have damaged the inner part of the connector. I also have several 7mm ferrites connected to the cable as I understand this reduces interference, but not sure.. The backside of the radio heats up pretty quickly when I connect the coax. The cable might be defective now with so much on and off that I tried before asking..

 

[slowmover]