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  #1  
Old June 14th, 2019, 14:59
notamechanic notamechanic is offline
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CB Radio Wiring set up and SWRs

Hey all,

looking for some advice from the electrical wizards that frequent here.
Not that this is at all technical, but over my head.

I have a midland 1001lwx that is wired directly to the battery.
I have my a firestik firefly mounted on the rockhard tire carrier antenna mount.
Using the K4R firestik mount, heavy duty spring. and a Wilson CB coax with fme connector and boot.

I cannot get my SWR below 2-2.3ish on channels 1 & 40. Went on a trail run and my transmits were received loud and clear, but I was getting terrible reception back. I could hardly hear the others and would loose reception in like 50 yards.

Wondering if I should just run the antenna on a tail light mount and if that would get me better reception or if i should drill a grounding mount on my tire carrier.

I made one out of 12gauge copper wire, but that did not help. Probably a little long and might need at least 10 gauge?
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  #2  
Old June 14th, 2019, 16:33
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Tim_MN Tim_MN is offline
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Re: CB Radio Wiring set up and SWRs

Are you sure the RF Gain is turned up to the maximum ?

Basic antenna system theory is the that the antennae is 1/2 of system and the body of the Jeep is the other half of the system known as the ground plane. The higher up the antenna, the longer the antenna, the more centered in the overall mass of metal, the lower the SWR will likely be, and the better the CB signal transmit and receive will be.

Tire swings are about the worst place you can mount a CB antenna. Often they are isolated from the rest of the Jeep body by the latch and the pivot point leading to a lack of the second half of the system known as the ground plane. Depending on the location of the antenna, it may be blocked by the tailgate which reflects and absorbs some of the signals, raising the SWR and reducing the CB signal TX and RX.

Try the set-up you have now but without the spring installed. A 4 foot FireStik should be able to achieve and SWR of 1.8 or less on ch 1 and ch 40.

Sometimes a very large braided strap will help improve the connection of the tire swing to the rest of the Jeep body metal ( ground plane ) and lower the SWR somewhat.

I have run a Wilson 1000 magnet mount, a Wilson 1000 roof mount, and a Antenna Specialists antenna in the center of the roof and all have excellent SWR, receive, and transmit.
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Quote:
Originally Posted by bimmerjeeper

Go ahead and slam the liftgate down on a blanket, and see how long you are laughing.
Quote:
Originally Posted by soyjer

Tim MAY be 100% correct, but why would a person automatically pick him as the expert .....

Last edited by Tim_MN; June 18th, 2019 at 07:17.
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  #3  
Old June 16th, 2019, 17:59
98xjaz 98xjaz is offline
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Re: CB Radio Wiring set up and SWRs

Quote:
Originally Posted by Tim_MN View Post
Are you sure the RF Gain is turned up to the maximum ?

Basic antenna system theory is the that the antennae is 1/2 of system and the body of the Jeep is the other half of the system. The higher up the antenna, the longer the antenna, the more centered in the overall mass of metal, the lower the SWR, the better the CB signal transmit and receive will be.

Tire swings are about the worst place you can mount a CB antenna. Often they are isolated from the rest of the Jeep body by the latch and the pivot point leading to a lack of the second half of the system known as the ground plane. Depending on the location of the antenna, it may be blocked by the tailgate which reflects and absorbs some of the signals, raising the SWR and reducing the CB signal TX and RX.

Try the set-up you have now but without the spring installed. A 4 foot FireStik should be able to achieve and SWR of 1.8 or less on ch 1 and ch 40.

Sometimes a very large braided strap will help improve the connection of the tire swing to the rest of the Jeep body metal ( ground plane ) and lower the SWR somewhat.

I have run a Wilson 1000 magnet mount, a Wilson 1000 roof mount, and a Antenna Specialists antenna in the center of the roof and all have excellent SWR, receive, and transmit.



When faced with this choice and after some research I decided that the tail light mount was easier than getting a solid ground from my swing out. Make sure you take the paint or powder coat off of the mount around at least one of the bolt holes. I paid a lot more attention to antenna ground on this install and its been the best performing and easiest to tune install I have ever had with this CB, this is the 4th vehicle I've had it in.
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  #4  
Old June 21st, 2019, 16:19
notamechanic notamechanic is offline
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Re: CB Radio Wiring set up and SWRs

Thanks for the responses.

I recently bought a tail light mount from ebay which seemed flimsy. I'm worried if i snag it on the trail that it will rip my tail light apart. Even with that my swrs will still slightly over 2.

Its definitely grounded and there are no kinks in the coax. I just ordered a fire ring coax and hopefully that will do the trick.

Has anyone had any experience or ever seen a tail light mount rip off on the trail??
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  #5  
Old June 22nd, 2019, 06:15
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Tim_MN Tim_MN is offline
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Re: CB Radio Wiring set up and SWRs

For a taillight mount I would use the lighter weight Firefly antenna. You could also mount a longer antenna to the bumper.

If you are going to compromise on the antenna mounting locating, you will never achieve the ideal transmit/receive signal pattern, or the ideal SWR. You might end up with good enough though. An SWR of 2.0 or less is functional.
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Quote:
Originally Posted by bimmerjeeper

Go ahead and slam the liftgate down on a blanket, and see how long you are laughing.
Quote:
Originally Posted by soyjer

Tim MAY be 100% correct, but why would a person automatically pick him as the expert .....

Last edited by Tim_MN; June 22nd, 2019 at 07:50.
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  #6  
Old June 23rd, 2019, 23:17
notamechanic notamechanic is offline
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CB Radio Wiring set up and SWRs

Quote:
Originally Posted by Tim_MN View Post
For a taillight mount I would use the lighter weight Firefly antenna. You could also mount a longer antenna to the bumper.



If you are going to compromise on the antenna mounting locating, you will never achieve the ideal transmit/receive signal pattern, or the ideal SWR. You might end up with good enough though. An SWR of 2.0 or less is functional.


Thanks Tim. I just bought the firestik door jam mount and the fire ring coax. Planing on using that mount on the tail light. I like how I can drill into the body and use the light screw. I have a 4í firefly and 3í firestik kw. Hoping the combo of quality parts will get my swrs down!
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  #7  
Old June 23rd, 2019, 23:19
notamechanic notamechanic is offline
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CB Radio Wiring set up and SWRs

Quote:
Originally Posted by Tim_MN View Post
For a taillight mount I would use the lighter weight Firefly antenna. You could also mount a longer antenna to the bumper.



If you are going to compromise on the antenna mounting locating, you will never achieve the ideal transmit/receive signal pattern, or the ideal SWR. You might end up with good enough though. An SWR of 2.0 or less is functional.


Also, do you consider the tail light a compromised location? Whatís a better or best place? Besides magnet on the roof.


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  #8  
Old Yesterday, 15:11
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Tim_MN Tim_MN is offline
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Re: CB Radio Wiring set up and SWRs

Taillight mounting for a CB antenna is a compromise, but it is not exactly a compromised location. The CB transmit and receive signal pattern will not be ideal, but will work mostly OK for trail usage. Any CB within 1/2 mile or less should easily be communicated with. The further away the other CB, the worse the distorted signal pattern affects your ability to communicate. With a taillight mount the CB the signal pattern is distorted compared to a center mounted antenna. The image is not to scale but does give you an idea of what is happening. Lots of people mount their CB antenna between the fender and hood which would be a bit better than by the taillight.

My center of the roof mounted CB antenna is up high in the air ( higher is better ) and has an excellent signal pattern, I can easily communicate with other CB's that are 3-5 miles away.

.
__________________
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Quote:
Originally Posted by bimmerjeeper

Go ahead and slam the liftgate down on a blanket, and see how long you are laughing.
Quote:
Originally Posted by soyjer

Tim MAY be 100% correct, but why would a person automatically pick him as the expert .....

Last edited by Tim_MN; Yesterday at 16:30.
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  #9  
Old Yesterday, 17:28
notamechanic notamechanic is offline
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Re: CB Radio Wiring set up and SWRs

Quote:
Originally Posted by Tim_MN View Post
Taillight mounting for a CB antenna is a compromise, but it is not exactly a compromised location. The CB transmit and receive signal pattern will not be ideal, but will work mostly OK for trail usage. Any CB within 1/2 mile or less should easily be communicated with. The further away the other CB, the worse the distorted signal pattern affects your ability to communicate. With a taillight mount the CB the signal pattern is distorted compared to a center mounted antenna. The image is not to scale but does give you an idea of what is happening. Lots of people mount their CB antenna between the fender and hood which would be a bit better than by the taillight.

My center of the roof mounted CB antenna is up high in the air ( higher is better ) and has an excellent signal pattern, I can easily communicate with other CB's that are 3-5 miles away.

.
Wow that's crazy. I have been contemplating the hood mount, but I have a 18ft coax and don't want to spend anymore money. I believe I would need a shorter coax ?

Mine will strictly be trail use. Last trip I took my range was like 100 feet and it was frustrating, especially on the faster bits of trail where we'd spread out.
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  #10  
Old Yesterday, 17:33
RCP Phx RCP Phx is offline
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Re: CB Radio Wiring set up and SWRs

The cables are all 18' because that's a half-wavelength.
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  #11  
Old Yesterday, 18:54
notamechanic notamechanic is offline
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CB Radio Wiring set up and SWRs

Quote:
Originally Posted by RCP Phx View Post
The cables are all 18' because that's a half-wavelength.


I see. Sorry for all the questions. Would you run it around your car to keep it straightish or would you coil the excess cable?

Iím definitely going to buy a hood or front bumper mount. The tail light mount is on and doesnít feel quite as stout as Iíd like. Also cracked my housings 🙃


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  #12  
Old Yesterday, 19:11
RCP Phx RCP Phx is offline
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Re: CB Radio Wiring set up and SWRs

What ever you do, "do not coil it".
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