CB tuning, what am i doing wrong? - JeepForum.com

 
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post #1 of 14 Old 02-01-2014, 05:59 PM Thread Starter
doclouie
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CB tuning, what am i doing wrong?

So I am running the fire-ring 18' cable and I made sure with my ohmmeter that the middle antenna pin is isolated from the ground with the plastic pieces on the top and bottom in the mount. The antenna base is the one that is made by Teraflex and goes behind the rear driver turn signal. The base is grounded properly as I checked it also with my ohmmeter. I went out to tune the 2' firestick II antenna in a field with the nearest anything is a good 150 yards and the best I can get on my SWR meter is around a 3. I did have extra wire from the 18' cable and I just coiled it up rather than run it all around the Jeep. Is that bad? The wire runs along the driver side of the Jeep until it gets to the driver's seat and then it runs under the console and out where the e-brake handle is. Any type of help would be appreciated as I have no idea what I am doing wrong.


2000 Sahara, 3.5" Rubicon Express Lift, 1" spring spacer & 1" Body Lift, 35" BFG Mud tires, Front & Rear ARB, Rancho 9000 shocks, UCF Ultra High Belly Up Skid.
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post #2 of 14 Old 02-01-2014, 11:51 PM
JPNinPA
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With the antenna assembled, What is the resistance from the outer shield at the mount to the body not the frame. And resistance from shield to tip?

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post #3 of 14 Old 02-02-2014, 07:35 AM
FIRECAPT
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What length antenna are you using. I struggled with this for a while with a 3ft firestick. I switch to a 4ft and it solved instantly.
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post #4 of 14 Old 02-02-2014, 11:48 AM
CJ7-Tim
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That is probably the best SWR you can achieve with a short antenna, and the mounting location you have chosen.

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post #5 of 14 Old 02-02-2014, 12:31 PM
gadogs
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Don't coil the coax cable up.... if u wind it up in a circle it chokes ur swrs. Best the u do if u have extra cable is to run it side to side and not in a circle postion. Try that and it should fix ur swrs. It also don't hurt to run a ground wire from one of the bolts on ur mount to make sure u have a good ground on the antenna.... high swrs = short range talking and poss burnt up cb
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post #6 of 14 Old 02-02-2014, 12:54 PM Thread Starter
doclouie
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Resistance to the outer part of the cable to the frame or the body is the same at 4.8. I changed the coiling of the wire to run it back and forth rather than in a circle.

2000 Sahara, 3.5" Rubicon Express Lift, 1" spring spacer & 1" Body Lift, 35" BFG Mud tires, Front & Rear ARB, Rancho 9000 shocks, UCF Ultra High Belly Up Skid.
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post #7 of 14 Old 02-02-2014, 12:55 PM Thread Starter
doclouie
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Quote:
Originally Posted by JPNinPA
With the antenna assembled, What is the resistance from the outer shield at the mount to the body not the frame. And resistance from shield to tip?
What do you mean by resistance from shield to tip?

2000 Sahara, 3.5" Rubicon Express Lift, 1" spring spacer & 1" Body Lift, 35" BFG Mud tires, Front & Rear ARB, Rancho 9000 shocks, UCF Ultra High Belly Up Skid.
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post #8 of 14 Old 02-02-2014, 04:49 PM
JPNinPA
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First you could use and tune a 2 ft antenna to good SWR values and you may even achieve 1.1:1. I have, it is just finer tuning on the shorter antenna than long. SWR of 3 is unacceptable.

Second the 4.8 resistance from outer shield to ground is a bit high. Look to improve the contact of the outer shield &mount a the antenna. But first do you measure any resistance fron the antenna tip to the outer shield?


For the above question. If you measure the resistance from the outer shield to the center conductor you should see an open. You could measure this a few ways, just be sure your antenna system is assembled ( like it may be already). Either at the radio remove the cable and measure the resistance between the outer shield and the center conductor. Or measure resistance from the antenna tip to the outer shield at the antenna mount.

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post #9 of 14 Old 02-02-2014, 05:15 PM Thread Starter
doclouie
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So I started a new thread about this problem with a lot more detail and pictures here.

http://www.jeepforum.com/forum/f20/c.../#post19997201

Thanks for your help.

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post #10 of 14 Old 02-02-2014, 05:34 PM
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Coiling the coax wont hurt anything other than physically hurting the coax if it is wound too tight. Coiling the coax is called a choke, it is used to keep rf from traveling down the outside of the coax, wont hurt the signal inside it though.

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post #11 of 14 Old 02-02-2014, 05:40 PM Thread Starter
doclouie
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It was not a small coil. Probably about 6" in diameter. I redid it without a coil just in case.

2000 Sahara, 3.5" Rubicon Express Lift, 1" spring spacer & 1" Body Lift, 35" BFG Mud tires, Front & Rear ARB, Rancho 9000 shocks, UCF Ultra High Belly Up Skid.
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post #12 of 14 Old 02-03-2014, 03:20 PM Thread Starter
doclouie
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I have picked up a new coax cable and will try tuning it again tonight. Cross your fingers for me.

2000 Sahara, 3.5" Rubicon Express Lift, 1" spring spacer & 1" Body Lift, 35" BFG Mud tires, Front & Rear ARB, Rancho 9000 shocks, UCF Ultra High Belly Up Skid.
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post #13 of 14 Old 02-05-2014, 12:02 AM Thread Starter
doclouie
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I did hook up a different CB and I ran a different coax cable to see if the current one had a problem. The SWR came back the same on channel 1 & channel 40, just above 3.0. I ordered a longer antenna so hopefully that will take care of the problem. I will let you know when it comes in. Thank you everyone for the help.

2000 Sahara, 3.5" Rubicon Express Lift, 1" spring spacer & 1" Body Lift, 35" BFG Mud tires, Front & Rear ARB, Rancho 9000 shocks, UCF Ultra High Belly Up Skid.
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post #14 of 14 Old 02-11-2014, 07:53 PM Thread Starter
doclouie
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Okay so I received my 3' firestik antenna and tuned it. I get a SWR of 2.5 on channel 1 & channel 40 with a SWR of 1.4 on channel 20. I am going to stick with this setup and call it good because I cannot fit a 4' firestik in my garage.

2000 Sahara, 3.5" Rubicon Express Lift, 1" spring spacer & 1" Body Lift, 35" BFG Mud tires, Front & Rear ARB, Rancho 9000 shocks, UCF Ultra High Belly Up Skid.
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