CB antenna issue


Modoc Guy

Jack of all trades, master of none
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OK cb experts, I’m a cb noob, and I’m having a problem getting my antenna tuned.

Here’s my setup. A Uniden 520xl with a 4 foot firefly mounted on the rear bumper, passenger side using a firewire 18 footer at full length.

I’ve double checked the firewire mounting and it’s grounded, continuity checks OK as well. But when I check SWR, the best I can get is 3 on channel 1, 2.1 on channel 19, and 1 on channel 40. That’s with the antenna as short as it can adjust.

If I make any changes in antenna length, all my SWR readings are in the red.

Am I seeing a weak ground issue? Or is it something else?
 

Blackjack

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Dec 16, 2018
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Location
Kenai
OK cb experts, I’m a cb noob, and I’m having a problem getting my antenna tuned.

Here’s my setup. A Uniden 520xl with a 4 foot firefly mounted on the rear bumper, passenger side using a firewire 18 footer at full length.

I’ve double checked the firewire mounting and it’s grounded, continuity checks OK as well. But when I check SWR, the best I can get is 3 on channel 1, 2.1 on channel 19, and 1 on channel 40. That’s with the antenna as short as it can adjust.

If I make any changes in antenna length, all my SWR readings are in the red.

Am I seeing a weak ground issue? Or is it something else?
What type of mount are you using? Make sure that the antenna is insulated properly.
 
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Modoc Guy

Modoc Guy

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On the road right now, but I’ll post a picture soon as I can.

Planning to get a bonding strap to make sure the bumper’s throughly grounded.
 

TurboTJ

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Jan 5, 2019
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Walnut Creek, CA
OK cb experts, I’m a cb noob, and I’m having a problem getting my antenna tuned.

Here’s my setup. A Uniden 520xl with a 4 foot firefly mounted on the rear bumper, passenger side using a firewire 18 footer at full length.

I’ve double checked the firewire mounting and it’s grounded, continuity checks OK as well. But when I check SWR, the best I can get is 3 on channel 1, 2.1 on channel 19, and 1 on channel 40. That’s with the antenna as short as it can adjust.

If I make any changes in antenna length, all my SWR readings are in the red.

Am I seeing a weak ground issue? Or is it something else?

I will Ignore for the moment your comment about any changes in length making SWR readings in the red. Based upon the VSWR readings you have posted, the antenna should be made longer.
 
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Modoc Guy

Modoc Guy

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Canby, Northern California
I’ll be adding a bonding ground tomorrow and rechecking the SWR. I’ll post the results.

And a picture of how I mounted the antenna.

I didn’t use a spring, but tried one and it put all my readings in the red IIRC.
 

Zorba

"The Veiled Male"
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I didn’t use a spring, but tried one and it put all my readings in the red IIRC.
FWIW, I had similar problems with my setup - and I'm fairly certain it had to do with the spring. In any event, I was able to get "better" tuning with a longer than stock tuning screw.
 
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Modoc Guy

Modoc Guy

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Well I got off my butt and cleaned my bumper ground connections, and put a bonding strap from one of those connections to the tub.

This is how and where the antenna mounts.

0EE54912-ECD6-4B8C-B9A9-3FA3061D483A.jpeg


And when I finished my ground cleaning exercises, I started checking the SWR again.

That did the trick. I’m below 2 on channel 1, 40, and 19.

So I’m thinking I’m good to go.

Thanks to all for your replies.

And TurboTJ, you were right. Once I had a good ground, I extended my antenna a little bit and I was there.
 
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