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Unread 10-04-2013, 03:11 PM   #1
Agent620
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SWR issue

So I recently got a 3ft antenna for my jeep, previously I had a 4ft, both with screw adjustment. However, I cannot get below 1.9 swr with the 3ft antenna, I can get to 1.3 with the 4ft. Whats going on? The 3ft only sits just below my soft top frame, maybe almost level with the top of it.

Anyone have insight for me? One person mentioned cable length, but I heard that was a myth. I only have about 2ft tied back along itself and it has always worked fine.

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Unread 10-04-2013, 04:28 PM   #2
Holder350
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Anything below 2 is fine. The longer your antenna the easier to get a low SWR.

With a whip I can get almost 1/1 SWR however with a 4ft on my jeep I'm lucky to get 1.5

That SWR is not bad. Shorter antennas are just harder to tune.

Sent from my phone where correct grammar is difficult.
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Unread 10-04-2013, 04:56 PM   #3
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Whether cable length is a myth or not, I thought bad to coil the cable or tie it back on itself like it sounds like you have done.
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Unread 10-04-2013, 05:32 PM   #4
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The shorter a CB antenna is, the smaller the bandwidth of the antenna. Translated, that means shorter CB antennas tend to have higher SWR at Ch 1 and 40 than a longer CB antennas, and shorter CB antennas are also more difficult to tune.

1.9:1 is just fine.
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Unread 10-04-2013, 07:26 PM   #5
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Well thats good to hear then. I guess I wont worry about it. I haven't checked what it is on channel 20 yet. I will give that a go tonight.


Edit: SWR 2.5 on channel 20 and 2.9 on 40.
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If you've ever been in that traffic, you would have ground down the steering wheel with a death grip too. "Just ****ing GOOOOOO!!!!"[/QUOTE]
[QUOTE=Luuca;15713642]I pitty anyone who tries to reach into that netting unaware.[/QUOTE]
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Unread 10-05-2013, 06:25 AM   #6
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What's your ground like? Also if your antenna is the same height as the jeep the jeep will interfere with the signal.
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Unread 10-05-2013, 06:28 AM   #7
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Your antenna is electrically too long.

Are you checking your swr with an external meter and out in an area away from buildings and electrical sources?
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Unread 10-05-2013, 06:30 AM   #8
Leeworthy
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2nd to that. Make sure your doors are closed when testing swr. And yes open field no electrical around. Also don't trust meters on the radio. Buy a cheap external at a truck or radio shop. Usually around 20 dollars. Make sure your cable isn't wrapped in a loop. Weave back and forth.
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Unread 10-05-2013, 08:27 AM   #9
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Quote:
Originally Posted by biffgnar View Post
Whether cable length is a myth or not, I thought bad to coil the cable or tie it back on itself like it sounds like you have done.
This ^^ Be sure your cable is not looped into a RF choke.

Or pinched by making sharp turns.
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Unread 10-06-2013, 07:57 PM   #10
Agent620
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Quote:
Originally Posted by Leeworthy View Post
What's your ground like? Also if your antenna is the same height as the jeep the jeep will interfere with the signal.
Ground attaches right to the body/tailgate, ground is not an issue, my 4ft gets perfect swr.

Quote:
Originally Posted by Holder350 View Post
Your antenna is electrically too long.

Are you checking your swr with an external meter and out in an area away from buildings and electrical sources?
External meter. I' checking it in my garage which is where I've always checked it and had perfect readings, just this 3ft antenna that is giving me issues.


Quote:
Originally Posted by JPNinPA View Post
This ^^ Be sure your cable is not looped into a RF choke.

Or pinched by making sharp turns.
It may or may not be looped, it is kind of folded back over itself a few times, not really looped.

I am going to try and change the mounting bracket and put it on some 3x3 angle iron to raise it up or something.
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If you've ever been in that traffic, you would have ground down the steering wheel with a death grip too. "Just ****ing GOOOOOO!!!!"[/QUOTE]
[QUOTE=Luuca;15713642]I pitty anyone who tries to reach into that netting unaware.[/QUOTE]
'99 TJ (DD)
'89 XJ (WIP)
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Unread 10-06-2013, 08:20 PM   #11
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Quote:
Originally Posted by Agent620 View Post
External meter. I' checking it in my garage which is where I've always checked it and had perfect readings, just this 3ft antenna that is giving me issues.
You should be testing out in an open area away from power lines and buildings.

Testing inside a garage will likely give you a false reading.

Sent from my phone where correct grammar is difficult.
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Quote:
Originally Posted by Azzy View Post
You can tell the character of a person in how they treat someone who can do nothing for them.
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Unread 10-07-2013, 04:57 PM   #12
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Yes you will get a false reading in a garage. I've been a ham and cb tech for 20 years. Open spaces.
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Unread 10-08-2013, 08:23 PM   #13
Agent620
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Tested in an open field today, no change really.

2.0 swr on 4, 2.5 on 20.
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[QUOTE=Anticanman;15443763]Chris Hansen is reading this thread.

If you've ever been in that traffic, you would have ground down the steering wheel with a death grip too. "Just ****ing GOOOOOO!!!!"[/QUOTE]
[QUOTE=Luuca;15713642]I pitty anyone who tries to reach into that netting unaware.[/QUOTE]
'99 TJ (DD)
'89 XJ (WIP)
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Unread 10-08-2013, 08:43 PM   #14
Holder350
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Have you tuned the antenna as short as it will go?

Sent from my phone where correct grammar is difficult.
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98' XJ Classic - D30/C8.25 - 4.5" RC Lift - 33x12.50R15 - 4.0 HO - AW4 - NP231
Quote:
Originally Posted by Azzy View Post
You can tell the character of a person in how they treat someone who can do nothing for them.
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Unread 10-08-2013, 09:03 PM   #15
JPNinPA
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I'd start over with basics.
Verify continuity of the center conductor from the back of the radio to the tip if the antenna.
Then continuity and resistance od the outer shield at the back of the radio to a good ground point on the body of the vehicle.
Verify there is no continuity between the center conductor to the outer shield at the radio. Do all without disassembling the antenna just remove the cable from the back of the radio.
Resistance in the ground should be under 5 ohms. The lower the better.
If you do not have these continuities where you should there is something broken, damaged or installed improperly.


You mention your antenna is on the rear tailgate? The hinges make poor ground conductors and cause many SWR issues.
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