Cutting cb antenna coax, any effects?

Submitted: Monday, Mar 09, 2009 at 13:19
ThreadID: 66661 Views:5568 Replies:7 FollowUps:5
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G'day

I need to remove my antenna from my bullbar (gettin new bar fitted) and the antenna doesn't have a disconnection fitting at the antenna, will it hurt cutting the coax then reconnecting using a joiner?

Regards

Chris
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Reply By: ExplorOz - David & Michelle - Monday, Mar 09, 2009 at 13:39

Monday, Mar 09, 2009 at 13:39
Chris,

Each joint has the potential to cause a loss of signal however it if far easier to put a join in the co-axial under the bonnet and join it and cover it with tape. I have done this in all my vehicles for years and never had any problems with the operations of the radio.

I think there is a better chance of stuffing up the cable or connections if you pull the whole thing out again. So for my money join it under the bonnet. If you need any help with the join see the diagram in the UHF Radio article.

David
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Follow Up By: Chris85 - Monday, Mar 09, 2009 at 14:53

Monday, Mar 09, 2009 at 14:53
Thanks for that, I think your idea is the best way to go.

Cheers
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Follow Up By: ExplorOz - David & Michelle - Monday, Mar 09, 2009 at 16:59

Monday, Mar 09, 2009 at 16:59
Chris,

I have just re-read what I wrote and the reason I pointed you at the UHF page was to look at the termination diagram as for the join I did mean to use a male and female plug and crimp/solder as per the article diagram. I did not mean solder it and tape it directly - the tape is to cover the male/female plugs completly to reduce water ingress.

Hope this helps!
David (DM) & Michelle (MM)
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Reply By: Member - Kiwi Kia - Monday, Mar 09, 2009 at 14:07

Monday, Mar 09, 2009 at 14:07
Hi Chris,
Your coax cable will not last forever, after a while it gets moisture down between the sheath and the braid and rots the braid wnere it is exposed to the air near the aerial. If the cable is older then say 5 years I would replace it, will not cost much.

.
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Reply By: Shaker - Monday, Mar 09, 2009 at 14:13

Monday, Mar 09, 2009 at 14:13
Why not just cut the plug off at the radio end & pull it through?
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Follow Up By: Chris85 - Monday, Mar 09, 2009 at 14:55

Monday, Mar 09, 2009 at 14:55
It will take alot longer doing that because I would have to dismantle part of my dash to pull the radio out.
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Reply By: Rangiephil - Monday, Mar 09, 2009 at 15:53

Monday, Mar 09, 2009 at 15:53
Usually on UHF antennas The outer sheath is captured by a threaded sleeve and the inner wire is held by a dob of solder at the top of the antenna base.

If you melt the solder and unscrew the sleeve it all will come apart, and give you the opportunity to shorten it a bit to give a fresh bit of inner and sheath for good connections.
You just cut a new bit to correct length and resolder.

Regards Philip A
AnswerID: 353084

Reply By: Nomadic Navara - Monday, Mar 09, 2009 at 15:58

Monday, Mar 09, 2009 at 15:58
Replacing the cable assumes that you can easily get to the cable termination at the bottom of the antenna. There is an increasing number of antennas that you can't get to replace the cable. I too would recommend replacing the cable if possible.

If you can not replace the cable then do not cut and rejoin the cable (by simple means.) You can not maintain the RF continuity of the cable. Get yourself a cable plug and cable jack (male and female connectors.) BNC or TNC connectors will be a lot less lossy than the PL 259 style. Crimp these onto the cut ends (or get someone else to do it for you) and use these to connect the two bits of cable together. This will allow you to remove the antenna and bull bar easily in the event that you get caught for major repairs on your vehicle.

PeterD
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AnswerID: 353086

Follow Up By: SteveL (WA) - Monday, Mar 09, 2009 at 20:08

Monday, Mar 09, 2009 at 20:08
I agree, at UHF frequencies, PL259s will cause signal loss and SWR problems.I would only use them in an emergency.-Steve
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Follow Up By: Member - Mike DID - Tuesday, Mar 10, 2009 at 15:40

Tuesday, Mar 10, 2009 at 15:40
The other advantage of BNC connectors is that they are totally waterproof - provided that they are correctly assembled.
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Reply By: MEMBER - Darian (SA) - Monday, Mar 09, 2009 at 20:04

Monday, Mar 09, 2009 at 20:04
When your antenna was built, the coax had to be installed - though a little more complicated than the PL259 plug on the radio end, and despite the very neat fit of some antenna parts, it should all unscrew and come apart, revealing the soldered end of the coax...... I have done mine that way, more than once.
AnswerID: 353135

Reply By: get outmore - Monday, Mar 09, 2009 at 22:02

Monday, Mar 09, 2009 at 22:02
I cut a slot through the bracket the ariel mounts on - no worries
AnswerID: 353170

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