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theFleured Lifetime member
Joined: 11 Jul 2012 Posts: 1810 Location: Newbury
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Posted: Sun May 19, 2013 18:42 Post subject: CB antenna |
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I've seen a few guides on how to use your CB antenna for your car radio (both at the same time) but can you do it the other way around.
I don't use my built in aerial but I do want a cb and I'd like to use the Aerial I already have if I can. _________________
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Posted: Sun May 19, 2013 18:42 Post subject: Google Ads keep this community free to join! |
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Yojimbo
Joined: 01 Dec 2005 Posts: 1202 Location: Bucks
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Posted: Sun May 19, 2013 18:51 Post subject: |
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I really wouldn't (but I admit as a licensed ham I am biased!), its been done in the past as 'stealth' antennas back in the day when a cb antenna meant "stuff you can steal inside", and you could do it, but its really too short, it would need to be matched to the right impedance, a quick google shows there are commercial products available. Basically if you did this it would work, but range would be quite restricted, if its just for greenlaning it will be okay, but it won't give anywhere near the performance of a a proper antenna using the right impedance coax to feed it. |
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theFleured Lifetime member
Joined: 11 Jul 2012 Posts: 1810 Location: Newbury
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Posted: Sun May 19, 2013 18:53 Post subject: |
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Yep, only for greenlaning so mostly the people I want to talk to will be only a few hundred meters away (although I suppose a couple of miles is possible) _________________
"The thing about quotes on the internet is that you cannot confirm their validity." - Abraham Lincoln |
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lostdreamer Lifetime member
Joined: 23 Sep 2011 Posts: 104 Location: Coventry
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Posted: Sun May 19, 2013 19:04 Post subject: |
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Interesting idea...
My understanding is 'yes, but you probably don't want to'.
It will be the wrong length, and therefore won't transmit/receive very well.
You may also get SWR issues leading to you overloading the output transistors and frying the CB.
That said, assuming it is for 'green lane' use, the limit on range seems to be mostly line of sight/tree/random rather than too dependent on the intricacies of the CB setup.
And using that steel whip in the drivers door pillar would give you a nicely protected and resilient aerial...
One of the interesting drawbacks of CB's however is it is often very hard to tell how well your own setup is performing - you don't hear it, and you don't know if difficulty picking up other users is down to environment, their setup or your own.
So I dunno. Would be kindof interested in seeing someone else try it and how it works tho... |
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Yojimbo
Joined: 01 Dec 2005 Posts: 1202 Location: Bucks
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Posted: Sun May 19, 2013 19:05 Post subject: |
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It would probably be easier to modify the existing mount to take one of the small, but very inefficient antennas that are around. Such as the original 'rubber duck' style, or short whip based antenna. |
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Yojimbo
Joined: 01 Dec 2005 Posts: 1202 Location: Bucks
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theFleured Lifetime member
Joined: 11 Jul 2012 Posts: 1810 Location: Newbury
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Posted: Mon May 20, 2013 19:11 Post subject: |
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I'm going to give it a go using just the stock ariel, I don't use it for the radio at all _________________
"The thing about quotes on the internet is that you cannot confirm their validity." - Abraham Lincoln |
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Yojimbo
Joined: 01 Dec 2005 Posts: 1202 Location: Bucks
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Posted: Mon May 20, 2013 19:15 Post subject: |
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okay the swr will be through the roof and the cb will go bang.
HTH
Oh and please get a nice rig, I will be happy to take it off you and repair it when you blow it up. |
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theFleured Lifetime member
Joined: 11 Jul 2012 Posts: 1810 Location: Newbury
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Posted: Mon May 20, 2013 19:19 Post subject: |
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It will be the shittiest one I can find _________________
"The thing about quotes on the internet is that you cannot confirm their validity." - Abraham Lincoln |
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theFleured Lifetime member
Joined: 11 Jul 2012 Posts: 1810 Location: Newbury
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Posted: Mon May 20, 2013 19:24 Post subject: |
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I'm kidding, I'll find a long thin ariel and see if I can mount it into the existing body so it can still slide out of sight. _________________
"The thing about quotes on the internet is that you cannot confirm their validity." - Abraham Lincoln |
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Yojimbo
Joined: 01 Dec 2005 Posts: 1202 Location: Bucks
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Posted: Mon May 20, 2013 19:35 Post subject: |
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Righto.
As a technical point you won't see an swr below around 2:1 as the impedance of the car radio coax is wrong.
You will also need an antenna in the region of 102" or roughly 9 foot, if its a pure whip.
You might get away with with something a little shorter since the coax will screw up the tuning anyway. But it won't be by much. |
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theFleured Lifetime member
Joined: 11 Jul 2012 Posts: 1810 Location: Newbury
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Posted: Mon May 20, 2013 19:37 Post subject: |
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I noticed you can get just wore antenna, are these rubbish or would running one around the headlining of the car get good reception? _________________
"The thing about quotes on the internet is that you cannot confirm their validity." - Abraham Lincoln |
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Yojimbo
Joined: 01 Dec 2005 Posts: 1202 Location: Bucks
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Posted: Mon May 20, 2013 19:50 Post subject: |
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Wire works very well, in the sky. However shielded inside the vehicle, next to what is also the earth its not going to be a happy bunny, and we get back to you letting the magic smoke out of the finals.
If you put a fibreglass poptop on it would possibly work! |
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Yojimbo
Joined: 01 Dec 2005 Posts: 1202 Location: Bucks
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Posted: Mon May 20, 2013 19:54 Post subject: |
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Just to clarify (lol, see what I did there? No? okay...) it would receive, it's transmitting thats the problem, you can receive on a wet piece of string. |
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theFleured Lifetime member
Joined: 11 Jul 2012 Posts: 1810 Location: Newbury
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Posted: Mon May 20, 2013 20:21 Post subject: |
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I've just bought a cheap kit, that way if I mess anything up It won't have cost me much money _________________
"The thing about quotes on the internet is that you cannot confirm their validity." - Abraham Lincoln |
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PinkPig Lifetime member
Joined: 05 Aug 2004 Posts: 2720 Location: Southampton, UK
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Yojimbo
Joined: 01 Dec 2005 Posts: 1202 Location: Bucks
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Posted: Mon May 20, 2013 20:48 Post subject: |
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Wire in the sky, my friends, thats what counts:
What actually happens under high swr is that the transistors actually back off their output, they can survive a surprisingly long time, but the smoke eventually escapes, if you could lower the power then they will cope a lot better.
Antenna matchers are a possibility, but it matches the impedance so that the radio can put out full power into the load, the antenna, being non-resonant still won't work well, but, at green laning ranges might be enough, even without the ATU.
Ultimately it goes against the grain to have an ineffective antenna, its the single most important part of the system, bit like buying a nice car and putting crap tyres on. |
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alex3025
Joined: 26 Nov 2011 Posts: 300 Location: Torrox Spain, Falkirk before that
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Posted: Mon May 20, 2013 23:36 Post subject: |
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Is that a 40 meter on the bull bar ? Iv the same one on other side
_________________ "Understeer" is when you hit the fence with the front of the car. "Oversteer" is when you hit the fence with the rear of the car. "Horsepower" is how fast you hit the fence. "Torque" is how far you take the fence with you. |
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Yojimbo
Joined: 01 Dec 2005 Posts: 1202 Location: Bucks
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Posted: Tue May 21, 2013 0:50 Post subject: |
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Close! Count the coils better! Its a 20, with a vhf/uhf dual bander on the mirror ;-)
73 de M0YOJ |
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Bat 21
Joined: 09 Jun 2013 Posts: 7 Location: Tauranga New Zealand
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Posted: Mon Jun 17, 2013 8:00 Post subject: |
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We use both VHF & UHF down here (NZ) the truckers generally use VHF and 4x4 the UHF, Pays to have both as the truckies give you the heads up where the police are hiding with the speed cameras. Having just bought the super exceed the cb will be next to go on, a loaded antenna giving overall lenfth of about 600mm.
Used it in a previous vehicle and got pretty good range (20K's) like everything its dependant on the terrain as much as your install!! |
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