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johnnyfixit
Joined: 05 Oct 2005 Posts: 70 Location: Durham
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Posted: Sat Oct 24, 2009 19:53 Post subject: cb help needed |
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I have a kitcar that I want to fit a cb into can anybody recommend a decent aerial that
1 doesn't need a ground
2 looks neat when fitted (as I don't really want more holes in my cabroilet)
3 I don't have a boot or gutter to fit it on
4 has to be a good match to my cobra 29 uk st
5 not white like other marine aerials
6 decent make
7 easy to take off when not in use
cheers Johnny _________________ honor is what a man gives himself,a voice inside him which gets louder the older he gets. its up to you to listen! |
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Posted: Sat Oct 24, 2009 19:53 Post subject: Google Ads keep this community free to join! |
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primate1970 Lifetime member
Joined: 30 Jun 2007 Posts: 1076 Location: north staffordshire
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Posted: Sat Oct 24, 2009 21:40 Post subject: |
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I'm not to sure but I think most Aerials need some sort of ground...? (ie need to be mounted either by magnet or by a bracket/hole in body)
I don't think the range would be very good and at worst could damage your CB if it's not transmitting properly..??
You can get some decent/neat mounting brackets nowdays and could always put a quick release on the antenna to make it easier to remove..???
As far as a the rig you can get some really neat sets now with front mounted speakers and fit in a standard DIN hole..
Try here... http://www.lorrybits.com/index.php?cPath=168&oscsid=8ea8cac5f3da7fa1f12a05b78de28bb7
Why not post up a pic of your car and see if we can tell you where to stick it????
HTH Ric. _________________ 霊長目1970年
Do not walk behind me, for I may not lead. Do not walk ahead of me, for I may not follow. Do not walk beside me, either. Just leave me alone. |
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johnnyfixit
Joined: 05 Oct 2005 Posts: 70 Location: Durham
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Posted: Sat Oct 24, 2009 21:49 Post subject: |
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just for you
I know you can get marine aerials that don't need a ground (egp) could I ground a normal one to the sub frame :?
then again wor lass will need one too
_________________ honor is what a man gives himself,a voice inside him which gets louder the older he gets. its up to you to listen! |
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Lewis Site Admin
Joined: 25 May 2006 Posts: 16299 Location: Huddersfield
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Posted: Sun Oct 25, 2009 1:40 Post subject: |
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Note that an antennae 'Ground' is not the same as 'earthing'. When refering to a Ground in relation to Antennae the correct phrase is 'Ground Plane', which is a conductive metal surface acting as a reflector for the antennae signal. Like the large rear section of a normal TV antennae. Think of the whip part of the antennae as being half of it and the vehicle being the other half.
With cars that have metal in the bodywork the car acts as a 1/4 wave groundplane and the larger the reflective surface around it then the better the efficiency of the antennae. An Artic with a CB has a much better efficiency than a Tranny van and a Van is better than a Mini.
Ground Plane kits exist as a mounting base for mobile whips, and have several wire terminals or hardwired ground radials attached. These kits are designed to have a mobile whip screwed on top. The ground radials take the place of the vehicle body, which is used as the reflector for the mobile whip in a typical vehicle installation.
A suitable mobile antenna for your vehicle would be a continuously-loaded half-wave antenna. These do not necessarily require a ground plane to present a near 50 Ohm load to the radio, and are often used on fiberglass vehicles such as snowmobiles or boats.
Note that Marine radio's operate at a higher frequency so their antennae are not suitable for CB's. All CB antennae need to be tuned to the radio, otherwise you run the risk of damaging it.
HTH _________________
Copyright is retained for all my photos. Please don't copy them without asking permission
Do not blindly go where the path may lead you. Go where there is no path and leave a trail that others may follow!
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Landrover lover
Joined: 23 Dec 2008 Posts: 36 Location: Oldham
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Posted: Sat Oct 31, 2009 13:52 Post subject: |
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The main problem you are facing is the mount for the antenna. You say no holes but you need to find some way of fixing the antenna. A marine type antenna has a small matching device in the base of the antenna as these type of antennas are designed primarily for GRP or wooden boats. You could use a normal CB antenna and base and then connect some wire from the earth side of the antenna base to the chassis (on the inside of the car out of site) which would probably work or you could use a few pieces of wire tucked out of the way. The length of the wires used would need to be worked out depending upon the wave length of the antenna. I would try the wire to chassis first as this will probably work but remember you must CHECK THE SWR as you may find you will need to adjust the antenna length slightly. Or buy a handheld
John |
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m0jfk
Joined: 19 Oct 2009 Posts: 11 Location: St Helens Lancashire
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Posted: Wed Nov 25, 2009 23:44 Post subject: Antenna tuning |
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Can I add here that the radio is 50ohm's by design the coax or cable that go's to the antenna is 50hms by design what is not 50ohm's by design is the Antenna and its by making the antenna bigger or smaller by sliding the antenna's whip up and down in its holder that you try to make the antenna become 50ohm's otherwise an out of match system will be evident and will show up on the SWR meter. You can have a antenna standing in free air with no ground anywhere near it and it will be matched giving a Isotropic value (a perfect zero loss match to the 50ohm's) however in the real world this does not exist and what your trying to do is make the antenna 50ohm's in relation to the place your trying to mount it also taking into account your location and the vehicle itself because even passing a large building will make your SWR reading rise and lower...try it and see. |
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Lewis Site Admin
Joined: 25 May 2006 Posts: 16299 Location: Huddersfield
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Posted: Thu Nov 26, 2009 11:30 Post subject: Re: Antenna tuning |
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m0jfk wrote: |
Can I add here that the radio is 50ohm's by design the coax or cable that go's to the antenna is 50hms by design what is not 50ohm's by design is the Antenna and its by making the antenna bigger or smaller by sliding the antenna's whip up and down in its holder that you try to make the antenna become 50ohm's otherwise an out of match system will be evident and will show up on the SWR meter. You can have a antenna standing in free air with no ground anywhere near it and it will be matched giving a Isotropic value (a perfect zero loss match to the 50ohm's) however in the real world this does not exist and what your trying to do is make the antenna 50ohm's in relation to the place your trying to mount it also taking into account your location and the vehicle itself because even passing a large building will make your SWR reading rise and lower...try it and see. |
Could you say that again in English please! _________________
Copyright is retained for all my photos. Please don't copy them without asking permission
Do not blindly go where the path may lead you. Go where there is no path and leave a trail that others may follow!
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m0jfk
Joined: 19 Oct 2009 Posts: 11 Location: St Helens Lancashire
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Posted: Thu Nov 26, 2009 18:41 Post subject: In English? |
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lol ... :D sorry I thought everyone on here spoke Spanish. |
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