Independent Ground Aerial ???

Submitted: Tuesday, Feb 23, 2010 at 22:40

ThreadID: 76277 Views:6340 Replies:4 FollowUps:7

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UHF Radio

If you are considering a trip into Australia’s vast outback, then a UHF Radio is an important communications device to have. Besides the entertainment value, such as chatting with other travellers,

Member - Wayne B (NSW)

What dose that mean and how do I know if the one fitted to my car is ground independent or not

I have an aerial mounted on the B / Bar, came with the vehicle ( No radio Though). I have no idea what Db it is or even if it is for UHF. I have ordered a new UHF Radio and 6.5db Aerial which looks like it will simply screw on to the original mounting on the Bar.

I suppose I am simply trying to avoid mounting the New Base and running the led through the vehicle if I don't have to.
Thanks
Wayne B

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Reply By: Notso - Tuesday, Feb 23, 2010 at 23:16

Tuesday, Feb 23, 2010 at 23:16

Check out this post.

Posts

AnswerID: 405668

Follow Up By: Member - Wayne B (NSW) - Tuesday, Feb 23, 2010 at 23:42

Tuesday, Feb 23, 2010 at 23:42

Ok Most of that went over my head. However I understand the difference between GI and Not GI. I really need to know if the Independent bit is in the Base or in the actual aerial. Also if some one shows you 2 aerials one Non GI and the other GI, how do you tell the difference when you are looking at them.

Thanks
WayneB

FollowupID: 675400

Follow Up By: Member - Wayne B (NSW) - Tuesday, Feb 23, 2010 at 23:47

Tuesday, Feb 23, 2010 at 23:47

For example Say I have a Non GI Aerial on the B/Bar. I then get a Independent Ground aerial and screw it on the the original base, Do I now have a fully operational Independent Ground aerial.
I think that is what i am trying to find out.
Thank you
Wayne B

FollowupID: 675404

Follow Up By: vk1dx - Wednesday, Feb 24, 2010 at 08:45

Wednesday, Feb 24, 2010 at 08:45

Wayne

Odds are the answer is NO. They wont mix.

The normal ground dependant antenna mount looks just the top row at this link.The top row are the normal CB ground dependant antenna mounts

A common ground independant base normally has a short tube on it with the coax running up through the middle of it. If you scroll down this link you will see antennas that "supply their own earth" At first glance the first gound independant antenna is the RF470. Mainly tube type bases with the coax runnint straight up into the bottom of the assembly.UHF CB Antennas

Again I would say they will not "counter" mount unless someone has put some kind of adaptor on them.

Does the old base look like one of these at the top: Basic ground dependant base

Phil

FollowupID: 675428

Follow Up By: Member - Mike DID - Wednesday, Feb 24, 2010 at 09:01

Wednesday, Feb 24, 2010 at 09:01

"I then get a Independent Ground aerial and screw it on the the original base, Do I now have a fully operational Independent Ground aerial. "

- Yes

FollowupID: 675429

Follow Up By: vk1dx - Wednesday, Feb 24, 2010 at 09:21

Wednesday, Feb 24, 2010 at 09:21

Mike

Wouldn't it be best to see if we can find out what type of base he has first.

The base may be a non CB commercial specific to service type of base Might even be from one of those early suitcase mobile phones.

Phil

FollowupID: 675431

Follow Up By: vk1dx - Wednesday, Feb 24, 2010 at 09:46

Wednesday, Feb 24, 2010 at 09:46

Sorry Wayne. I was not aware the links to the antenna bases I wanted you to look at did not work.

Is it like the ones at the top of the page when you to this link and click on Bases, cables and Accessories near the top right hand corner?

Click on Bases, Cables and Accessories

Is it like these?

Phil

FollowupID: 675437

Reply By: vk1dx - Wednesday, Feb 24, 2010 at 05:38

Wednesday, Feb 24, 2010 at 05:38

How about this explanation. And its based on the ground independent design of the antenna that we have.

There are always two parts of an antenna. Some call them the positive and negative side. Others call them the active and earth (or ground side).

Our antenna consists of a metal mount on the bullbar with a spring in it. On to the spring is a metal tube about 25 to 30 cms long. The coax comes up through the centre of the mount, the spring and the tube. The coax is opened up with the outer braid connected back to the metal tube. This forms the negative or ground part of the antenna. The centre of the coax is connected to a coax connector into which the active (or positive) part of the antenna is mounted.

Summing up; A ground independant antenna basically consists of two parts. The "ground" section (spring and tube) below the connector and its active part being everything from the connector up including the "antenna" you screw into the top. See the antenna assembly on the left in the link below.

Hope this helps.

Phil

The antenna on the left is ours.

AnswerID: 405688

Reply By: Member - Mike DID - Wednesday, Feb 24, 2010 at 18:16

Wednesday, Feb 24, 2010 at 18:16

There are three types of antenna bases

- Single conductor
A single conductor that's a 5/16ths or 3/8ths metal screw. Definitely NOT Ground Independant.

- Two conductors
Usually a coaxial socket (SO239) as seen on the back of a CB radio to match a PL259 plug. Could be Ground Independant or Ground Dependant.

- Fixed Cable
The antenna is permanently connected to the base of the antenna. Nearly always a Ground Independant Antenna.

AnswerID: 405784

Follow Up By: vk1dx - Wednesday, Feb 24, 2010 at 20:54

Wednesday, Feb 24, 2010 at 20:54

Exactly Mike.

This is why I asked him if it he could give us a guide to the antenna type.

Then we can proceed. Its a bit difficult doing it blind.

Wayne

Did you look at the link and see which model antenna base you have?

Phil

FollowupID: 675527