Clansman type antennas, -are they ok to use for C.B. radio use?

[oily]

Hi, not sure if this is the correct location for my post/thread...

In addition to my Saracen, I have, and run as my everyday vehicle, a mini-based kit-car, which sort of resembles a Light-Strike type off-road buggy, albeit a 'shrunk-in-the-wash' version.

I have repainted it in DBG, and have started to adorn it with military type accessories, jerry-can, pick, shovel etc. I use it regularly for green-laning, and at off-road fun parks, some of which advise using a C.B. Radio to call for assistance. I have a minature C.B. Radio ready to install, and was wondering if it was possible to use a clansman type antenna for the C.B. and just make up a lead to suit.... some mates say I'll blow a transistor or 2 in the C.B. because the antenna might draw to manny watts or something... I didn't really understand what was meant.

Can anyone throw any light upon my dilemma?

[Pete]

I remember in my old CB days that we had to "SWR in" our twigs. ie, adjust the length of the aerial to suit the body (ground plane) that they were mounted on.

Hope this helps:

http://www.4x4cb.com/public/page.cfm?Page=795

[andrewroberts.1953]

Like all antennas, with the correct tuner unit you can use them for any frequency. However, that's not likely with what you are trying to do. It will be much simpler to use a purpose made antenna. Even that will not be easy, as you don't have what is call much of a "ground plane". You will need to try and antenna at several places on the vehicle, with an SWR meter in place. You need to place the antenna to get the lowest SWR at mid channel numbers. If the SWR is more that 1.5 to 1, you would be better of shouting and the output transistors of the radio will get cooked.

[lightweight]

I don't know if this helps, but I have a normal clansman aerial mounted on the normal bracket on the 101.

 

When I did the London to Brighton Run, I removed the aerial base from the vehicle mount, bolted a circular piece of steel in its place (to provide a magnet-friendly surface) and whacked a magnetic cb aerial mount on top of it.

 

This way I can swap the two aerials over depending on whether I was out 'military' or doing Land Rover type events.

 

I'm swapping it for an Aussie style mount so am hoping that my plate will transfer straight over....

[gazzaw]

as already stated you need to SWR the Antenna in to represent a 1/4, 1/2 or full wavelength suitable to the transceiver. what you can get is an electronic antenna tuner that will 'electronically' adjust the antenna length to achive the lowest SWR reading. This acts similar to the TUAAM unit on the clansman vehicle mounted VHF radios etc (PRC353) Depending on the radio wattage will determine how much you can 'push out' in radio waves =distance and clarity etc.

And sometimes depending on the antenna and the radio wattage this can overload the electronic circuits so the set up would need an amplifier unit to amplify or provide more wattage to overcome the resistance required to push out the signal etc.

 

Again, as already stated, you will need to provide a good ground plane for the antenna -you might want to look at vehicles and trucks that are fibreglass etc (Some fodens etc) and what they had to do to provide a groundplane and get a lower SWR. It is possible and there are different ways to overcome this.

 

hope it helps

 

Gary

[andrewroberts.1953]

As a rule of thubm, a ground plane needs to be as large in diameter as the antenna is long. It should be as close to a flat perfect conductor. This is why the VHF antenna (CB frequencies are very close), fitted to the front wings of Landrovers for Clansman etc, are very poor from an efficancy point of view. And why at times, you moust point the vehicle to get the coverage in the correct direction. The best place would be in the middle of the vehicle, but that's very hard in most practical cases.

I have spent my whole working life doing this, and dune buggy type vehicles are the hardest. to get one project to transmit 10% of the transmitter power, cost the well over 20 times the cost of the vehicle. Also remember, modern electroincs don't like porr radio installs. We have to check things like anti-lock breaks, before the vehicle can be signed offf as safe. If you don't do it right, your insurance is void, as is your vehicle type approval.