David Bowyer's Off Road Centre
Woodworking Village Workshop
CB Radio Communication for Green Laning and Off Roading
Yes, of course, nearly everyone these days has a mobile phone, but these only allow you to speak to one person which is not much good to get a message across quickly to those in your off road convoy in a hurry. In any case, there are many parts in Wales and Scotland where you wonít have a signal!
The answer is of course to have a CB fitted in your vehicle and every vehicle in the Green Laning convoy. With CB (Citizens Band) you have instant communications between everyone in the group.
This is very important for the leader to explain to tail end Charlie the status of the gate, what might be travelling towards the group, vehicles, bikers, walkers and horses. Maybe watch out for that big rock, or a dodgy bit of track! Other things may come to mind, when we are stopping for a lunch, or somebody needs to stop for a convenience break ......., or my engines making a funny noise.
CB has been around for a long time now and became legal in the mid Seventies. CB also became license free about 10 years ago which makes life easier with one less thing to think about.
If you are serious about Green Laning and Off Roading I urge you to fit one, as it makes it so much more enjoyable and you will all feel part of the group, and you will learn from your group leader, and other useful knowledge on whatís around you and whatís ahead.
When choosing a CB, you need to work out where you are going to fit it in the vehicle. Speak to others who have them in your type of vehicle to give you ideas. They come in all shapes, styles, sizes, functions and prices to suit you.
On the top of my dashboard, Iíve got a small Midland unit, and for my restored Ninety Iíve got this all singing all dancing President Grant 11 which is going in a central roof consol. In other words, it needs to be handy to reach and see, to check itís switched on, still on the same channel, to easily adjust the volume and squelch controls.
I donít suggest that you get a model with UP/DOWN keys on the mike as itís too easy to accidentally change the channel!
You will need to go for a 40 channel UK FM model which is on the original 27 MHz band. The max output is just 4 watts, but with a good installation with a well tuned Antenna, you can reach and receive up to about 9 miles on a long straight road and absolutely no problems in the valleys and across mountain tracks, even if your convoy gets stretched out.
Having chosen your unit and screwed the bracket into place, the next thing to do is wire it up. I suggest you wire the live red wire (positive) to a live feed, so when you switch off the ignition, you donít switch the CB off every time, and possibly resetting it! All CBís have an in-line fuse for the setsí protection. Make sure too that you have a good clean earth for the black (negative) wire. If the CB is going to be moved and hidden away after off roading, you could always fit a good quality cigarette lighter plug.
The next thing to do is install a good antenna just
like the simple one I have on my Ninety. Itís a simple whip with a built in open
coil at the bottom which is set for the right length for 27MHz.
All vehicle antennas need a ground plane, i.e.: the metal of the vehicle. To get the best out of your signal, the centre of the roof is best for an even front to back throw. Second best is the centre of the back of the roof. The trouble is the first overhanging branch you are going to knock it clean off!
On a Land Rover Defender the best place you can have it is above the offside rear quarter light using a good quality gutter bracket mount to a surface mount, which I prefer the latter as it keeps your connection inside the vehicle. With either mount you keep the open coil of the antenna below the roof line which keeps it out of harmís way when driving under trees and the springiness of the loading coil with its whip will put up with most things. Iíve kept this same antenna now for at least eight years!
You can buy ready made up antenna leads in various lengths to suit the application between the gutter mount and the set and if using surface mount you could make up your own using good quality RG58/U or RG8/U coax which is easily fitted to the surface mount and solder a PL259 plug on the other end to go onto the CB.
Another bit of advice is, run an earth wire from the gutter mount, or surface mount, from their frames direct down to the chassis which we say in winch and amateur radio terms, gives the antenna a ground, a good earth!
At this stage, I have not mentioned plugging in the microphone for two good reasons! Itís not a bad idea to check out the set end of your newly installed antenna wiring. Simply use a meter or a test lamp and make sure that you donít have a connection fault between the centre pin and outside of the PL259 plug. If you are showing up a fault with a fine bit of coax outer sleeve wire touching the centre pin of the plug or at the other end of the cable thatís going into the antenna mount, sort it out now, rather than blowing up the output stage of your new CB!
The second important thing to do is to adjust the
length of the antenna whip to suit the centre of the frequency band and to
ensure that its length matches that of the radio wave. If the length is
incorrect, some of the power will not radiate, but is bounced back into the coax
and into the CB itself. If the reflected power is too high, it can cause your
output power transistors some problems.
You can find out if your antenna is the right length by using an SWR meter. An SWR meter can be purchased at most radio outlets on eBay. SWR means Standing Wave ratio. Sounds a mouthful doesnít it. Well donít let it scare you off. Itís simple.
You need a short, 1-2 foot long coaxial cable with a PL259 connector on each end. Plug in one end to your rig and the other to the socket on the meter labelled transmitter or TX. Plug the coax that goes to your antenna into the socket on your meter labelled to ANT.
Turn the knob on the meter all the way down. Put the switch in the FORWARD or CALIBRATE position. Turn on your radio and listen for other stations. It should be working normally. Tune your channel selector to some unused channel where you wonít bother anyone.
Press your mike button and without saying anything into the microphone, adjust the knob on the SWR meter until the meter reads SET, or full scale. Then flip the switch to REFLECTED or SWR and read the SWR scale of your meter.
Now that you know what it is, take your finger off that button! If the meter reads less than 1.5, your antenna is working properly. If it reads more than 2, your antenna probably needs adjustment. If it reads more than 3, check all connections at the antenna for possible bad connections, or the antenna or the centre wire of the coax might be touching the body of the vehicle. Coiling your excess coax into a small bundle can cause a high standing wave, especially with magnetic mounted antennas. When this happens, the coax can be coiled into long loops to avoid causing a high SWR.
When installing an antenna, make sure that you scrape the paint away on the underside of the gutter when the little set screws make contact. A poor ground connection here is a major cause of high SWR.
Adjusting your Antenna.
So letís say that your SWR turns out to be 2:1, and you want to bring it down. There are 2 ways to change an antennaís SWR, one is to lengthen it, and the other is to shorten it. You can figure out which way to go in the following manner: Take and SWR reading on channel 1, then take one on channel 23. Which channel had the higher SWR? If the SWR was higher on channel 23, you need to shorten the tip. If the SWR was higher on channel 1, you need to lengthen the tip. Move it about ľĒ at a time. Check the SWR on some of the middle channels and try to set the antenna so that it has the lowest SWR on the middle channels.
Most antennas have a set screw you can loosen so that the tip can slide up and down. If this does not give enough adjustment, you can cut or file ľĒ at a time off the bottom of the tip and re-insert it in the coil. Make sure to reset the SWR meter every time you take a reading.
One good rule to remember when adjusting antennas is, if you bring your hand near the loading coil or top of the antenna and the SWR goes down, the tip of the antenna needs to be lengthened, if the SWR goes up, the tip needs shortening. Donít cut too much off now!
If the SWR is high, do not hold the mike button in for more than ten seconds at a time. This is to protect the power transistors.
So now you have a really good neat, well thought out and tested installation. Youíll be set to thoroughly enjoy your next green laning trip and be fully part of all the conversation whilst driving our ancient byways and learning from each other what you see in front and each side. Thereís so much history and places of interest that can be discussed whilst driving along these routes.
Using the CB could not be easier. Before all driving off, agree a suitable channel, which is not already in use, and let the organiser or lead person do a radio check with the rest of the convoy to make sure all is well.
If you have never used a CB before, and you need to speak to a certain person, providing nobody else is speaking already, press the mike key and say ďJames, David hereĒ and say what you need to. Jamesí ear will catch on straight away and listen to what David says.
Just talk naturally into the mike, but donít hold it too close to the lips or your audio wonít sound right. Three inches away is fine. Also, let the person finish talking, count 1, 2 (to yourself), and then key up. This way you will not be chopping off the last words of their conversation! Likewise, when you have finished speaking, donít release the key too quickly.
Whereís best to put the mike? Most will probably use the supplied mike clip and screw it on the dash, but I prefer to use some wide elastic around the sun visor and let the mike simply dangle just off of it. I find this ideal as when driving you simply only need to put your left hand up to the mike and key it to speak and itís only a short distance from your mouth and when you have finished you just let go of it.
As we all know itís illegal to use a mobile phone when driving, but as I understand it, you are allowed to simply key a mike and reply to a fellow CBíer.
Talking of ĎCBĎersí, thereís no need to use CB language like the truckers do in the USA!
Other small tips: set the volume for receiving so itís just right for you and your passenger. Set the squelch to just cut out the background noise. Make sure from time to time that you are still on the same channel! If the reception is not too clever because the CB loudspeaker output is talking down onto the dashboard, if it is a bottom facing one, then fit a suitable extension loudspeaker with possibly a Noise limiter and a Noise Blanker as this can make all the difference. Some of the more expensive CBs have more buttons, switches and further functions. Learn from their handbooks and enjoy.
Thereís also a range of hand held portable battery operated CBs with rubber duck antennas, not really that good for Ďin vehicleí use, even if you connect to a cigarette lighter plug and an external antenna, but where they do score is where you send a passenger off on foot to check the track ahead. They then donít have to return to say ďyes, itís OK to proceed, or forget it, the lanes too tight or a large tree is blocking the track, or the erosion is too badĒ.
Iíve been using CB in my various Land Rovers since the mid Seventies and to me I think itís only right and proper to have one fitted and to always use it when either Green Laning on Public Byways and UCRís or at Off Road Play days. Should there be an emergency with no mobile coverage, youíll be thankful of having a good CB set up to get through to somebody on one of the channels to summon help. Incidentally, Channel 9 is only used for an emergency/assistance and Channel 19 is the Truckers channel. However, if you have a serious problem, listen on all 40 channels, open up the squelch a bit until you hear somebody to ask for their kind help in raising the alarm. I trust you will never be in a position to have to do this, but itís something to bear in mind.
Finally, I became a licensed Amateur Radio operator in the Mid Nineties, call sign M1AEI and itís my intension to fit a mobile VHF/HF transmitter into one of my vehicles and carrying the appropriate antennas to give me the capacity of calling on several Amateur radio bands to summon help should the need ever arise. Hopefully it wonít, but itís a brilliant hobby and can be fun making contacts from wherever you are in the wilds. If you are interested in becoming a Amateur Radio Operator, like many have who are part of the various Response Groups and RAYNET, please drop me an email and Iíll put you in touch with the RSGB, (Radio Society of Great Britain), and their monthly publication called RADCOM which lists all the radio clubs where you can take the exams to become fully licensed. This is a good way of combining two hobbies, Green Laning and Amateur Radio.
David Bowyer M1AEI
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