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<<<<< What Is Cb >>>>>
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GDX INTERNATIONAL DX GROUP
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1/ What is CB radio?
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CB stands for citizens band and is obviously a radio band for citizens. There are two bands available for UK users. 27/81 and PR27 (80 channels in total).
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2/ Some practicalities......
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It is a radio system that is for the personal use of radio equipment. It is for local and national communications, and in some cases, internationally. It is not intended for commercial use, some communities use it as local town security where the police monitor a channel for citizen emergency calls. Some countries restrict communication distance by law!
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3/ Who can become a CB radio operator?
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Anyone can become a CB radio operator, even the able and disabled, who come from all walks of life. CB radio is also a source for `the cheap man's Amateur' radio.
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4/ How much does it cost? (In UK)
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Seeing there are two different bands in the UK, it can vary drastically between £50 and upwards. An average station with both bands would cost under £200. The equipment can be set up just about anywhere such as a shack, garage, bedroom, study etc. Car setups cost less as they do not require transformers, and the car battery is more than adequate to drive a CB. The aerials can cost over £70. A decent car installation can cost as little as £100 or maybe around £400 to £500 for the hobbyist.
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5/A little bit of history...
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The origins of Citizens' Band Radio date back as far as the late 50's early 60's when it was decided a low power, easy to use, cheap radio system was needed in the USA for business and the local community to use.
It was decided in the early 70's to use 27 Mhz, at this time a part of the amateur band, this band was originally split into 23 channels and controlled by means of a bank of crystals one for each channel which made the radios large, and bulky the channel selection was done by a means of a rotary dial on the front of the radio with each click corresponding to its crystal inside the unit. The power output of the radio was limited to 4 watts ERP (Effective Radiating Power). and the mode of transmission was A.M. (Amplitude Modulation).
This sufficed until the demand grew and it was decided to increase the channel availability to 40, and with the advent of the silicon chip, PLL (Phased Locked Loop) control came into being, this reduced the amount of crystals in the radio to two, and the frequencies needed for the channels were mixed together and the control was now an LED rotary channel selector on the front of the radio the power output was still 4 watts but SSB Single Side band was introduced, this worked by using the same frequencies as before but making each channel available in two different modes by eliminating the need for the carrier signal needed by AM it was possible to make each channel three times larger by using USB, LSB and AM, also with the carrier signal removed more power could be concentrated into the transmission increasing the distance which the operator could talk, introducing DX (Skip Talking) over long distances and making it possible, under the right conditions, to communicate with other countries, although the latter still remains against licensing regulations. The power available on SSB is 12 watts PEP (Peak Envelope Power).
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6/ CB Radio in the United Kingdom
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CB started to be introduced into the UK in the mid 70's, with the popularity of such films as Convoy, Smokey and the Bandit, Citizens' Band and Breaker-Breaker. And the excellent TV series The Dukes Of Hazard (who can forget the lost sheep) CB became a craze, twigs were popping up everywhere, cars looked like porcupines, all 40 channels were as full as the motorway service stations were "Breakers" used to congregate until the TV shut down and then went home to cause havoc on the airwaves.
But at this stage the imported AM and SSB rigs being brought in from the States were illegal and you risked a hefty fine if caught using one.
CB was legalised by the then Home Secretary "Willie" Whitelaw on the second of November 1981, 40 channels FM (27/81), (a full band higher than the illegal sets) 4 watts output, and the craze grew.
In the early nineties an extra 40 Channels were introduced (PR27) "Mid Band or Block" depending on where you live giving us the choice of two separate radio's, later to be combined into one affectionately known as "Muppets and Mid".
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Hints & Tips For Cb Use
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GOLF DELTA X-RAY INTERNATIONAL DX GROUP
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Here are some general hints and tips for CB use:
Use the biggest aerial that you can, there is no such thing as a good, small CB aerial.
Stick to branded makes of aerials; avoid "cheapo specials."
Try to use an aerial with the loading coil in the middle (center loaded) they give much better performance.
Never coil up excess Co-Ax cable, try to use straight runs.
Use good quality Co-Ax cable - For long runs, (over 15 meters,) use RG 8 or RG 213 low loss Co-Ax.
Always solder PL-259 aerial plugs.
Mount the aerial as close as possible to the centre of the vehicle. Magnetically mounted CB aerials are very convenient, but for best performance try to use an aerial mount with a proper metal-to-metal earth or ground, such as a body, gutter, mirror or hatch back mount.
Always make sure that the aerial mount has a good earth connection, this is very important. Try to avoid joints in the Co-Ax; if you must join it, there is only one way to do it. Fit a PL-259 plugs on each end of the cable and join them together with a PL-258, (Double female,) connector.
For an easy life, try to stick to aerials that are pre-tuned in the factory such as a "Stinger." or Wilson, however, most aerials need to be SWR'ed.
SWR stands for Standing Wave Ratio, without getting too technical, this is a way of comparing the (forward,) power going to the aerial with the (reflected,) wasted power coming back if the aerial is not tuned or resonant.
To check your aerial you will need an SWR meter and a short connecting, (Patch,) lead.
You don't need to spend a fortune on a meter! Because it is a ratio, a perfect reading would be 1:1 in normal conditions however; a good reading would be 1.5:1
Getting the reading lower is really wasting your time for you get in performance, instead, why not spend more quality time with the family, or even take the dog for a long walk? You will feel better!
Something you need to understand is that SWR is not a measure of aerial performance, e.g. a big aerial with a bad SWR will still easily out-perform a small aerial with a perfect SWR.
You may have noticed that the CB has not even been mentioned, that is because the aerial is by far the most important part of your system, many people spend a small fortune on a rig, and virtually nothing on their aerial, then they wonder why they can't get out far!
Much of the "advice" that you hear on the air is WRONG. If you need to know something, ask your local CB shop. The same "on-air experts" sometimes offer to "tweak" your rig for more performance; usually they have to be repaired! You have been warned!
Good luck and happy tuning :-)
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GDX International DX Group, PO BOX 7200,
Glasgow, G46 8WA
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IS CB RADIO A DYING MEDIUM
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I hear some of you ask yourself what is a CB radio? CB stands for citizens band radio. A CB is a radio which now operates legally on FM frequencies, but hasn’t always. Breakers (operators of a CB), use to operate on AM illegally before the legalisation of it on 2nd November 1981.
Today due to a recent change in the law, breakers can now use 80 channels legally. These channels cover FCCs (26.965-27.405) and FM (27.60125-27.99125) and both operate on FM mode. However to allow for control over this medium breakers are advised to buy a licence. This licence cost a mere £10 per year, and you can contact anyone, anywhere in the world.
With new technology such as the Internet, the CB radio seems to be dying out and breakers are hanging their microphones up for a keyboard and mouse. Yes both mediums have similar qualities, but what an achievement when you make a contact using a simple set up, such as a small 40 channel CB radio producing 4 watts of power, a small magmount (1-2ft magnetic based antenna) and as little power as a 3 amp power pack.
Switching on a computer, dialling up your modem, then clicking on a chat room doesn’t need too much skill. The whole concept of the CB is much more appealing due to the factors involved when contacting these divisions (countries in which breakers operate). Weather, and positioning of your antenna are just 2 factors that have to be taken into consideration if you want your contact to go smoothly.
Sometimes it is really difficult to make a contact, something such as the language barrier or the amount of static on a channel may put you off, don’t let it. This is one of the cheapest ways of communication there is, and it is fun, useful and educational too!
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Radio Math
Here are some calculations for CB and HAM radio:
How do I find the wavelength of a frequency ?
In meters: 300 divided by frequency in MHz
In feet: 984 divided by frequency in MHz
In inches: 11,811 divided by frequency in MHz.
How do I find the frequency of a wave length ?
300 divided by wavelength in meters equals frequency in MHz.
Example, What frequency has a 6 meter wave length ?
300 divided by 6 equals 50 MHz.
How do I calculate the length of wire I need to build a wire antenna. ?
Full wave: 984 divided by frequency in MHz equals the length in feet
Three-quarter wave: 738 divided by frequency in MHz equals the length in feet
Five-eighths wave: 615 divided by frequency in MHz equals the length in feet
One-half wave: 492 divided by the frequency in MHz equals the length in feet
One-quarter wave: 246 divided by the frequency in MHz equals the length in feet
How do I convert meters to feet ?
Meters multiplied by 3.281 equals an equivalent length in feet.
How do I convert feet to meters ?
Feet multiplied by 0.3048 equals an equivalent length in meters.
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