It completely depends on sunspot intensity on the surface of the sun. Other days there is no skip and you can only talk line of sight. Some days it is very strong and you can talk all over the world. At 2007 we are just past the lowest activity part of the cycle. Sunspots which cause skip are on an 11 year cycle (currently cycle 24), therefore band conditions go on a 11 year cycle. Some serious DX stations run hundreds of watts and the odd few have over 1000w or more to play with. Low power stations in theory can still DX, however with all the high powered stations they are sometimes drowned out by the higher powered stations. The ionosphere is between 30-250 miles above the earths surface. It is possible for the signals to bounce off the charged ionosphere and end up 100 miles away, or up to 12,000 miles away on the other side of the world. This is caused when solar magnetic radiation emanating from sunspots (magnetic storms on the sun) charges the Earth’s ionosphere causing it to act like a mirror for radio signals. The higher you are (you guessed it) the less obstruction there is, this also means you can effectively see further round the planet, remember signals travel via line of sight and then there is “SKIP” a phenomenon that allows long distance communications. Which leads on to the fact that water has virtually no obstruction so signals pass over it easily. The flatter the landscape between you and your contact the less your signal is broken down, therefore staying stronger at the receiving end. However, many things can affect distance of a transmission:
#Freeband frequencies to avoid plus
With favorable landscape 25 miles plus is not a problem for a legal set up. Generally CB in the UK was intended to transmit over short distances on FM only, however in reality this is not the case. It’s a great example of a modern all mode transceiver capable of around 40W PEP output on SSB. Shown here on the right, a typical modern day 10/11m band radio, the CRT 7900. 25 MHz – 30 MHz of course includes the legal EU and 27/81 frequencies as well as 27.555 MHz etc. New style 10m radios (28 MHz-29.7 MHz) with AM/FM/SSB that can be easily modified to cover 25 MHz to 30 MHz (usually) and some even have a built in frequency counter and power output sometimes greater than 100w.Older style FM/AM/SSB transceivers with the ability to cover more frequencies normally with slightly above normal power out i.e.Standard legal transceivers (UK FM + EU AM and SSB).
There are a few types of CB type radios available to you. What the CB community generally refer to as the 11m band or freeband is considered to cover is 25 MHz to the beginning of 28 MHz although most activity happens around 26-28 MHz. AM is also used extensively in the United States where FM mode operation is much less common and rarely used on the CB frequencies. It is however used in the USA and AUSTRALIA for instance.ĪM is also an available mode of transmission and is used legally by a number of European countries but many often favour FM for it’s audio fidelity. The other SSB mode available is LSB (Lower SideBand) this is not usually used in the UK. The normal mode used for DX in the UK is USB (Upper SideBand). Nevertheless many SSB operators usually use the “illegal” frequencies that are in between these 2 bands normally centred around the international calling freq of 27.555 USB (sometimes referred to as high-band). These are very convenient if you wish to operate a fully legal set up. Some modern CB radios such as the President McKinley contain both of the bands and can be switched between FM only and Multi Modes (AM, FM and SSB) for the EU Mid Block. Therefore we now have 40 legal channels permitted in the mid block where AM and FM are permitted at 4 watts and SSB at an output power of 12W PEP. Several years ago the UK finally came into line with most of the other European countries and legalised AM and SSB. In the United Kingdom there are 2 bands of 40 Channels that are legal to operate with: This is a small guide with a few links thrown in as an attempt to inform both new and old radio users as to the ways and means of DXing (long distance contacts) on both legal FM UK/EU bands and SSB (11m).
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