Amateur radio, which has been around since the early days of radio, allows operators to be able to transmit on allocated frequencies aside from the handful of channels on 27MHz and the PMR446 service in Europe.
To transmit on the Amateur bands requires a license issued by the communications regulator, in the UK this is currently Ofcom. To obtain the license requires taking a course and then a test at the end. There are currently 3 tiers of license in the UK, Foundation, which gives you a callsign beginning M7 (previously M6 and M3 which can still be heard on the bands) and limits you to 10 watts though you will probably find 10 watts is more than enough to make long distance contacts, Intermediate, which gives you a callsign in the 2×0 series (x represents a letter depending on which country of the UK the callsign is used in), 50 watts and a few more bands, and full which gives you a callsign in the M0 series, 400 watts, access to all Amateur bands allocated in the UK, ability to operate overseas, and ability to apply to run beacons and repeaters and unattended gateways.
Amateur radio can be listened to by anyone licensed or not with the right equipment, this can be helpful if you are wanting to get an idea of what is going on on the bands, to listen you just need a scanner that covers all the bands you want to listen to, the cheapest option is the inexpensive RTL-SDR. Any specialist radio retailer will be able to assist you on which piece of equipment is most suited to your needs
The Amateur bands are usually referred to by wavelength rather than frequency, the shorter the wavelength, the higher the frequency, below are a few examples.
- 10 Meters – usually around 28MHz
- 2 Meters – usually between 144 and 146MHz, a lot of repeaters are used here, see next topic
- 70 centimeters – usually around 430 to 440MHz, part of this is coshared with LPD433 and the primary user is the military, in some countries it extends down to 420MHz and up to 450MHz, but normally this is outside of ITU region 1
I will update this fully later
Repeaters are normally found in the 2 meter and 70 cm bands, due to the nature of the bands, these usually have 2 frequencies, an input which the repeater listens on, and an output which it transmits on. Repeaters are normally protected by either a 1750Hz tone burst requirement (getting rare now as repeaters get modernised) or CTCSS, and are generally found in high locations to ensure the best coverage. A lot of repeaters now are also connected to the Echolink system, meaning an Amateur radio operator can use their computer and the Echolink software once their callsign is verified onto the Echolink system to use repeaters all over the world. Repeaters can also be linked to other repeaters on the Echolink systems, other similar systems exist such as IRLP.
If you wish to listen to the transmissions of your local repeater, identify it’s output frequency, you can normally find information on repeaters by doing a Google search or going via websites such as that of the Radio Society of Great Britain
The radios used for Amateur radio use generally fall into 3 types
- Home base – Large and bulky, most have various different bands on them, normally for the lower bands such as 10 meters and below but some cover VHF and UHF.
- Mobile – these can be used both in a vehicle and at home, generally for higher bands such as 10 meters and up though some can go as low as 160 meters
- Handheld – usually available for either 2 meters, 70cm, or both, generally supplied with a battery pack, a detachable antenna, a belt clip, and a drop-in charger. They near enough always have a keypad for entering the required frequency or sending DTMF to control a repeater, can be uses in the car with a speaker microphone, battery eliminator, and external antenna, though in some cases a small adaptor is usually needed such as SMA to BNC or SMA to SO239 depending on the radio and antenna
Amateur radios generally include features not found on CB radios, such as a switch to select mode of transmission, including CW which is used with a morse key, DTMF dialling, VFO selection, transmit power selection, auto tuner, as well as the usual volume and squelch controls, and S-meter
The frequency you operate on will dictate the size of the antenna practical to use on it, though some antennas can work on multiple bands, and in other cases an antenna tuner will be needed, sometimes found in the radio though sometimes not so an external one is used to create the match, though the antenna will still not be efficent. Some antennas for CB have enough bandwidth to cover the 12 through to 10 meter bands, though not all do, also you can make your own antenna out of some wire, which, along with insulators and baluns, are sold at most radio suppliers.
There are other Amateur radio accessories available, these are as follows:
- Desk microphones – Some people use these instead of the normal hand microphone supplied with the radio, these are in most cases preamplified and incorporate features such as a locking PTT switch for those longer overs, tone controls, and a VU meter, when using such microphones, care must be taken to not cause overmodulation, as this will cause distortion and possible bleedover
- BCI/TVI filter – This device sits permanently inline between the radio and the antenna, it’s purpose is to reduce interference, it does this by attenuating anything not on frequency, harmonics to be precise, use one as good RF housekeeping, it is a requirement to check you are not causing interference and deal with any interference complaints received to make sure you are not the cause of it
- Linear amplifier – This device sits permanently in line with between the radio and antenna, it is used for increasing the transmit power above what the radio can put out, however you must check the power restrictions on your license, as UK foundation license holders are restricted to 10 watts they should not use one of these as the power output will normally be above that, if you choose to use one, use 2 BCI filters, one between the radio and the amplifier, and one between the amplifier and the antenna, this will keep the harmonic interference down. It is also important to know if the antenna you are using can handle the power being fed to it or you risk damaging it.
- Extension speaker – This is in it’s simplest form, a loudspeaker in an enclosure and can be made at home, there are also some with tone controls to reduce the harshness of some signals, this is used either when your mobile radio is used in a homebase installation, or if used in a vehicle, in the shack or out portable a pair of headphones may be a better choice.
- Dummy load – takes the place of an antenna and is used to test the radio to ensure it is working, the simplest type contains a special light bulb that lights up when transmitting, this sort is normally rated at 5 watts, so suitable for low output radios, there are others with higher ratings for more powerful equipment. Always make sure there is a load connected, be it an antenna or dummy load, devices such as switches (see below) or meters do not count as a load, and radio damage can result if you key up.
- Antenna switch – This device, connected permanently, allows you to connect two antennas to a radio or two radios to an antenna, if used to connect two radios to one Antenna it is important to make sure that the radio you use is the one with the load, or damage to the radio will occur, the switch alone is not a load, so take care.
- Antenna rotator – As directional beam antennas are permissable on the Amateur bands, this device helps to point the antenna in whatever direction the operator so desires without having to go up the tower or onto the roof and do it manually.
- Speaker microphone – Used normally with handheld radios in a homebase or mobile environment
- Antenna tuner – actually an antenna matcher, presents the correct impedance to the radio and makes the best of a bad situation, the antenna may still be inefficient, it is better to use the correct antenna for the band you’re operating however in many cases this simply is not possible