The UK has a network of around 300 amateur radio repeaters. These are mainly on 2 metres and 70cm, although there are repeaters for other bands and modes. There is a comprehensive list of all of the UK’s repeaters at www.ukrepeater.net – Here, you’ll find some advice on setting up and using a repeater, plus some common terms.
How does a repeater work?
A repeater can receive a weak signal, or a signal from a portable or mobile user, and re-transmit it over a wider area. A repeater listens on a particular frequency, called the Input frequency. If it hears a valid signal, it will re-transmit the signal on the Output frequency. Only one person should transmit at a time, otherwise the signals will be lost.
Accessing the GB3GU Repeater
Before you can use a repeater, you will need to programme your radio with the settings for that repeater. How this is done varies with each radio, and you will need to refer to the manual, or chat to someone familiar with that radio to work out how to enter and store the settings correctly.Many find it easier to get a cable and connect the radio to a computer to use that for programming, as it’s often easier than the fiddly on-screen menu on the radio.
To access GB3GU you will need the following information.
Output Frequency: The frequency that the repeater transmits on, and you listen on for GB3GU this is 433.325Mhz
The Offset: The difference between the Output and the Input frequencies and for GB3GU a positive 1.6Mhz sift is required. So you transmit on 434.925Mhz
A CTCSS tone B 71.9Hz or a 1750Hz tone burst is required for accessing GB3GU. This is required to allow your signal to be forwarded by the repeater
You need to program your radio to switch from the Output to the Input frequency when you push the Transmit button, and to send the correct identifying tone. Only then will the repeater let you pass a message. Once you have the settings correct, save them to a memory on the radio for easy use next time.
Over-deviating: Transmitting with too much audio energy / volume will result in over-deviation, and the audio ‘clipping’ and not being completely readable. When programming your radio for a 70 cms voice repeater, you would normally want to set the Bandwidth to “Narrow”, and not “Wide”, to help reduce the risk of over-deviation. It’s also imporant not to set the ‘mic gain’ too high, or if you have a loud voice, to talk too close to the mic, or shout.
Using a repeater
Before getting started with repeaters, it’s a good idea to have a listen to your local repeater to see what the etiquette is for using that repeater. Some things you should know:
Calling “CQ” on a repeater is generally not done. Instead, if you’re looking for a contact, say something like: “GU0ABC listening for any calls”
Repeaters are primarily for mobile-to-mobile use. Many people do use repeaters at home, but you should always give priority to mobile users who need to get a call out, and leave pauses so that others can get in.
Break’ – Those looking to join in an existing conversation on a repeater, or to get a priority message out will normally wait for a pause between ‘overs’ and call “break”. The next person to speak should bring in the station to let them send their message, or join the chat. You will often hear “break acknowledged”
Timeout – The GB3GU repeater has a timeout to guard against people keeping the repeater open for too long. The GB3GU repeater has a timeout of only 90 seconds, to encourage users to keep their ‘overs’ short.
When someone stops talking and releases the transmit button, the repeater sends out a tone. This is to confirm that the repeater as reset the timeout. Try not to talk over the tone.
RB13 Repeater Output
433.325 MHz Repeater Input
434.925 MHz CTCSS B-71.9Hz or 1750Hz Tone Burst
49.2800N,2.3230W Repeater Keeper GU6EFB QTHR
Serving Guernsey and the Channel Islands.
The contours represent 24dBµV/m (magenta), 32dBµV/m (blue) for a receiving antenna of 0dBd gain at 1.5 metres above ground level.
As is the case with all radio amateur situations, reception may be obtained by the use of improved gain and favourable locations.