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Syllabus Sections:-

8b Repeaters

8b.1 Recall the purpose and operation of repeater and the correct procedures in using them, eg.offsets on 144 and 433MHz, "time-out" and reset tone; voice procedures.

Purpose

Initially when repeaters were conceived the idea was to allow mobile stations to make contacts over longer distances / from difficult location where due to being mobile the signal would fluctuate and thus could make a contact with another station directly difficult.

With the repeater located at an advantageous position the mobile station has a better chance of its signal reaching the repeater and being re-radiated to the other station.

Correct voice procedure

To be able to access a repeater you will need to know

where it is,

what is its input frequency, and output frequency set by the offset (more about that later)

what is the CTCSS tone / access tone.

With your transceiver set up properly you will hear the repeater if it is being used by other amateurs. It is the case that at the end of each over when the transmitting station drops carrier the repeater will give an acknowledgement tone often the letter "K" in morse code - often called the "K" tone. This is the moment for you to put a call into the repeater.

Usually this call would be as simple as "your callsign listening by". If the other stations wish you to join the QSO then they will invite you in - which is usual - else you will need to wait until they have finished their QSO.

Assuming that you are making a fresh start at the end of a previous QSO or when the repeater has been without traffic press the PTT and say "your callsign listening through the repeater for any contact". You will then hear the "K" tone when you drop the carrier by releasing the PTT. Should you not hear a "K" tone then you have not made a successful access to the repeater.

This could be for one of three reasons :-

your system is not set up property

you are too far away from the repeater

the repeater is out of action.

So wait on the frequency and after 15 minutes the repeater will give a CW ident. You will then know that the repeater is operational.

Try to access again. If still no "K" tone then assume it is your set up and check it out.

Offset

The UK repeaters on the 144MHz band use an offset from the receive frequency of minus 600kHz

The UK repeaters on the 433MHz band use an offset from the receive frequency of plus 1.6MHz

"time out"

Some of the UK repeaters have what is called a "time out".

What is a time out ??

It is a device used by the repeater keepers, usually in the software that runs the repeater, that if a contact goes over a certain length of time, say 4 minutes, the repeater automatically shuts down. This is to try ensure that users do not "hog" the air time especially when there are other users waiting to access the repeater.

When a time out has occurred the repeater needs to be "woken" up again using normal access procedure. If the original station is still talking then that station, if they are nearer the repeater than the station that re-accessed, may well end up again talking and possibly timing out again if they do not know about the "time out" device. However other users usually "politely" mention the fact and hopefully the overs of the culprit will be kept shorter - but that does not always happen.

Reset tone

The re-accessing is achieved by using the 1750Hz tone or a CTCSS tone appropriate for the repeater. These tones are programmed into a modern rig, are selected for a particular repeater and are transmitted automatically when you press the PTT but on older rigs sometimes a separate "tone burst" button has to be use in-conjunction with the PTT. The user manual must be consulted which should / will give information as to access to repeater.


The local repeater in the Medway Towns Kent is GB3IK

TX frequency: 145.7625MHz - RX frequency: 145.1625 CTCSS 103.5Hz.

Another local repeater is GB3KN located near Detling, Kent

TX frequency: 145.700MHz - RX frequency 145.100MHz CTCSS: 103.5 Hz

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