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by disinfoniacs #69 & #1




in depth

A repeater is a device that listens to a radio signal on one frequency and repeats it simultaneously on another frequency. The purpose of a repeater is to take the signal from a ham radio operator and broadcast it over a much farther distance. This is typically done from an antenna on a tall tower, building or mountaintop. Repeaters are a popular aspect of the ham radio hobby, as they allow operators to communicate with other ham radio operators over a wider area.

To let others know you are listening on a repeater, you would say your station call sign followed by the word "monitoring". For example, you can say "KD2ZOT - monitoring". Then, someone else can answer you.

Repeater usage is slightly more complicated than simplex and there is a little equipment setup required.

One important term to know is the "repeater offset". This is the difference between the repeater's transmit frequency and its receive frequency. Repeaters transmit on one frequency and listen on another. To find the offset of a repeater, you can use the transceiver "reverse split" function. On some radios, this function allows you to listen on a repeater's input frequency. You don't want to transmit in this mode as it will compete with the repeater broadcasts.

In the 70 cm band, a common repeater frequency offset is plus or minus 5 MHz. For example, a repeater transmitting on 443.500 with a positive 5 megahertz offset, has a receive frequency of 448.500. In the 2-meter band, which is very important for amateur radio operators due to its local and reliable nature, the repeater's offset frequency is commonly plus or minus 600 kHz. This is equivalent to 0.6 megahertz. A repeater with an output on 146.350 and a negative offset would have an input frequency of 146.950.

You can look up local repeaters in places like repeaterbook.com, though you'll need an amateur radio or GMRS license to register.

But this isn't the whole story. To use repeaters, you'll need to know about squelch, tones, and other signals to successfully transmit. Continue to the next lesson to find out.

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