How a repeater's offset works
A repeater receives on one frequency, its input, and retransmits on another, its output, at the same time. To use it, your radio must receive on the output and transmit on the input. The difference between them is the offset or shift, and the direction is set on most radios as duplex plus or minus. Most modern radios set the standard offset automatically, but it's often wrong for local exceptions, and many radios don't know the UK's 70cm shift at all.
Standard offsets
- UK 2m: repeaters transmit on 145.6 to 145.8 MHz, and you transmit 600 kHz lower.
- UK 70cm: most repeaters transmit on 433.0 to 433.4 MHz, and you transmit 1.6 MHz higher. Some newer channels use a 7.6 MHz shift.
- Europe 70cm: many countries use outputs at 438.65 to 439.425 MHz, with you transmitting 7.6 MHz lower.
- US 2m: 600 kHz, down below 147 MHz and up above it. US 70cm: 5 MHz, usually up from 442 to 445 MHz.
- Australia: 600 kHz on 2m and mostly 7 MHz on 70cm.
Local exceptions are common, so always check a repeater list for the repeater you want to use.
The access tone
Most repeaters also need a CTCSS tone before they'll pass your signal. In the UK the tone depends on the region and is listed for each repeater. If you can hear a repeater but it doesn't respond, the tone is the usual culprit. The CTCSS tones page lists all of them, with the UK letter codes.
Check before you call
Press reverse to listen on the repeater's input. If you can hear the other station there, you can work them direct on a simplex channel and leave the repeater free. The 2m and 70cm band plan shows the simplex channels.
Questions
What offset do UK 2m repeaters use?
600 kHz. The repeater transmits on 145.6 to 145.8 MHz and you transmit 600 kHz lower, on 145.0 to 145.2 MHz.
What offset do UK 70cm repeaters use?
Most use +1.6 MHz: the repeater transmits on 433.0 to 433.4 MHz and you transmit 1.6 MHz higher. Some use a 7.6 MHz shift.
What is the US 2m repeater offset?
600 kHz: minus for repeaters below 147 MHz and plus for those from 147.0 to 147.4 MHz, with some local exceptions.
Why can I hear a repeater but not get in?
Usually because it needs a CTCSS tone, or your offset or shift direction is set wrong. It might also be that your signal isn't strong enough to reach it.