3.2 Amateur Repeater Stations, Duplex Offsets & Access Protocols

Follow the signal path

A fixed amateur repeater receives a signal and automatically retransmits it. A site with good coverage can connect stations that have difficulty hearing each other directly. A conventional duplex repeater receives on its input and transmits on its output, often at the same time. Filters in a duplexer can let a repeater share an antenna while reducing the strong transmitted signal reaching its receiver.

Worked example. A 2-metre station lists an output of 146.800 MHz and a −600 kHz offset. Convert −600 kHz to −0.600 MHz and add it to the output. Listen on 146.800 MHz and transmit on 146.200 MHz. Those frequencies fit the WIA 2026 Block A ranges. On 70 cm, a station listing 438.500 MHz output and −7 MHz would use 431.500 MHz input. The WIA also provides for −5 MHz in some 70 cm arrangements. Check the actual station listing before assuming a band-wide offset.

Open the repeater with the right signal

An FM repeater may require CTCSS, a continuous sub-audible tone sent with the voice signal. The repeater can use it to reject inputs that lack the configured tone. Some systems use audible DTMF tone pairs, a short tone burst or a different published access method. The 2025 Amateur LCD section 26 and Schedule 3 describe access-control systems used where its specific direct or linked frequency conditions apply. A tone controls access to equipment. It leaves the operator responsible for their own frequency permissions.

Check both the user and the infrastructure

Using a repeater with your own class-licensed radio and operating the fixed repeater are different activities. Class Licence section 13(2)(b) prohibits the latter under that class licence. Section 13 of the Class Licence also governs personal station purposes. Read the applicable Schedule 2 frequencies and conditions for your own station. The repeater itself is individually authorised under a transmitter licence. The 2025 Amateur LCD sections 9(7), 24 and 26 separately regulate operation under apparatus licences, including transmissions through single and linked repeaters, the originator’s authorisation on the output, and the station’s access control. Section 23 requires the repeater operator’s call sign at least once every ten minutes during transmission under the default determination conditions. Sections 24–25 cover retransmission and identification purposes and repeater links.

Worked link check. An assigned repeater receives a Foundation station on a 2-metre input and uses a 6-metre output. The Foundation station’s Class Licence Table A includes 2 metres and has no 6-metre entry. The repeater operator checks the originator’s authority before retransmitting under Amateur LCD section 24(3). The section 26 access-control requirements are separate and can apply to the assigned infrastructure when a direct or linked path reaches an output outside the originator’s authority. An access tone the radio can generate does not extend the originator’s authorised frequencies. If an apparatus-licensed user wants to transmit through a chain, section 9(7) expressly requires authority on each relevant repeater output, not just the local input.

Plan an assigned station or use an existing one

ACMA describes both one-frequency and two-frequency repeater arrangements. A one-frequency repeater still has a receive function and a retransmit function, so a zero split does not make it equivalent to an ordinary simplex contact. For a proposed assigned repeater, an accredited person coordinates the frequencies and can apply to ACMA on behalf of the applicant. For an existing repeater, consult its listing and local access instructions. The WIA channel plan helps with coordination. The individual licence establishes the station’s authorised operation.

Before calling, listen to learn whether the repeater or linked system is in use. ACMA guidance suggests giving your call sign and saying that you are listening. Allow breaks between turns, especially on linked systems, and move to simplex when it is suitable for both stations. Section 4.3 explains the personal call sign timing. The repeater’s own identification and the access tones do not identify you.

ACMA amateur radio licences · WIA Australian band plan · ACMA operating procedures · Amateur Class Licence · 2025 Amateur LCD