Use communication:amateur_radio:repeater:toneburst=* to assign activation tone of an amateur radio repeater.
The value is given in (Hz), a typical value is 1750.
The tone burst is sent for a few seconds at the start of a conversation using an amateur radio repeater to activate this repeater. During the conversation repeater usually is controlled by carrier of mobile station only. After conversation and some time-out repeater transmitter cannot be activated by mobile station carrier anymore, but requires the tone burst signal to be activated.