In Australia there are two CB (Citizen Band) services set aside for the use of the general public.
These CB bands are:
- 27MHz or HF band – 40 channels between 26.965 MHz and 27.405 MHz; and
- 477MHz or UHF band – 80 channels between 476.425 MHz and 477.4125 MHz*.
Both of these bands include channels that are reserved for emergencies only by federal law.
UHF Emergency Channels
The UHF CB band has TWO channels reserved for emergencies only. These apply to both 80 and the older 40 channel sets. They are:
Used as the primary channel and the output for all 5/35 emergency repeaters. Generally this is the channel you would choose and, if a repeater is within range, you would also select DUPLEX or REPEATER mode (sometimes referred to as “range extender” on some hand-held sets.) If no repeater services the area leave these off.
Primarily reserved as the emergency repeater input channel, it is sometimes used as a secondary emergency channel in regions where no repeater is operational. However this use is discouraged due to the risk of interference to any 5/35 emergency repeaters near by. General use of channel 35 can totally block any emergency repeater within range and, under the right atmospheric conditions, any repeater within 100’s of kilometres.
27MHz Emergency Channel
On the HF or 27MHz band channel 9 is reserved for emergencies only. This applies to both 40 channel and the older 23 channel CB sets. If using an old 18 channel CB the emergency channel is 5 (it’s the same frequency – 27.065 MHz – just using a different channel number for 18 channel units.)
The 27MHz emergency channel can be used in AM, USB or LSB mode, however it is most common to find AM for local use and USB for longer distance.