The 27 MHz CB service is capable of both local and interstate communication. However the latter cannot be relied upon. What 27 MHz can do depends on the transmission mode (AM or SSB) see modulation for more information, with SSB providing better results when signals are weak and/or over long distances. Locally, expect communication distances of between 5 and 15 kilometres on AM. Actual range achieved will depend on antenna efficiency, terrain and interference levels. Well-equipped home stations will do better than a mobile station. On SSB, distances of between 15 and 30 kilometres are common, with 3000 km sometimes possible under favourable conditions. Good conditions are often called 'skip', so-called because the signal bounces ('skips') off the ionosphere on its way to the other station. Long-distance propagation is most common in December/January each year and throughout the year during times of high sunspot activity. In the last decade or so 27 MHz AM activity has declined enormously. These days, you'll have no problem finding a vacant channel; even in major cities it is common to flick through them all and hear nothing. Major retailers have stopped selling 27 MHz radios, so you will need to find one of the few specialised communications shops, haunt the pawnshops or peruse the local classifieds to find equipment for sale. Nevertheless AM remains suitable for groups desiring cheap car-to-car communications amongst themselves. If your interest is more recreational, you'll do much better if you get a set with SSB (i.e. LSB and USB settings) as well as AM. SSB maintains a significant 'hobby' following, with many operators erecting large beam antennas to allow interstate communications. CB is a public medium so be prepared to hear all types on the air!
27Mhz HF CB Mobile radio with SSB
27Mhz HF CB Portable radio
Pros |
Cons |
Licence Free |
Public Service |
Will work in Valleys and dense bush |
Rage over 50Km cannot be relayed on |
Can talk long distances under some circumstances |
Hard to find equipment |
Low cost |
Large Antennas needed |
|
Can be interfered with by Power lines and storms |
|
Hard to use for untrained persons |
27Mhz CB Channels
Channel |
Uses |
Modulation |
1 |
Conversations |
AM |
2 |
Conversations |
AM |
3 |
Conversations |
AM |
4 |
Conversations |
AM |
5 |
Conversations |
AM |
6 |
Conversations |
AM |
7 |
Conversations |
AM |
8 |
Highway |
AM |
9 |
Emergency |
AM/USB |
10 |
4WD |
AM |
11 |
Caling AM Channel (part of calling net) |
AM |
12 |
Conversations |
AM |
13 |
Conversations |
AM |
14 |
Conversations |
AM |
15 |
Conversations |
AM/LSB |
16 |
Caling LSB Channel (part of calling net) |
LSB |
17 |
Conversations |
USB/LSB |
18 |
Conversations |
USB/LSB |
19 |
Conversations |
USB/LSB |
20 |
Conversations |
USB/LSB |
21 |
Conversations |
USB/LSB |
22 |
Convoy Channel |
AM/USB/LSB |
23 |
Conversations |
USB/LSB |
24 |
Conversations |
USB/LSB |
25 |
Conversations |
USB/LSB |
26 |
Conversations |
USB/LSB |
27 |
Conversations |
USB/LSB |
28 |
Conversations |
USB/LSB |
29 |
Conversations |
USB/LSB |
30 |
Conversations |
USB/LSB |
31 |
Conversations |
USB/LSB |
32 |
Conversations |
USB/LSB |
33 |
Conversations |
USB/LSB |
34 |
Conversations |
USB/LSB |
35 |
Caling LSB Channel (part of calling net) |
LSB |
36 |
Conversations |
USB/LSB |
37 |
Conversations |
USB/LSB |
38 |
Conversations |
USB/LSB |
39 |
Conversations |
USB/LSB |
40 |
Conversations |
USB/LSB |
Emergency Situations
To call for help simply follow this procedure :
1. Select the emergency channel on your CB - channel 9 AM or SSB. Be aware some emergency Monitors may monitor other local channels in addition to, or instead of, the emergency channels. If no response is received, try other local channels.
2. Call "Any emergency monitor", this is "call sign or first name" calling any emergency monitor"
3. Give the Monitor time to answer if no response is received call again.
4. Respond with the nature of the incident, exact location and other information. The Monitor will ask you for the information that he/she needs in order to notify the required services.
5. Remember To Stay Calm!