UHF CB in Australia is known as a class-licensed (meaning license free use for most users) citizen's band radio service authorized by the government of Australia in the UHF 477 MHz band.
In NZ it is called a General User Radio License (GURL), meaning that possession and operation of approved radio apparatus on these channels does not require an individual license.
UHF CB provides 40 channels, including 16 channels (8 output, 8 input) allocated to repeater stations.
It is similar in concept to the HF 40 AM & SSB channels used in United States, Australia and New Zealand.
User equipment designs are similar to commercial land mobile two-way radio. Except for repeater stations, the maximum legal output power is 5 Watts.
External antennas are permitted and common commercially manufactured antennas have gain as high as 12dB.
Handheld transceivers (Portables, walkie talkies) are permitted and have transmit power from 500mW to full legal power and are relatively cheap compared to full-sized transceivers.
Other similar personal radio services used in other countries do not share the same band plan, power output, channels etc as UHF CB. It is usually illegal to use these systems in Australia and New Zealand because they will interfere with other licensed services. Care must be taken with radios imported from overseas to ensure they comply with local regulations.
Here are the links to the NZ Radio Spectrum Management documents outlining all regulations otherwise know as PIB20 and General User Radio License (GURL).
Simplex
Basically this means radio to radio. The radio uses the same frequency to receive as it does to transmit. In open air with no obstructions you can expect quite large distances depending on radio style, transmit power, height above ground etc. We are constantly asked "how far can I transmit?, well how long is a piece of string? Unless we have surveyed the terrain and performed actual on air tests etc, we cannot accurately answer this.
Duplex or Repeater mode
Duplex means basically 2. The radio in Duplex mode uses 2 different frequencies, one for receive, one for transmit. This is used for repeater use. See below.
First thing that you must know that a repeater will only repeat what it hears, so if your signal is low in strength to the repeater site, it will repeat exactly what it hears.
Now that we have got over that first step the next step is, how it all works and what to expect from a repeater.
A repeater is a single device that stands by itself on a hill top, Mountain top, Silo (grain Store), or very tall buildings.
UHF (Ultra High Frequency) will only travel line of sight, due to the frequency it uses. Here in new Zealand we are lucky to have a UHF CB service in the middle of the Commercial Radio "F" Band with 40 Channels in total and about 50 Repeaters around New Zealand. Channel 1 - 476.425 Mhz to Channel 8- 476.600 Mhz & Channel 31 - 477.175 Mhz to Channel 38 - 477.477.350 FM (Frequency Modulation) just like the commercial FM radio stations.
Repeater work as Pairs ie: 1 to 31 , 2 to 32 , up to 8 to 38, the Lower Number is what you put your radio on and Press the DUP or REPT button on your radio, The Display will not change when you are in Repeater Mode.
In most cases you will have a range of about 30Kms to 100Kms on the Repeater in your area. This range will depend on the location of the Repeater, the height it is above the ground and the clear view in all directions, if not you will find the range decreased in that direction. A mountain ridge or a large hill in that direction will reduce the coverage area also.
One more thing that we get asked, is can one repeater talk to another repeater to extend your range, the answer is NO.
Each repeater has its own target area and in some cases another repeater on another channel will over lap the area you are in, so if you travel around New Zealand a lot you will find the odd repeater, and as stated before they are all stand alone devices and are not connected to each other to make a larger coverage area.
Repeaters use two channels to operate, First I will explain that when you push your DUP, or REPT button on your radio it will do the changeover each time you push and release the PTT button on the side of your Microphone.
When you press the PTT Button, the radio internals will switch the Transmitter up 30 channels to the input channel, ie channel 1 on your radio will now transmit on channel 31 but the display will not change to 31, then when you release the button the radio's receiver will come back to channel 1. See information picture below.
Some repeaters have what is commonly called a "tail". This is usually a noise or blank air transmitted by the repeater after you release the PTT. This is there to inform users they have successfully triggered the repeater.
Repeaters are free to use but usually are privately owned and therefore the owners can shut it down at any time for many reasons including maintenance. If you abuse the use of repeater, the owners may report you under MED rules outlined in the GURL.
Remember, think before you speak! Many people might be listening!
