Review: UHF Radio

My Article Rating: My Rating 5/5

Congratulations to Exploroz. This is a fantastic article regarding the use of CB Radio in Australia. I would just like to clarify one point regarding the use of Ch 35 as an emergency channel. Quote "35 - Can be used in case of Emergencies also" is generally correct however, it is important to understand how Ch 35 works in an area where there is a Ch 5 emergency repeater. Ch 35 is what is know as the uplink or input channel to an emergency repeater. All transmissions that are uplinked to a repeater on Ch 35 are then rebroadcast back on Ch 5. This is known as DUPLEX transmission (uses 2 channels) and explains the comonly found red button (DUP) that most UHF CB radios have on the front panel. In simple terms, even though your radio is showing Ch 5, when in duplex mode you are automatically transmitting on Ch 35 and the emergency repeater automatically rebroadcasts your message to the other person on Ch 5. This being the case, Ch 35 should only be used in Duplex mode otherwise the person responding to your call, depending on distance, will not receive your transmission. When you are not within an emergency repeater area, you will need to de-select the DUPLEX button and transmit on Ch 5. This will be a direct 1 to 1 transmission on Ch 5 without the use of a repeater and is better known as SIMPLEX transmission (uses 1 channel only). The simplest rule for using the emergency channels is, don't select Ch 35 to report an emergency. Always select Ch 5 and switch between DUPLEX and SIMPLEX until you receive a response. To identify if you are in range of a repeater, select Ch 5 Duplex and press the talk button for around 1 second. If you receive a static type noise for a few seconds after releasing the talk button, you are in a repeater area. If you don't hear a static type noise, then de-select the DUPLEX button and transmit on Ch 5 in SIMPLEX mode. Citizens Radio Emergency Service Teams (CREST) is a volunteer emergency radio monitoring organisation based throughout Australia and our members maintain a listening watch on Ch 5 UHF and Ch 9 AM CB. Please, never use Ch 5 or 35 for non emergency transmissions. For more information, visit or
Contact: Ray Keuning, State Operations Director, CREST Queensland
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