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CB Information


The CB Radio Service was legalised in Australia in 1977, initially as an 18 channel service on the 27MHz HF band, then soon after also as a 40 channel service on the 476/477MHz UHF band. Eventually the 18 channel HF service was also changed to 40 channels to match the US frequency allocations.

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Planned changes to UHF

In 2011 the ACMA announced that 40 channel 25kHz (wide band) sets will become illegal as of 1 July 2017. This was to allow for the new 80 channel 12.5kHz (narrow band) sets to operate without the risk of interference from the wide band transmissions (the new set of 40 channels were placed in-between the existing 40 channels, so that channel 41 sat between channels 1 and 2, etc.)

In early 2017 the ACMA announced that it would not outlaw 40 channel wide band sets on 1 July 2017 as planned. Much of this decision was due to the fact that several interest groups did not seem to know about the changes announced back in 2011, and so had made no plans to upgrade to 80 channel narrow band equipment before mid-2017.

Why you should still upgrade

While the 40 channel sets will still work, and talk to the “bottom half” of the 80 channel band, they pose a real risk of interference to the new 80 channel band sets and repeaters. Why this happens is very simple.

40 channel wide band sets have a channel spacing of 25kHz and transmit a signal that is 16kHz wide (8kHz either side of the channel). When there were only 40 channels this was fine as there was 25kHz between channels, so a nice buffer (9kHz to be exact), but when the 80 channel band was introduced this changed. Suddenly there was a channel placed in between the channels, so now there is only 12.5kHz between the old and new channels. This is a problem when you have a signal on (let’s say) channel 1 extending up 8kHz, and another on channel 2 extending down 8kHz. Now the new channel 41 is being swamped by a signal from either side! This becomes worse when the new repeater band starts to be allocated and users on the upper channels operating wide band radios wipe out the input channels for the new repeaters.

More info on CB?

If you want more information about CB, and the protocols to use on CB and on the highway while travelling, look at Glenn Farmer’s book UHF/CB Use & Highway Protocol

Book Review

Glenn contacted ACREM some time ago to request permission to use some of the information on our site in his eBook. Glenn has presented some of the essential information for anyone travelling on our highways and roads - how to converse with the many trucks, and how to use one of the most common communications items among truckies, the UHF/CB Radio. UHF and CB Radio equipment is more common than many believe, and it can be an invaluable source of contact, especially in an emergency.

We welcome the creation of this eBook, and the information it contains. Not only does it provide valuable information about the use of CB equipment, but it also offers car drivers an insight into some of the other communications methods used by truck drivers - indicators and headlights - something that probably confuses many that don’t frequent our highways. I highly recommend this eBook, and trust that it will enlighten everyone who shares the roads with our truck driving friends!

Martin Howells
Chief Commissioner
Australian Citizens Radio
Emergency Monitors Inc.

Purchase the full eBook, or download the free version, at: UHF/CB Use & Highway Protocol

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UHF 5 AND 35

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