What is the difference between a 40 and 80 channel CB radio?

The difference may seem obvious at first – an 80 channel radio has more channels. While this is absolutely correct, there is a little more going on behind the scenes.

Can 40 and 80 channel radios talk to each other?

Short answer? Yes, but with a few notable issues:

• 40 channel radios can only talk on the first 40 channels on 80 channel radios. Channels 41-80 are not available on these older units.
• 80 channel radios may also appear “softer” or “fainter” when received by 40 channel units.
• 40 channel units may appear distorted or significantly louder when received by 80 channel units.

So which one is better?

There has been some debate among users between which system is better to use. Ultimately there is very little difference between the two systems, however there is some merit to the argument that a 40 channel unit is better due to the larger number of existing installed units.  This will change over time as users upgrade their radios, as 40 channel units are no longer produced. The two systems work well with each other, so there is no point attempting to purchase a 40 channel unit if you are installing a new radio.

There is a much better chance of finding an unused channel on an 80 channel unit, so if you are trying to find a free channel to talk on with a group of people who have 80 channel units, this is a significant advantage.

Wideband vs Narrowband

The technical difference between an 40 and 80 channel unit lies in something called “bandwidth”. Not to be confused with the measurement for computer network speed, bandwidth in radio refers to how wide the transmitted signal is. 40 channel UHF CB uses 25Khz wide channels (FM) while 80 channel UHF CB uses 12.5Khz channels – only half as wide.

This narrower bandwidth is how the 80 channel units manage to get twice as many channels into the same amount of allocated radio spectrum.