Originally Posted by
wingrider
System is on 27mhz. PRS in NZ is UHF so not compatible. PRS is widly used in NZ for kids walkie talkies, roading gangs and other undesirables.
Perhaps a summary of the differences between 27MHz CB and UHF CB would help?
Firstly, UHF and 26, or 27 MHz CB are not at all compatible with each other, and never could be. Pricing between the two is perhaps similar.
In use, the two systems work exactly the same. They are are just "radios".
Both systems have 40 channels, and there is stacks and stacks of free channels at any time, except perhaps on 27MHz during the daytime in the summer, where interference can be huge.
26/27 MHz
26 and 27 MHz are operationally equivalent in every respect that I can think of. During the daytime in the summer, 27MHz can have quite a lot of interference.
27MHz is not legal in NZ, and equipment is not available whatsoever, unless you import it. 26MHz equipment IS legal, and is cheaply and widely available from Dick Smith stores etc.
26/27MHz is more suitable for undulating terrain. The signal can slide around hills and hop over obstacles much better than UHF, by an order of magnitude at least.
26/27MHz can be used with a mode called SSB which sacrifices sound quality for communications effectiveness. It is a bit more complex to use, and can't really be used when moving, but will get you out of a hole occasionally.
26/27MHz antennas are much larger than UHF antennas. You can still use a small antenna, but they are not very efficient. You might still be better off using a small inefficient antenna on 26/27MHz than a big antenna on UHF if the terrain is heavy.
26/27MHz can and does bounce off the atmosphere in the summer months, leading to interesting conversations many hundreds of km away (sometimes thousands). This is not remotely reliable enough to use on a daily basis.
UHF (450 MHz)
UHF (450MHz) is a much higher frequency, and is very very readily blocked by trees and hills, and in dense foliage, signal coverage can be vastly reduced, particularly when small antennas are used.
There are some very small UHF radios that are still packed with features and have lots of transmit power.
Strong UHF signals are much "clearer" as they use the FM modulation scheme.
UHF radios are more modern, and have all sorts of technology built into them such as a facility to block unwanted transmissions by other users, even of they are transmitting on the same channel. Sometimes this technology creates more problems than it solves.
There is little or no interference on UHF CB. If there is, you simply change channel and it's gone.
UHF radios can use a mountain-top "repeater" to dramatically extend their range. Even small low-powered pocket radios with two-inch antennas can talk hundreds of kilometers away with very clear sound. Repeaters need a little bit of education to use - You have to google the location of the repeaters, find out what channel they are on, select that channel, and then press the DUP button on your radio. Remember at all times you must have a clear line of sight to the repeater mountain-top site, or you will have no coverage - even if you have clear line-of-sight to the person you are talking to. Repeaters are useful if others are on the other side of the mountain. Repeaters are not useful if all the riders are within one kilometer of each other, where they become very frustrating and technical to use. Basically, you should not be using a repeater unless you know what you are doing.
UHF radios can use a very small small antennas.
In my opinion, the most useful system is UHF 450MHz CB, because the equipment is modern, widely available, and many people already have them.
If I was outfitting a group of bikes with radios for a months' touring, I would probably use UHF, but I do think that 26MHz would quite possibly be superior.
Steve
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